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General/Emergency

Katz D. S.; Cho M.; Fantauzzi J. P. Winthrop-University Hospital, Mineola, NY

Address correspondence to D. Katz (dsk2928{at}pol.net)

Background: CT is the imaging test of choice for suspected nontraumatic aortic emergencies, and radiologists should be familiar with the common as well as the unusual presentations of aortic aneurysm and dissection, as well as the appropriate protocols and techniques for emergent CT imaging when such disorders are suspected.

Key Issues: The purpose of this educational exhibit is to review the CT findings of abdominal and/or thoracic nontraumatic aortic rupture and impending rupture, as well as of acute aortic dissection, intramural hematoma of the aorta, its forms and variants, and of uncommon and unusual aortic disorders which may present emergently for CT imaging.

Format: Protocols for CT angiography of the aorta will be reviewed, as will the literature on the subject in some detail, using case material from a single tertiary care teaching hospital, emphasizing multidetector CT. Complications of aortic dissection will be discussed, as will pitfalls of CT interpretation, such as motion artifacts of the ascending aorta and inflammatory aortic aneurysm. Uncommon and unusual aortic disorders which may present acutely or subacutely, including mycotic aneurysm, graft infection, and aortoenteric fistula will be shown and the imaging findings and CT and clinical literature on these topics reviewed.

Teaching Points: Multidetector CT angiography is the imaging test of choice for suspected nontraumatic aortic emergencies. Radiologists should be familiar with the common as well as unusual acute presentations of aortic aneurysm and dissection, and its variants.

E117. An Additional CT Attenuation Pattern Describing Pulmonary Infarction

Wang Y. J.; Mardiat J. Santa Barbara Cottage Hospital, Santa Barbara, CA

Address correspondence to Y. Wang (yewang_1975{at}yahoo.com)

Objective: The aim of this study is to describe lung attenuation patterns of pulmonary infarction with retrospective data analysis. It is proposed that a lacy, hazy area of opacification without air bronchograms in the periphery of lung is a common pattern associated with pulmonary ischemia and infarction.

Materials and Methods: Data were compiled from patients diagnosed with pulmonary embolism (PE) on PE protocol chest CT. Patients were identified using an ICD code search over a time period of 18 months. Patterns of lung attenuation were described and recorded, especially in areas of lung within the vascular distribution of the occluded vessels. The categorization of the radiographic patterns was by a consensus of at least two radiologists.

Results: A total of 96 positive cases were analyzed. A significant percentage of patients (48%) with PEs do not have any acute lung abnormalities on CT. 41% of the positive cases have peripheral lung opacities abutting the pleura. Of these peripheral densities, 80% demonstrated the proposed pattern of hazy, lace-like opacification without any air bronchograms. 32% of total PE cases demonstrated the proposed pattern, while only 2% demonstrated the classic description of a peripheral wedge-shaped opacity, with the broad-base against the pleura.

Conclusion: A large percentage of patients with PEs will not have associated parenchymal lung abnormality, but a significant percentage is observed to have this proposed pattern of hazy, lacey attenuation in the periphery of the affected lung. This pattern we believe suggests pulmonary infarction. In comparison, the classic descriptors of pulmonary infarct have much lower sensitivity than the proposed pattern (2% versus 32%, respectively). If this pattern is observed incidentally on CT, such as at the lung bases of an abdomen and pelvis CT, the possible diagnosis of pulmonary embolism should be suspected. The radiologist then can confidently recommend additional workup to exclude PE as a diagnosis. We expect knowledge of this pattern to be especially useful for unsuspected and atypical presentations of PEs.

E118. Use of Contrast Medium for CT in Abdominal Trauma: An International Survey of Hospital Practice

Wat S. J.¹; Groves A. M.² 1. McMaster University, Hamilton, Canada; 2. University College Hospital, London, Canada

Address correspondence to S. Wat (josiewat{at}aol.com)

Objective: Aspects of the use of computed tomography (CT) contrast medium (CM) are controversial in abdominal trauma. There has been concern about the use of oral contrast medium (OCM) in this setting with possible reports of adverse incidents such as aspiration. Nonetheless OCM is universally recognized as useful in defining anatomy and aiding the identification of intestinal perforation. A literature search suggested that there was a lack studies in this area and there is also a paucity of clinical guidelines. We therefore performed a survey to assess the use of CT CM in abdominal trauma patients.

Materials and Methods: A seven-point questionnaire was constructed on the use of contrast medium in CT for patients undergoing abdominal trauma. It covered usage of oral, intravenous and rectal contrast medium. Many of the questions had been validated in an earlier study. The survey was sent to the correspondent authors of abdominal articles in the major radiological journals covering a 3-month period. In total 50 questionnaires were sent worldwide.

Results: Replies were obtained from 25/50 centers, however incomplete datasets were found in 5 thus leaving 20/50 fully completed forms. 4/20 institutions routinely used OCM, 6/20 used OCM only if patient is stable with a high index of suspicion for bowel injury particularly of the upper gastrointestinal tract or upon request from referring surgeons. OCM volume ranged from 200–1000mls and the timing varied between 20–60 minutes preexamination. None used rectal CM routinely, but 4/20 sites used rectal CM if there is suspicion of colonic perforation particularly if there was penetrating trauma to the flank or upon request of referring surgeons. Intravenous CM was given by all centers–16/20 employed multiphase technique, 3/20 used portal phase only and 1/20 used only arterial phase imaging.

Conclusion: The survey reveals marked lack of consistency in the use of contrast medium in CT imaging of abdominal trauma patients. The reason for this inconsistency may be multifactorial, but in part, a lack of evidence base is likely to be the root of this problem. Given the frequency of abdominal trauma and its associated morbidity and mortality, further research is required to determine the best imaging strategy used in acute trauma patients so clinical guidelines can be set.

E119. Active Vascular Extravasation in Abdominal Trauma Patients: Diagnosis by Multidetector Row Computer Tomography

Gonzalez-Beicos A.¹; Sangster G.²; Carbo A.²; Heldmann M.²; Otero H.¹; Pilat M.²; D'Agostino H.² 1. Brigham and Women's Hospital, Boston, MA; 2. Louisiana State University Health and Sciences Center, Shreveport, LA

Address correspondence to A. Gonzalez-Beicos (agonzalez-beicos{at}partners.org)

Background: The advent of multidetector computed tomography (MDCT) has made the imaging diagnosis and evaluation of stable and unstable patients feasible in the setting of abdominal trauma. MDCT high quality and fast acquisition time make this method an important diagnostic tool for accurate recognition and localization of active extravasation, with minimal clinical risk for the patient. From January to December 2005, 420 consecutives patients that suffered blunt (n = 319) or penetrating (n = 101) abdominal trauma where evaluated with MDCT at our level 1 trauma center. A total of 8 patients had evidence of active extravasation on MDCT.

Key Issues: This presentation will demonstrate the MDCT imaging findings of active contrast extravasation after abdominal trauma. The following spectrum of MDCT imaging findings is depicted and correlated with angiography or surgery: Type 1 focal high density areas of contrast extravasation surrounded by hematoma, Type 2 diffuse high density area of contrast extravasation surrounded by hematoma and Type 3 focal jet of contrast extravasation in continuity with a vessel or an abdominal organ. Also we will demonstrate and discuss MDCT examples of false positive cases of post traumatic contrast extravasation in the abdomen.

Format: This exhibit is a multimedia pictorial review of cases gathered from a level 1 trauma center. The review is organized by cases of active extravasation and false positive cases. MDCT images for each type of radiological sign will be presented and correlated with angiographic or surgical findings of active extravasation. Finally, the benefits and limitations of MDCT for the initial evaluation of hemodynamically unstable patients are briefly discussed.

Teaching Points: After reading this exhibit the reader should be able to 1) discuss the advantages and limitations of MDCT in the evaluation of hemodynamically unstable patients 2) recognize the MDCT imaging findings of active intra-abdominal hemorrhage after abdominal trauma, and 3) recognize pitfalls and false positive findings that may mimic contrast extravasation on MDCT.

E120. Multidetector Computer Tomography of Traumatic Splenic Injuries: Spectrum of Findings and Diagnostic Pitfalls

Gonzalez-Beicos A.¹; Sangster G.²; Carbo A.²; Heldmann M.²; Otero H.¹; Pilat M.²; D'Agostino H.² 1. Brigham and Women's Hospital, Boston, MA; 2. Louisiana State University Health and Sciences Center, Shreveport, LA

Address correspondence to A. Gonzalez-Beicos (agonzalez-beicos{at}partners.org)

Background: The spleen is the most frequently injured organ after abdominal trauma. Abdominal computed tomography is the gold standard for traumatic splenic injury diagnosis and has had an essential role in the advent of non surgical management of these injuries as a valid and preferred choice. Multi-detector computed tomography (MDCT) allows accurate correlation between the imaging and surgical grading of splenic injuries following the American Association for the Surgery of Trauma-Organ Injury Scale (AAST-OIS). Therefore, MDCT is not only a diagnostic tool but also a predictor of morbidity, and an aid for management decision making in traumatic splenic injuries.

Key Issues: This presentation will demonstrate the MDCT imaging findings and AAST-OIS grading of traumatic splenic injuries. Radiographic and clinical background of the following injuries is discussed: subcapsular and intraparenchymal hematomas, capsular and parenchymal lacerations, hilar vessel lacerations, partial or total devascularization and shattered spleen. Also we will demonstrate and discuss MDCT evidence of active contrast extravasation, clinical and imaging findings of delayed splenic rupture, and examples of false positive cases of splenic injury.

Format: This exhibit is a multi media pictorial review of cases gathered from a level 1 trauma center. The review is organized by splenic injury type and false positive cases. MDCT images and a brief clinico-epidemiologic background for each traumatic splenic injury will be presented.

Teaching Points: After reading this exhibit the reader should be able to 1) recognize the spectrum of imaging findings of the AAST-OIS grades of splenic injury on MDCT, 2) discuss the benefits of MDCT for the detection of active bleeding (contrast extravasation) in splenic injuries, and 3) identify pitfalls and false positive findings that may mimic a traumatic splenic injury on MDCT.

E121. Pneumatosis Intestinalis and Its Significance

Paspulati R.; Martin C. Case Western Reserve University, Cleveland, OH

Address correspondence to R. Paspulati (prajmohan{at}hotmail.com)

Background: Pneumatosis intestinalis is the presence of intramural gas in the small or large intestine and has always been considered a sign of gangrenous bowel. Pneumatosis is due to extension of air into the bowel wall due to disruption of its mucosal lining. This breach can be due to infection, ischemia, ulceration, iatrogenic trauma from surgery, endoscopy or intubations. Pneumatosis can be linear or cystic and can be focal or more extensive. A benign cystic form of pneumatosis is also seen in organ transplant patients with immunosuppression and in patients with chronic obstructive air way disease. This benign cystic form of pneumatosis has characteristic appearance on conventional radiographs and CT imaging.

Key Issues: Pneumatosis intestinalis has a wide range of causes from benign iatrogenic to life threatening. Proper knowledge of the pathogenesis, imaging features and pitfalls in the diagnosis is essential for effective management of these patients. Examples of various benign and life threatening causes of pneumatosis will be illustrated. Examples of mimics of pneumatosis will also be illustrated.

Format: Didactic format. The presentation includes 1. Imaging technique. 2. Cross-sectional anatomy of the bowel. 3. Pathogenesis of pneumatosis. 4. Imaging features. 5. Pitfalls and mimics of pneumatosis.

Teaching Points: 1. To understand the pathogenesis and various causes of pneumatosis intestinalis. 2. To illustrate the imaging features of pneumatosis. 3. To illustrate the pitfalls in the diagnosis of pneumatosis.

E122. CT Imaging of Liver Injuries to Create a Model for Blunt Hepatic Trauma

Sammet S.¹; Koch R. M.¹; Sparks J.²; Bolte J. H.¹; Knopp M. V.¹ 1. The Ohio State University, Department of Radiology, Columbus, OH; 2. The Ohio State University, Division of Anatomy, Columbus, OH

Address correspondence to S. Sammet (sammet.5{at}osu.edu)

Objective: The aim of this study was to develop a model to assess liver injury severity in blunt hepatic trauma. Isolated porcine and human liver specimens were investigated by CT imaging.

Materials and Methods: This study was performed on a clinical 64 slice CT scanner (SOMATOM Sensation, Siemens Medical Solutions). 25 isolated pig livers and 2 human livers were scanned prior and after a blunt impact of defined forces and velocities. Catheters in portal vein and hepatic artery quantified the pressure changes in the liver during the impact. The extent of the injuries was assessed using contrast-enhanced CT and compared to preinjury scans. Contrast agent was injected over catheters in portal vein and hepatic artery. (Scan parameters: FOV = 39 x 39 cm, matrix size = 512 x 512, slice thickness = 5 mm, reconstruction with 1.5 mm). 3D reconstructions of the livers were created to evaluate the injuries using a Leonardo workstation (Siemens Medical Solutions).

Results: Injuries of the liver caused by a simulated blunt trauma could be identified and their extent could be assessed and quantified in 3D reconstructions from CT scans prior and after induced trauma. The results show a correlation between the extent of liver injuries detected in CT and measured intravascular pressure changes during the impact.

Conclusion: The CT data evaluation and reconstruction helped to develop a model for blunt hepatic trauma. CT imaging and 3D reconstruction are useful methods to determine the extent of a simulated liver trauma and can help in developing better protection for human organs in blunt trauma. Blunt hepatic trauma in accidents often leads to severe complications. The developed model can help to create better protective devices in vehicles.

E123. Multidetector CT of Pancreatic Injury in Blunt Abdominal Trauma

Geoghagen T.; Harris A.; Zwirewich C.; Nicolaou S.; Walsh S. Vancouver General Hospital, Vancouver, Canada

Address correspondence to M. Hochman (mitchelhochman{at}hotmail.com)

Background: Injury to the pancreas in the setting of blunt abdominal trauma is relatively uncommon, occurring in less than 2–3% of blunt abdominal trauma patients. Early and accurate diagnosis is imperative, as pancreatic injuries can be associated with a high morbidity and mortality, especially if diagnosis is delayed. The clinical signs of pancreatic injury are often subtle, and elevation of serum amylase and lipase is not always sensitive or specific for injury. Therefore, imaging plays a key role in the detection of pancreatic trauma. However the imaging findings can also be subtle, and are potentially overlooked in the common setting of concurrent associated injuries.

Key Issues: MDCT is the primary imaging modality in trauma. In this exhibit, we illustrate the key CT features of pancreatic injury and examine the mechanism of pancreatic injury in blunt abdominal trauma. Direct findings of trauma such as pancreatic edema, laceration and duct transaction are demonstrated. The detection of secondary findings such as fluid adjacent to the splenic vein and retroperitoneal hematoma is discussed. We demonstrate the role of MRCP and ERCP to confirm pancreatic duct injury. Examples of the delayed complications of pancreatic injury, including acute pancreatitis, and abscess and fistula formation are provided.

Format: The format is a didactic pictorial review, organized by pathology.

Teaching Points: 1. The mechanism of pancreatic injury in blunt abdominal trauma. 2. The MDCT imaging features of pancreatic injury and its complications. 3. Familiarize the radiologist with the findings of pancreatic injury, in order to facilitate a timely diagnosis and allow for appropriate management to be initiated expeditiously

E124. Alternative Diagnoses of Appendicitis As Seen with CT Using Only IV Contrast

Ernst R.; Cano O.; Cook B. G.; Oto A.; Cesani F.; Ethridge K. University of Texas Medical Branch, Galveston, TX

Address correspondence to R. Ernst (rdernst{at}utmb.edu)

Background: Use of oral, rectal and IV contrast material has traditionally been used for CT diagnosis of patients with abdominal and pelvic pain. Exclusion of oral and rectal contrast may expedite triage of these patients in a busy emergency department.

Key Issues: Illustrate the CT features of conditions mimicking appendicitis in patients scanned with IV contrast alone. Demonstrate images of patients with suspected appendicitis who were scanned without the use of oral and rectal contrast and were diagnosed with conditions other than appendicitis.

Format: Cases of patients who were referred to CT from the emergency department for abdominal pain will be presented in a quiz format. While the cases have been collected over a four year time span, all were obtained using only IV contrast. The majority of the cases show female patients since they are more likely to experience conditions with alternative diagnoses. The cases include tuboovarian abscess, ovarian torsion, ovarian vein thrombosis, ectopic pregnancy, diverticulitis, and cholecystitis.

Teaching Points: IV contrast-enhanced helical CT without oral or rectal contrast is a useful technique for identifying alternative causes of pain in patients suspected of having acute appendicitis. A correct alternative diagnosis in patients with suspected appendicitis may prevent unnecessary surgery. Emergent CT without enteric contrast may decrease patient discomfort, time to diagnosis and chances of aspiration at surgery.

E125. Trauma During Pregnancy: An Imaging Review

Moin P.; Truong J.; Inaba K.; Reddy S. USC Keck School of Medicine, Los Angeles, CA

Address correspondence to P. Moin (paymann.moin{at}gmail.com)

Background: Trauma during pregnancy can be a challenging situation for emergency, surgical, and radiologic providers. Trauma caused by accidents and violence coupled with the complexities of maternal and fetal physiology present a unique set of clinical and imaging considerations for the life of both mother and fetus in the rapid and accurate diagnosis and treatment of traumatic injury. Moreover, preservation of fetal viability entails both immediate and long term outcome assessment during the selection of diagnostic imaging methods. Communication between radiologic and clinical providers is also a key component of a favorable treatment outcome.

Key Issues: Some common presentations of trauma during pregnancy such as gunshot wounds, stab wounds, motor vehicle collisions, burns, falls, and toxic exposures (e.g., drug overdose), will be addressed in our presentation. Important imaging findings and their clinical correlates will be discussed, with cases from our institution included. Selection of imaging modality will also be highlighted. The rapid maturation multi-slice CT and other modalities such as ultrasound and MRI warrant reassessment of imaging study selection criteria.

Format: Microsoft PowerPoint 2003 will be utilized to include didactic information regarding imaging related concerns in the diagnosis and treatment of various presentations of trauma during pregnancy. The presentation will also discuss essential clinical and radiographic findings. Accordingly, interactive cases with corresponding clinical and radiographic findings will be provided.

Teaching Points: 1) To provide an overview of common presentations and key considerations of trauma during pregnancy for both mother and fetus. 2) To highlight the appropriate selection of diagnostic imaging methods that maintain high study acuity while reducing potential harmful effects for both mother and fetus. 3) To illustrate the importance of communication between emergency, surgical, and radiologic personnel in the favorable treatment outcome of trauma during pregnancy.

E126. Shock Thyroid: A New Radiographic Sign Associated With the Hypovolemic Shock Complex in Trauma Patients

Rafoth J.²; Brochert A.¹ 1. Eisenhower Medical Center, Rancho Mirage, CA; 2. Memorial Health University Medical Center, Savannah, GA

Address correspondence to J. Rafoth (joshrafoth{at}yahoo.com)

Objective: The hypovolemic shock complex (HSC) is an infrequently encountered entity found on computed tomography (CT) in trauma victims. CT findings of the HSC include: shock bowel, peripancreatic fluid, decreased caliber of the aorta or IVC, and abnormal solid organ enhancement patterns. We describe a new finding associated with the HSC–"shock thyroid." The CT findings of shock thyroid are heterogeneous thyroid enhancement, thyroidal edema, and low density perithyroidal fluid (–5 to 20 Hounsfield Units).

Materials and Methods: Thoracic CT scans of patients admitted to Memorial Health University Medical Center (MHUMC) were retrospectively reviewed with emphasis placed on the thyroidal region. Computed tomography scans were obtained with either a GE Lightspeed 4-detector or Siemens Sensation 16-detector scanner. Imaging studies, laboratory values, and clinical information were reviewed in patients with CT findings of shock thyroid.

Results: We discovered ten patients with the shock thyroid pattern, all of whom were admitted for traumatic injuries. Nine were involved in motor vehicle collisions; one was admitted with a gun-shot-wound. The spectrum of injuries included pulmonary contusion/hemothorax, solid organ injury, bowel injury, closed head injury, and skeletal trauma. Pertinent results are outlined below: -100% were intubated at the time of initial CT -90% had peripancreatic fluid on initial CT -70% demonstrated shock bowel pattern on initial CT -60% demonstrated a flattened IVC on initial CT -60% demonstrated intraabdominal injury on initial CT -50% had intracranial injury on CT or MRI -50% demonstrated complete resolution of the "shock thyroid" findings on follow-up CT, while the remaining 50% had no follow-up imaging performed

Conclusion: The pattern of shock thyroid is a previously undescribed finding based on our literature search. The exact etiology and significance of the "shock thyroid" is unknown at this time, but it is important to recognize the findings so they are not misinterpreted as traumatic injury to the thyroid gland or adjacent structures.

E127. CT of Abdominopelvic Trauma: "Do Not Miss" Injuries!

Ghermay T.; Adusumilli S.; Patel S.; Al-Hawary M.; Wang S. C. University of Michigan, Ann Arbor, MI

Address correspondence to T. Ghermay (tghermay{at}med.umich.edu)

Background: Computed tomography (CT) of the abdomen and pelvis is the examination of choice for evaluating patients who have suffered blunt trauma. As such, most internal injuries with high morbidity and mortality, including subtle injuries are first diagnosed on CT. Early recognition of these findings can ensure prompt interventional or surgical treatment, or in some cases prevent unnecessary surgery. The purpose of this exhibit is to illustrate the subtle and not so subtle characteristic CT findings of clinically important injuries related to blunt trauma and emphasize the salient diagnostic features and therapeutic implications of each injury.

Key Issues: The exhibit will provide key imaging features of the following "do not miss" injuries as well as highlight imaging techniques to aid in their diagnosis: solid organ injury with an emphasis on recognition of active arterial extravasation; easily overlooked abdominal organ injury (pancreatic, renal collecting system, gallbladder), small bowel and mesenteric injury (including subtle indirect findings), concept of shock bowel and hypoperfusion state, vascular injury of the abdominal aorta and its branch vessels, and typical radiologist's blind spots (including frequently overlooked osseous fractures and body wall injuries).

Format: An interactive tutorial format will be used in this exhibit. Each case will be initially presented as an unknown, and then the viewer will be given the opportunity to have the characteristic findings directly illustrated with arrows and informative text.

Teaching Points: Characteristic CT findings aid in the early diagnosis of serious blunt traumatic injury. The timely recognition of these findings can guide clinical management and potentially improve patient outcome by reducing morbidity and mortality.

E128. Left Lower Quadrant Pain-A Systematic Approach

Sidhu R.; Bhatt S.; Dogra V. University of Rochester, Rochester, NY

Address correspondence to R. Sidhu (Ravinder_Sidhu{at}urmc.rochester.edu)

Background: Causes of right lower quadrant abdominal pain are relatively well known. However, left lower quadrant pain is not very well understood. The etiology of lesions involving left lower quadrant is diverse. In addition to classical urinary tract and gynecological diseases, diverse bowel, omental lesions are also commonly seen. Bowel and omental lesions include sigmoid colon diverticulitis, sigmoid colon malignancy, polyp, inflammatory bowel disease, metastatic/inflammatory omental infiltration and epiploic appendagitis. Gynecologic causes include left ovarian torsion, tubo-ovarian masses, and pelvic inflammatory diseases. Common urinary tract causes include left uretric calculi, and cystitis.

Key Issues: This exhibit will describe the multimodality approach using plain X ray, barium, ultrasound, CT and MR analyzing the lesions involving bowel, omentum, urinary tract, and female pelvic organs.

Format: Didactic presentation with images showing key diagnostic features of left lower quadrant lesion using multimodality approach.

Teaching Points: 1. To understand the diverse causes of left lower quadrant pain. 2. To differentiate imaging features of various pathological processes resulting in left lower quadrant pain.

E129. Imaging Spectrum in Schistosomiasis mansoni: The Findings Revealing the Disease

Manzella A.²; Borba Filho P.²; Correia T.²; Albuquerque A.²; Aguiar A.¹; Carneiro C.²; Kaercher J.²; Helluey K.²; Zelaquett C.²; Rodrigues K.² 1. Hospital da Aeronautica do Recife, Recife, Brazil; 2. Hospital das Clinicas da Universidade Federal de Pernambuco, Recife, Brazil

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

Objective: Schistosomiasis is one of the most important tropical infectious diseases in the world. It is estimated that around 200 to 300 million people are infected and an additional 600 million to 1 billion are at risk for acquiring the infection. The species of major global importance are Schistosoma mansoni, S. haematobium and S. japonicum. The purpose of this essay is to discuss and illustrate the large spectrum of manifestations of Schistosomiasis mansoni.

Materials and Methods: The authors will: 1. Review the pathophysiology of this disease. 2. Illustrate the broad spectrum of typical and atypical imaging findings using multiple imaging modalities (US, CT, MR, angiography, barium contrast studies). 3. Discuss common and unusual complications.

Results: This review includes imaging findings with pathologic correlation (in some cases) of multiorganic involvement of Schistosomiasis mansoni. Involvement of skin, lung, central nervous system, bone, kidney, genital tract, breast, eye, heart and gastrointestinal tract is discussed. Recently reported manifestations of this tropical disease are also presented.

Conclusion: Schistosomiasis is considered to be the most important helminthic disease of man constituting a huge public health problem and radiologists should be aware of the broad spectrum of radiographic findings in patients with this complex disease.

E130. Modern Day Exodus: A Houston Academic Radiology Department Responds to the Large Influx of Hurricane Katrina Refugees

Prabhakar A. M.; Jaimes M.; Diaz-Marchan P. Baylor College of Medicine, Houston, TX

Address correspondence to A. Prabhakar (amprab{at}gmail.com)

Background: In August 2005, Hurricane Katrina caused the displacement of thousands of New Orleans residents to Houston, TX. As part of the relief response, a temporary medical facility was set up in the Astrodome. Our institution was responsible for organizing the radiology department at this clinic.

Key Issues: We will establish the importance and value of having 24-hour radiology services in the wake of a disaster. In addition, we will identify the most important modalities, equipment, and personnel required in disaster radiology. We will also discuss means to deliver radiologist interpretations to a disaster clinic and archive studies and interpretations for later clinical use and billing.

Format: This exhibit will be didactic and have the following structure. 1) Timetable of Katrina and demographics on number of refugees. 2) Organizing and mobilizing radiology equipment to an auxiliary clinic. 3) Staffing requirements and schedule. 4) Utilization data regarding radiological studies at clinic and an associated city hospital. 5) Future directions and summary and what we have learned.

Teaching Points: 1) The importance of integrating a hospital radiology department in disaster preparedness including bioterrorism. 2) How to staff and run a temporary radiology imaging clinic efficiently in a short period of time. 3) The radiologist's role in disaster relief.

E131. Spectrum of Radiographic Abnormalities in 2004 Tsunami Victims: a Pictorial Essay

Prasitvoranan W.¹; Srisuwan T.¹; Kaewlai R.²; Muennuch W.¹; Yenarkarn P.¹; Chuapetcharasopon C.¹ 1. Bumrungrad International Hospital, Bangkok, Thailand; 2. Massachusetts General Hospital, Boston, MA

Address correspondence to W. Prasitvoranan (wit3070{at}csloxinfo.com)

Background: A Tsunami is one of the rarest and most devastating natural disasters on Earth. A Tsunami affected many Asian countries on December 26, 2004, causing loss of lives and infrastructures. In Thailand, there were nearly 5000 deaths, 3000 missing and 8000 injured victims. Because of the rare event and unique radiographic findings, the pictorial review aims to describe the spectrum of abnormalities as seen radiographically.

Key Issues: This presentation is directed toward radiology residents and practicing radiologists. Purpose of this exhibit is to: 1. To review imaging findings of the victims of the 2004 Tsunami. 2. Discuss the imaging features which are unique in the Tsunami setting

Format: Content organization: 1. Information on Tsunamis 2. Injuries related to Tsunamis 3. Imaging features in musculoskeletal (retained foreign bodies, avulsion wounds, laceration wounds, fractures and ligamentous) injuries, neurologic (sand in the sinus, tsunami sinusitis), thoracic (aspiration pneumonitis, pneumonia, hemothorax) and abdominal systems (abdominal wall hematomas, foreign bodies, contusions, visceral organ injuries) in multiple imaging modalities 4. Review of the literature

Teaching Points: 1. Spectrum of abnormalities in Tsunami victims 2. Recognize unique findings found in radiologic imaging of Tsunami patients

E132. Lost in Translation? Classic Signs in Abdominal Radiology: From KUB to CT Scout

Wagner-Bartak N., Mukhi, S.; Chandrasekhar C. The University of Texas Medical School at Houston, Houston, TX

Address correspondence to C. Chandrasekhar (Chitra.Chandrasekhar{at}uth.tmc.edu)

Background: The advent of newer and faster imaging techniques with multislice CT scanners, coupled with easy access, has resulted in the long trusted, dependable KUB to fall by the wayside. CT scouts of the abdomen now inadvertently are substitutes for the traditional KUBs. A wealth of information on KUBs including previously described "classic signs" is still seen on CT scouts. The recognition of these "classic signs" is certainly very useful and adjunctive diagnostic tools that compliment CT diagnoses.

Key Issues: This exhibit will be a comprehensive and educational pictorial review of classic signs in abdominal imaging from the perspective of a CT scout. The educational exhibit will be in a quiz format with correlation of findings on the CT scout with side by side correlation of the findings on cross-sectional imaging.

Format: This exhibit will be in a quiz format.

Teaching Points: 1.To recognize "classic signs" on abdominal CT scouts which have replaced traditional KUBs. 2.Correlate "classic signs" on abdominal CT scouts with the cross-sectional CT images.

E133. Diagnosing Type of NonViral Hepatitis Based on Imaging: Pathologic Correlation and Impact on Management

Sindhwani V.; Singh A.; Mino-Kenudson M.; Thiim M.; Sahani D. Massachusetts General Hospital, Boston, MA

Address correspondence to V. Sindhwani (vsindhwani{at}partners.org)

Background: Never has anyone before tried to chart specific features of different types of nonviral hepatitis (NVH) on one platform and its impact on management. Types of NVH generally encountered are: 1. Alcoholic 2. Autoimmune 3. Metabolic disorder related 4. Secondary to primary sclerosing cholangitis (PSC) and 5. Primary biliary cirrhosis (PBC) 6. Nonalcoholic steatohepatitis (NASH) 7. Obstructive 8. Drug induced 9. Alpha 1-antitrypsin deficiency related and 10. Toxin induced hepatitis.

Key Issues: Enlargement of the caudate lobe and presence of right posterior hepatic notch on MR and CT imaging are more frequent findings of alcoholic cirrhosis. PSC is also associated with caudate hypertrophy but is invariably associated with biliary dilatation. Micronodular cirrhosis is characteristic of alcoholic cirrhosis. Extensive reticular and/or confluent fibrosis with global liver atrophy without caudate or left lobe enlargement and without lymphadenopathy are features of autoimmune hepatitis. Periportal halo sign with lymphadenopathy is pathognomonic of primary biliary cirrhosis. Cholestasis on MRCP is hallmark of cholestatic hepatitis secondary to drugs. Wilsons and hemochromatosis both demonstrate increased attenuation on CT, however marked decreased signal intensity on T2-weighted images is only seen in hemochromatosis as copper is nonferromagnetic. In NASH perivascular fatty infiltration is seen as hyperattenuating perivascular halos.

Format: In an interactive quiz format the exhibit outlines the specific features and differentiating points of different types of NVH. The readers initially answer the basic questions regarding etiopathogenesis of NVH graduating to imaging features and finally to its usefulness in patient management.

Teaching Points: 1. An approach to diagnosis of different types of NVH based on imaging. 2. Hallmark imaging features of different forms of NVH on varied Imaging modalities. 3. By the end, the readers will be able to organize their thoughts as to how different imaging modalities are to be used in a particular sequential order to reach diagnosis alleviating the need of biopsy and thus affecting patient management.

E134. Interventional Radiology: A Powerful Imaging and Therapeutic Strategy Awaiting to Reveal Its Full Potential in Management of Complications of Crohn's Disease

Sindhwani V.; Rabinowitz C.; Gervais D.; Prabhakar H.; Sahani D. Massachusetts General Hospital, Boston, MA

Address correspondence to V. Sindhwani (vsindhwani{at}partners.org)

Background: Surgical exploration with resection and anastomosis is considered as a gold standard for treating napkin ring strictures and fistulous communications. Extensive invasiveness, long hospital stay, potential risks of surgery and poor patient acceptance have driven the exploration for alternatives. Thus, the use of percutaneous management strategies are being advocated more and more in the treatment of complications of Crohn's disease and has a significant impact on management.

Key Issues: A brief overview of varied percutaneous interventional treatment strategies used in management of complications of Crohn's disease with special reference to the pattern of disease, depth of inflammation, mesenteric reaction, sinus tract depiction, formation of abscess, fistulous communications and neoplasms is given.

Format: In didactic format the exhibit charts: 1. Review of etiology and natural history of Crohn's Disease. 2. Brief discussion of imaging techniques in the detection of disease complications a. Small bowel follow through / Fluoroscopy b. CT c. MRI d. Ultrasound/TRUS 3. Case based review of complications and the role of percutaneous diagnosis and intervention in a. Abscess b. Bowel fistula / Fistula in ano c. Neoplasm

Teaching Points: 1. Imaging diagnosis and image-based intervention can be performed to address several specific complications of Crohn's disease. 2. Recognition of complications amenable to image based intervention will optimize patient management.

E135. Extranodal Manifestations of Lymphoma in the Abdomen

Ji H.; Ramaiya N.; Israel D.; Ros P. Department of Radiology, Brigham and Women's Hospital/Dana Farber Cancer Institute, Harvard Medical School., Boston, MA

Address correspondence to H. Ji (hji{at}partners.org)

Background: The survival of the patients with malignant lymphoma has markedly improved, not only due to increase in knowledge of pathologic patterns and new therapeutic concepts, but also in the accurate staging and determination of therapeutic response, especially with advances in imaging techniques. Advances in imaging techniques have increased our ability to detect and characterize the extranodal lymphomatous involvement, resulting in improvements of diagnostic capability and assessment of therapeutic response of lymphoma. This has driven the interest for knowing the imaging features of extranodal manifestation of lymphoma in the abdomen.

Key Issues: We describe the characteristic imaging features of the extranodal involvement of lymphoma, and discuss the various typical and atypical imaging patterns of metastasis to the visceral organ and bone marrow. The spectrum of imaging features, with emphasis on CT, MRI, and PET/CT will be presented. The role of functional imaging in assessing therapeutic response of malignant lymphoma will also be discussed.

Format: The presentation will be in a didactic format. We will present examples of the most common imaging pattern of the extranodal involvement of malignant lymphoma, with relevant images of CT, MRI, and PET/CT.

Teaching Points: 1. To know the common imaging patterns of the extranodal involvement of lymphoma. 2. To appreciate the spectrum of imaging findings of extranodal involvement of lymphoma, with emphasis on PET/CT. 3. To understand the role of PET/CT in the diagnosis, and assessment of therapeutic response of lymphoma, especially in this era of new targeted therapy.

E136. Imaging of Venous Thrombosis in Oncologic Patients

Khosa F.; Ramaiya N.; Johnston C.; Disalvo D.; Jagannathan J.; an Den Abbeele A. Dana-Farber Cancer Institute, Boston, MA

Address correspondence to F. Khosa (fkhosa{at}partners.org)

Background: Venous thrombosis is a multicausal disorder. It is frequently encountered in the oncology setting and is responsible for substantial comorbidity and mortality in these patients. The association between cancer and venous thrombosis was first described by Trousseau more than 100 years ago and studies have documented that cancer patients have a higher risk of venous thrombosis. This may be due to hyper-coagulable effects, direct invasion by the neoplasm, direct or indirect effects of chemotherapy, hormonal therapy or radiotherapy, the presence of indwelling central lines, and following bone marrow transplantation.

Key Issues: The imaging modalities employed for the diagnosis and staging in oncology range from plain radiography to MRI and PET/CT. Once venous thrombosis (VT) is suspected, depending on the anatomy of the region involved, standard objective investigations (compression/Doppler ultrasonography, ventilation-perfusion lung scan, radionuclide venography, computed tomography, MRV or conventional angiography/venography) are all useful for the diagnosis and follow-up. There are four main presentations of VT in an oncology setting i.e. 1. Direct local invasion e.g., sarcoma invading directly into surrounding vessels. 2. Intravenous extension of primary tumor e.g., renal cell cancer growing into the renal vein and IVC. 3. Hypercoagulable state related to the presence of tumor. 4. Thrombosis related to long term central lines and chemo-radiotherapy.

Format: The exhibit will take the form of a didactic presentation. Through a pictorial review, we intend to illustrate the spectrum and emphasize the imaging features of venous thrombosis in an oncology setting as seen on ventilation perfusion scans, radionuclide and conventional venography, ultrasound, C.T and MRI.

Teaching Points: The radiologist may be the first clinician to suggest the diagnosis of venous thrombosis especially in cases where it is not suspected or is clinically silent. Familiarity with the imaging findings of venous thrombosis and the optimal technique for its detection are therefore imperative.

E137. Radiologic Manifestations of the Extracardiac Complications of Infective Endocarditis.

Colen T. W.²; Cook E. E.²; Dubinsky T.²; Gunn M.¹ 1. Harborview Medical Center, Seattle, Washington; 2. University of Washington Medical Center, Seattle, Washington

Address correspondence to T. Colen (tcolen{at}post.harvard.edu)

Background: Infective endocarditis (IE) is a disease which has high morbidity and a mortality rate of 9–30%, even with appropriate diagnosis and therapy. Septic emboli, caused by IE, can affect any organ or tissue in the body with an arterial supply and occur in 12–40% of IE cases. The most common extracardiac organ system involved in IE is the central nervous system. Other organs frequently involved are the lungs (especially in right-sided IE) spleen, kidneys, liver, and the musculoskeletal system. In addition, the arterial system itself is susceptible to the development of potentially fatal mycotic aneurysms. As extracardiac complications often antedate the clinical diagnosis of IE, it is important that the diagnosis is suggested when characteristic findings are encountered during imaging.

Key Issues: This educational exhibit reviews common radiological findings in the extracardiac complications of IE. Imaging techniques include conventional radiography, multidetector CT (MDCT), MRI, angiography and scintigraphy. Emphasis is placed on the MRI and angiographic findings of neurologic complications (e.g., cerebral infarctions, brain abscess, meningitis, intracranial mycotic aneurysm rupture), MDCT findings in thoracic and abdominal complications (e.g., pulmonary septic emboli, splenic, renal and hepatic infarctions and abscesses, and visceral mycotic aneurysm rupture), and scintigraphic and MRI findings of musculoskeletal complications (osteomyelitis/discitis and septic arthritis).

Format: This educational exhibit is organized in an organ system-based format. Complications are grouped by neurologic, thoracic, abdominal and musculoskeletal complications. Illustrative IE cases are shown which demonstrate multiple complications within an organ system and/or cases with complications within multiple organ systems.

Teaching Points: (1) Common extracardiac manifestations the radiologist should look for. (2) Extracardiac findings that can suggest the ultimate diagnosis of IE. (3) Appropriate radiological work-up with conventional radiography, MDCT, MRI, angiography and scintigraphy.

E138. Comparative Study between the Anteroposterior (AP), Anteroposterior with Flexion of the Knees and Hips and Posteroanterior in Ventral Decubitus (PA) Projections for the Lumbar Spine Radiographic Evaluation

Gomes de Almeida F. A.; Franco L. L.; Cerri F.; Domenicis O.; Peng Y.; Costacurta M. A.; Cerri G. G. Hospital Sirio Libanes, Sao Paulo, Brazil

Address correspondence to F. Gomes de Almeida (fabio.abilio{at}ig.com.br)

Objective: Lumbar spine radiography is an important tool for the evaluation of patients with lumbar pain. Besides the fact that the AP projection in dorsal decubitus is the most used projection, other incidences can improve this kind of examination technically, in safety and in its diagnostic accuracy. The purpose of our study is to compare the anteroposterior (AP), anteroposterior with flexion of the knees and hips and posteroanterior in ventral decubitus (PA) projections for the lumbar spine radiographic evaluation in image quality, diagnostic improvement, patient's radiation exposure and X-ray tube wastage.

Materials and Methods: 75 patients were evaluated between 2002 and 2003 in a Siemens Siregraf D2 automatic device with Kilovolt dosage varying between 70 and 81Kv according to the patient biotype. All patients had previously signed an informed consent form. These patients were submitted to three lumbar spines techniques of examination: AP, AP with flexion of the knees and hips, and PA in ventral decubitus. These incidences were then evaluated in terms of image quality and radiation dosage. Two radiologists and one orthopedist individually evaluated and graded each examination.

Results: Our study has shown that the PA projection decreases the radiation dosage in 32% when compared with the AP projection (p < 0.0001), with consequent reduction in patient's radiation exposure and in the X-ray tube wasting. These results were not observed in the AP with flexion of the knees and hips, instead we could see an increase of 8.2% in the radiation dosage (p = 0.010). It was also observed in the PA projection a significant enhancement in the visualization of the vertebral bodies (p > 0.00001), of the pedicles (p > 0.00001), of the discal spaces and surfaces (p > 0.00001), as well as in the visualization of the pathological findings (p > 0.00001). In the AP with flexion of the knees and hips we could only see an improvement in the visualization of the pedicles and the discal spaces and surfaces, although it was not as significant as observed in the PA projection (p > 0.01 and p > 0.0002, respectively).

Conclusion: Based on these results, the authors recommend the use of the PA projection during the radiographic examination of the lumbar spine.

E139. Focal Calvarial Lesions Algorithmic Approach to the Diagnosis

Kanekar S. Penn State Milton Hershey Medical Center and College of Medicine, Hershey, PA

Address correspondence to S. Kanekar (san17kan{at}yahoo.com)

Background: Focal calvarial lesions are often incidentally encountered on cross-sectional examination. They could be either lytic or sclerotic. Though majority of them are incidental and asymptomatic, but yet times vault of information may be available from these lesions and of the underlying disease process. This exhibit highlights the various clinically important verses benign, asymptomatic lesions.

Key Issues: Calvarial lesions could be either lytic or sclerotic. Lytic are more common then sclerotic. For the purpose of this exhibit we have used this classification and further classified them into the following categories: 1) Normal variants 2) Congenital defects 3) Tumors: primary and secondary 4) Iatrogenic 5) Infective and inflammatory 6) Msc: e.g., fibrous dysplasia, Paget's disease, Brown tumor. Commonly encountered sclerotic lesions are osteoma, osseous changes by meningioma, blastic metastasis, sclerotic fibrous dysplasia, healed osteomyelitis. In addition to the illustration of a variety of focal lytic and sclerotic calvarial lesions this exhibit also provides an algorithmic approach to the diagnosis of the focal calvarial lesions depending on various criteria such as whether the lesion is sclerotic or lytic, single or multiple and is involving the inner or outer table.

Format: Our presentation will be a didactic electronic exhibit, illustrating the imaging features of various calvarial lesions.

Teaching Points: 1. Exhibit illustrates spectrum of imaging findings of the focal calvarial lesions. 2. Discuss the plain radiograph, CT and MRI features that allow differentiation between the various focal calvarial lesions

E140. Malignant Melanoma - Not Just Skin Deep!

Jagannathan J.; Ramaiya N.; Van Den Abbeele A. Dana Farber Cancer Institute, Boston, MA

Address correspondence to J. Jagannathan (jjagannathan{at}partners.org)

Background: Malignant melanoma is a high-grade aggressive malignancy with unique potential to metastasize to almost any organ in the body, thus mimicking various primary and metastatic lesions including lymphoma. Awareness of the relevant imaging characteristics is necessary to provide an accurate differential diagnosis. Although CT remains the primary modality for staging, PET/CT is now emerging as a powerful tool for directing treatment issues and assessing response.

Key Issues: We will describe the characteristic clinicopathological behavior of metastases from melanoma, and discuss the various typical and atypical patterns of metastasis from melanoma. The spectrum of findings and imaging features, with emphasis on CT, MRI and PET will be presented. The role of imaging in patients selected for vaccine therapy will also be discussed.

Format: The presentation will be in a didactic format. We will present examples of the most common sites of metastatic involvement, which include the regional and distant lymph nodes, skin and subcutaneous tissue and also illustrate patterns of visceral spread to the lung, liver, spleen, bowel, brain and bones, with relevant images from CT, MRI and PET/CT.

Teaching Points: 1. To understand the clinicopathological behavior of metastases from melanoma. 2. The spectrum of imaging findings, with emphasis on CT and PET. 3. The role of PET/CT in staging melanoma, determining prognosis, and assessing treatment response.

E141. Whole-Body Screening with CT and MRI: Aurea Mediocritas (The Golden Mean)

Sebastian S.; Lauenstein T.; Martin D. Emory University School of Medicine, Atlanta, GA

Address correspondence to S. Sebastian (Sunit.Sebastian{at}emoryhealthcare.org)

Background: Whole-body screening can be regarded as a by product of recent technological advancements in MDCT and MRI. Faster scanning times and superior spatial resolution have propelled the use of Imaging as a screening tool in a predominantly asymptomatic population. However, several issues like protocol optimization, minimizing radiation dose exposure, use of intravenous contrast agents need to be addressed before whole-body screening attains widespread acceptance. Ethical, moral and medicolegal dilemmas further fuel the debate on whole-body screening. This educational exhibit explores the technical aspects of whole-body screening with MDCT and MRI while discussing sensitive moral, ethical, legal and economic issues at the same time.

Key Issues: Whole-body screening using MDCT and MRI with several illustrations, figures and video clips.

Format: Didactic, interactive content organization: A. Introduction B. Clinical indications C. Protocols D. Advantages, disadvantages of each technique E. Ethical, moral, legal and economic issues F. Future directions

Teaching Points: A. Various technical requirements for whole body MDCT and MRI screening with the help of several illustrations, figures and video clips. B. Advantages, drawbacks and artifacts related to each technique.

E142. Various Findings of Epidermal Inclusion Cysts of Whole Body: Demonstration with Sonography

Whang I.; Kim J.; Jang E. Catholic University of Korea, Uijongbu St. Mary's Hospital, Uijongbu City, South Korea

Address correspondence to I. Whang (tiger{at}catholic.ac.kr)

Objective: To include epidermal inclusion cysts (EIC) in differential diagnosis of malignancy mimicking subcutaneous lesions on daily sonogram practice.

Materials and Methods: We scanned 20 patients (M:10, F:10) referred to our clinic with subcutaneous nodules for characterization and differential diagnosis. The scanned region encompassed dermal layers of back (2), flank (1), coccyx (1), buttock (6), suprapubic region (1), neck (2), occipital region (1), axillar (1), and breast (5).

Results: The sonographic findings of EIC varied usually according to their accompanying status not to their location as we expected: Silent nodules only tactually perceptible revealed characteristic benign morphology (10) and malignancy mimicking echogenicity was observed in inflammatory process (7). 3 benign looking findings were noted in inflammatory and postruptured state. The benign sonographic features include well marginated nodule and cord-like structure, and malignancy mimicking features include spiculated border and extremely heterogeneous internal echotexture. Peculiar finding like mass with internal rod-like echogenicity, suggestive of degraded keratin material in cyst was noted in 4 cases.

Conclusion: The most trivial, but most common type of epidermal cyst, or EIC can be noted as wide spectrum finding on sonography: From a well defined nodule to a malignancy mimicking mass. In cases of sonographic findings of dermal origin malignancy mimicking mass plus clinical episode of inflammation or recurrence, complicated EIC should be included in differential diagnosis. The finding of mass with internal rod-like echogenicity could be another characteristic sonography finding.

E143. Scar—From Head to Toe—Imaging Significance of Scars/Central Scars Visualized in Various Lesions throughout the Body

Uppot R. N.; Sahani D. V.; Blake M. A.; Hahn P. F.; Gervais D. A.; Mueller P. R. Massachusetts General Hospital, Boston, MA

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

Background: The appearance of scars visualized within organs and lesions through the body can help characterize the lesion. The detection of a scar may help identify postoperative/postradiofrequency/fibrotic changes. The specific characteristics of a central scar correlate to the pathophysiology of the lesion and can help determine the potential for malignancy and therefore the prognosis for the patient.

Key Issues: The purpose of this exhibit is to review the appearance, location, and clinical significance of a scar/central scar when visualized within various organs and lesions throughout the body.

Format: The format will be didactic. It will be multimodal imaging organized by pathology.

Teaching Points: 1. Review incidence and appearance of scars, central scars within lesions throughout the body. 2. Review multimodal imaging protocols including slice thickness, resolution, MRI sequences, and phase of enhancement used to detect and characterize scars. 4. Provide pathophysiological correlation to the imaging findings. 5. Review the clinical significance of identifying a scar within an organ or lesion within the body.

E144. Fat - From Head to Toe - Imaging Significance of Fat Visualized in Various Lesions throughout the Body

Uppot R. N.; Hahn P. F.; Sahani D. V.; Blake M. A.; Gervais D. A.; Mueller P. R. Massachusetts General Hospital, Boston, MA

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

Background: Fat location is very important for the general prognosis of the patient. Intraperitoneal fat, pelvic lipomatosis, fatty liver and vascular fat carry poor general health prognosis for the patient. Intralesional fat such as myolipomas, adrenal adenomas, angiomyolipomas, benign teratomas visualized on imaging can suggest a benign lesion and therefore a more favorable prognosis.

Key Issues: This exhibit will review fat visualized throughout the body and review the clinical significance for the patient.

Format: The format is didactic and the exhibit will be organized by anatomical structure.

Teaching Points: 1. To review various fat categories including: intracellular fat, extracellular fat, and brown fat and the best imaging modalities to identify them—US, MDCT, PET/CT, In/out phase MRI. 2. To review various locations of fat including subcutaneous, intraperitoneal, retroperitoneal, and the clinical significance for heart disease, diabetes. 3. To review significance of visualizing fat in various organs and lesions throughout the body and the clinical significance on the patient.

E145. Missed Metastases—Causes and Clinical Relevance

Jagannathan J.; Ramaiya N.; Van Den Abbeele A. Dana Farber Cancer Institute, Boston, MA

Address correspondence to J. Jagannathan (jjagannathan{at}partners.org)

Background: The reported error rates in oncological imaging at major academic institutions, have ranged from 25% to 90%, and are surprisingly uniform among all radiological modalities. The majority of cases involve missed cancers, especially lung and breast, at screening procedures. We present some examples of metastases that were missed on restaging scans at our institution, discuss the clinical relevance, analyze the contributing technical and interpretative factors, and steps that can be taken to minimize such errors.

Key Issues: Possible causes for missed metastases in patients undergoing routine staging CT scans can be broadly classified into technical and interpretative factors. Technical factors include absence of oral and intravenous contrast, incorrect window settings and inherent limitation of the modality. Errors of perception, misinterpretation of a suspect finding, subtle abnormality, and slow growth are some of the interpretative factors that may contribute to the missed findings. As a radiologist, proper understanding of the atypical patterns and sites of metastases spread, being alert to the subtle findings and judging a finding in the appropriate clinical context, will significantly enhance the accuracy of image interpretation.

Format: The presentation will be in the form of a quiz. Missed findings reflecting a variety of neoplastic processes will be presented in a random fashion. This will be followed by a short discussion of the factors leading to the misdiagnosis, their clinical significance, and steps that could be taken to avoid such errors. The cases have been carefully selected, each highlighting a teaching point. Emphasis would be on body imaging, including CT, MRI and PET/CT.

Teaching Points: 1. To understand some common pitfalls in oncological imaging and the clinical significance of missed findings. 2. To illustrate the technical and interpretive factors contributing to errors of omission. 3. To highlight steps that can enhance the accuracy of interpretation.

E146. CT Power Injectors: A Primer for Radiologists

Namasivayam S.²; Kalra M. K.²; Waldstein P.¹; Heagy T. A.³; Knipfer J. E.; Sahani D. V.² 1. E-Z-EM Inc., Lake Success, NY; 2. Massachusetts General Hospital, Boston, MA; 3. Medrad Inc, Indianola, PA; 4. Tyco Healthcare/Mallinckrodt, St. Louis, MO

Address correspondence to S. Namasivayam (namasivayam2005{at}yahoo.com)

Background: In the United States more than 58% of CT examinations are performed with IV contrast, and 52% of all CT studies use power injectors. Several advances in injector technology paralleling the advances in CT technology have expanded the clinical applications of CT. In this exhibit we illustrate the classification, features and protocols for CT power injectors and discuss their technical advances.

Key Issues: CT power injectors play a key role in performing contrast-enhanced CT studies in modern state-of-the-art multidetector row CT (MDCT) scanners. Power injectors enable a uniform IV contrast bolus at the preselected injection rates at a carefully controlled pressure. When used with current MDCT scanners, power injectors enabled CT acquisition in multiple dedicated phases of enhancement with a single IV contrast bolus. Power injectors may be broadly classified as single- and dual-head injectors. Dual-head injectors have an additional saline syringe which enables a saline chaser bolus. We will describe the various IV contrast injection protocols, which will be supported by pertinent clinical examples, figures and tables. Recent advances in power injector technology include multi-bolus injections, programmed pause, dual-phase injection, extravasation detection accessory, injector reporting information system and CT scanner integration. Although rare, extravasation can occasionally occur with power injection of contrast if not monitored properly. In conclusion, a thorough knowledge of power injectors is essential for radiologists for appropriate selection of injection protocols, guiding CT technologists for optimal quality CT studies and work flow management.

Format: Didactic electronic exhibit 1. Evolution of injectors 2. Classification 3. Features of each injector 4. Advantages and disadvantages 5. Contrast injection protocols 6. Clinical examples 7. Recent advances 8. Complications 9. Conclusions

Teaching Points: 1) CT power injectors allow uniform and nonfragmented contrast delivery at a preselected injection rate precisely. 2) This enables improved enhancement and dedicated multi-phase acquisition CT studies 3) Recent advances in injector technology include multi-bolus injection, programmed pause, dual-phase injection, extravasation detection accessory, injector reporting information system, and CT scanner integration. 4) Although rare, adequate monitoring during injection is essential to avoid extravasation while using power injectors.

E147. Automated Segmentation of 3D Rendered MDCT Datasets with an Interactive Watershed Transform Algorithm: Applications in Body Imaging

Johnson P. T.¹; Heath D. G.¹; Hahn H. K.²; Fishman E. K.¹ 1. Johns Hopkins School of Medicine, Baltimore, MD; 2. MeVis, Center for Medical Diagnostic Systems and Visualization, Bremen,Germany

Address correspondence to P. Johnson (pjohnso5{at}jhmi.edu)

Background: Three-dimensional (3D) rendering of CT datasets has become an integral component of various applications, particularly vascular and orthopedic imaging. Computer technology has improved dataset editing, one step in the rendering process that was initially cumbersome and time consuming. A variety of computer editing programs for radiologic datasets have been described in the literature and used clinically. The purpose of this manuscript is to describe a promising automated segmentation tool, which uses and extends an Interactive Watershed Transform (IWT) technique to remove selected portions of the anatomy.

Key Issues: The principles behind the interactive watershed transform algorithm will be reviewed, in conjunction with a demonstration of the utility for automated editing of 3D MDCT datasets. Osseous structures are rapidly removed from the volume with minimal interactivity, to enhance viewing of the vasculature. Alternatively, the bones can be selectively extracted to facilitate evaluation of surfaces. Advantages of this tool include efficient segmentation of large datasets.

Format: This educational exhibit is presented in a didactic format. A description of the algorithm is followed by demonstration of clinical applications organized by anatomic location and pathologic entity.

Teaching Points: 1. The reader will gain an understanding of the principles of the watershed transform algorithm as it applies to MDCT volumes. 2. After reviewing the exhibit, the reader will know how to use the segmentation tool for both initial dataset segmentation and refinement of the edited volume. 3. The anatomic regions and pathologic entities best suited for the segmentation tool will be demonstrated through a series of vascular and orthopedic cases.

E148. Utility of FIESTA Sequence in Day to Day MRI Imaging.

Bhosale P. R.; Choi H.; Ma J. MD Anderson Cancer Research Center, Houston, TX

Address correspondence to P. Bhosale (Priya.Bhosale{at}di.mdacc.tmc.edu)

Background: Fast Imaging Steady State Acquisition (FIESTA) is a fully balanced steady state acquisition technique. Because of its high signal-to-noise ratio (SNR) and short acquisition time, FIESTA has been very useful for cardiac imaging but can also be used to produce high SNR and motion-free abdominal images. The contrast in FIESTA images, however, is determined by T2/T1. Therefore, the characteristics and the utility of FIESTA for imaging normal and pathological abdominal anatomy have not been fully studied. With the hardware currently available at MD Anderson, we can routinely acquire FIESTA images of an abdomen with 5 mm slice thickness and in a single breadth hold (<16 seconds) The purpose of this exhibit is to present our early experience with FEISTA for the abdominal MRI.

Key Issues: This exhibit will demonstrate the normal anatomy of abdominal and pelvic organs along with imaging characteristics of various pathologies by organ system. The exhibit will be organized as genitourinary and the gastrointestinal system.

Format: Information regarding the imaging features of common and uncommon abdominal and pelvic masses and their clinicopathological background will be presented. The technical pitfalls will be discussed at the end.

Teaching Points: Upon completion of this exhibit the attendant will learn the values of FIESTA in abdominal imaging and its technical pros and cons, which can be applied to the daily practice for oncologic and non oncologic imaging.

E149. Gadolinium—Associated Nephrogenic Systemic Fibrosis— Why Radiologists Should Be Concerned

Girguis M.; Broome D.; Baron P.; Cottrell A.; Kjellin I.; Kirk G. Loma Linda University Medical Center, Loma Linda, CA

Address correspondence to M. Girguis (mgirguis{at}ahs.llumc.edu)

Objective: Nephrogenic systemic fibrosis (NSF) is a rare multi-systemic fibrosing disorder that affects renal insufficiency patients most commonly resulting in skin fibrosis but may also affect skeletal muscle and other organs. The purpose of our study was to identify any common risk factors and determine whether intravenous gadolinium is associated with the development of NSF.

Materials and Methods: A retrospective chart review was performed of all eleven patients with NSF between 2000 and 2006 at our institution to identify the onset of clinical manifestations, histologic diagnosis, timing and dose of gadolinium administration, dialysis records, concurrent medications, co-morbid conditions and surgeries, laboratory findings, imaging findings and clinical outcome.

Results: The diagnosis of NSF was established by clinical findings, absence of scleroderma serologic markers, and biopsy of skin or skeletal muscle. All eleven patients had renal insufficiency–seven with dialysis-dependent chronic renal insufficiency and five with acute hepatorenal syndrome. All eleven patients had received intravenous gadolinium for MRI examinations within 2 months prior to the development of skin fibrosis. The patients had no other common medications, medical conditions, or surgical history, although six had a vascular surgical procedure in the interval between gadolinium administration and development of NSF. Four patients had abnormal bone scans with skin and muscle uptake and lower extremity MRI finding of edema in the muscles, intermuscular fascia and skin. Despite the fact that nine patients were dialyzed within 2 days of gadolinium administration, this did not prevent the development of NSF. Examples of the bone scan and MRI images will be demonstrated as well as clinical photos of the skin manifestations.

Conclusion: NSF was strongly associated with intravenous gadolinium administration in the setting of either acute hepatorenal syndrome or dialysis-dependent chronic renal insufficiency. Dialysis following gadolinium administration failed to prevent the development of NSF.

E150. Prevalence of Contrast Induced Nephropathy Risk Factors in Patients Receiving IV Contrast Enhanced CT

Rempel J.; Carstensen M.; Jeon P.; Barrett B. Memorial University of Newfoundland, St. John's, Canada

Address correspondence to J. Rempel (jrempel{at}mun.ca)

Objective: Contrast-induced nephropathy (CIN) is a topic of growing concern in radiology departments. Risk factors for developing CIN are well documented, however the prevalence of these risk factors in patients receiving outpatient CT examinations is less well known. CIN has the potential to increase patient morbidity and mortality as well as raise liability concerns for the radiologist.

Materials and Methods: We prospectively studied 200 patients receiving outpatient IV contrast-enhanced CT examinations. By telephone interview, patients were surveyed for risk factors for developing CIN according to the Canadian Association of Radiology guidelines. Records of this cohort were also reviewed for recent serum creatinine values (SCr), and creatinine clearance (CrCl) calculations were performed utilizing the Modification of Diet in Renal Disease Study formula.

Results: Preliminary results of the first 53 patients studied are available at this time. The average patient age was 52 years, with 15% of patients being over 70 years, and 60% being female. One or more risk factors for developing CIN were present in 75% of patients, with hypertension (18) and nephrotoxic drug use (25) being most commonly encountered. Multiple risk factors were present in 51% of the sample. Serum Creatinine values were available for 92% of study patients. Current SCr values (defined as having been obtained in the previous 3 months) were available in 49% of patients. Only 53% of patients with one or more risk factors for CIN had a SCr measured in the preceding 3 months, of which 19% had CrCl values less than 60 ml/min/1.73 m², a value used as an independent risk factor for developing CIN.

Conclusion: CIN risk factors are highly prevalent in this group of patients referred for outpatient IV contrast-enhanced CT examinations, with three-quarters of patients having one or more risk factors. Further, approximately half of those patients at risk for CIN have not had recent evaluation of their renal function, and a significant number of at risk patients with a recent SCr were given contrast with a CrCl under 60 ml/min/1.73 m². It is difficult to say how many patients in this study proceeded to develop CIN, however we have revealed a significant prevalence of patients at increased risk. This necessitates a more proactive role by the respective radiology departments to effectively screen for at risk patients and therefore reduce the incidence and associated morbidity of CIN.

E151. Automatic Kilovoltage Selection Technique in Abdomen MDCT: Radiation Dose and Image Quality

Li J.¹; Udayasankar U. K.¹; Kalra M. K.²; Small W. C.¹ 1. Emory University School of Medicine, Atlanta, GA; 2. Massachusetts General Hospital, Boston, MA

Address correspondence to J. Li (jhli98{at}hotmail.com)

Background: Increased radiation burden is major limiting factor of multidetector CT scanners. Different technological advancements have been introduced in the recent past to reduce the radiation dose. Reducing tube voltage is one of the options; however, random reduction in tube voltage often results in significant deterioration of image quality.

Key Issues: Low KVp can help to reduce radiation dose in MDCT of the abdomen. However, arbitrary reduction in KVp leads to significantly increased image noise and degrades the image quality. Appropriate reduction in KVp should be based on patient size and anatomic characteristics. Automatic KVp selection technique is an innovative technique for optimum radiation dose. It allows an individually tailored reduction in KVp with preservation of diagnostic image quality at a minimum radiation dose.

Format: 1. Effect of low KVp on radiation dose and image quality 2. Application of automatic KVp selection technique in MDCT of abdomen A. technique, B. clinical application (1) radiation dose (2) image quality C. Scanning Protocols D. Limitations, image noise.

Teaching Points: 1. To illustrate effect of low KVp on radiation dose and image quality in abdominal MDCT. 2. To describe the clinical applications, image quality, radiation dose and the limitation of automatic kilovoltage selection technique in MDCT of the abdomen.

E152. Imaging of Fever of Unknown Origin

Trivedi Y.; Yung E.; Motroni B. T.; Kranz A.; Katz D. S. Winthrop–University Hospital, Mineola, NY

Address correspondence to Y. Trivedi (ytrivedi{at}winthrop.org)

Background: The diagnostic workup of patients with fever of unknown origin (FUO) remains a challenge. The spectrum of diseases that may cause FUO include infection, malignancy, inflammatory processes, and idiopathic disorders. The diagnosis of FUO should begin with a thorough history and physical examination. The correct sequence of routine noninvasive laboratory studies should then be performed, based on potential diagnostic clinical clues. The purpose of this exhibit is to discuss the utility of nuclear medicine studies, US, CT, MR, and PET, in the diagnostic work-up of patients with FUO, to demonstrate representative imaging cases, and to review the literature on this topic.

Key Issues: Traditionally, in addition to chest radiography and in some cases sonography, nuclear imaging studies have played a pivotal role in diagnosis of patients with FUO. The literature on this subject, especially with respect to the utility of cross-sectional imaging studies and PET/PET-CT, is unfortunately and surprisingly limited to date.

Format: We will demonstrate a variety of cases where imaging was used to establish a diagnosis in patients with up until that point fever of unknown origin, and will review the literature on this topic.

Teaching Points: A labeled WBC scan, with CT if needed, is preferred with suspected occult infection, whereas a gallium scan is still useful in "classical" FUO. In light of the recent withdrawal of labeled monoclonal antibodies to WBCs, PET/CT will likely become the test of choice for imaging patients with FUO.

E153. The Rim Sign: A Multispecialty, Multimodality Pictorial Review with Pathophysiologic Correlation

Jaimes M.; Nazario J.; Govea C. Baylor College of Medicine, Houston, TX

Address correspondence to M. Jaimes (mjaimes{at}gmail.com)

Background: The "rim sign" has been used by many authors as a general term to describe and characterize the radiologic diagnosis of disease. Because the term has been broadly used in the literature, it has attained multiple definitions leading to ambiguity of the original description. We reviewed the literature in order to unify the concept based on pathophysiologic mechanisms.

Key Issues: An extensive Pubmed literature search using the terms "rim sign" and "rim sign" + "radiology" from 1950–2006 was performed. The search yielded numerous articles, from which 48 were selected from peer reviewed journals. Rim signs that were no longer clinically relevant were excluded. A pictorial review of the most clinically relevant rim signs are presented in an audio-visual format classified by pathophysiologic mechanism.

Format: A rim sign was identified in most imaging modalities and organ systems. The pathophysiology of each rim sign was identified. Rim signs where then grouped into categories including flow dynamics, inflammatory response, mass effect, differential perfusion and tissue composition.

Teaching Points: In the correct context, the rim sign can be utilized as a diagnostic tool of specific disease. This pictorial review provides a subclassification strata to organize "rim signs" based on the pathophysiological mechanisms.

E154. Role of Curved Multiplanar Reformation for Multidetector Row CT in Body and Vascular Imaging

Namasivayam S.; Kalra M. K.; Kalva S.; Sahani D. V. Massachusetts General Hospital, Boston, MA

Address correspondence to S. Namasivayam (namasivayam2005{at}yahoo.com)

Background: Traditional techniques for visualizing anatomical structures are based on planar sections from volume datasets, like images obtained by multi-detector row CT (MDCT). However, planar slices taken in the coordinate system of the volume data often do not provide sufficient diagnostic information. This is because planar slices do not follow the curved course of anatomical structures such as arteries, veins, biliary or pancreatic ducts, and urinary tract, and not all the important details can be shown simultaneously. For better visualization of such curved structures, reformatted images in the coordinate system of a structure must be created which is called curved multiplanar reformation (cMPR). In this exhibit we will discuss the techniques of cMPR for MDCT studies of the body. We will illustrate the various clinical applications of cMPR in body and vascular imaging with pertinent clinical examples.

Key Issues: Advances in MDCT technology enabled near-isotropic voxel volumetric datasets. Thus, high quality multiplanar CT reformation in any arbitrary plane is possible. Depiction of complex course of structure of interest in single two-dimensional image by reformation along its central axis is called cMPR. Object's central axis is determined by connecting a sequence of points along the center of the object through several images. The cMPR techniques may be classified as projected, stretched and straightened. We will discuss the benefits and pitfalls of each technique. Common clinical applications of cMPR in body imaging include better evaluation of perivascular invasion of pancreatic tumors, pancreatic duct abnormalities, bile duct obstruction and urinary tract obstruction. Anomalous vascular anatomy and lesions such as stenosis, aneurysm and thrombosis may also be better demonstrated by cMPR.

Format: Didactic electronic exhibit 1. Background 2. Techniques of curved multiplanar reformation (cMPR) 3. Clinical applications of cMPR for solid organs and tracts in body imaging 4. Clinical applications of cMPR for vascular structures in body imaging 5. Clinical examples 6. Recent advances such as automated cMPR 7. Pitfalls

Teaching Points: 1) cMPR allows structures that run through multiple oblique planes to be displayed in a single two-dimensional image. 2) cMPR enables better evaluation of perivascular pancreatic tumor invasion, pancreatic duct abnormalities, bile duct obstruction, anomalous vascular anatomy, and pathologies of vascular structures such as stenosis, thrombosis and aneurysm.

E155. CT Findings of Groin Hernia Appendicitis

Maizlin Z. V.²; Mason A.¹; Brown C.³; Brown J. A.² 1. Department of Medical Imaging, Ridge Meadows Hospital, Maple Ridge, Canada; 2. Department of Radiology St. Paul's Hospital, Vancouver, Canada; 3. Department of Surgery St. Paul's Hospital, Vancouver, Canada

Address correspondence to Z. Maizlin (zeev25{at}yahoo.com)

Background: Acute appendicitis with the vermiform appendix located in groin hernias is a rare condition. The preoperative diagnosis is important to decrease morbidity. The CT characteristics of appendicitis in groin hernias have not been described in detail. We describe three cases of normal and inflamed appendices found in inguinal and femoral hernias, with demonstration of the imaging characteristics and a review of the literature.

Key Issues: The presence of the normal appendix within a hernia sac is an infrequent finding. The appendix may be found within inguinal, femoral, incisional, or spigelian hernias. Even more rare is acute appendicitis presenting with the inflamed appendix in a hernia, reported in 0.08%–0.13% of hernia operations. The first recorded appendectomy for appendicitis in a hernia sac was performed by Claudius Amyand in 1735 and the condition is often referred to as "Amyand's hernia." The preoperative diagnosis of hernial appendicitis is difficult. Signs and symptoms of acute appendicitis are overshadowed by clinical findings related to hernia and may be mistaken clinically for bowel strangulation or abscess within the hernia. We present cases demonstrating features helpful in preoperative diagnosis of appendicitis in groin (inguinal and femoral) hernias.

Format: Didactic description of the images with background and clinical correlation.

Teaching Points: The viewer will learn: 1. To visualize the presence of inflammatory changes in the hernial sac (fat stranding and fluid collections) which should alert the radiologist to the possibility of hernial appendicitis. 2. To differentiate other causes of abscess formation in a hernial sac. 3. Ways to visualize the appendix in the hernia which is the key to diagnosis. 4. Look for the proximity of the cecum and visualization of the appendix in the hernial sac.

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