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GI/Liver/Biliary/Pancreas

Kruger A.Y.; Ghoshhajra B.B.; Beasley H.S.; Radiology, Western Pennsylvania Hospital, Pittsburgh, PA.

Address correspondence to A.Y. Kruger (IFDG442{at}YAHOO.COM)

Background: Laparoscopic Roux-en-Y gastric bypass (LRYGBP) is a surgical procedure that is gaining in popularity amongst patients and surgeons in order to facilitate weight reduction in obese patients. As more of these procedures are being performed, so are the numbers of follow up CT scans. Radiologists must become familiar with the expected anatomic changes from LRYGP as seen on cross sectional imaging.

Key Issues: At our institution, LRYGBP is performed using the retrocolic, retrogastric approach. Using this technique, the Roux limb is brought through a surgically created window in the transverse mesocolon into the lesser sac, anterior to the pancreas and posterior to the transverse colon. It is then attached to the neogastric pouch, posterior to the larger gastric remnant of the hepatobiliary limb. Following the expected courses of the Roux and hepatobiliary limbs can be challenging when only viewing the axial images. However, when images are reconstructed and viewed in the coronal and sagittal planes, this can aid in evaluation of the surgically reconstructed anatomy. This exhibit will review the expected anatomic changes in patients after LRYGBP in axial, coronal and sagittal planes as well as 3D imaging using a 64 slice CT scanner.

Format: Didactic format with a combination of text, axial, sagittal, and coronal CT images, 3D images, illustrations, and diagrams. Organizational Structure: By anatomy.

Teaching Points: 1. To recognize the expected anatomic changes in patients who have undergone LRYGBP. 2. To understand how reconstructed images in the coronal and sagittal planes aid in evaluation of the post surgical anatomic changes after LRYGBP.

E119. Routine Isotropic Scanning of the Abdomen and Pelvis with 64-Channel CT Scanner

Rydberg J.¹; Sandrasegaran K.¹; Tann M.¹; Kopecky K.²; Maglinte D.T.¹; 1. Radiology, Indiana University School of Medicine, Indianapolis, IN; 2. Radiology, Community Group of Hospitals, Indianapolis, IN.

Address correspondence to J. Rydberg (jrydberg{at}iupui.edu)

Background: For the past 30 years radiologists have viewed routine CT examinations of abdomen and pelvis in the axial plane. Till recently it was not possible to get sub-millimeter sections over this long anatomical coverage. Using a recently introduced 64-channel CT scanners it has been possible to obtain isotropic acquisition of the whole abdomen and pelvis within 10 seconds. The thin source images are reformatted into thicker axial, coronal and occasionally sagittal data sets on the CT scanner host computer using preset protocols. Only the multiplanar reformats are sent to the picture archiving and communication system for routine evaluation.

Format: The authors present twelve months' experience in assessing abdomino-pelvic disease in multiple planes. The specific uses of reformats in diagnosis and staging of cancer, acute abdomen and postoperative complications will be discussed.

Teaching Points: 1. Review basic scanning protocols for 64-channel scanning of abdomen and pelvis. 2. Demonstrate the usefulness of routine coronal and sagittal reformats in depicting disease. 3. Discuss management of large image sets.

E120. Comparison of Isotropic and Anisotropic Scan Acquisition on Pre-transplant CTA of the Hepatic Arterial System

Day C.M.¹; Dalrymple N.C.¹; Gutta K.²; El-Merhi F.¹; Prasad S.R.¹; Freckleton M.W.¹; Chintapalli K.N.¹; 1. Radiology, The University of Texas Health Science Center at San Antonio, San Antonio, TX; 2. Medical School, Medical University of South Carolina, Charleston, SC.

Address correspondence to C.M. Day (cmday{at}satx.rr.com)

Background: Since the introduction of multidetector CT, the technology has progressed rapidly. As the number of available data channels increases, initial advantages of relatively rapid volume coverage and near-millimeter section thickness available on 4-channel scanners have been overshadowed in a dramatic transition to rapid scan acquisition of sub-millimeter sections. Since most institutions do not replace all of their CT scanners every few years, many currently possess scanners with varied platforms, which may range from single channel to 64-channel technology. Workflow demands triage of cases to scanners with differing capabilities, and radiologists must decide the quality of scan data necessary for diagnostic information.

Key Issues: Our exhibit illustrates the impact of acquisition data on image quality in CT angiography of hepatic arterial anatomy in pre-liver transplant patients on platforms ranging from 4 to 64 data channels. Topics discussed include long-axis spatial resolution, visualization of central and peripheral branches, and uniformity of contrast bolus and its effects on automated programs for image post-processing. Variant arterial anatomy to the liver is emphasized with consideration of potential impact of image quality on clinical decision making in the transplant patient.

Format: Didactic exhibit featuring comparisons of image quality using images created using different types of acquisition data on each scan platform. Presentation is organized according to anatomic variants and pathological conditions which may affect surgical decision making with side-by-side comparisons of images from different types of data.

Teaching Points: 1. Sub-millimeter section thickness is not mandatory for accurate depiction of most hepatic arterial variants. 2. By decreasing acquisition time, high volume multichannel scanners improve uniformity of the contrast bolus, making automated segmentation methods more effective and convenient. 3. Small peripheral arterial branches and small accessory arteries are more conspicuous with isotropic scan data.

E121. The Esophagram; Normal Anatomy, Normal Function and Disease

Demos T.C.; Posniak H.V.; Olson M.; Nagamine W.; Diagnostic Radiology, Loyola University Medical Center, Maywood, IL.

Address correspondence to W. Nagamine (wnagamine{at}lumc.edu)

Background: The esophagram is the first imaging study for many patients who have signs and symptoms related to the esophagus. Esophagrams provide both morphologic and functional information. Esophageal abnormalities range from gross abnormalities such as dilation due to achalasia to subtle abnormalities such as erosions on double contrast studies in patients who have reflux esophagitis. The radiologist conducting and evaluating an optimum examination who has knowledge of the wide variety of intrinsic and extrinsic diseases that can affect the esophagus is thus in a position to make a diagnosis or narrow a differential diagnosis and provide direction for further evaluation.

Key Issues: This exhibit will present both normal esophageal anatomy and function. Technical factors for esophagrams will be detailed. Various types of functional abnormalities, diverticula, and hernias will be illustrated followed by illustration of a wide variety of other intrinsic abnormalities and extrinsic diseases that affect the esophagus. Emphasis will be on esophagrams and correlative secondary imaging studies, mostly computed tomography, will be presented.

Format: This exhibit will be didactic and interactive with quiz cases. Normal anatomy and function will be illustrated along with techniques used for esophagrams. This will be followed by illustration of the various types of esophageal diverticula, hernias, and functional abnormalities. Then a wide variety of other intrinsic diseases will be illustrated and arranged by disease category; congenital, inflammatory and infectious, neoplastic, traumatic, and idiopathic. Extrinsic diseases that affect the esophagus will then be illustrated. The exhibit will conclude with quiz cases.

Teaching Points: Normal esophageal anatomy. Normal esophageal function. Techniques used for esophagrams. Characteristics of intrinsic esophageal diseases and their differential diagnosis. Characteristics of extrinsic diseases that can affect the esophagus and their differential diagnosis.

E122. Submucosal Gastroduodenal Lesions: CT Findings and Differential Diagnosis

Oto A.¹; Dave A.¹; Qui S.²; Ernst R.D.¹; 1. Radiology, UTMB, Galveston, TX; 2. Pathology, UTMB, Galveston, TX.

Address correspondence to A. Dave (adave{at}utmb.edu)

Key Issues: Submucosal gastroduodenal lesions are often difficult to visualize at endoscopy. As a result, barium studies and CT are particularly helpful for diagnosing these lesions. In addition to detection of these lesions, CT allows evaluation of the extent of the mass and in some cases (such as lipomas) can give the histopathologic diagnosis. In this exhibit, we will illustrate the CT findings of common (gastrointestinal stromal tumors) and some of the rare (neurofibroma, hemangioma, duplication cyst, hematoma, lipoma) submucosal lesions of the stomach and duodenum.

Format: Didactic Organizational structure: CT findings with histopathologic correlation.

Teaching Points: Learning points: 1. To illustrate the CT findings of submucosal lesions of stomach and duodenum. 2. To review the role of CT in the differential diagnosis and management of these lesions.

E123. Efficacy of Three-Dimensional, 64-Slice Multidetector Row CT for Preoperative Evaluation of Gastric Cancer

Yang D.; Kim H.; Kang J.; Kim H.; Radiology, Gachon Medical School Gil Medical Center, Incheon, South Korea.

Address correspondence to D. Yang (dmyang{at}gilhospital.com)

Objective: To assess the accuracy of three-dimensional, 64-slice multidetector low CT (MDCT) in the diagnosis and staging of gastric cancer.

Materials and Methods: This study was approved by the institutional review board, and patients gave informed consent. Forty four patients (34 male, 10 female; mean age, 57 years) with gastric carcinoma underwent preoperative 64 slice MDCT (SOMATOM Sensation 64, Siemens AG, Forchheim, Germany) (slice collimation, 0.6 mm; slice width, 5 mm; feed/rotation, 23 mm; pitch factor, 1.2; kernel, B30f; and gantry speed, 0.5 second per rotation). Gastric distension was achieved by ingestion of 8g of effervescent granules. Scanning was performed during arterial and portal phases as determined with bolus tracking and automated triggering technique after intravenous administration of 100 ml of contrast materials injection (4 ml/sec). All CT scans were retrospectively reviewed by two radiologists. Each tumor was staged according to the TNM classification system. All patients underwent surgery. Results of CT were compared with histologic staging of tumor invasion depth and regional lymph node metastasis.

Results: The accuracy of three-dimensional, MDCT for detection of gastric cancer was 90% (18/20) and 100% (24/24) in early and advanced gastric cancer, respectively, with overall detection rate of 95% (42/44). The accuracy of three dimensional, MDCT for determination of depth of tumor penetration was 80% (16/20) and 88% (21/24) in early and advanced gastric cancer, respectively, with overall accuracy of 84% (37/44). The accuracy of three-dimensional, MDCT for determination of lymph node metastasis was 90% (18/20) and 71% (17/24) in early and advanced gastric cancer, respectively, with overall accuracy of 80% (35/44).

Conclusion: The three-dimensional, MDCT is a promising technique for detection and preoperative staging of gastric cancer.

E124. A Systematic Approach to Radiographic Findings of Complications Following Laparoscopic Roux-en-Y Gastric Bypass

Friend C.J.¹; Patel N.A.²; Colella J.J.²; Lupetin A.R.¹; 1. Diagnostic Radiology, Allegheny General Hospital, Pittsburgh, PA; 2. Surgery, Allegheny General Hospital, Pittsburgh, PA.

Address correspondence to C.J. Friend (cfriend{at}wpahs.org)

Background: Obesity continues to be a major health problem in the United States. Surgery is the only therapy proven to achieve sustained weight loss and significant reduction in obesity related co-morbidities. Currently, Roux-en-Y gastric bypass (RYGB) is the surgical procedure of choice. Of the 150,000 RYGBs performed annually, nearly 40% are performed laparoscopically. While the acceptance of this procedure has grown, most of them are performed at tertiary care centers. As a consequence, when postoperative complications arise, patients frequently seek medical attention at the nearest facility, which often is not the institution where they underwent surgery. Most of these complications are surgical emergencies requiring prompt diagnosis. Any delay in diagnosis can lead to grave consequences in such a high-risk patient subset.

Key Issues: The complications of laparoscopic roux-en-y bypass (LRYGB) can be divided into early and late complications. Early complications include anastomotic leakor stricture formation at the gastrojejunostomy and in the majority of cases are readily recognized and promptly addressed. Less common and more subtle complications include leak or obstruction at the entero-enterostomy. Late complications include perforation of the gastrojejeunostomy and small bowel obstruction due to internal hernias, stricture of the roux limb, and bowel obstruction due to adhesions. These complications most frequently present after the patient has left the tertiary care center and can be life threatening; thus, it is imperative that the radiologist suggest the proper diagnosis to expedite proper treatment.

Format: Our exhibit will explain the operative procedure and demonstrate normal postoperative anatomy. We will then discuss a systematic approach to review diagnostic studies for early and late postoperative complications. Particular attention will be paid to frequently missed subtle findings associated with late complications. For each complication, characteristic features will be outlined.

Teaching Points: 1.) To review normal post-operative anatomy following laparoscopic roux-en-y gastric bypass. 2.) To classify expected complications following LRYGB as occurring in either the early or late postoperative period. 3.) To understand a systematic approach to the identification of common early and late postoperative complications of LRYGB. 4.) To recognize pearls and pitfalls in the identification of subtle and not so common late complications following LRYGB.

E125. Complications in LRYGBP: Pearls and Pitfalls

Ghoshhajra B.B.; Kruger A.Y.; Beasley H.S.; Department of Radiology, The Western Pennsylvania Hospital, Pittsburgh, PA.

Address correspondence to B.B. Ghoshhajra (ghoshhajra{at}yahoo.com)

Background: Laparoscopic Roux-en-Y gastric bypass (LRYGBP) is a surgical procedure that is gaining in popularity amongst patients and surgeons in order to facilitate weight reduction in obese patients. As surgical techniques are refined and the patient volume increases, the radiologist must become proficient in guiding the imaging workup of the potential complications of gastric bypass. Clinical information such as the time course after surgery, the patient's symptoms, and surgical technique must be weighed when deciding the imaging modality and potential diagnoses.

Key Issues: Understanding the normal imaging appearance after LRYGBP requires detailed knowledge of the patient's post-surgical anatomy. The surgical techniques used at our institution as well as the major alternatives will be reviewed, with a focus on examples of normal anatomy at fluoroscopy and 64-slice multidetector CT. The major complications of LRYGBP can be categorized by the length of the postoperative period. Early complications (days after surgery) include pulmonary embolism, deep-vein thrombosis, wound infection, abscess, acute gastric distention, and anastamotic leak. Delayed complications (weeks to years), include anastamotic leak/breakdown, gallstone formation, stomal stenosis, stomal ulceration, occlusion of the Roux limb, small bowel obstruction, adhesions, anastamotic ulceration, and neoplasm within the Roux limb. Imaging findings will be reviewed using multiple modalities (fluoroscopy, 64-slice MDCT, ultrasound, and MRI/MRCP), with a focus on the gastrointestinal complications unique to LRYGBP.

Format: Didactic with a combination of text, images, illustrations, and diagrams. Organizational Structure: Postoperative time course and patient symptomatology.

Teaching Points: 1. To recognize the expected normal anatomic changes in patients who have undergone gastric bypass across multiple modalities. 2. To generate a differential diagnosis based on symptomatology and postoperative time course. 3. To select the best imaging modality to detect potential abnormalities. 4. To understand the limitations of imaging with respect to the complications of LRYGBP.

E126. Normal Anatomy and Complications Related to Jejuno-jejunal Anastomosis Following Roux-en-Y Gastric Bypass Surgery

Yu J.; Turner M.A.; Fulcher A.S.; Carucci L.R.; Diagnostic Radiology, VCU Medical Center, Richmond, VA.

Address correspondence to J. Yu (jyu1{at}vcu.edu)

Background: Roux-en-Y gastric bypass (RYGBP) is the most commonly performed operation for the treatment of morbid obesity in the US. The surgery is characterized by a proximal gastrojejunal anastomosis (G-J) and a distal jejuno-jejunal (J-J) anastomosis. Although much attention has been directed to the G-J anastomosis, to the best of our knowledge, no studies have focused on the normal anatomy and complications of the J-J anastomosis.

Key Issues: Alteration of the gastrointestinal tract associated with the J-J anastomosis may create confusion at post-surgical CT or UGI if one is not familiar with the appearance of the altered anatomy. Complications related to the J-J anastomosis include postoperative edema with subsequent dilatation of the proximal jejunum or the excluded duodenum and stomach; leak; stenosis or adhesion with bowel obstruction, involving efferent loop, afferent loop or both; internal hernia; staple line or small bowel bleeding; and intussusception. Familiarity with the CT and UGI imaging features of the normal anatomy and complications related to the J-J anastomosis is necessary to avoid misdiagnosis in this complex patient population

Teaching Points: To learn CT and UGI features of the normal anatomy and complications related to the J-J anastomosis; to grasp imaging features that allow for distinction between the altered normal anatomy and complications; to identify pitfalls commonly encountered in the interpretation of post-surgical CT or UGI.

E127. Imaging in Gastric Bariatric Surgery: A Practical Guide to Post Surgical Anatomy and Common Complications

Chandler R.; Gujjarappa S.; Chintapalli K.; Schwesinger W.; Rahal A.; Prasad S.; Dalrymple N.; El Merhi F.; Radiology, UT Health Science Center, San Antonio, San Antonio, TX.

Background: Obesity is a serious, multi-factorial chronic illness that affects all ages. Bariatric surgery is being increasingly performed on patients to control morbid obesity. Novel surgical and endoscopic techniques are being developed to minimize patient morbidity. Imaging plays an important role in the pre- and post-operative evaluation of patients. Practical knowledge of post surgical anatomy allows accurate interpretation of imaging findings related to normal post-surgical anatomy and common post-surgical complications. The purpose of this exhibit is to review the surgical techniques, imaging findings of the post-operative stomach and complications associated with current bariatric procedures.

Key Issues: Focus will be on surgical anatomy involved in gastric bypass procedures and radiologic correlation based on fluoroscopic contrast and CT studies.

Format: Didactic pictorial review encompassing radiologic findings in gastric bariatric surgery with correlation to illustrative drawings/diagrams.

Teaching Points: 1. To understand the normal post-surgical anatomy in patients undergoing bariatric procedures. 2. To describe normal imaging appearances of the post-operative stomach and to distinguish them from complications. 3. To identify pearls and potential pitfalls in the interpretation of imaging studies performed on morbidly obese patients after bariatric surgery.

E128. Small Bowel Imaging: Where Does Radiology Stand?

Sandrasegaran K.¹; Maglinte D.¹; Lappas J.¹; Chiorean M.²; 1. Radiology, Indiana University School of Medicine, Indianapolis, IN; 2. Medicine, Indiana University School of Medicine, Indianapolis, IN.

Address correspondence to K. Sandrasegaran (ksandras{at}iupui.edu)

Background: The diagnosis of small bowel disease has rapidly changed in the last 5 years. Wireless capsule endoscopy and the double balloon enteroscopy have revolutionized diagnosis and treatment of small bowel disease. CT enteroclysis and enterography have evolved. MR enteroclysis is increasingly used.

Key Issues: This paper will look at the current research to identify the roles of CT enteroclysis / enterography before and after capsule endoscopy in Crohn's disease, unexplained gastrointestinal bleeding and small bowel neoplasms.

Format: The exhibit will be organized by disease and imaging technique. A review of relevant literature will be presented.

Teaching Points: 1. Learn the value and limitations of wireless capsule endoscopy. 2. Learn the usefulness of CT enterography and CT and MR enteroclysis.

E129. CT Enterography: Use of Negative Oral Contrast Agents in CT for the Evaluation of the Stomach and Small Bowel

Uppot R.N.; Sahani D.V.; Zalis M.E.; Shah Z.; Division of Abdominal Imaging; Department of Radiology, Massachusetts General Hospital, Boston, MA.

Address correspondence to R.N. Uppot (ruppot{at}partners.org)

Background: For years abdominal CT has been performed with positive oral contrast agents such as gastrograffin or barium to opacify the bowels for the purposes of distinguishing bowel from the remaining intraabdominal structures. With recent advances in multidetector CT including the ability to obtain isotropic volumes, more detailed evaluation of the bowel is now possible. Positive contrast agents which completely opacify the bowel lumen allow only for the evaluation of the bowel wall and associated surrounding mesentery and may no longer be adequate for the evaluation of the GI tract, particularly the mucosa and submucosa. Negative contrast agents such as water, volumen, and methyl cellulose can distend small and large bowel loops without opacification of the loops, allowing isotropic mucosal and submucosal details to be visualized on CT.

Key Issues: 1. Imaging protocols on 4-, 8-, 16-, and 64-slice multidetector CT using negative oral contrast agents. 2. Anatomy and pathology of stomach and bowel lesions on CT are discussed.

Format: Didactic Organizational Structure: 1. Techniques 2. Anatomy 3. Pathology 4. Pitfalls

Teaching Points: 1. To distinguish the role of negative oral contrast agents such as water, volumen, and simethicone based methyl cellulose versus positive contrast agents for the evaluation of the GI tract on multidetector CT. 2. To discuss protocols and findings using negative oral contrast on 4-, 8-, 16-, and 64-slice multidetector CT in the evaluation of the bowel.

E130. Multidetector Row CT Enterography: Pictorial Review

Santillan C.S.; Santosa A.C.; Casola G.; San Diego, University of California, San Diego, CA.

Address correspondence to C.S. Santillan (csantillan{at}ucsd.edu)

Background: The diagnosis of small bowel pathology is often difficult due to the length, tortuosity, and variable distension of the ileum and jejunum. Traditionally, small bowel follow-through, enteroclysis, or endoscopic studies have been used to evaluate for small bowel diseases. These techniques, however, can miss extraluminal pathology. Although multidetector computed tomography (MDCT) is frequently used for the evaluation of abdominal pain and complications related to small bowel disease, traditional MDCT techniques are often limited in their evaluation for pathology of the small bowel, particularly due to variable distension. CT enterography, the use of a large volume of low attenuation oral contrast in combination with intravenous contrast, can provide valuable information regarding the small bowel as well as extraluminal pathology. In patients with inflammatory bowel disease, CT enterography can provide important information regarding not only the extent and location of the affected bowel, but also aid in distinguishing between active inflammation and chronically diseased bowel, which can greatly influence treatment. In patients with symptomatic low-grade intermittent small bowel obstruction, CT enterography can demonstrate the areas of obstruction by accentuating the sites of small bowel narrowing.

Key Issues: This exhibit reviews (1) various techniques to achieve luminal distension with low attenuation oral agents, such as water, VoLumen (E-Z-EM, Inc.) and Metamucil®, (2) key diagnostic findings in various types of small bowel disease, (3) the use of multi-planar reformations and 3-D volume rendered images to better demonstrate the small bowel pathology, and (4) management implications of these findings.

Format: The format is an interactive digital presentation of different examples of small bowel pathology organized by CT imaging findings.

Teaching Points: The teaching points of this exhibit are: 1. To describe and illustrate the advantages of the use of low attenuation oral contrast agents for the evaluation of small bowel pathology 2. To illustrate key imaging findings in small bowel pathology using CT enterography 3. To understand the management implications of these findings

E131. Small Bowel CT: Role of Negative Oral contrast Agent and Post Processing

Singh A.H.; Shah Z.K.; Uppot R.; Blake M.; Sahani D.V.; Abdominal Imaging, Massachusetts General Hospital, Boston, MA.

Address correspondence to A.H. Singh (dranandsingh{at}yahoo.com)

Background: Designed to overcome the limitations posed by water and high-density positive oral contrast for CT, a negative oral contrast like VoLumen or water provides improved bowel wall visualization, clear delineation between adjacent soft tissue and lumen and desired bowel distension and transit times. Unlike positive oral contrast agents, bowel imaging with negative oral contrast is devoid of any streak artifacts, which enables better image post-processing and high quality multi-planar reformats (MPR) for bowel.

Key Issues: An improved bowel wall visualization along with better quality bowel reformats can be useful for accurate differentiation between pathologies in the bowel wall from extrinsic and intrinsic bowel wall involvement. This offers better evaluation of the proximal small bowel than offered by any other contrast agent, which could be useful in pre-surgical planning of pancreatic carcinoma. Such reformats could also be useful for differentiation of inflammation or malignant recurrence at the bowel anastomosis and determination of diseased bowel length and wall thickness in certain bowel inflammations.

Format: This didactic format exhibit highlights the importance of CT technique and post processed CT images for small bowel using negative oral contrast in the above listed clinical settings.

Teaching Points: To emphasize the importance of negative oral contrast agent in small bowel CT examination and image post-processing. To highlight clinical settings where small bowel CT with negative oral contrast can play a crucial role.

E132. Small Bowel Obstruction Demonstrated by Multidetector CT (MDCT) - A Pictorial Review

Alyas F.; Viney Z.; Woo E.K.; Menezes L.; Tappouni R.; Rottenberg G.; Radiology, Guys and St Thomas' Hospital, London, United Kingdom.

Address correspondence to F. Alyas (faisal_alyas{at}hotmail.com)

Background: Small bowel obstruction is a common surgical emergency. Primary diagnosis is based on clinical history, examination and plain radiography which are often not specific to the cause. MDCT with its high resolution and multi-planar reformatting capabilities is valuable in demonstrating the level of obstruction and the specific diagnosis in many cases. This is invaluable information in preoperative planning.

Key Issues: The causes of mechanical small bowel obstruction using the general principle of extrinsic compression, intrinsic bowel wall lesion and luminal occlusion will be illustrated. This includes adhesions, hernias (inguinal, spigelian, parastomal), volvulus (cecal, small bowel), intussusception, Crohn's disease, cecal carcinoma, Meckel's diverticulum and gallstone ileus.

Format: A PowerPoint case presentation with annotated images using multi-planar reformats of MDCT images will be shown.

Teaching Points: The purpose of this educational exhibit is to familiarize the reader to the causes and MDCT features of small bowel obstruction.

E133. "The Colorectal Module" - A Comprehensive, Multidisciplinary Web Based Resource for Colorectal Disease

Davidoff A.; Allison C.; Khanna A.; Lee D.; Tsai S.S.; Radiology, Caritas St. Elizabeth's Medical Center, Boston, MA.

Background: "The Colorectal Module" is a web resource that recognizes the importance of the multidisciplinary approach to colorectal disease and provides each discipline the common thread that unites the knowledge base.

Key Issues: The program is rich in images, deep and broad in applied content. Content spans the history, histology, anatomy, pathology, radiology, and clinical aspects. The infrastructure is grounded in basic principles which evolve from the simple to the complex.

Format: The image library consists of over 1000 images, augmented by over 20 Power-Point shows. Imaging and therapeutic strategies provide guidelines for a variety of clinical scenarios. Links to selected Internet sources contribute added breadth and depth.

Teaching Points: "The Colorectal Module" thus provides integrated in depth knowledge for members of a multidisciplinary team in one comprehensive, web based resource. The uniform use of principles allows integration both within the module as well as incorporation into a larger system with other organs.

E134. CT of Colitis: An Illustrative Review

Kruger A.Y.¹; Katyal S.¹; Javed N.²; Clarke K.²; Surampudi R.³; 1. Radiology, Western Pennsylvania Hospital, Pittsburgh, PA; 2. Medicine, Western Pennsylvania Hospital, Pittsburgh, PA; 3. Pathology, Western Pennsylvania Hospital, Pittsburgh, PA.

Address correspondence to A.Y. Kruger (ifdg442{at}yahoo.com)

Background: Colitis is a common disease process that requires prompt and accurate diagnosis to avoid significant morbidity and mortality. Patients with colitis most often report symptoms of abdominal pain, diarrhea, hematochezia, and fever. For patients with these symptoms, a CT scan is often the imaging test chosen as part of the diagnostic workup. Specific therapy for the patient with colitis depends upon the underlying etiology. Radiologists, therefore, must be familiar with the CT features of the different types of colitides in order to be able to suggest appropriate therapy.

Key Issues: Colitis is an inflammation of the colon with several infectious and noninfectious etiologies. Common etiologies of colitis include pseudomembranous colitis, inflammatory bowel disease, ischemic colitis, radiation colitis, neutropenic colitis, and vasculitis. The different colitides all share a common CT feature of wall thickening. The degree and distribution of wall thickening, along with other discriminating features, such as pneumatosis, lymphadenopathy, ascites, and fat infiltration can help to reliably differentiate among the various types of colitides. This exhibit will correlate several CT imaging features of the various colitides with pathological results.

This will allow the radiologist to formulate either a single diagnosis or more specific differential diagnoses.

Format: Didactic with a self-assessment examination at the conclusion of the exhibit. Organizational Structure: By anatomy and diagnosis.

Teaching Points: 1. Recognize the spectrum of CT changes associated with the different types of colitis and be able to differentiate amongst them.

E135. A Simple Algorithm to Determine the Need for Intravenous Contrast in Patients Undergoing CT for Suspected Acute Appendicitis

Liu I.J.; Brown M.A.; Wolfson T.; Tamburrini S.; Sirlin C.; Radiology, University of California, San Diego Medical Center, San Diego, CA.

Address correspondence to I.J. Liu (medliu{at}yahoo.com)

Objective: Many centers routinely administer intravenous contrast (IVC) for CT of suspected appendicitis, however IVC is often unnecessary for diagnosis. Other centers routinely perform non-enhanced CT (NECT) but must rescan patients if findings are inconclusive. The purpose of this study was to develop a simple algorithm to predict the need for IVC based on a single axial CT slice through the pelvis.

Materials and Methods: We retrospectively evaluated 39 NECT exams performed for suspected appendicitis. 13/39 (33%) were nondiagnostic and required rescanning with IVC. 3 readers with 1 month (R1), 10 years (R2), and 9 years (R3) of CT experience reviewed a single slice through the level of the anterior superior iliac spine based on scannogram. The fat distance from the common insertion site of the right transversus abdominis and iliacus muscles on the iliac bone to the nearest bowel serosa was measured, and visibility of the appendix was noted. The slice above and slice below were also evaluated. ROC analysis was performed, frequencies were compared by Fisher's exact test, and reliability was assessed by intraclass correlation coefficient. Frequencies of correct triage (to NECT or IVC) were analyzed descriptively. All analyses were performed for each slice and each reader, and a prediction algorithm was formulated.

Results: ROC analysis suggested the following algorithm: a visible appendix or fat measurement > 15 mm indicated IVC was not required. Otherwise, IVC was necessary. Using this algorithm, R1 correctly triaged 32, 32 or 31 of the 39 patients depending on the slice analyzed. R2 correctly triaged 30, 30 or 28 patients, and R3 32, 30 or 32 patients. Frequency of repeat imaging for R1 decreased from 13 cases to 5, 5 or 4 cases, R2 6, 7 or 7 cases, and R3 5, 6 or 4 cases. Unnecessary IVC would have been administered by R1 in 2, 2 or 4 cases, R2 3, 2 or 4 cases, and R3 2, 3 or 3 cases. Time required for image review and measurement was 15 to 30 seconds. Inter- and intraobserver measurement reliability was 0.96 to 0.997 for all readers.

Conclusion: A simple algorithm based on a single axial CT slice may reduce repeat imaging and unnecessary IVC administration in patients with suspected appendicitis.

E136. Downward Displacement of the Transverse Colon: A CT Finding Associated with Internal Hernias Through the Transverse Mesocolon After Gastric Bypass

Kruger A.Y.¹; Beasley H.S.¹; Garvin R.²; Papasavas P.²; Gagne D.²; Caushaj P.²; 1. Radiology, Western Pennsylvania Hospital, Pittsburgh, PA; 2. Surgery, Western Pennsylvania Hospital, Pittsburgh, PA.

Address correspondence to A.Y. Kruger (ifdg442{at}yahoo.com)

Background: Laparoscopic Roux-en-Y gastric bypass (LRYGBP) is a surgical procedure that is gaining in popularity amongst patients and surgeons in order to facilitate weight reduction in obese patients. Small bowel obstructions caused by internal hernias through the transverse mesocolon in patients who have undergone LRYGBP are surgical emergencies and carry with them significant morbidity and mortality if not quickly and accurately diagnosed.

Key Issues: The transverse mesocolon, which is a posterior boundary of the lesser sac, is disrupted during retrocolic, retrogastric LRYGBP. When multiple loops of small bowel herniate through the surgical defect created in the transverse mesocolon, they become enclosed in the lesser sac. As these loops of small bowel fill the lesser sac, they can preferentially lay against its anterior and inferior boundaries, the gastrocolic ligament and the greater omentum, which causes the transverse colon and its mesenteric attachment, the transverse mesocolon, to be displaced inferiorly and posteriorly. This displacement can exacerbate the small bowel obstruction by further compressing the distal-most loop of small bowel as it passes through the transverse mesocolon defect. This creates the effect of a closed loop small bowel obstruction caused by the internal hernia.

Format: Didactic with a combination of text, multiplanar CT images, illustrations, and diagrams. Organizational Structure: By pathology.

Teaching Points: 1. To recognize the expected anatomic changes on CT in patients who have undergone gastric bypass. 2. To recognize the specific anatomic changes on CT associated with small bowel obstructions caused by internal hernias through the transverse mesocolon in patients who have undergone gastric bypass.

E137. Magnetic Resonance Imaging of Colonic Diverticulitis

Buckley O.; Geoghegan T.; Mc Auley G.; Persaud T.; Torreggiani W.C.; Radiology, Adelaide and Meath Hospital, Dublin, Ireland.

Address correspondence to O. Buckley (orla.buckley{at}amnch.ie)

Background: Previously, MRI was not commonly used in the assessment of patients with acute abdominal pain. This was due to a combination of MRI time constraints, availability and MR image artifacts that limited its ability to assess the gastrointestinal tract. Faster imaging sequences as well as fluid sensitive sequences have greatly improved the sensitivity of MRI in the detection of inflammatory changes in the bowel wall. Heavily weighted T2 sequences may increase the conspicuity of the inflamed bowel wall as well as detecting associated intra-peritoneal fluid. Intravenous gadolinium may aid in the detection of inflammation and abscess formation.

Key Issues: The MRI diagnosis of colonic diverticulitis can be made by identifying the three findings of bowel wall thickening, pericolonic stranding and the presence of diverticula. The severity of acute diverticulitis is classified into mild, moderate and severe according to MR findings. The presence of fluid in abscess cavities is best appreciated on fluid sensitive sequences. Fat saturation allows excellent demonstration of free fluid. Fistula, abscess, and microperforations are well demonstrated by MRI. MR also may have the advantage over CT in differentiating circumferential wall thickening secondary to inflammation from malignancy. MR images showing examples of the above will be demonstrated.

Format: The poster will take on a didactic format and will consist of a review of the imaging findings of MRI in acute diverticulitis and its complications. The evolving role of MR in acute diverticulitis will be discussed.

Teaching Points: 1. The utility of MRI in the diagnosis of acute diverticulitis and its complications. 2. The features of acute diverticulitis and its complications on MR imaging. 3. To discuss future trends in MR evaluation of acute diverticulitis

E138. CT Evaluation of Unusual Colitides and Colonic Neoplasms

Lamba R.¹; Bindra J.¹; Aminololama Shakeri S.¹; McGahan J.P.; Radiology, UC Davis Medical Center, Sacramento, CA.

Address correspondence to R. LAMBA (ramit_22{at}hotmail.com)

Background: Colitis manifests as thickening and inflammation of the colonic wall on computed tomography (CT). Colitides that are commonly encountered include Clostridium difficile colitis, diverticulitis, ulcerative colitis, Crohn's colitis and ischemic colitis. Occasionally uncommon entities can result in colitides and radiologists need to be aware of these entities. Colonic masses can occasionally mimic colitides. While colonic adenocarcinoma is the commonest colonic mass, unusual neoplasm are occasionally encountered and can cause a diagnostic dilemma.

Key Issues: Unusual etiologies of colitis such as enterohemorrhagic E. coli colitis, CMV colitis, amebic typhlitis, tuberculosis, neutropenic colitis, cystic fibrosis, radiation colitis, stercoral colitis, glutaraldehyde colitis and graft versus host disease will be reviewed. Unusual colonic tumors such as primary and secondary lymphoma, colonic metastases and GIST will also be presented and reviewed. Certain CT features that may enable a specific diagnosis will be discussed.

Format: Cases will be grouped according to different disease entities.

Teaching Points: 1. Review the CT appearance of unusual colitides. 2. Review the CT appearance of unusual colonic tumors. 3. Review features that may enable a specific diagnosis of these entities.

E139. Sonography of Adult Inguinal Hernia Revisited

Jamadar D.A.; Jacobson J.A.; Gest T.; Morag Y.; Girish G.; Franz M.; Kalume-Brigido M.; Ebrahim F.; Radiology, University of Michigan Hospital, Ann Arbor, MI.

Address correspondence to D.A. Jamadar (djamadar{at}med.umich.edu)

Background: Hernia of the inguinal region are a frequent source of morbidity and rarely mortality in the adult general population. Differentiating between the varieties of inguinal hernia may be difficult clinically, and some may go unrecognized. The relatively superficial location of anterior abdominal wall and the dynamic capability of sonography, make this modality very useful in the evaluation of inguinal hernia. This exhibit will review the anatomy of the inguinal region, describe our technique for evaluating for inguinal hernia and illustrate this with surgically proven cases of hernia.

Key Issues: The anatomy of the inguinal region, including the inguinal canal, the femoral canal and Hasselbach's triangle bounded by the inferior epigastric artery, the inguinal liga-ment and the lateral margin of the rectus abdominis muscle will be described. Our technique for evaluating for inguinal hernia will be presented and hernia of the inguinal region including the femoral, direct and indirect inguinal and spigelian hernia will be illustrated.

Format: The information will be presented in a didactic format. The anatomy will be described followed by the normal ultrasound appearances of the landmarks, then our technique and finally examples of pathology.

Teaching Points: 1. Understand the essential anatomy of the inguinal region. 2. Be familiar with the normal sonographic appearances of the landmarks of this region. 3. Identify the sonographic features of inguinal hernia and how to differentiate between the four common varieties of hernia.

E140. Primary Interpretation of CT Colonography Using Colon Flattening Software: Typical Appearance of Common Findings and Pitfalls

Katz S.S.; Soto J.A.; Radiology, Boston University Medical Center, Boston, MA.

Address correspondence to S.S. Katz (sethkatz{at}onebox.com)

Background: One potential issue faced by departments in implementing high-volume CT colonography is the time required for interpretation. Currently, the standard of care involves either a primary review of multiple axial images of the abdomen or a primary 3D approach via a virtual fly-through. As more and higher-level multi-slice scanners come into use, the number of images requiring review is rising, and the effect on interpretation time is not yet clear. Enabling the interpreter to view the entire colonic surface at one glance, flattening software is one among several approaches designed to enhance and speed detection of colonic pathology.

Key Issues: Analysis of the luminal surface initially requires segmentation of the data, which requires time and necessitates sufficiently low image noise and adequate colonic distension. Use of 64-detector CT scanners can reduce motion artifact and increase resolution, but also may increase image noise. A low volume of residual fluid is highly desirable. Interpreters will need to become familiar with the typical flattened-view appearance of motion, folds, fluid, residual stool, rectal tube, ileocecal valve, and diverticuli as well as polyps and masses.

Format: Interactive: Several information screens will be provided describing detailed information on patient preparation and scan acquisition as well as data comparing the speed and accuracy of primary flattened view vs. primary 2D cine taken from 100 consecutive cases, including many acquired using 64 detector scanners. Steps involved in the segmentation of the data from selected cases will be shown, along with a series of colon-flattened images of common pitfalls, such as fluid, retained stool, motion, image noise, interrupted segments, diverticula, ileocecal valve, and appendiceal orifice, as well as polyps and masses of various morphology with their corresponding appearance on 3D endoluminal views and traditional 2D axial images.

Teaching Points: 1) Inform the reader of the relative accuracy and time savings of primary flattened-image review. 2) Familiarize the viewer with acquisition requirements for colon flattening software. 3) Introduce the viewer to the typical colon-flattened appearance of common colonic wall findings, both artifactual and pathologic.

E141. Common Colonic Abnormalities and Interpretative Pitfalls at MDCT Colonography

Lee W.K.; Seale M.; Pitman A.G.; Department of Medical Imaging, St. Vincent's Hospital, Melbourne, Victoria, Australia.

Address correspondence to W.K. Lee (leewk33{at}hotmail.com)

Background: Multidetector CT (MDCT) colonography is a rapidly evolving, minimally invasive diagnostic technique in the imaging of the colon. MDCT has improved longitudinal and temporal resolution that enables high quality multiplanar 2D reformations as well as 3D virtual colonographic views. MDCT allows evaluation of the mucosal surface of the entire colon as well as characterization of the colonic wall and the extracolonic extent of disease.

Key Issues: This pictorial exhibit aims to illustrate the 2D and 3D MDCT colonographic appearances of a spectrum of common colonic diseases that can be encountered in clinical practice, including polyps, carcinoma, flat lesions, benign tumors and inflammatory conditions, as well as common interpretative pitfalls.

Format: This is a didactic pictorial exhibit organized into introduction and CT findings (pathology and pitfalls).

Teaching Points: To be familiar with the 2D and 3D appearances of a spectrum of common colonic abnormalities and interpretative pitfalls at MDCT colonography.

E142. Imaging Findings of Unusual Anorectal, Rectal and Perirectal Pathology

Rouse H.C.; Barnard S.A.; Cooperberg P.L.; Brown J.A.; Radiology, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.

Address correspondence to H.C. Rouse (hannah.rouse{at}gmail.com)

Background: Primary rectal adenocarcinoma is undoubtedly the commonest cause of a rectal mass identified on imaging. However, there are a number of much less frequent causes of lesions occurring in the anorectal, rectal and perirectal regions that require differentiation from carcinoma due to important implications for management and prognosis.

Key Issues: This exhibit will illustrate the radiologic appearance of several uncommon but important anorectal, rectal and perirectal pathologies. The imaging features of carcinoid, gastrointestinal stromal tumor, leiomyoma, foreign body reaction, Klippel-Trenaunay-Weber hemangiomata, nerve sheath tumor, laceration of anorectal junction, retrorectal cystic hamartoma, extramedullary hematopoesis, colitis cystica profunda, endometriosis and leiomyosarcoma are presented. We discuss imaging characteristics of each entity on different modalities that may allow differentiation of one from another.

Format: · Didactic format · Organized by pathology.

Teaching Points: After reading the exhibit, the viewer should: 1) be aware that there are several less common causes of anorectal/rectal/perirectal masses; 2) be able to describe the radiological appearance of these less frequently encountered lesions; 3) be able to differentiate one lesion from another, where possible; 4) understand the importance of a multimodality imaging approach; 5) appreciate the importance of recognizing these entities as distinct from rectal carcinoma in order to plan appropriate management.

E143. Phased Array MRI in Local Staging of Rectal Cancer

Tsai S.S.¹; Allison C. ¹; Aish L.¹; Hackford A.W.²; Mendel J.B. ¹; Davidoff A.¹ 1. Radiology, Caritas St. Elizabeth's Medical Center, Boston, MA; 2. Surgery, Caritas St. Elizabeth's Medical Center, Boston, MA.

Background: Rectal cancer is a common disease. Accurate preoperative local staging of rectal cancer is important for treatment planning. T1 lesions involve the submucosa, T2 lesions involve the muscularis propria, T3 lesions invade through the muscularis propria into the subserosa or perirectal tissues and T4 lesions invade other organs or structures. Tumor stage determines those patients who would benefit from preoperative neoadjuvant chemotherapy and radiation therapy. The circumferential resection margin is the distance from the tumor to the mesorectal fascia, and can be used to stratify patients with T3 tumors into low or high risk for local recurrence. This is useful for determining the need for more extensive treatment.

Key Issues: This exhibit illustrates local staging of rectal cancer with phased array MRI. Anatomy of the rectum and pelvis is reviewed. Examples of each tumor stage are provided. The role of preoperative neoadjuvant chemotherapy and radiation therapy for surgical planning and the use of the circumferential resection margin for treatment planning are shown. The utility of phased array MRI for evaluation of recurrent rectal cancer is demonstrated.

Format: The exhibit is didactic with illustrative cases.

Teaching Points: To illustrate how phased array MRI is used to locally stage rectal cancer.

E144. Physical Principles and Clinical Applications of Various Magnetic Resonance Pulse Sequences in Abdominal and Pelvic Imaging

Piziali D.J.; Shirkhoda A.; Shetty A.; Diagnostic Radiology, William Beaumont Hospital, Royal Oak, MI.

Address correspondence to D.J. Piziali (danjpmd{at}comcast.net)

Background: In this exhibit the basic principles of a variety of magnetic resonance pulse sequences are briefly described. These include fast-spin-echo technique, inversion-recovery technique, fat-saturation technique, in-phase/opposed-phase sensitive technique, three-dimensional gradient-recalled-symmetric-echo (VIBE) technique etc. Under each category, various cases will be illustrated in order to emphasize the clinical application of the particular pulse sequence in a variety of pathologic conditions.

Format: Didactic, educational exhibit on a poster organized by imaging technique.

Teaching Points: To describe physical principles of various pulse sequences and their clinical applications in the evaluation and diagnosis of abdominal and pelvic pathology.

E145. What to Do With That Coronal MR "Scout" View? FIESTA and SSFSE Sequence Optimization and MR Appearance of Normal Anatomy and Common and Uncommon Abdominal Masses

Patnana M.; Szklaruk J.; Tamm E.P.; Gonzalez M.A.; Diagnostic Imaging, MD Anderson Cancer Center, Houston, TX.

Address correspondence to M. Patnana (mpatnana2004{at}yahoo.com)

Background: Magnetic Resonance Imaging (MRI) of the abdomen is often used in the diagnosis and staging of cancer and for surveillance of recurrence. The initial "scout" coronal images for these examinations are commonly obtained with a fast T2 weighted sequence such as SSFSE and FIESTA. These may often be underutilized or used solely for the purpose of anatomical localization. However, the "scout" T2-weighted images, when optimized can prove to provide a wealth of information on normal and variant anatomy as well as the pathology in question.

Key Issues: This educational exhibit will demonstrate the MR appearance on the coronal SSFSE and FIESTA sequences of normal anatomy, common and uncommon abdominal pathology subdivided by organ of origin. For example, in the evaluation of the pancreas we will present the imaging characteristics of pancreatic divisum, pancreatic adenocarcinoma, islet cell tumors, pancreatitis, intraductal papillary mucinous tumors, and metastatic disease to the pancreas. The role of these sequences in staging will also be discussed. For example, we will present the utility of the "scout" view in the evaluation of extension of disease to the vascular and lymphatic systems as well as distant metastases. The benefit of both SSFSE and FIESTA for a specific diagnosis will be demonstrated to aid in appropriate sequence selection. Finally, technical parameters for optimization of these coronal MR sequences in abdominal imaging will be emphasized.

Format: The format will be an interactive educational exhibit. From a master menu the participant will first select a specific organ of interest and will be asked to then select from a list of topics that include anatomy, variant anatomy, disease processes, and tumors. After a brief review of the MR appearance and relevant clinical information, coronal SSFSE and FIESTA images will be displayed. The images will then be compared and contrasted. Information regarding optimization of these techniques will also be provided.

Teaching Points: Learn the role of coronal SSFSE and FIESTA sequences in oncologic imaging. Learn how to select and optimize the SSFSE and FIESTA coronal images. Become familiar with the MR appearance of normal and abnormal pathology using coronal SSFSE and FIESTA sequences.

E146. 3Tesla Magnetic Resonance Imaging of the Abdomen and Pelvis: An Atlas of Imaging Artifacts, How to Recognize Them and How to Minimize Them

Nooryani F.; Broumandi D.D.; Morrow B.; Tran T.; Kim S.; Keesara S.; Valencerina S.S.; Palmer S.L.; Radiology, Keck School of Medicine, University of Southern California, Los Angeles, CA.

Address correspondence to D.D. Broumandi (dbroumandi{at}yahoo.com)

Background: As 3 Tesla (3T) magnetic resonance imaging (MRI) systems become more common in the imaging community, more abdominal and pelvic imaging will be performed on these high field strength systems. Higher image resolution, improved signal to noise ratio and greater contrast resolution are possible with 3T imaging. The expectation of improved image quality along with the possibility of reduced imaging times and contrast volumes make 3T MRI an emerging standard. However, the potential for improved quality is not without potential pitfalls, and chief among them are artifacts. Artifacts make identifying anatomy more difficult and may mimic disease processes if not fully understood and appreciated. For the promise of 3T MRI to be fully realized, radiologists must develop a keen understanding of how these artifacts can impact decision-making in abdominopelvic imaging.

Key Issues: This educational exhibit demonstrates artifacts, both common and uncommon, found during imaging of the abdomen and pelvis on 3T MRI systems. The exhibit will focus on artifacts that can lead to misdiagnosis while addressing their causes and means to reduce their impact in daily practice. Some of the specific artifacts featured include: magnetic susceptibility, flow, ghosting, cross talk, chemical shift, radio-frequency and dielectric effect.

Format: This exhibit is based on interactive learning principles that will provide the viewer with the opportunity to demonstrate MRI knowledge and technical skill by recognizing an artifact and suggesting a means of diminishing that artifact. Each interactive example will include a complete discussion of the featured artifact, its etiology and strategies to minimize its occurrence and impact.

Teaching Points: After reviewing this exhibit the viewer will be able to: 1. Easily identify artifacts that have the potential to reduce the accuracy of abdominopelvic imaging on 3T systems. 2. Understand the cause of each artifact and how to reduce its impact. 3. Develop technical strategies for optimizing imaging sequences specific to abdominopelvic imaging.

E147. CT Appearance of Abdominal and Pelvic Pseudoaneurysms and their Endovascular Management

Lamba R.¹; Suri R.²; Bindra J.¹; McGahan J.P.¹; 1. Radiology, UC Davis Medical Center, Sacramento, CA; 2. Radiology, UT Health Sciences Center, San Antonio, TX.

Address correspondence to R. LAMBA (ramit_22{at}hotmail.com)

Background: Pseudoaneurysms in the abdomen and pelvis can be post-traumatic, iatrogenic, mycotic or inflammatory. The great morbidity and mortality associated with pseudoaneurysms makes early detection critical. Most cases are initially detected on Computed Tomography (CT). Hence it is important for radiologists to be familiar with their CT appearance. Early diagnosis and treatment are crucial given the risk of rupture. Endovascular techniques allow for minimally invasive treatment obviating surgery. Endovascular treatment can be performed by transcatheter embolization and or the use of stent grafts.

Key Issues: Examples of hepatic, splenic, renal, gastroduodenal artery, pancreaticoduodenal artery, abdominal aortic and iliac pseudoaneurysms will be presented. In addition their endovascular treatment will be illustrated and discussed. Mimics of pseudoaneurysms will also be presented.

Format: Cases will be organized by the organ or artery involved. Angiographic images of endovascular treatment will be presented alongside the CT images.

Teaching Points: 1. Review the appearance of pseudoaneurysms in the abdomen and pelvis. 2. Review the appearance of pseudoaneurysm mimics to avoid diagnostic pitfalls. 3. Review the endovascular management of these pseudoaneurysms.

E148. Correlation of Tumor Markers with Abdominopelvic Imaging for Diagnosis of Cancer, Monitoring Treatment Response, and Detecting Recurrent Disease

Maheshwari S.; Mujoomdar A.; Mesurolle B.D.;. Division of Abdominal Imaging, Department of Radiology, McGill University Health Centre, Montreal, QC, Canada.

Address correspondence to A. Mujoomdar (amm921{at}hotmail.com)

Background: Tumor markers are substances, usually proteins, produced systemically or by tumoral cells in response to cancer growth. The accuracy of using tumor markers alone for the diagnosis of cancer is limited, given their poor sensitivity and specificity. For example, some tumor markers may be specific to a particular malignancy, while others are seen in several cancer types. Also, many of the markers can be elevated in non-cancerous conditions. Lastly, these markers may not be elevated in every person, especially in the early stages of disease. Although limited when assessed alone, the evaluation of tumor marker levels performed in conjunction with abdominopelvic cross-sectional imaging, becomes very useful in the diagnosis of cancer, assessment of treatment response, and detection of recurrent disease.

Key Issues: The purpose of our exhibit is to illustrate the importance of tumor marker correlation with imaging for diagnosis of various abdominopelvic primary and metastatic cancers, and more so in monitoring the treatment response and disease recurrence. Relevant CT and MRI images of different oncologic patients will be presented with the level of specific tumor markers, at the time of diagnosis. Subsequently, the tumor response to chemotherapy and recurrence detected by serial imaging and serial tumor marker estimation will be demonstrated. During each case presentation, a short description of each tumor marker, with respect to biochemical and clinical significance, will be discussed.

Format: The exhibit will be presented in a didactic format, with multiple case presentations using CT and MR imaging modalities.

Teaching Points: 1. To review the various tumor markers. 2. To review and illustrate imaging (CT/MRI) examples of various abdominopelvic primary cancers and metastatic disease with elevated tumor markers. 3. To understand the importance of serial tumor markers and imaging in suspected recurrence.

E149. Pneumatosis Intestinalis in the Adult, Benign to Life Threatening

Ho L.M.; Paulson E.K.; Thompson W.M.; Radiology, Duke University Medical Center, Durham, NC.

Address correspondence to L.M. Ho (lisa.ho{at}duke.edu)

Background: Pneumatosis intestinalis (PI) implies the presence of gas within the bowel wall. PI can be easily overlooked and when found its clinical relevance is often misinterpreted. This important imaging finding is due to a wide variety of etiologies ranging from benign or harmless to life threatening. Relatively new surgical procedures (ex. transcutaneous feeding tubes and organ transplant) are associated with harmless PI, but its presence in the post-operative period can lead to clinical confusion and sometimes unnecessary surgical intervention. PI is a radiographic sign not a disease. Therefore the clinical relevance of PI must always be related to the clinical status of the patient.

Key Issues: The pathogenesis of PI is uncertain but the two main theories are mechanical and bacterial. The mechanical theory proposes that gas dissects into the bowel wall from either the intestinal lumen or the lung. The bacterial theory proposes that gas-forming bacteria enter the submucosa through rents in the mucosa. The imaging appearance on radiographs and CT varies from the more benign cystic form (mainly in the colon) to the more severe linear form (mainly in the small intestine). The imaging findings can be subtle in some cases of PI related to bowel ischemia. In other in-stances, extensive apparent PI with extraluminal gas can be completely harmless. Occasionally, dependent air trapped within stool can cause diagnostic problems. To confound the problem pneumoperitoneum may accompany either the harmless or the life threatening forms of PI.

Format: This exhibit will demonstrate the wide variety of PI on radiographs, barium studies of the gastrointestinal tract and CT. Benign PI will be contrasted with the life threatening form of PI, indicative of bowel ischemia. Problem cases will be emphasized.

Teaching Points: 1. PI occurs in a wide variety of clinical conditions both harmless and life threatening. 2. The only radiographic findings to suggest harmless PI are cystic air collections primarily within the colon. 3. In the clinical context of peritonitis or sepsis, PI may indicate bowel ischemia and life-threatening disease which would warrant surgical intervention.

E150. CT Imaging Appearances of Sclerosing Encapsulating Peritonitis: A Pictorial Review

George C.; Al-Zwae K.; Nair S.; Puthuran M.; Cast J.; Radiology, Hull Royal Infirmary, Hull, United Kingdom.

Address correspondence to C. George (cheriangeorge{at}hotmail.com)

Background: Sclerosing encapsulating peritonitis is a serious complication of PD characterized by thickened peritoneal membranes which lead to decreased ultra filtration and intestinal obstruction. Previous reports place the prevalence of SEP at 0.54%-7.3% and the diagnosis is often established at a late stage of the disease at laparotomy. This is however changing with increasing awareness of CT findings in SEP. Its presence should be suspected in patients treated by CAPD who develop small bowel dysfunction with associated abdominal pain and progressive loss of ultra-filtration.

Key Issues: Learning Objectives: 1. To illustrate the computerized tomography (CT) appearances of sclerosing encapsulating peritonitis (SEP) in patients undergoing peritoneal dialysis (PD). 2. To describe the clinical and radiological presentations of SEP along with the treatment options available.

Format: We present a pictorial review of the CT appearances in SEP. CT appearances of SEP in the literature include peritoneal thickening, peritoneal calcification, loculated fluid collections, and adherent small bowel loops. The clinical course of SEP along with the current treatment options are also discussed.

Teaching Points: SEP is a typical, but at the same time, not so frequently observed complication of PD which is associated with a high mortality. It should be borne in mind whenever a patient with a history of PD reports episodes of abdominal pain, nausea and vomiting associated with weight loss. CT of the abdomen should be performed in such patients and this may help in attaining an early, correct, and noninvasive diagnosis of SEP for which optimal intervention can be planned.

E151. Multidetector CT Depiction of Radiological Anatomy and Diseases Involving the Transverse Mesocolon

Mukhi S.; Viswanathan C.; Charnsangavej C.; Raval B.; Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX.

Address correspondence to S. Mukhi (vickyshalini{at}yahoo.com)

Background: Identifying the transverse mesocolon in the usual axial plane of CT is difficult because of its oblique orientation, predominant fat composition and its proximity to other fat containing structures such as the omentum and small bowel mesentery. Current CT scanners display the relevant vascular anatomy very well and can allow us to develop an anatomical approach that aids in the detection of diseases involving the transverse mesocolon.

Key Issues: The middle colic vessels are the key anatomic landmark in the transverse mesocolon. Identification of the marginal, middle colic, gastroepiploic, gastrocolic trunk and superior mesenteric vessels on MDCT helps localize important anatomic structures in and around the transverse mesocolon and in detection of direct spread of disease. Since the lymphatic drainage follows the vascular pathway, prediction of lymphatic spread of disease is also greatly aided by a working knowledge of the vascular anatomy.

Format: This interactive electronic exhibit will show a step by step approach to understanding the anatomy of the transverse mesocolon, the adjacent structures and the vascular anatomy as seen by MDCT. Various disease processes involving the transverse mesocolon will highlight this approach using examples of ascites, colonic and pancreatic malignancy, GI stromal tumor, pancreatitis, and venous collaterals in splenic and portal vein occlusion.

Teaching Points: (1) Review the vascular anatomy related to transverse mesocolon as seen by MDCT (2) Utilize the knowledge of important vascular anatomy to allow consistent detection of diseases that involve the transverse mesocolon.

E152. Non-neoplastic Pathologies of the Peritoneum; Spectrum of Helical & Multidetector-row CT Findings

Furuya K.¹; Sakino I.²; Yasumori K.¹; Muranaka T.³; 1. Radiology, National Hospital Organization Kyushu Medical Center, Fukuoka, Japan; 2. Radiology, Saiseikai Yahata General Hospital, Kitakyuushu-City, Japan; 3. Clinical Institute of Research, National Hospital Organization Kyushu Medical Center, Fukuoka, Japan.

Address correspondence to K. Furuya (Kymfuruya{at}aol.com)

Background: A wide variety of non-neoplastic diseases affect the peritoneum and spread to adjacent organs. Great improvement in CT has made it possible to demonstrate them precisely. The purpose of this exhibit is to present the CT features of non-neoplastic pathologies of the peritoneum and to assess the diagnostic value of current CT in their evaluation.

Key Issues: The pathologies presented are peritoneal abscess, peritonitis of various etiologies, acute appendicitis, diverticulitis, acute cholecystitis, acute pancreatitis, Crohn's disease, Behcet's disease, tuberculosis, sclerosing mesenteritis, mesenteric ischemia including occlusion of mesenteric artery and non-occlusive mesenteric ischemia, amyloidosis, intestinal perforation, pneumatosis cystoides intestinalis, and encapsulating peritoneal sclerosis in patients with peritoneal dialysis, and opportunistic infectious diseases. CT reveals these peritoneal disorders and their spread very well. Awareness of their specific pathogenesis and CT manifestations will help in correct diagnosis.

Format: Didactic organizational structure; by imaging technique.

Teaching Points: 1. To present the CT features of non-neoplastic pathologies of the peritoneum 2. To better understand the peritoneal anatomy and spread way of diseases 3. To assess the diagnostic value of updated CT in the evaluation of these pathologies.

E153. The Spectrum of Peritoneal Metastases - A Pictorial Review

Carrel C.E.; Charnsangavej C.; Tamm E.P.; Diagnostic Imaging, MD Anderson Cancer Center, Houston, TX.

Address correspondence to C.E. Carrel (Radcarrel{at}yahoo.com)

Background: Metastases to the peritoneum most commonly arise from primary neoplasms of the abdomen and pelvis including appendiceal, gastric, ovarian, pancreatic and colonic carcinomas. Rare etiologies include lymphoma and gastrointestinal stromal tumors among others. These metastases can present with various morphologies and patterns on imaging studies. Additionally, advanced lesions are easy to recognize but early and small lesions can easily be missed due to close proximity to normal organs and other structures.

Key Issues: Peritoneal metastases can present with different morphologic appearances, distribute in different anatomic locations, and lie within various spaces of the peritoneal cavity. Lesions can appear nodular, plaque-like, diffuse, infiltrative, or in a pseudomyxoma pattern. Each of these locations and patterns will be illustrated.

Format: This didactic exhibit will describe key anatomic spaces and landmarks of the peritoneal cavity illustrated by multiplanar imaging. Cases organized by pathology will demonstrate various patterns of disease from both common and uncommon primaries with emphasis on morphology, patterns of progression, and anatomic localization. Tumor specific patterns will be highlighted.

Teaching Points: Teaching points of the exhibit include 1) Methods of anatomic localization 2) Descriptions of different morphologic patterns, and 3) Examples to improve sensitivity in detection of small and early lesions. A review of these points will allow for more accurate tumor staging, treatment planning and diagnosis of recurrent disease.

E154. Imaging Visceral Fatty Lesions

Rajiah P.; Khan A.; Radiology, Royal Manchester Children's Hospital, Manchester, Lancashire, United Kingdom.

Background: Fat is present in a wide variety of visceral lesions, including congenital, inflammatory, neoplastic and non neoplastic lesions. Some of these lesions are incidental findings in imaging examinations, but larger lesions are usually symptomatic.

Key Issues: The various fat containing visceral lesions include lipoma, liposarcoma, teratoma, angiomyolipoma, myelolipoma, adrenal adenomas, fat infarction, hernias, intussusception, mesenteric panniculitis, fibrofatty mesenteric proliferation and epiploic appendagitis. The pictorial review illustrates the imaging spectrum of various fat containing lesions in abdomen and pelvis in ultrasound, CT and MRI. Techniques for evaluation of fat such as STIR, Fat saturation and In phase/Opposed phase imaging are also reviewed. Differential diagnosis of these lesions are discussed.

Format: The pictorial review illustrates all the visceral fatty lesions. The various MR sequences that are important for characterizing these lesions are discussed.

Teaching Points: 1. To learn about visceral lesions with microscopic or macroscopic fat. 2. To illustrate the imaging spectrum of fat containing lesions in different locations 3. To learn the optimal techniques for visualization of fat in a lesion.

E155. Current Eponyms in Gastrointestinal Anatomy

Manzella A.; Borba P.Q.; Rojas H.; Correia T.; Macedo K.; Campelo C.; Dourado M.; Rodrigues A.; Albuquerque A.; Siqueira L.; Radiology, Hospital das Clinicas da Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil.

Address correspondence to A. Manzella (adonismanzella{at}yahoo.com.br)

Background: Eponyms are labels that provide two kinds of information: the pattern of a complex injury or pathologic problem and the name of an individual who has been closely identified with that problem, reminding us that the medicine of today is not entirely the work of our contemporaries. The word eponym is derived from the Greek word eponymos, which means named after. The multiplicity of the names attributed by scientists and researchers to some organs and anatomical structures has made difficult reading and elaborating scientific papers. Frequently such difficulty increases when one sees that for the same structure, there are various denominations. Although nowadays frowned on by the authorities, eponyms were once widespread, and many still persist.

Key Issues: The purpose of this pictorial review is to present the current eponyms in Gastrointestinal Anatomy. The anatomic structures presented in this exhibit are islets of Langerhans, Bauhin's valve, sphincter of Oddi, folds of Kerckring, Auerbach's plexus, Meissner's plexus, ampulla and papilla of Vater, Peyer patches, Glisson's capsule, arcade of Riolan, duct of Santorini, duct of Wirsung, foramen of Winslow, ligament of Treitz, crypts of Lieberkuhn, Brunner's gland, valves of Heister, Morgagni sinuses and columns. The presentation also includes the biographies of the following individuals: Paul Langerhans, a German pathologist, Gaspar Bauhin, a Swiss anatomist, Ruggiero Oddi from Italy, Theodor Kerckring from Holland, Leopold Auerbach, Georg Meissner and Abrahan Vater from Germany, Johann Conrad Peyer a Swiss anatomist, Francis Glisson from England, Jean Riolan, a French surgeon, Giovanni Santorini and Giovanni Battista Morgagni from Italy, Johann Wirsung, Jacob Winslow from Denmark, Wenzel Treitz from Austria, Johann Lieberkuhn, Johann Brunner from Switzerland and Lorenz Heister, a German surgeon.

Format: The authors define and illustrate each anatomic structure using different imaging modalities as well as photographic illustrations or drawings when pertinent. They also describe a brief biography of each individual (anatomist, pathologist, surgeon) whose name has been closely related to the structure. A picture of each scientist is provided.

Teaching Points: (1) To present some of the eponyms still used in Gastrointestinal Anatomy (2) To illustrate the anatomic structures related to these eponyms using different imaging modalities and drawings. (3) To pay a tribute to these great individuals describing their biographies.

E156. "The Liver Module" - A Comprehensive, Multidisciplinary Web Based Resource for Liver Disease

Davidoff A.; Allison C.; Khanna A.; Lee D.; Tsai S.S.; Radiology, Caritas St. Elizabeth's Medical Center, Boston, MA.

Background: "The Liver Module" is a web resource that recognizes the importance of the multidisciplinary approach to liver disease and provides each discipline the common thread that unites the knowledge base.

Key Issues: The program is rich in images, deep and broad in applied content. Content spans the history, histology, anatomy, pathology, radiology, and clinical aspects. The infrastructure is grounded in basic principles which evolve from the simple to the complex.

Format: The image library consists of over 1000 images, augmented by over 20 Power-Point shows. Imaging and therapeutic strategies provide guidelines for a variety of clinical scenarios. Links to selected Internet sources contribute added breadth and depth.

Teaching Points: "The Liver Module" thus provides integrated in depth knowledge for members of a multidisciplinary team in one comprehensive, web based resource. The uniform use of principles allows integration both within the module as well as incorporation into a larger system with other organs.

E157. Evaluation of Liver Lesions by T2-weighted Imaging at 3T and 1.5T Magnetic Field Strengths

Szklaruk J.; Bhosale P.; Ma J.; Ng C.S.; Tamm E.P.; Balachandran A.; Diagnostic Imaging, University of Texas MD Anderson Cancer Center, Houston, TX.

Address correspondence to J. Szklaruk (jszklaru{at}di.mdacc.tmc.edu)

Objective: To compare the diagnostic value of T2 weighted images performed in patients with known liver masses at 3.0T and 1.5T field strengths.

Materials and Methods: Patients with known solid liver lesions larger than 1cm and first detected at 1.5T magnetic field strength were enrolled in the study. Within a one-week period after the 1.5T exam the patients underwent an additional MRI of the liver at 3T. At 1.5T a total of 60 solid lesions were detected in 16 patients. The T2 weighted images at 1.5 T were acquired with fast recovery fast spin echo (FRFSE) and both with TE/TR/ETL = 85 ms/2,500 ms/23 and with TE/TR/ETL = 140 msec/2,500 msec/23. Additionally, regular FSE images were acquired with TE/TR/ETL = 85 msec/6,000 msec/16. At 3T, regular FSE images were acquired at three different TEs (85, 160, and 200 msec) and with a TR of 3,200 msec and an ETL of 24. All images were obtained at 7 mm/0 mm slice thickness. Except for the FSE sequence at 1.5T, the images were all acquired in breath-hold. Fat suppression was used with all sequences. To decreased specific absorption rate at 3T partially parallel imaging with an acceleration factor of 2 was utilized. Three radiologists with specialty in body MRI Independently review the images. Each radiologist scored for lesion detection on a 1 to 5 scale: 1 = definitely absent; 2 = probably absent; 3 = equivocal; 4 = probably present; and 5 = definitely present. The null hypothesis that the six average scores are the same was tested with the ANOVA statistical analysis and the hypothesis is rejected if the p < 0.05.

Results: A total of 60 solid liver lesions were detected at both 1.5T and 3T. At 1.5T, the T2 weighted images received an averaged score of 4.0 ± 0.08, 4.1 ± 0.07, and 4.4 ± 0.07 for the FRFSE at TE = 85msec, FRFSE at TE = 140 msec, and the regular FSE at TE = 85 msec, respectively. At 3T the T2 weighted images received an averaged score of 4.2 ± 0.07, 4.2 ± 0.07, and 4.1 ± 0.08 for the FSE at TE = 85, 160, and 200 msec, respectively. The null hypothesis was not rejected with p = 0.15.

Conclusion: Evaluation of liver lesions by T2-weighted images at 3T and 1.5T did not alter the sensitivity for lesion detection. Confidence of lesion detection was not statistically significant between the two different magnetic field strengths.

E158. Ferucarbotran (Resovist®) - Super-Paramagnetic Iron Oxide-enhanced MRI of the liver. Properties of ferucarbotrans, imaging techniques and characterization of focal liver lesions.

Jain R.; Sawhney S.; Radiology, Sultan Qaboos University and Hospital, Muscat, Oman.

Address correspondence to S. Sawhney (sukh48{at}yahoo.com)

Background: Ferucarbotrans are new liver-specific MRI contrast agents that have shown increased sensitivity in detection of focal hepatic lesions, differentiation of benign and malignant hepatic lesions, and detection of hepatocellular carcinoma (HCC) in cirrhosis.

Key Issues: Imaging technique and findings 60 patients with focal hepatic lesions were studied with ferucarbotran-enhanced MRI. Gradient-echo T1 weighted, T2 and FSE T2 weighted images were obtained before and after contrast injection in the early (T1) and accumulation (T2 and FSE-T2) phases. Histopathological correlation was obtained in 28 patients. The ferucarbotran-enhanced MRI diagnoses included hepatocellular carcinoma (17), metastases (16), adenoma (4), cirrhosis (8), benign cystic lesions (6), others (4) and normal (5). Ferucarbotran-enhanced MRI is useful in detection of HCC in cirrhotic livers, pre-operative evaluation of metastatic disease, differentiation of benign from malignant lesions, and response of lesions to local ablative therapy. Limitations of the technique include high costs and increased procedure times.

Format: Didactic. Organizational Structure: Imaging technique - MRI, Contrast Agent - Ferucarbotran (Superparamagnetic iron oxide), Pathology - Focal liver lesions.

Teaching Points: 1. Ferucarbotran (Resovist® or SPIO) - description, pharmacokinetics, techniques of administration and mechanism of action. 2. Imaging protocols. 3. Characterization of focal liver lesions using Resovist®-enhanced MRI. 4. Limitations and pitfalls.

E159. The Focal Hepatic Mass: A Multimodality Approach

Yeghiayan P.; Laifer-Narin S.L.; Radiology, Columbia University Medical Center, New York, NY.

Address correspondence to P. Yeghiayan (pyeghiayan{at}yahoo.com)

Background: Focal liver masses are detected in a variety of clinical settings. They may be incidentally detected in a patient who undergoes abdominal imaging for various reasons, or may be identified during abdominal imaging performed as part of a detailed workup in a patient at risk for hepatic neoplasm. The role of medical imaging is to determine which lesions are clinically significant and which lesions are likely benign and "leave alone" lesions. The spectrum of these lesions include common benign neoplasms such as hemangiomas, focal nodular hyperplasia, and adenomas, less common fatty lesions including lipomas and angiomyolipomas, cystic disease includingsimple cysts, hemorrhagic cysts, and hydatid disease, pyogenic, amebic, and fungal abscesses, vascular entities which may be confused for masses including cavernous transformation of the portal vein and aneurysmal dilatation of portal vein or hepatic artery, and pseudomasses such as focal fatty infiltration or sparing. Malignant lesions include hepatocellular carcinoma, intrahepatic cholangiocarcinoma, metastatic disease, and rare malignant lesions including hemangiosarcoma and hepatic epithelioid hemangioendothelioma.

Key Issues: This exhibit will present detailed examples of the various entities described above including ultrasound, computed tomography, and magnetic resonance imaging. The use of color and spectral Doppler technique as well as imaging with ultrasound contrast will be discussed. The triple phase technique of liver imaging on computed tomography will be reviewed in the evaluation and characterization of hepatic masses. The various sequences utilized in magnetic resonance imaging with regard to characteristic findings and diagnostic criteria will be presented.

Format: This will be a didactic presentation describing focal hepatic masses, their diagnostic workup, including imaging findings and biopsy results, and clinical management including serial imaging followup, medical treatment, interventional procedures including drainage, embolization, ablation, and cryotherapy, and surgical resection.

Teaching Points: The spectrum of focal hepatic masses will be presented for the viewer. The viewer will learn the characteristic imaging findings of focal hepatic masses on US, CT, and MRI. Features of benignity versus malignancy will be discussed. The various management pathways of the spectrum of focal hepatic masses will be reviewed.

E160. CT Features of Missed Hepatocellular Carcinomas in Serial Follow-up Patients

Choi J.W.; Lee C.H.; Kim K.A.; Park C.M.; Seol H.Y