A preliminary report on the impact of ¹8F-FDG PET/CT in the management of paediatric head and neck cancer.

INTRODUCTION: Paediatric head and neck malignancy accounts for 5% of all paediatric cancers. The choice of treatment and prediction of prognosis depend on the histological type of tumour, initial staging, evaluating treatment response and detection of early recurrence. Conventional imaging modalities have many limitations. Positron emission tomography/computed tomography (PET/CT) is more accurate; however, so far, the literature lacks reports of large groups of paediatric patients. AIM: To report the role of PET/CT in factors affecting the choice of treatment at the newly established Children Cancer Hospital in Cairo, Egypt, which is one of the busiest dedicated paediatric oncology centres in the world. All findings were proven by histopathology, radiology and by clinical follow-up. PATIENT POPULATION: Thirty-six paediatric patients (30 boys and six girls) with various histologically proven head and neck cancers were included in this study. Their age ranged from 2 to 17 years. High-resolution diagnostic CT and/or MRI of the head and neck, and in relevant cases also of the chest and the abdomen, were performed in all patients at a mean interval of 1.6 weeks (range, 1-3 months) before the PET/CT study. Results of PET/CT were compared with the findings of these conventional imaging modalities. RESULTS: The sensitivity, specificity, accuracy, positive and negative predictive values of PET/CT against the conventional imaging were as follows: sensitivity 100 and, 53%, specificity 89.5 and 47%, accuracy 94.5 and 50%, positive predictive value 89.5 and 47% and negative predictive value 100 and 53% respectively. PET/CT changed patient management in 50% of the cases. CONCLUSION: PET/CT in paediatric head and neck carcinoma is more accurate than conventional imaging. Therefore, it also has a significant impact on further patient management. We recommend that it should be the first imaging modality for all purposes in initial staging, evaluating treatment response and follow-up in paediatric head and neck carcinoma.

Role of PET/CT in malignant pediatric lymphoma.

INTRODUCTION: Malignant pediatric lymphoma accounts for 10-15% of all pediatric cancers, (representing 2-3% of all malignancies), with a peak incidence between 5-9 years. Chemotherapy is usually the first and most common mode of treatment. The choice of treatment and prediction of prognosis depend on the histological type of tumor, initial staging, evaluating treatment response, and detection of early recurrence. Conventional imaging modalities have many limitations. PET/CT is more accurate, however so far the literature lacks the results of a large group of patients. AIM OF STUDY: To report the role of PET/CT in the above-mentioned objectives at the newly established Children's Cancer Hospital in Cairo, Egypt, which is one of the busiest dedicated pediatric oncology centers of such purposes in the world. All findings were proven by histopathology, clinically, and by clinical follow-up. PATIENT POPULATION: A total of 152 patients (35 girls and 117 boys) with histologically proven malignant lymphoma (117 HD, 35 NHL) were included in this study. They were divided into four groups. Group I: 41 patients for initial staging. Group II: 51 patients for evaluating early treatment response after two to three cycles of chemotherapy. Group III: 42 patients for evaluating treatment response 4-8 weeks after the end of their treatment. Group IV: 18 patients evaluated for long-term follow-up. Results of PET/CT were compared with the other conventional imaging modalities (CIM). RESULTS: The sensitivity, specificity, accuracy, and positive and negative predictive values of PET/CT and CIM were as follows: In Group I: PET/CT modified staging and treatment in 11 out of 41 cases (26.8%), upstaged 5(12.2%) patients and down-staged six (14.6%) patients. Group II: 100%, 97.7%, 98%, 85.7%, 100%, respectively, for PET/CT and 83%, 66.6%, 68.6%, 25%, 96.7% for CIM respectively Group III: At the end of chemotherapy 100%, 90.9%, 92.8%, 75%, 100%, respectively, for PET/CT and 55.5%, 57.5%, 57.1%, 26.3%, 82.6% for CIM, respectively. Group IV: For long-term follow-up, all the parameters scored 100% for PET/CT, 100%, 38.4%, 72.2%, 50%, 100% for CIM, respectively. CONCLUSION: PET/CT in pediatric lymphoma is more accurate than CIM. We recommend that it should be the first modality for all purposes in initial staging, evaluating treatment response and follow-up.

False-positive F-18 FDG uptake in PET/CT studies in pediatric patients with abdominal Burkitt's lymphoma.

INTRODUCTION: In pediatric patients with abdominal Burkitt's lymphoma, the involvement of the gastrointestinal tract and abdominal lymph nodes are the main presenting feature of the disease. Chemotherapy is the main treatment modality and could be preceded by surgical excision of the abdominal masses. To achieve cure or long-term disease-free survival a balance has to be struck between aggressive chemotherapy and the probability of tumor necrosis secondary to treatment complicated by acute infections, perforation or intestinal bleeding. F-18 fluorodeoxyglucose-positron emission tomography/computed tomography (F-18 FDG-PET/CT) has been recommended over conventional imaging modalities for the follow-up of these patients and for monitoring treatment response. As the incidences of postchemotherapy complications are high, the positive predictive value of PET/CT studies in these patients is very low and the false-positive rate is high from acute infections and tumor necrosis. Accordingly, histopathological confirmation of positive lesions on F-18 FDG-PET/CT studies is essential. This is especially important as post-therapy complications might present with nonspecific and nonurgent symptoms. At the same time initiating a second course of salvage chemotherapy is risky. AIM OF STUDY: Retrospectively reviewed F-18 FDG-PET/CT studies for 28 pediatric patients with abdominal Burkitt's lymphoma and diffuse large B-cell lymphoma after their treatment with chemotherapy or surgery. RESULTS: Four positive studies were found. All had pathological verification and were because of acute inflammation and tumor necrosis and there was no evidence of viable tumor cells. One patient had multiple recurrent lesions in the abdomen after the initial surgical excision and before starting chemotherapy. The incidence of acute complications in this series is 10.7%. CONCLUSION: This study confirms the high incidence of tumor necrosis and inflammation after chemotherapy for the abdominal Burkitt's lymphoma and consequently, the incidence of true-positive F-18 FDG studies is low. This necessitates the need for histopathological confirmation of positive studies.

PET/CT image fusion error due to urinary bladder filling changes: consequence and correction.

OBJECTIVE: A considerable change of urinary bladder (UB) shape in PET compared with CT in integrated PET/CT system is frequently noted. This study initially evaluated this finding with and without oral contrast (OC) use. In addition, a one bed pelvic section (PLV) repeat acquisition was investigated as a solution to this problem. METHODS: (18)FDG PET/CTs of 88 patients were analyzed. OC was administered in 68 patients, of whom 31 had PLV images taken 5-10 min later. Three-dimensional mid-UB CT and PET matching measurements were compared. In addition, UB walls displacement between CT and PET were analyzed. RESULTS: The mean UB height was significantly increased (P < 0.001) in PET when compared with CT, both anteriorly and posteriorly; however, UB width and depth were not significantly different. An upward shift of superior UB wall in PET from equivalent CT images was noted, whereas there was no appreciable displacement of the other UB walls. The percent UB height increase on PET from CT was significantly greater with than without OC use. The UB height difference between PET and CT was markedly reduced on PLV when compared with the original scans. CONCLUSIONS: Caution should be exerted during the interpretation of PET/CT scans of the pelvis as there is significant upward expansion of UB on PET compared with CT that appears to be exaggerated by OC use, likely due to additional fluid load. The PET/CT fusion errors of UB can be substantially resolved through a separate PLV acquisition presumably due to the shorter time interval of UB scan completion between CT and PET.

Impact of PET and CT in PET/CT studies for staging and evaluating treatment response in bone and soft tissue sarcomas.

PURPOSE: Study impact of F-18 FDG PET/CT on initial staging, restaging, and evaluating treatment response (ETR) in bone and soft tissue sarcomas (BSTS), focusing on discrepancy between CT and PET portions. PATIENTS AND METHODS: Ninety-three BSTS patients having 204 F-18 FDG PET/CT studies were retrospectively reviewed. They were divided into 4 groups. Group I for initial staging included 16 patient studies. The other 3 groups were divided according to the time interval from last treatment received. Group II for ETR up to 2 months included 83 studies. Group III was for early restaging after 2 to 6 months included 45 studies. Group IV was for long-term follow-up after 6 months included 60 studies. All results were confirmed either by pathology, or by clinical follow-up. RESULTS: Sixteen studies for initial staging were concordant in 14 and discordant in 2 patients (48 lesions, 46 concordant, and 2 discordant). PET showed 97.2% sensitivity and 100% specificity versus 100% and 91.6% on CT. Regarding the other 3 groups, 498 lesions were detected; PET and CT were concordant in 436/498 (88%) and discordant in 62/498 (12%). In group II for ETR, PET and CT were concordant in 64/83 (77%) and discordant in 19/83(23%) studies-13 showed excellent to complete response on PET with partial response (PR) or stable disease (SD) on CT; 6 studies in PET showed PR versus SD or progression of disease (PD) on CT. In group III, for early restaging of disease 36/45 (80%) concordant and 9/45 (20%) discordant (3 showed excellent to complete response and 2 PR on PET versus CT SD, 3 PET PR versus CT PD, and 1 PET study showed PD while CT showed SD). In group IV, for long-term restaging, 49/60 (82%) were concordant and 11/60 (18%) were discordant; 9 PET studies were negative for active disease versus CT positive and 2 PET studies showed PD, CT was negative. PET alone showed 94.1% sensitivity and 94.6% specificity versus 97.2% and 63.5% for CT, 100% and 95.9% for PET/CT. CONCLUSIONS: In BSTS for the purpose of initial staging, ETR, short-term, or long-term restaging, FDG-PET is more accurate than CT. Combined PET/CT has higher accuracy than either alone.

Combined rest redistribution thallium-201 SPECT and low-dose dobutamine contractility assessment in a simple and practical new viability protocol.

OBJECTIVE: Rest-redistribution (RR) thallium-201 (Tl-201) imaging is commonly used for myocardial viability evaluation. Contractile reserve (CR) assessment with low-dose dobutamine (LDD) is another method that highly predicts functional recovery following revascularization. In this study, we investigate the feasibility of a new protocol that provides combined Tl-201 uptake, resting and CR functional regional myocardial information in a single examination. METHODS: A total of 41 patients underwent RR-gated-SPECT Tl-201 myocardial perfusion imaging. The LDD infusion was maintained during delayed imaging. Segmental Tl-201 uptake was classified into normal, fixed decrease (mild to absent) and reversible, and sub-classified by wall motion (WM)/thickening (WT) changes between early resting and delayed LDD gated images into normal, fixed or improved dysfunctional (CR present) segments. RESULTS: Out of 820 examined segments, 33 showed no appreciable Tl-201 uptake to evaluate WM/WT. In a dysfunctional myocardium, CR was significantly higher (P < 0.001) in reversible and fixed than in normal Tl-201 segments. The CR in dysfunctional segments with fixed decrease Tl-201 uptake was significantly higher (P < 0.05) in mild and moderate than in severe fixed defects. Both fixed Tl-201 defects and lack of CR were observed more (P < 0.05) in akinetic/dyskinetic than in hypokinetic segments. CONCLUSIONS: Simultaneous assessment of myocardial viability by RR Tl-201 uptake, resting and CR functional regional information is feasible and can be easily attained using this new protocol. Moreover, this protocol requires no additional time or radioactivity when compared with the usual RR Tl-201 protocol. Validation of this protocol with patients' revascularization data is needed.

Impact of PET/CT in comparison with same day contrast enhanced CT in breast cancer management.

PURPOSE: To evaluate the impact of F-18 fluorodeoxyglucose (FDG) positron emission tomography with fused computerized tomography (PET/CT) in comparison with same day contrast enhanced CT (CE-CT) in breast cancer management. METHOD: Seventy studies in 49 breast cancer patients, 17 for initial and 53 for restaging disease were included. All patients underwent PET/CT for diagnostic purposes followed by CE-CT scans of selected body regions. PET/CT was started approximately 90 minutes following IV injection of 10-15 mCi of F-18 FDG on a GE Discovery PET/CT system. Oral contrast was given before F-18 FDG injection. The CE-CT was performed according to departmental protocol. RESULTS: Out of a total of 257 lesions, 210 were concordant between PET/CT and CE-CT. There were 47 discordant lesions, which were verified by either biopsy (35) or follow-up (12 PET positive CE-CT negative lesions). PET/CT correctly identified 25 true positive (TP). CE-CT identified 2 TP lesions missed by PET/CT which were false negatives (FNs): one liver metastasis with necrosis, which was nonavid to FDG uptake because of necrosis and a second one missed on abdominal metastatic node, which did not change staging or treatment. PET/CT incorrectly identified 2 false positive lesions while CE-CT incorrectly identified 18 false positive. TP recurrence of the disease was found by PET/CT in 44% (15/34 pts), whereas 56% (19/34 pts) were free of disease. The CE-CT described progression of the disease in 1 true negative PET/CT study and no progression in 2 TP PET/CT studies. The sensitivity, specificity, accuracy, positive productive value, and negative productive value for PET/CT were 97.8%, 93.5%, 97.3%, 99.1%, 85% and for CE-CT were 87.6%, 42%, 82.1%, 91.6%, 31.7%. CONCLUSION: In this study, PET/CT played a more important role than CE-CT scans alone and provided an impact on the management of breast cancer patients.

Scintigraphic visualization of an epigastric sentinel node in recurrent breast cancer after lumpectomy and postoperative radiation therapy.

Sentinel node imaging and biopsy have become standard procedures for staging early breast cancer. Positive sentinel lymph node (SLN) biopsy necessitates the need for axillary lymph node dissection (ALND). Failure to visualize a sentinel lymph node in recurrent breast cancer after treatment by surgery, chemotherapy, and high-dose postoperative radiation therapy is almost the case in every patient. The reason for failure to visualize the sentinel node is the fibrosis that follows high-dose radiotherapy and blocks the lymphatics preventing spread of the tumor cells to the lymph nodes. Alternative pathways for the drainage of lymph from the breast are developed in these patients. We have previously reported on the alternative pathways of lymphatics to the contralateral axilla, supraclavicular area, and also reported on the development of intramammary lymph nodes. In this report, we are presenting another alternative pathway of lymphatics to the region of the epigastrium below the lower end of the sternum.

Pigmented purpuric dermatosis and hepatitis profile: a report on 10 patients.

BACKGROUND: Pigmented purpuric dermatosis comprises a group of vascular disorders of unknown etiology. Histologically, it is characterized by lymphocytic capillaritis in the papillary dermis. Although leukocytoclastic vasculitis confined to the skin is frequently reported with hepatitis C, lymphocytic vasculitis is rarely reported. METHODS: Ten patients with pigmented purpuric dermatosis were studied clinically and histopathologically. Hepatitis profile was carried out in all of the patients to evaluate the possible relation. RESULTS: Of the 10 patients, five tested positive for hepatitis C and two for hepatitis B antibodies. CONCLUSION: Hepatitis C and B virus may play a role in the pathogenesis of pigmented purpuric dermatosis. Further case-control studies are necessary to confirm this conclusion.

Technetium-99m diphosphonate imaging of psammocarcinoma of probable ovarian origin: case report and literature review.

Technetium-99m methylene diphosphonate (Tc-99m MDP) bone scans have long been used by clinicians to diagnose osseous metastases in patients with cancer. However, in several benign and malignant diseases, notably those characterized by extensive soft tissue calcification, Tc-99m MDP may be taken up by the tumor itself. We present a case of a stage IIIC psammoma-rich low-grade serous carcinoma of the ovary, whose identity and extent of disease were first suggested by Tc-99m MDP scintigraphy. The literature concerning this form of cancer, and the use of Tc-99m MDP bone scans to image soft tissue lesions, are reviewed.

Alternative lymphatic pathway after previous axillary node dissection in recurrent/primary breast cancer.

OBJECTIVES: The sentinel lymph node approach has almost become the standard procedure of choice in the management of patients with early breast cancer. The status of sentinel nodes, whether or not pathologically involved by cancer cells, represents those of the axillary nodes with a negative predictive value of almost 100%. If the axillary lymphatic nodal drainage is altered, alternative lymphatic pathways and accordingly sentinel node location will be changed. METHODS: In this article, 4 patients are presented, 3 with recurrent breast cancer who had already undergone lumpectomy, axillary node dissection, and radiotherapy in the past and 1 with primary breast cancer after surgical removal of a malignant melanoma on her back and had axillary node dissection on the same side as the breast cancer. These patients underwent lymphoscintigraphy followed by sentinel node localization using the gamma probe and also blue dye injection during surgery. RESULTS: All patients showed alternate lymphatic pathways, 1 had an ipsilateral internal mammary node and crossed lymphatics to a contralateral axillary node, 2 had intramammary sentinel nodes, and 1 had an internal mammary on the same side. Pathologic examination of the intramammary and contralateral sentinel nodes were negative for metastases. Internal mammary sentinel nodes were not biopsied. CONCLUSION: We feel that sentinel node lymphoscintigraphy should be done even in patients who have altered lymphatic pathways resulting from previous axillary node dissection. It allows identifying and biopsy of the sentinel node at its new unpredicted location.

Value of low-dose dobutamine addition to routine dual isotope gated SPECT myocardial imaging in patients with healed myocardial infarction or abnormal wall thickening by echocardiogram.

There is overlap in myocardial viability detection by thallium-201 uptake and contractile reserve (CR) using low-dose dobutamine (LDD). The dual isotope protocol was modified in this study by acquiring thallium-201 images using LDD to enhance viability detection in addition to coronary flow reserve assessment. One hundred twenty-four patients with coronary disease underwent gated single-photon emission computed tomographic thallium-201 imaging at rest with LDD (10 microg/kg/min) during acquisition followed by stress technetium-99m sestamibi myocardial perfusion (MP) imaging with dobutamine, adenosine, or treadmill exercise. F-18-fluorodeoxyglucose (FDG) positron emission tomography was obtained in 41 patients. Myocardial perfusion (MP) imaging was divided into normal, fixed, and ischemic segments, and subclassified by wall motion and/or thickening changes between 1-hour poststress and LDD into normal, fixed, or improved dysfunctional segments (CR present). Mean left ventricular ejection fraction was 39% at 1 hour after stress and 47% with LDD (p <0.001). In dysfunctional myocardium, CR was significantly higher (p <0.001) in ischemic (233 of 368) and fixed segments (150 of 335) than in normal MP segments (43 of 220). Combined MP and CR analysis showed higher accuracy and negative predictive value in identifying FDG-viable myocardium than either method alone, whereas a high positive predictive value was maintained, similar to both markers. Quantitative analysis showed significant increased wall motion and thickening with LDD compared with 1 hour after stress, which was highest in ischemic segments and lowest in fixed segments. Thus, LDD dual isotope is a practical protocol that improves viability detection by simultaneous MP and CR analysis in addition to coronary flow reserve assessment in 1 study. Moreover, it requires no extra imaging time or radioactivity than the routine protocol.

Retrospective analysis of sentinel node localization in multifocal, multicentric, palpable, or nonpalpable breast cancer.

UNLABELLED: Multicentric or multifocal breast cancer is considered as one of the limitations for sentinel lymph node (SLN) localization. We did a retrospective analysis to evaluate the success rate, sensitivity, accuracy, and negative predictive values of SLN localization in multicentric or multifocal breast lesions. METHODS: Fifty-nine patients with multifocal or multicentric breast lesions proven by either fine-needle aspiration (19/59), core biopsy (39/59), or lumpectomy (8/59) underwent SLN localization. Of these patients, 46 had SLN localization by both radiocolloid and blue dye, and 13 had SLN localization by radiocolloid alone. Approximately 10 MBq (99m)Tc-labeled unfiltered sulfur colloid in 0.3-0.4 mL were injected intradermally over the 1 or 2 breast tumor locations 2-4 h before surgery. During surgery, vital blue dye was injected intraparenchymally in 4-6 places around the tumor. All lymph nodes with counts of >10 times that of the background counts, whether or not blue dye positive, and all blue dye-positive lymph nodes, whether or not radiocolloid positive, were excised and labeled accordingly. All lymph nodes underwent frozen sectioning and were examined by hematoxylin and eosin and immunohistologic (cytokeratin) staining. RESULTS: Of the 59 patients, 48 had axillary lymph node dissection irrespective of the results of pathologic examination of the SLN. The success rate, sensitivity, negative predictive value, and accuracy were 93%, 100%, 100%, and 100% using the radiocolloid probe, 87%, 100%, 100%, and 100% using blue dye, and 93.5%, 100%, 100%, and 100% using combined methods, respectively. Concordance between blue dye and radiocolloid was 91% (the incidence of the number of sentinel nodes detected was 37.5%, 30.3%, 10.7%, and 21.4% for 1, 2, 3, and 4 or more lymph nodes, respectively). Metastatic lymph node involvement was found in 39.5% of patients. CONCLUSION: The sentinel node localization approach showed a high negative predictive value in breast cancer patients with multifocal or multicentric lesions, contrary to the common belief of significant false-negative results in these patients.

Transient postischemic stunning evaluation by stress gated Tl-201 SPECT myocardial imaging: Effect on systolic left ventricular function.

BACKGROUND: Transient postischemic stunning (TIS) has been reported in images obtained (1/2) to 1 hour after stress with technetium 99m tracers but has not been investigated in images obtained shortly after stress with thallium 201. We also quantified the global extent and severity of TIS, which has not been done previously. METHODS AND RESULTS: We evaluated 82 patients with either treadmill or dobutamine stress Tl-201 myocardial perfusion imaging. Images were semiquantitatively examined with a 20-segment model. The extent and severity of myocardial ischemia and TIS were assessed by the summed difference score from the early and delayed scores of perfusion, wall motion (WM), and wall thickening (WT). The mean left ventricular ejection fraction (LVEF) was significantly lower in early images than in delayed images in patients with ischemia (P <.01), TIS by WM (P <.001), and TIS by WT (P <.001), and the LVEF difference was more significantly different as the summed difference score of perfusion, WM, or WT increased. No significant LVEF difference was seen in patients with ischemia who did not have TIS. CONCLUSIONS: In stress gated Tl-201 single photon emission computed tomography myocardial perfusion imaging, early TIS is frequently seen in patients with ischemia and is equivalently detected by WM and WT assessments. Significant exercise-induced transient left ventricular global dysfunction is associated with more severe and extensive ischemia and can be predicted by the measurement of the extent and severity of TIS from the same images.

Transient ischemic stunning of the myocardium in stress thallium-201 gated SPET myocardial perfusion imaging: segmental analysis of myocardial perfusion, wall motion and wall thickening changes.

Prolonged and persistent myocardial stunning has recently been demonstrated using technetium-99m sestamibi gated single-photon emission tomography (SPET) myocardial perfusion imaging post exercise or pharmacological stress test. In this study, we investigated the early postischemic transient myocardial stunning on early and delayed poststress thallium-201 gated SPET myocardial perfusion imaging using segmental wall motion (WM) and wall thickening (WT) analysis. A total of 1,680 segments from 84 patients' studies (53 men and 31 women, mean age 60 years) were evaluated on both early and delayed thallium-201 gated SPET treadmill exercise (59) or dobutamine stress (25) myocardial perfusion imaging. Semiquantitative analysis of perfusion, WM and WT in all segments was performed by two observers. Segments were classified according to changes in WM and WT between early and delayed images into normal, fixed abnormality, or improved abnormality (transient stunning), and were further classified according to changes in perfusion into normal, fixed defects, or ischemic. There were significant correlations between perfusion and WM, perfusion and WT, and WM and WT segmental scores on both early and delayed images. Transient stunning was seen significantly ( P < 0.001) more often in ischemic segments than were normal or fixed perfusion defects using WM (58%) and WT (50%) assessments. There was also a significant correlation between the severity of ischemia and transient stunning with either WM ( P < 0.05) or WT ( P < 0.005) evaluation. Segmental myocardial contractility assessment from gated SPET (201)Tl myocardial perfusion imaging using WM and WT was comparable, and results correlated well with the myocardial perfusion assessment. Early transient myocardial stunning was frequently observed in ischemic segments and was related to the severity of myocardial ischemia.

Postchemoembolization liver abscess: findings on hepatobiliary scintigraphy.

We describe a 41-year-old man with a 1-week history of nausea and vomiting 1 month after chemoembolization of a liver metastasis. The patient subsequently became febrile and developed right upper quadrant abdominal and midback pain. Findings of initial laboratory and imaging studies (a noncontrast computed tomographic [CT] scan and ultrasound) were not remarkable. Hepatobiliary scintigraphy, performed to rule out cholecystitis, revealed an abnormal area in the right lobe of the liver consistent with a focal bile leak into an abscess cavity. The patient was subsequently treated for liver abscess. In conclusion, hepatobiliary scintigraphy should be considered as a first-line test in the work-up of patients whenever a postchemoembolization complication is considered likely.

Clinical Experience with Dual Head Gamma Camera Coincidence Imaging.

The authors report their experience with F-18 FDG coincidence imaging (CI) on a Dual Head Gamma Camera system employed for more than 2 years starting on August 23, 1996 within a community hospital. The latest version of this system included attenuation correction since May 1998. The problems with such systems and approaches in correcting these problems are described. This new technology promises to make F-18 FDG imaging available to community hospitals that may have a limited patient population and cannot afford the costs of a dedicated PET system. We feel that CI is cost effective and provides useful clinical information. We stress that this is our own opinion supported by the satisfaction of referring clinicians in answering clinical questions regarding their patients' clinical problems. CI with these systems provide imaging of F-18 FDG using three to six mCi. These systems are not suitable for short half-life positron emitters such as Carbon-11 and Oxygen-15.

Role of Fluorine-18-Fluorodeoxyglucose in the Work-up of Febrile AIDS Patients. Experience with Dual Head Coincidence Imaging.

OBJECTIVE AND METHODS: This study was undertaken to find the role of fluorine-18-fluorodeoxyglucose (F18-FDG) in the diagnostic work-up of febrile Acquired Immune Deficiency Syndrome (AIDS) patients. Forty-seven (42 male and 5 female; mean age = 40.3 years) febrile patients with AIDS underwent imaging with F18-FDG by Dual Head Coincidence Imaging (DHCI). Findings were correlated with other imaging modalities.RESULTS: Our data show good sensitivity for scanning with F18-FDG by DHCI in determining the extent of Castleman's disease, lymphoma, Kaposi's sarcoma (KS), adenocarcinoma, and germ cell carcinoma. Various opportunistic infections also manifest with increased F18-FDG uptake.CONCLUSION: Total-body imaging can be done with F18-FDG with better resolution and a shorter procedure time compared to imaging with Gallium-67 (Ga-67). Furthermore, F18-FDG is more sensitive than Ga-67 for evaluating extent of involvement in various pathologies affecting AIDS patients. The new technology of DHCI is a good alternative for hospitals with no dedicated positron emission tomography (PET) scanner.