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Purpose: A matched case-control study was performed to assess the relationship between metformin use and the degree of F-18 fluorodeoxyglucose (FDG) bowel activity in diabetic patients., Materials and Methods: Seventy-seven diabetic patients referred to our department for a positron emission tomography/computed tomography study, including 45 on metformin, were compared with nondiabetic controls matched for sex, age, and body mass index. Positron emission tomography studies were obtained in a standard manner and reviewed in a blinded fashion. F-18 FDG uptake in the GI tract was evaluated quantitatively using maximal standardized uptake values and visually using a previously published semiquantitative scale., Results: F-18 FDG uptake in small and large bowel was significantly increased in metformin patients compared with nondiabetic controls both visually and quantitatively (all P < 0.0001), as well as compared with nonmetformin patients with diabetes. Control sites (liver, fat, muscle) showed similar uptake. Multiple regression analysis confirmed that metformin was the variable most strongly associated with bowel uptake., Conclusion: Physiologic accumulation of F-18 FDG in bowel is increased in diabetic patients maintained on metformin.

A 48-year-old man with squamous-cell carcinoma of the left tonsillar fossa and cervical lymph node metastases was being staged before radiation and chemotherapy. The patient had periodontal disease, and extraction of 2 teeth was performed before therapy. A staging PET/CT was performed 1 week after extraction. This case demonstrates increased FDG uptake at the extraction sites, which could be potentially mistaken for metastatic lesions, especially without the fused PET/CT images.

A 67-year-old man with progressive dysphagia was recently diagnosed with a gastroesophageal junction adenocarcinoma. Contrast-enhanced CT scans of the abdomen and pelvis reported a large GE junction tumor without evidence of metastatic disease. FDG positron emission tomography revealed intense tracer accumulation in the soft tissue mass at the GE junction consistent with the primary neoplasm. In addition, PET scan also identified a solitary focus of intense FDG accumulation at the musculotendinous junction of the right gluteus minimus muscle. Subsequent MRI demonstrated mild enhancement and could not differentiate between tumor versus inflammation. Needle biopsy was performed and confirmed metastatic esophageal adenocarcinoma. A case of skeletal muscle metastases from late-stage (IV) gastroesophageal adenocarcinoma was previously reported. However, a solitary metastasis to a distant skeletal muscle without evidence of other lymphatic and hematogenous metastasis is quite unusual. The case supports the previous report that PET is superior in detecting distant metastases for initial staging of esophageal carcinoma over CT.

A 47-year-old man with chronic renal failure underwent renal transplantation. He remained anuric and was diagnosed with an intraperitoneal urine leak by Tc-99m MAG3 renal scintigraphy. The diagnosis was confirmed by imaging fluid withdrawn via the peritoneal dialysis catheter.