Avid 18F-FDG uptake of pectoralis major muscle: an equivocal sequela of strenuous physical exercise

Avid functional 18F-FDG uptake of skeletal muscle is a known false positive finding of PET-CT study especially after involuntary muscle exercise just prior to the study. We describe the case of a 50-year-old man in whom the finding of avid 18F-FDG uptake of pectoralis major muscle was encountered during investigation of metastatic melanoma

Potential of 3'-fluoro-3' deoxythymidine as a cellular proliferation marker in PET oncology examination

Development of the positron emission tomography (PET) diagnostic radiopharmaceutical (18F) fluoro-2-deoxy-D-glucose (18F-FDG) subsequently facilitated the discovery and clinical evaluation of several new tracers as imaging markers for cancer. While 18F-FDG is a widely employed marker forenhanced intracellular glycolysis and metabolic function, one of the newer tracers, (18F)-3'-fluoro-3'deoxythymidine (18F-FLT), has been developed as a biomarker for cell proliferation. In this review, the potential of 18F-FLT as a biomarker for cancer imaging is discussed

Localization and prediction of malignant potential in recurrent pheochromocytoma/paraganglioma (PCC/PGL) using 18F-FDG PET/CT

Background: To our knowledge, data are lacking on the role of 18F-FDG PET/CT in the localization and prediction of neuroendocrine tumors, in particular the pheochromocytoma/paraganglioma (PCC/PGL) group. Purpose: To evaluate the role of 18F-FDG PET/CT in localizing and predicting the malignant potential of PCC/PGL. Material and Methods: Twenty-three consecutive patients with a history of PCC/PGL, presenting with symptoms related to catecholamine excess, underwent 18F-FDG PET/CT. Final confirmation of the diagnosis was made using the composite references. PET/CT findings were analyzed on a per-lesion basis and a per-patient basis. Tumor SUVmax was analyzed to predict the dichotomization of patient endpoints for the local disease and metastatic groups. Results: We investigated 23 patients (10 men, 13 women) with a mean age of 46.43±3.70 years. Serum catecholamine levels were elevated in 82.60% of these patients. There were 136 sites (mean SUVmax: 16.39±3.47) of validated disease recurrence. The overall sensitivities for diagnostic CT, FDG PET, and FDG PET/CT were 86.02%, 87.50%, and 98.59%, respectively. Based on the composite references, 39.10% of patients had local disease. There were significant differences in the SUVmax distribution between the local disease and metastatic groups; a significant correlation was noted when a SUVmax cut-off was set at 9.2 (P<0.05). Conclusion: In recurrent PCC/PGL, diagnostic 18F-FDG PET/CT is a superior tool in the localization of recurrent tumors. Tumor SUVmax is a potentially useful predictor of malignant tumor potential

Does addition of a diagnostic contrast-enhanced CT to a contemporaneous PET/CT provide incremental value in patients for restaging of colorectal carcinoma?

Abstract Background Both constrast-enhanced computed tomography (ceCT) and 18F-Fluorodeoxyglucose positron emission tomography (PET) are widely used for evaluation of colorectal cancer. Not infrequently patients undergo both tests, increasing cost and radiation burden. Whether this combination provides useful incremental diagnostic information remains unclear. Our purpose was to determine whether the addition of ceCT to PET/CT results in an appropriate change in the N or M stage in patients with colorectal cancer. Methods This was a single centre, retrospective study in a tertiary referral hospital. Over 9 months, 74 consecutive patients with colorectal carcinoma were referred for PET with a recent ceCT scan and adequate follow-up were analysed. The N and M stage of each modality was compared. Management was determined according to institutional guidelines with incremental impact of ceCT results on management categorised as appropriate, inappropriate or unchanged, based on pathological results, clinical or imaging follow-up of discrepant findings. Results Of 74 patients, PET/CT and ceCT N and M stages were concordant in 56 patients (76%) but PET/CT and ceCT identified additional abnormalities in 9 cases each respectively. Of the 18 discordant cases, accepting the ceCT result would have appropriately changed management in only 2 patients and inappropriately in 1 with most management plans unchanged. When comparing PET/CT and ceCT, kappa agreement (95% confidence interval) for N and M stage was 0.58 (0.20–0.95) and 0.60(0.41–0.79) respectively reflecting moderate agreement. Conclusions Whole-body ceCT probably has limited management impact in colorectal cancer patients who are also undergoing PET/CT and therefore may possibly be omitted from routine use. Targeted regional MRI or ceCT should, however, be considered based on clinical suspicion or when high-resolution anatomical information is required for treatment planning