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Objective: The current guidelines for 2-deoxy-2-[18F]fluoro-d-glucose PET/CT scanning do not address potential inaccuracies that may arise due to patients with renal failure. We report a retrospective analysis of standard uptake values (SUVs) in patients with and without renal failure in order to warrant a protocol adjustment., Methods: Patients were matched based on age, gender, and BMI all of which are potential effectors on observed SUV. Thirty patients were selected with clinically diagnosed renal failure, of which 12 were on dialysis. All 30 patients had age, gender, and BMI control matches. Blood urea nitrogen and creatinine levels were measured within 1 month of the scan to assess renal failure. PET/CT scans for both the renal failure patients and controls were performed 60 min after FDG injection. SUVs were measured by placing circular regions of interest in the right hepatic lobe (LSUV) and left psoas muscle (PSUV)., Results: For the 30 renal failure patients, the mean LSUV was 2.77 (SD = 0.57) and PSUV was 1.43 (SD = 0.30) while the controls had mean LSUV 2.74 (SD = 0.50) and PSUV 1.42 (SD = 0.37). The SUVs from both the liver and psoas muscle were not significantly different between the renal failure patients and the normal controls with p values >0.05. In addition, dialysis and gender also had no effect on SUVs., Conclusion: Our data suggest that renal failure patients do not require an adjustment in protocol and the standard protocol times should remain.

Objectives: The aim of our study is to assess the frequency of detection of PET-positive computed tomography (CT)-negative skeletal metastases (SM) and determine the impact of such detection on staging and/or management in patients who had FDG PET/CT as part of the cancer work-up., Methods: We retrospectively reviewed 2000 18F-FDG PET/CT scans of known cancer patients. A log was kept to record cases of suspected SM with or without bone changes from the low-dose non-contrast CT. The presence or absence of SM was evaluated based on available pathological and clinical data. The impact of detection of such lesions on cancer staging and/or management was evaluated by a board certified oncologist., Results: Of the 2000 cases, 18F-FDG PET/CT suggested SM in 146/2000 (7.3%). Of those 146 cases, 105 (72%) were positive on both PET and CT. The remaining 41 (28%) had PET-positive CT-negative bone lesions. SM was confirmed in 36/41 (88%) PET-positive/CT-negative cases. This was based on biopsy, imaging, or clinical follow-up. The detection of PET-positive CT-negative SM did not change staging or management in 7/36 (19.4%). However, staging and/or management was affected in 29/36 (80.6%)., Conclusion: SM is not uncommon in 18F-FDG PET/CT, as it accounts for 146/2000 (7.3%) of cases. PET demonstrated FDG-avid SM without a CT abnormality in at least 36/146 (25%). Patients staging and/or management changed in 29/36 (80.5%). We concluded that 18F-FDG PET is sensitive in the detection of SM with significant impact on staging and/or management.

Sjögren syndrome (SS) is an autoimmune disease with exocrine glands dysfunction and multiorgan involvement. It is associated with increased risk of lymphoproliferative disorders, especially B-cell marginal zone lymphoma. While the role of F-18 Fluorodeoxyglucose position emission tomography/computed tomography (F-18 FDG PET/CT) for evaluation of lymphoma has been established, its use in patients with a chronic history of SS to evaluate for possible lymphoproliferative disorders or multiorgan involvement is limited. We present a case of chronic SS in which F-18 FDG PET/CT demonstrated FDG avid intraparotid and cervical lymph nodes pathologically proven to be mucosa-associated lymphoid tissue lymphoma. In addition, the patient had bibasilar cystic changes consistent with lymphocytic interstitial pneumonia.

Objective: To determine whether FDG PET/CT was more sensitive than CT in detecting metastatic disease in the cardiophrenic space and whether the presence of disease in this location would change the staging and clinical management., Materials and Methods: About 1200 PET/CT scans were retrospectively reviewed over 20 months for the presence of FDG-avid cardiophrenic lymph nodes. The SUVmax was used to quantify the metabolic activity in each of the lymph nodes. The radiographic data was used for correlation. A retrospective review of diagnostic CT reports performed within a 1-month period of time of the PET/CT in the same subset of patients determined whether cardiophrenic lymph nodes were mentioned., Results: About 9 (0.8%) of the 1200 studies were found to have FDG-avid cardiophrenic lymph nodes (four males and five females with a mean age of 55 years; range 7-69, median 59). The mean SUVmax was 2.4 (range 1.2-7.9; median 1.9). Only three of the patients were found to have suspicious lymph nodes on CT. The presence of cardiophrenic lymph nodes had the potential to change the staging and/or management in three of the patients., Conclusion: PET/CT is more accurate in the detection of pathologic cardiophrenic lymph nodes than CT, especially when they are subcentimeter in size. When present, staging and/or management was potentially affected in 33%. Therefore, these nodes should be included in the TNM staging classification.

We present the case of a 56-year-old male with a history of recurrent follicular lymphoma undergoing chemotherapy with multiple (18)F-FDG PET-CT studies at an outside facility. He developed a painful erythematous, pruritic rash in the left back requiring a visit to the emergency room. He was diagnosed and treated for Varicella zoster infection. He then presented to our imaging center 2 months later for a follow up (18)F-FDG PET/CT study. Imaging demonstrated a cutaneous band of increased metabolic activity in the upper back following a dermatomal distribution. This was confirmed to be in the same area as the treated Varicella zoster eruption. A subsequent follow up (18)F-FDG PET-CT scan 4 months later to confirm tumor resolution demonstrated the abnormal band of uptake in the back had resolved. This case illustrates the significance of being aware of this entity and to distinguish it from metastasis, especially in patients with a known history of malignancy.

We present the case of a 77-year-old male with a history of prostate cancer. Follow up PET-CT and contrast-enhanced CT demonstrated a small peritoneal loose body or "mouse" in the pelvis. This is an uncommon, benign, asymptomatic finding which is usually incidentally discovered. The significance of being aware of this entity is to distinguish it from metastasis, especially in patients with known abdominal and pelvic malignancies.

Purpose: To assess the value of extending the routinely used base-of-skull (BOS) to upper-thigh field of view (FOV) to include the head on (18)F-FDG PET/CT in cancer patients., Methods: We retrospectively reviewed 1000 consecutive top-of-head to foot PET/CT studies. Abnormalities above BOS were categorized as unsuspected or known and were correlated with pathology, MRI/CT, and clinical follow-up., Results: Of the 1000 patients, 102 (10.2%) had potentially significant findings above BOS. Of these, 70/102 (69%) were known and 32/102 (31%) were unsuspected. Of the patients with unsuspected findings, follow-up data was unavailable in 7/32 (22%) and abnormalities were confirmed in 25/32 (78%). Of the 25 confirmed unsuspected findings, 4/25 (16%) were false positives and 21/25 (84%) were true positives. Of these, 13/21 (62%) were confirmed metastatic, and 8/21 (38%) were benign. Unsuspected finding of brain metastasis changed the management in 11/13 (85%) and staging in 4/13 (31%)., Conclusion: Including the head in PET/CT FOV incidentally detected clinically significant findings in 2.1% (21/1000) of patients. The detection of previously unsuspected metastasis had significant impact on patient management and provided more accurate staging.

Objectives: Positron emission tomography (PET)/CT with 18F-FDG has proven to be effective in detecting and assessing various types of cancers. However, due to cancer and/or its therapy, intravenous (IV) FDG injection may be problematic resulting in dose extravasations. In the most frequently used field of view (FOV), arms-up, and base of skull to upper thigh [limited whole body (LWB)], the injection site may not be routinely imaged. The purpose of this study was to evaluate the frequency of dose extravasations in FDG PET and the potential impact on standard uptake value (SUV) measurements., Methods: True whole body FDG PET/CT scans (including all extremities) of 400 patients were retrospectively reviewed. A log recorded cases of IV dose extravasations. When possible, SUVs were measured in two frequently used reference locations: mediastinum and liver. The SUVs were obtained in the same patients who had studies with and without FDG extravasations within an average of 3 months without interval therapy., Results: Of the 400 scans, 42 (10.5%) had extravasations on the maximum intensity projections images. In scans with or without dose infiltration, FDG injection site was at or distal to the antecubital fossa in 97% of studies. Of those 42 cases, dose infiltration was within the LWB FOV in 29/42 (69%) and outside in the remaining 13/42 (31%). Of those 42 patients, 5 had repeat PET studies with no interval therapy. For those 5 patients, liver maximum SUV was 11.7% less in patients with infiltration than those without (2.22 ± 0.54 vs. 2.48 ± 0.6). Mediastinum SUVmax was 9.3% less in patients with infiltration than those without (1.72 ± 0.54 vs. 1.88 ± 0.49)., Conclusion: We conclude dose extravasations were commonly encountered (10.5%) in PET/CT. However, it is underreported by at least 31% due to omitting injection site from the FOV. When present, extravasations may lead to underestimation of SUVmax. Therefore, it should not only be avoided but also reported in order to avoid false interpretations of the exam.