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ABSTRACT |
Prasad S. R.3; Surabhi V.3; Vibhute P.3; Fatterpekar. M.1; Som P. M.1; Choyke P. L.2; Chintapalli K. N.3 1. Mount Sinai Medical Center, New York, NY; 2. National Institutes of Health, Bethesda, MD; 3. University of Texas Health Science Center at San Antonio, San Antonio, TX
Address correspondence to S. Prasad (prasads{at}uthscsa.edu)
Background: 1. To review oxygen sensing and homeostasis including the role of Hypoxia-Inducible Factor (HIF) in tumor physiology. 2. To review prototype examples of cancers that depend on the HIF pathway, imaging findings and radiologic-pathologic correlation. 3. To discuss the implications on imaging and management of patients with select cancers (HIF pathway).
Key Issues: • Genes that regulate oxygen sensing and homeostasis • Role of hypoxia-inducible factor (HIF) in oxygen homeostasis and oncogenesis • Role of tuberous sclerosis (TS) genes, Kreb's cycle enzymes (SDH/FH) in HIF regulation • Prototype hereditary disorders of unregulated HIF activity: VHL, TS, hereditary paraganglion syndrome (HPS) and hereditary leiomyomatosis-RCC syndrome (HLRCC) • Role of HIF in sporadic cancers: implications on diagnosis, therapy, and prognosis.
Format: Didactic by imaging with pathologic correlation.
Teaching Points: Select cancers develop mechanisms to activate and sustain hypoxic-response pathways even in normoxia leading to generation of vascular/somatic growth factors. HIF plays a central role in regulating hypoxia and oncogenesis. VHL, TS, HPS, HLRCC, and sporadic cancers such as clear cell RCC show inappropriate HIF overproduction. Cytogenetic changes explain the hypervascular nature of these neoplasms on imaging. Molecular drugs targeting HIF are being developed to improve prognosis.
E419. Radiological Response and Toxicity of the New Targeted Molecular Therapies for Cancer—What the Radiologist Needs to Know
Johnston C.; Ramaiya N.; Sheehy N.; Khosa F.; Van den Abbeele A. Dana Farber Cancer Institute, Boston, MA
Address correspondence to C. Johnston (ciaranjohnston{at}yahoo.co.uk)
Background: Novel antineoplastic agents are frequently being added to the oncologist's armamentarium. Recently, these have included targeted molecular therapies, the prototype of which is imatinib mesylate (Gleevec) for the treatment of gastrointestinal stromal tumors. However, other agents including monoclonal antibodies and small molecule inhibitors have been subsequently employed in the treatment of various malignancies. These include: • anti- angiogenesis agents with activity against vascular endothelial growth factor (VEGF) receptor and epidermal growth factor receptor (EGFR) • other anti- tyrosine kinases inhibitors (such as trastuzumab which blocks the HER2 receptor in Her 2-positive breast cancer) • nontyrosine kinase inhibitors (for example rituximab, antibodies used for CD20 positive large B-cell non Hodgkin's lymphoma). These agents have demonstrated activity against various solid organ and hematological malignancies and are capable of producing a dramatic clinical and radiological response. However, the novel therapies are not without toxicity, which has not been well described to date.
Key Issues: This presentation will outline the typical imaging changes seen after introduction of the targeted molecular therapies, and emphasize that a decrease in lesion size may not always occur and that other parameters, such as enhancement pattern, may be more important. In addition, both agent and class specific toxicities will be demonstrated, some of which may be unfamiliar to the general radiologist and which should not be confused with disease progression.
Format: The exhibit will take the form of a didactic presentation, divided into the following sections: • Types of targeted molecular therapy and their clinical applications • Typical and atypical responses to therapy • Class and agent specific toxicities.
Teaching Points: Radiologists should be aware of the increasing use of targeted molecular therapies for cancer, and know that evaluation by size criteria alone may not adequately reflect disease status. These therapies have potential to cause systemic toxicity, which should be recognized as such, rather than as disease progression.
E420. Extraosseous Tc-99m MDP Uptake in Bone Scintigraphy: Pictorial Review
Lee J. H.; Lewis D.; Shields A. Department of Radiology, University of Washington, Seattle, Washington
Address correspondence to J. Lee (jeanhlee{at}u.washington.edu)
Background: The bone scan using Technetium-99m labeled diphosphonates such as Tc-99m methylene diphosphonate (Tc-99m MDP) has been performed for decades to evaluate various skeletal diseases. The bone scan is highly sensitive for disease, is readily available, can image the entire skeleton at reasonable cost. Therefore, skeletal scintigraphy remains popular despite technological advances in magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography (PET). The normal biodistribution has been well described in the literature, including skeleton, kidneys and bladder. Tc-99m MDP binding occurs by chemoadsorption in osteoid at the interface where the hydroxyapatite mineral component is incorporated into the collagenous matrix. In addition, Tc-99m MDP binds in areas of amorphous calcium phosphate deposition in sites outside the bone. Therefore, bone scintigraphy can potentially delineate a wide spectrum of nonosseous disorders. The extraosseous Tc-99m MDP can be crucial to the diagnosis and may not be apparent in other imaging or clinical evaluation of the patients. Because of the opportunity to make an additional diagnosis, the extraosseous uptake should be inspected in every case.
Key Issues: This pictorial review will illustrate the scintigraphic appearances of an extraosseous Tc-99m MDP uptake that can be encountered in clinical practice including neoplastic (e.g., hepatic metastasis from colon cancer, breast cancer, meningioma, heterotopic ossification, calcinosis in scleroderma), hormonal (e.g., metastatic calcification in hyperparathyroidism), inflammatory (e.g., paranasal sinusitis), ischemic (e.g., autosplectomy in sickle cell anemia), traumatic(e.g., muscle and tendon uptake after injury) and abnormal excretory (e.g., hydronephrosis, neobladder in bladder cancer) conditions. Possible mechanisms leading to extraosseous uptake on Tc-99m MDP in each case will also be discussed. Recognition of these extraosseous uptake abnormalities can enhance the diagnostic value of bone scintigraphy.
Format: This is a didactic pictorial exhibit organized into introduction, basic mechanism of Tc-99m MDP and scintigraphy findings of extraosseous Tc- 99m MDP uptake.
Teaching Points: To be familiar with appearance of pathologic extraosseous Tc-99m MDP uptake in various clinical conditions and to highlight its clinical significance.
E421. The Heterogeneity of PET Meta-Analyses
Williamson J. A. Loyola University Medical Center, Maywood, IL
Address correspondence to J. Williamson (drjawilliamson{at}yahoo.com.au)
Objective: Heterogeneity is the term used for the measure of likeness of tests in a meta-analysis. There are a number of analyses with corresponding parameters for this measure. However there have been no accepted ranges for these parameters. Quality scoring has previously been shown to be disappointing for identifying useful, high quality reviews of diagnostic studies. However, high quality, focused meta-analyses should have low heterogeneity. PET scanning is probably the most highly studied new diagnostic technology since the widespread adoption of meta-analysis as a technique, and is a prime subject for this type of study.
Materials and Methods: A wide-ranging sample of major, high quality meta-analyses of PET oncology scanning were re-analyzed, along with some corresponding low quality reviews of PET oncology scanning. Some of these studies included comparison to CT, and this data was also re-analyzed. It was necessary to derive some equations for the extraction of this data, and these are given.
Results: The results were compared and establish objective empirical ranges of diagnostic test meta-analysis heterogeneity. It was confirmed that it may be possible to distinguish high quality meta-analyses from low quality meta-analyses on an objective basis.
Conclusion: These ranges should allow future researchers to establish the quality of their meta-analytic reviews of diagnostic investigations on an objective basis. It may also allow reviewers, and clinicians to judge the quality of a review of a diagnostic investigation.
E422. Cutaneous Imaging on FDG-PET: Benign and Malignant
Blumer S.; Wax B. N.; Johnson R.; Motroni B.; Katz D. S.; Yung E. Winthrop-University Hospital, Mineola, NY
Address correspondence to S. Blumer (steve492{at}yahoo.com)
Background: With the increased indications for, and utilization of FDG-PET technology, more cutaneous lesions are being detected. This exhibit serves to highlight the PET findings of hypermetabolic cutaneous and subcutaneous lesions including benign and malignant conditions. We will also correlate these PET findings with gross and CT images of these conditions when possible. By demonstrating these cutaneous findings we aim to increase their recognition and expand on differential diagnoses for these findings.
Key Issues: Benign cutaneous lesions will include colostomy sites, inguinal hernias, rhinophema, dermatomyositis and others benign conditions that demonstrate hypermetabolism on PET imaging will be highlighted. Malignant lesions such as metastases, melanoma and lymphoma will also be demonstrated. These lesions are seen on PET imaging and will be correlated with CT images and gross pictures when available.
Format: The proposed exhibit will be in a didactic format organized by false-positive lesions contrasted with true-positive lesions seen on PET.
Teaching Points: By demonstrating these cutaneous findings we aim to increase their recognition and expand on differential diagnoses for these findings.
E423. Lambda Sign in Sarcoidosis on F-18 FDG Positron Emission Tomography: To identify the Specific Pattern of Lymphadenopathy in the Mediastinum to Avoid Potential False Positives in Staging and Restaging of Various Malignancies
Reddy M. P.2; Takalkar A.2; Heldmann M. G.2; Sangster G. P.2; D'Agostino H.2; Lilien D. L.1 1. BRI of Northwest Louisiana, Shreveport, LA; 2. LSUHSC, Shreveport, LA
Address correspondence to M. Reddy (madhupreddy{at}yahoo.com)
Background: Sarcoidosis is a multi-system granulomatous disorder frequently present with bilateral hilar and right para tracheal adenopathy on initial chest radiographs. Now, for staging and follow-up of various malignancies, F-18 FDG is exclusively used and has essentially replaced Ga-67 citrate as a radiotracer of choice including for lymphomas. Identifying this pattern is highly suggestive of sarcoidosis as shown by our illustrated cases of various malignancies with pathologically proven sarcoidosis
Key Issues: To illustrate the importance of identifying this specific pattern of F-18 FDG uptake in the mediastinum involving the bilateral hilar and right paratracheal lymph nodes (Lambda sign) in various malignancies at initial presentation or subsequent development of this pattern after treatment to avoid potential false positives.
Format: This exhibit illustrates various malignancies with typical pattern of Lambda of FDG uptake in the mediastinum in various malignancies which were proven to be sarcoidosis by biopsy. There are different malignancies showed this pattern, mainly including lymphoma.
Teaching Points: 1) To illustrate F-18 (FDG) fluorodeoxyglucose uptake in the whole body on PET in sarcoidosis. 2) To demonstrate the specific pattern of FDG uptake in the mediastinum in the shape of Lambda. 3) To recognize and avoid the potential false positives in staging and restaging of various malignancies.
E424. Value of PET Imaging in Diagnosing Pleural Diseases
Chaudhry S.; Vesselle H. University of Washington, Seattle, WA
Address correspondence to S. Chaudhry (sidhartha.chaudhry{at}gmail.com)
Background: Conventional imaging techniques are suboptimal in characterizing pleural diseases. Pleural thickening and effusion are usually nonspecific in appearance on CT, especially when these findings are primary in origin. Positron emission imaging with FDG is useful in differentiating benign pleural thickening from malignant causes, such as malignant mesothelioma or primary spindle cell tumor of the pleura.
Key Issues: Imaging technique: All patients were scanned after overnight fasting. The blood glucose was tested on the morning of the study. 7-11 mCi of F-18 deoxyglucose (FDG) is administered followed by scanning after 45 mins. All patients receive 1 mg. Lorazepam (Ativan) before the study to reduce paraspinal muscular contractions. Our typical protocol consisted of 5 field of view emission images obtained over the chest and upper abdomen over 45 mins. 3 FOV axial transmission images are obtained for attenuation correction of 15 minutes duration each. Standardized uptake values were obtained over the most metabolically active region by drawing region of interest over the most metabolically active foci. SUV values are normalized using patent's body weight. Imaging Findings: Malignant mesothelioma demonstrates high FDG uptake in a (multi)focal or diffuse manner. This appearance is mimicked by metastatic breast and bronchogenic adenocarcinoma of the pleura. Primary spindle cell tumor generally presents with a focus of significant FDG uptake. Pleural implants from malignant thymoma and lymphoma demonstrate multifocal pleural masses demonstrating moderate uptake, often associated with pleural effusion. Benign conditions of the pleura, even when diffuse in distribution, demonstrate relatively low SUV, usually below 2.8 with high specificity. A notable exception is inflammation from talc pleurodesis which exhibits high FDG uptake, simulating malignant pleural conditions. CT scan appearance or patient history helps in such cases.
Format: This exhibit would be presented in a didactic format highlighting clinical issues, technical factors and pitfalls in the imaging and diagnosis of pleural conditions.
Teaching Points: The viewer at the end of this exhibit will: 1. Know how to perform an FDG-PET examination of the pleura. 2. Be able to differentiate features of different benign and malignant conditions of the pleura. 3. Know the classical PET and imaging pitfalls of different pleural conditions.
E425. Lymphoma Imaging: Pitfalls and Pearls with FDG PET
Brown R. K.; Wong K.; Weadock W. J.; Elstrom R.; Kaminski M.; Frey K. A. University of Michigan, Ann Arbor, MI
Address correspondence to R. Brown (rkjbrown{at}umich.edu)
Background: There is growing utilization of FDG PET in lymphoma patients for staging, restaging and response to therapy. Accurate characterization of findings is critical to appropriate patient care.
Key Issues: This exhibit features a discussion of some common and unusual entities which can be problematic in the interpretation of FDG PET images in patients with lymphoma. Topics covered include benign bone lesions, biopsy sites, trauma, surgery and scarring. In addition, there is a discussion of the significance of incidental uptake in skin, subcutaneous soft tissue, bowel and thyroid. Atypical, but normal patterns of benign muscle uptake and artifacts are also reviewed. Examples of misregistration and attenuation correction errors are demonstrated.
Format: The exhibit will feature illustrative cases that can lead to errors in interpretation.
Teaching Points: Viewers should learn the following: 1. How to recognize normal physiologic variants that can lead to errors in diagnosis. 2. The significance of incidental findings in the thyroid, bowel, muscle and soft tissues. 3. Acquire a better understanding of when foci of uptake may require a biopsy.
E426. Pitfalls in PET/CT: Physiologic or Not Physiologic?
Shin L. K.; Iagaru A.; Quon A.; Kamaya A. Stanford University Medical Center, Stanford, CA
Address correspondence to L. Shin (lshin{at}stanford.edu)
Background: 18F-FDG PET/CT imaging utilizes the strengths of each modality by acquiring both functional and anatomic information, respectively. Analyzing fused images have improved accuracy and confidence levels in PET/CT interpretation. However, errors in interpretation can still occur when normal, physiologic uptake and excretion of 18F-FDG mimics disease (false positive) and when abnormal activity is misinterpreted as normal physiologic processes (false negative).
Key Issues: The physiology of normal 18F-FDG activity will be reviewed as it pertains to different organ systems. The quiz taker will be educated by clinical case examples of false positive and false negative PET/CT exams. Examples of false negative "mimics of normal physiology" include: malignancy of the heart mimicking normal cardiac uptake (angiosarcoma), uptake in bowel mimicking physiologic gastrointestinal uptake (gastric cancer, small bowel lymphoma, neuroblastoma), malignancy masquerading as normal renal excretion of FDG (renal lymphoma, squamous cell of the urethra), uptake in the gonads mimicking normal physiologic activity (krukenberg tumor). Different examples in each category will be shown. Physiologic activity simulating disease (false positives) include: uptake in colon mimicking liver metastases (Chiladiti's), asymmetric muscular activity in compensatory muscles due to adjacent or contralateral muscle atrophy (unilateral vocal cord paralysis), ovarian activity due to fertility treatment hyperstimulation, and uterine uptake due to menstruation.
Format: An interactive quiz will be presented. The audience member will be allowed to click on the site of suspected abnormality with feedback as to whether they are correct. The quiz will be divided into general systems (gastrointestinal, urinary, genital/reproductive, myocardial, musculoskeletal, etc). Clinical history and PET and CT images will be shown. The examiner will be quizzed on identifying the suspected abnormality and then a review of the normal physiologic process and pearls to detect abnormal activity will be discussed.
Teaching Points: 1) Review normal physiologic activity of 18F-FDG. 2) Review pearls when apparent "normal" activity is seen in physiologic locations as to avoid false negative interpretations. 3) Review limitations 18F-FDG PET/CT as a result of physiologic activity. (false negatives) 4) Emphasize importance of clinical history and scrutiny of CT images to avoid false positives.
E427. F-18 FDG PET/CT Imaging of Inflammatory and Infectious Diseases
Nguyen B. D.; Roarke M. C.; Ram P. C.; Ingui C. J. Mayo Clinic, Scottsdale, AZ
Address correspondence to B. Nguyen (nguyen.ba{at}mayo.edu)
Background: F-18 FDG PET/CT is a valuable imaging modality for oncologic evaluation based on the high glucose metabolism of cancer. However not all positive hypermetabolic findings on PET/CT are malignant.
Key Issues: This educational exhibit presents a large spectrum of inflammatory and infectious diseases with radiotracer uptake simulating cancer on PET/CT. They may target different parts of the body including the endocrine, pulmonary, cardiovascular, urinary, digestive and musculoskeletal systems. Each of those benign entities is described with PET, CT, US and/or MR features. Effort is focused on the distinction of those lesions from malignancy. Limitations and pitfalls of PET findings are also discussed.
Format: This electronic educational exhibit is presented as a pictorial essay. For each part of the body and organ system, inflammatory and infectious processes are illustrated with companion malignant cases they may mimic. The scintigraphic patterns of these benign PET/CT findings are discussed in correlation with other conventional cross-sectional imaging modalities in order to differentiate those lesions from malignant tumors. Inflammatory lesions encompass thrombophlebitis, cholecystitis, sarcoidosis, other types of granulomatous formation, pneumoconiosis, sclerosing mesenteritis, musculoskeletal injury, and postradiation and postsurgical changes. Infectious processes include focal and disseminated coccidioidomycosis, histoplasmosis, and abscess with Streptococcus viridans, enterococcus and Actinomyces.
Teaching Points: 1. To present, by organ system, different inflammatory and infectious entities with positive F-18 FDG uptake. 2. To discuss the scintigraphic patterns of these PET findings in correlation with other conventional cross-sectional imaging modalities in order to differentiate those benign lesions from malignant tumors.
E428. More Than Tumor: Taking Another Look at PET/CT.
Veselicky K. A.; Veselicky K. A.; Sawyer K.; Martin D. West Virginia University, Morgantown, WV
Address correspondence to K. Veselicky (kenvrad{at}adelphia.net)
Background: Since its introduction, PET, and now PET/CT has moved to the forefront of oncologic imaging. The combination of functional imaging and anatomic detail offered by PET/CT allows the Radiologist to provide crucial information to clinicians treating patients with cancer. However, PET/CT imaging reveals more than tumor. In fact many disease processes (and benign conditions) besides malignancy can demonstrate increased metabolic activity on PET/CT. Although by definition these are incidental findings on tumor imaging it is important for the radiologist to recognize and differentiate between neoplastic and nonneoplastic conditions in order to facilitate the appropriate medical care for the patient and to avoid that which is not.
Key Issues: The exhibit will address nonneoplastic hypermetabolic activity on PET/CT imaging seen as incidental findings in relation to the patient's stated medical history and the indication for the study.
Format: The format is didactic with multiple examples of nonneoplastic hypermetabolic activity seen as incidental findings on PET/CT. The scope, while limited by exhibit size constraints, will nonetheless include a wide range of etiologies involving nearly every major organ system. Each case will include both CT and fused PET/CT images along with brief narrative describing the findings
Teaching Points: 1. Not all hypermetabolic activity on PET/CT is neoplastic. 2. Not all nonneoplastic hypermetabolic activity on PET/CT is benign. 3. Incidental findings on PET/CT can be clinically significant in the patient's medical care.
E429. 18FDG-PET/CT in Soft Tissue Sarcoma: Looking Beyond GIST
Sheehy N. P.; Johnston C.; Israel D.; Ramaiya N.; Van Den Abbeele A. D. Dana Farber Cancer Institute, Harvard Medical School, Boston, MA
Address correspondence to N. Sheehy (nsheehy{at}partners.org)
Background: The combination of positron emission tomography with 18-F-fluorodeoxyglucose (FDG) and computed tomography (PET/CT) allows functional PET and anatomical CT images to be acquired under identical conditions and rapidly co-registered allowing for accurate localization of pathological areas of tracer uptake. Furthermore, FDG-PET/CT has demonstrated its usefulness in the assessment of the response to novel drugs such as the tyrosine kinase inhibitors in gastrointestinal stromal tumors (GIST). FDG-PET/CT can also be of great utility in diagnosing and monitoring therapeutic response in other soft-tissue sarcomas.
Key Issues: In this educational exhibit, we will use images drawn from 223 wholebody FDG-PET/CT scans in patients with a variety of soft tissue sarcomas. We will demonstrate how FDG-PET/CT is helpful in disease localization, treatment monitoring, and pre- and postoperative staging and restaging. We will describe the utility of FDG-PET/CT in assessing the response of sarcomas to conventional chemotherapy and treatment with novel agents. We will also discuss strategies for optimization of the technique in this setting and the pitfalls that may occur in image acquisition and analysis.
Format: Our presentation will be given in 3 sections: Section 1: This section will deal with the fundamental aspects of FDG-PET/CT and its application in the assessment of soft tissue sarcomas. Section 2: This section will present the typical imaging findings on FDG-PET/CT for the main categories of sarcoma, the use of the technique in assessing response to treatment, and common imaging pitfalls. Section 3: This section will present a number of unknown cases, each of which will be associated with a short quiz. These cases will be carefully chosen to illustrate a number of teaching points.
Teaching Points: 1. FDG PET/CT is a valuable technique in the diagnosis, staging, and restaging of soft tissue sarcomas. 2. FDG PET/CT has the potential ability to rapidly assess the response of these tumors to conventional and molecular-based therapy. 3. The uptake of FDG in soft tissue sarcomas is a complex process and is dependent in part on the cellular differentiation of the tumors. This results in potential pitfalls in diagnosis and in assessment of response to therapy.
E430. Critical Diagnoses Not Detected on Metabolic Imaging
Zarzhevsky N.; Brown R. K.; Weadock W.; Manoharan P.; Alvarez R.; Frey K. A. University of Michigan, Ann Arbor, MI
Address correspondence to N. Zarzhevsky (nzarzhev{at}umich.edu)
Background: PET/CT is a hybrid modality which requires expertise in both functional and anatomic imaging. There are a number of entities which are only detected on either anatomic or functional imaging, but not on both. In addition, there are artifacts unique to functional imaging which can confound interpretation if not properly recognized.
Key Issues: Review of critical findings on hybrid imaging detected only on anatomic images. These include vascular entities such as pulmonary emboli, aneurysms, dissections; solid lesions such as renal cell carcinomas, angiomyolipoma; fistulas; and bone lesions including multiple myeloma, nonFDG-avid metastatic disease; pneumothoraxes and free intraperitoneal air.
Format: The exhibit will feature illustrative cases that demonstrate the above artifacts and pathology.
Teaching Points: 1. Recognition of artifacts that can propagate into functional images. 2. Identification of critical anatomic findings that can be missed on the metabolic imaging. 3. Learn limitations of hybrid PET/CT.
E431. Applications of SPECT/CT in Nuclear Radiology
Roarke M. C.; Nguyen B. D. Mayo Clinic Arizona, Scottsdale, AZ
Address correspondence to M. Roarke (roarke.michael{at}mayo.edu)
Background: With the growing popularity of minimally invasive surgery and intensity modulated radiation therapy (IMRT), precise localization of anatomic targets has become increasing important. Until recently, nuclear imagers relied on planar scintigraphy and conventional SPECT to provide such localization. While these techniques are generally used successfully, exact anatomic localization remains a challenge in many cases. SPECT/CT is a relatively recent addition to the nuclear imaging armamentarium which provides simultaneous coregistered SPECT and CT images, providing more precise anatomic localization than conventional techniques. In addition, most surgeons and radiation oncologists today are already comfortable with reading CT images and therefore the location of a surgical or IMRT target can be more effectively communicated prior to the procedure.
Key Issues: Precise anatomic localization of surgical and radiation therapy targets is becoming increasingly important with the growing use of minimally invasive surgery and IMRT. SPECT/CT can more quickly and accurately localize these targets than planar or SPECT scintigraphy alone. Communication of the findings via CT images provides a rapid, telegraphic way for the surgeon and radiation oncologist to review the location of such targets.
Format: In didactic format, this exhibit will present multiple clinical examples of how SPECT/CT enhanced the localization of surgical or radiation treatment planning targets. Examples presented will include localization of parathyroid adenomas, sentinel lymph nodes, neuroendocrine tumors, prostate cancer and bone metastases.
Teaching Points: 1. Clinical situations in which use of SPECT/CT provides more precise localization of surgical and IMRT targets and improves communication of the findings to the referring clinician. 2. Learn how SPECT/CT can be effectively incorporated into typical clinical nuclear imaging protocols.
E432. The Value of Combining Single Photon Emission Computerized Tomography and Computerized Tomography SPECT/CT in the Investigation of Spondylolysis and Lower Back Pain
Paluch M.; Klein D. A.; Scharf S. C.; Epstein N. Lenox Hill Hospital, New York, NY
Address correspondence to M. Paluch (mariopaluch{at}hotmail.com)
Objective: Demonstrate the utility of a novel technology, SPECT/CT fusion imaging in the diagnosis of spondylolysis and other etiologies of lower back pain. SPECT/CT fusion provides precise anatomic correlation between SPECT radionuclide imaging, and computerized tomography.
Materials and Methods: In our experience at Lenox Hill Hospital New York, NY we have utilized SPECT/CT in several patients who presented with lower back pain and the presumptive diagnosis of spondylolysis. This presentation is based on 6 cases of lower back pain, 4 of them were diagnosed as spondylolysis. Utilizing a dual head gamma camera bone SPECT images are routinely obtained 2 hours after the administration of 20 mCi of technetium-99m oxidronate sodium. The data is reconstructed in axial, sagittal and coronal planes. Computerized tomographic images are obtained in the sections of 3mm thickness and in 3mm intervals. Multiplanar reformats are produced for each case. Proprietary software is then used to combine the nuclear data with the CT data to provide fused imaging. The images are then reviewed by nuclear medicine and musculoskeletal radiology specialists in cohort. Spondylolysis or a stress fracture of the pars interarticularis is a common finding in the lumbar spine. Single photon emission computed tomography has been shown to be effective in detection of spondylolysis. However other etiologies of pain arising from the spine such as, osteoid osteoma, infection, facet joints osteoarthritis or other fractures may have a similar appearance.
Results: Active spondylolysis is symptomatic disruption of the pars interarticularis, identified on SPECT/CT as a fracture with focally increased scintigraphic activity. Bone stress response, which may progress to a fracture, is identified as an area of increased scintigraphic activity at the pars interarticularis, without evidence of lucent fracture line on SPECT/CT. The combination of SPECT with computed tomography gives the most precise location of the abnormal scintigraphic activity in patients with lower back pain and assists in differentiating spondylolysis from other etiologies with similar clinical and scintigraphic presentations and confounding or nonspecific CT findings.
Conclusion: 1.SPECT/CT provides superb precision in the localization of tracer uptake in patients who present with low back pain. 2. The improved localization in conjunction with CT imaging findings assists in differentiating the different etiologies of lower back pain.
E433. Combined Transmission and Emission Tomography in Challenging Cases of Ectopic Splenic Tissue
Friedkin A. M.; Brown R. K.; Ellis J.; Weadock W.; Meyer C.; Frey K. University of Michigan, Ann Arbor, MI
Address correspondence to A. Friedkin (friedkin{at}umich.edu)
Background: Ectopic splenic tissue, either in the form of accessory spleens or splenosis, can present a diagnostic dilemma when seen on CT, ultrasound, and/or MRI, often mimicking more ominous lesions.
Key Issues: This exhibit features illustrative cases demonstrating that combined functional and anatomic imaging in the form of fused CT and SPECT data can aid in the detection of ectopic splenic tissue.
Format: The exhibit will utilize a didactic format with multiple imaging examples including various modalities (ultrasound, MRI, CT, nuclear scintigraphy, and SPECT/CT) to demonstrate the challenges of accurately identifying and localizing ectopic splenic tissue.
Teaching Points: 1. Demonstrate how ectopic splenic tissue can be a diagnostic dilemma on anatomic imaging. 2. Demonstrate the benefit of combined transmission/emission tomography for accurately identifying and localizing ectopic splenic tissue. 3. Understand the indications for imaging with heat damaged red blood cells versus sulphur colloid.
E434. Mysterious Radiopharmaceutical Localization: A Pictorial Interactive Exhibit
Joseph U. A.2; Barron B. J.2; Wan D. Q.2; Raspberry D. L.1 1. Memorial Hermann Medical Center, Houston, TX; 2. U. of Texas-Houston Medical School, Houston, TX
Address correspondence to U. Joseph (usha.a.joseph{at}uth.tmc.edu)
Background: Numerous reports have been published about various classic altered distributions of radiopharmaceuticals. Classic examples are free pertechnetate on a bone scan, clumping of MAA or metabolic disturbances. This presentation offers more complex and intriguing alterations collected from various affiliated nuclear medicine departments over the past several years. Altered radiopharmaceutical production may produce unwanted end products. Chromatography is commonly used to help guide the physician in understanding the mechanism of aberrant uptake. Most radiopharmaceuticals aberrations can be detected through standard Quality Control (QC) procedures. However, some problems cannot be found by standard technique. Knowing the possible variations of radiotracer distribution will allow physicians to more accurately interpret the findings.
Key Issues: This presentation will review standard quality control procedures for radiopharmaceuticals and will set up an algorithm to determine the cause of unexplained distributions. Representative cases to be discussed include abnormal FDG uptake in the lungs and IV lines, brain uptake on a bone scan, FDG localization due to altered fasting patterns, the effect of radiation on FDG images, liver/spleen uptake on bone scan, splenic uptake on bone scan (nonsickle cell), bone tracer in the liver spleen only, bone uptake on DMSA scan, liver spleen uptake on DMSA scan, ureteral uptake on DMSA scan and nonvisualization of the heart on a tagged RBC study. In addition more common presentation like lung uptake on bone scan and bowel uptake on various scans will be shown.
Format: After each case is presented, the viewer will be given the option of several possibilities and will be taken through various steps in the QC process to determine the etiology
Teaching Points: 1. Standard QC of radiopharmaceuticals 2. Unusual occurrences that can affect distribution. 3. Relatively rare disease states that can show unusual distribution. 4. Viewer should be able to follow algorithm as aid to determination of altered distribution etiology and significance.
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