FDG uptake in lipomatous hypertrophy of the interatrial septum is not likely related to brown adipose tissue.

Lipomatous hypertrophy of the interatrial septum (LHIS) may be associated with arrhythmias or sudden death. Increased fluorine-18 fluorodeoxyglucose (FDG) uptake in LHIS is occasionally found on positron emission tomography, and has been attributed to metabolically active brown adipose tissue (BAT) contained within LHIS. We report a case of a patient suggesting that neither of the 2 currently known mechanisms of glucose uptake by BAT is responsible for FDG uptake in LHIS, unless a mechanism of BAT activation exists that has not been previously described. This study also suggests that FDG uptake is unlikely to be due to cardiomyocytes contained within LHIS. Inflammation is a potential mechanism, although further investigation is needed.

Utilizing computed tomography as a road map for designing selective and superselective neck dissection after chemoradiotherapy.

OBJECTIVE: To determine whether computed tomography can distinguish low risk neck levels that can be omitted when neck dissection is undertaken after chemoradiotherapy. STUDY DESIGN: Case series with chart review. SETTING: Tertiary care center. SUBJECTS AND METHODS: Head and neck squamous cell carcinoma patients undergoing neck dissection after chemoradiotherapy between January 1998 and June 2008. We compared computed tomography findings after chemoradiotherapy with neck dissection pathology results; used primary location and computed tomography findings to design selective or superselective neck dissection; and determined whether these surgeries would have contained all metastatic disease. RESULTS: A total of 104 patients were identified, providing 110 heminecks, 531 neck levels, and 3009 lymph nodes for analysis. Neck dissections were positive in 20 (19%) of 104 patients, corresponding to 20 hemineck dissections, 31 neck levels, and 53 lymph nodes. The negative predictive value for computed tomography was 95 percent. The negative predictive value for computed tomography per neck level was as follows: I, 100 percent; II, 96 percent; III, 96 percent; IV, 97 percent; and V, 96 percent. A selective neck dissection or a superselective neck dissection, guided by level specific computed tomography findings and limited to necks with post treatment partial response in one level, would have captured all disease in 52 (95%) of 55 and 51 (93%) of 55 heminecks. CONCLUSION: Negative computed tomography accurately predicts pathologic complete response at neck dissection. Neck dissection can be avoided in these patients. Additionally, computed tomography reliably identifies low risk neck levels that do not require dissection, permitting selective neck dissection or superselective neck dissection in partial response patients with limited residual disease.

Evaluation of low-density neutral oral contrast material in PET/CT for tumor imaging: results of a randomized clinical trial.

OBJECTIVE: The objective of this study was to determine the impact on image quality and risks in terms of artifacts and side effects of a low-density barium-based suspension as oral contrast material for CT during PET/CT examinations of an oncologic patient population. SUBJECTS AND METHODS: Eighty-five patients (51 men and 34 women; mean age, 53 years; age range, 21-87 years) were prospectively randomized to receive either 0.1% barium sulfate oral suspension or no oral contrast material during PET/CT. Patients in the oral contrast group were given 1,350 mL over 60-75 minutes. The (18)F-FDG PET component of each examination was reviewed for the presence of artifacts by two nuclear medicine physicians and was classified as adequate (no presence of artifactual focal FDG uptake attributed to attenuation-correction errors) or inadequate (focal uptake in attenuation-correction PET images with no corresponding uptake in non-attenuation-corrected PET images). Two radiologists reviewed the CT studies and scored the degree of bowel opacification using a 5-point scale, ranging from 0 for no opacification (i.e., not possible to delineate the bowel structures from the surrounding tissues) to 4 for excellent opacification (i.e., bowel structure identifiable and bowel wall clearly visible). The attenuation values (in Hounsfield units) were recorded in the stomach, duodenum, mid jejunum, and terminal ileum for quantitative analysis. Interobserver variability was assessed using kappa coefficients. RESULTS: None of the patients who received oral contrast material experienced side effects. All 85 PET examinations were considered adequate with no observable artifacts. The mean bowel opacification scores of the oral contrast group (2.59 and 2.93) as evaluated by radiologists 1 and 2, respectively, were significantly higher (p < 0.01) than those of the control group (1.55 and 1.59). The level of attenuation achieved in the contrast group was significantly higher than in the control group. The interobserver variability was moderate (kappa = 0.32). CONCLUSION: The use of low-density neutral oral contrast material for CT during combined FDG PET/CT studies significantly improves visualization of the bowel structures compared with no contrast material without causing side effects or clinically detectable errors in the attenuation correction of the FDG PET study.

CT and PET: early prognostic indicators of response to imatinib mesylate in patients with gastrointestinal stromal tumor.

OBJECTIVE: We report results from a pilot study aimed at optimizing the use of CT bidimensional measurements and 18F-FDG PET maximum standardized uptake values (SUVs-(max)) for determining response to prolonged imatinib mesylate treatment in patients with advanced gastrointestinal stromal tumors (GISTs). SUBJECTS AND METHODS: Sixty-three patients enrolled in a multicenter trial evaluating imatinib mesylate therapy for advanced GIST underwent FDG PET at baseline and 1 month after initiation of treatment. Of these 63 patients, 58 underwent concomitant CT. Time-to-treatment failure (TTF) was used as the outcome measure. Patients were followed up over a range of 23.7 to 37 months (median, 31.7 months). The predictive power of change in CT bidimensional measurements, change in PET SUVmax, and PET SUVmax at 1 month after initiation of treatment were determined, optimized, and compared. The effectiveness of combining metrics was also evaluated. RESULTS: Both a threshold PET SUVmax value of 2.5 at 1 month (p = 0.04) and the European Organization for Research and Treatment of Cancer (EORTC) criteria for partial response on FDG PET (25% reduction in PET SUVmax) at 1 month (p = 0.004) were predictive of prolonged treatment success. The Southwest Oncology Group (SWOG) criteria for partial response ((3) 50% reduction in CT bidimensional measurements) at 1 month were not predictive (p = 0.55) of TTF. Optimizing metrics improved results performance. An optimized PET SUVmax threshold of 3.4 (p = 0.00002), a reduction in the SUVmax of 40% (p = 0.002), and an optimized CT bidimensional measurement threshold--that is, no growth from baseline to 1 month (p = 0.00005)--outperformed the existing standards (i.e., EORTC and SWOG criteria). Combinations of metrics did not improve performance. CONCLUSION: The two best metrics were the optimized PET SUVmax threshold of 3.4 at 1 month (p = 0.00002) and the optimized CT bidimensional measurement threshold (no growth from baseline to 1 month, p = 0.00005) in this patient group.

Acute varicella infection mimics recurrent Hodgkin's disease on F-18 FDG PET/CT.

We report a case where acute varicella infection, chickenpox, mimics the findings of recurrent Hodgkin disease on F-18 FDG PET/CT. A 28-year-old man with a history of Hodgkin disease in remission had fatigue, pyrexia, and a raised ESR. His F-18 FDG PET/CT, performed to exclude lymphoma recurrence, demonstrated FDG-avid lymphadenopathy and increased FDG uptake in his spleen. A day later he developed the generalized rash of acute varicella infection. This was managed with valacyclovir. Repeat F-18 FDG PET/CT done 1 month later showed no evidence of FDG-avid disease. In this patient the stimulation of an immune response by the acute viral infection mimics recurrent lymphoma.