False positive for malignancy of a lung nodule on FDG PET/CT scans--a lesion with high FDG uptake but stable in size.

A highly F-18 fluorodeoxyglucose-avid lung nodule was stable in both size and metabolic activity over 4 months. This was most likely nonneoplastic because a true tumor would grown in volume overtime. The high level of energy consumption was contributing functional activities or by inflammatory cells. Because the speed of tumor growth is proportional to its energy consumption, we consider the higher the metabolic activity of a lesion, the less likely of malignant if it was stable in size over time.

Significance of upper urinary tract urothelial thickening and filling defect seen on MDCT urography in patients with a history of urothelial neoplasms.

OBJECTIVE: The purpose of this article is to assess the ability of CT urography to depict urothelial tumors in the upper renal collecting systems, compared with ureteroscopy and pathologic analysis, and to describe the relative implication of the radiologic signs of urothelial thickening and endoluminal filling defects. MATERIALS AND METHODS: We conducted a retrospective study to evaluate 326 consecutive CT urography examinations (using the split-bolus technique) performed at our institution between February 2006 and May 2009 in 188 patients (145 men and 43 women; median age, 65.5 years; range, 32.4-90.2 years) undergoing surveillance because of a history of urothelial tumor. Initial CT urography reports from multiple board-certified body imaging radiologists were reviewed for upper tract lesions and were classified by radiologic sign (filling defect or urothelial wall thickening) and lesion location (pelvicalyceal or ureteral) by one of the authors. The reference standard for comparison was pathologic analysis or visualization of tumor on ureteroscopy. Sensitivity and positive predictive values (PPVs) were calculated for upper tract tumors. RESULTS: Thirty-eight lesions were reported on initial CT urography examinations, 24 of which were subsequently confirmed to be tumors (PPV, 63.2%). Urothelial thickening was reported in 14 lesions, nine of which were tumors (PPV, 64%). Endoluminal filling defects were seen in 24 lesions, 15 of which were tumors (PPV, 62.5%). When stratified by location, urothelial thickening was more predictive of tumor in the pelvicalyceal system (PPV, 87.5% [7/8]) than in the ureter (PPV, 33.3% [2/6]). In contrast, filling defects were more predictive in the ureter (PPV, 87.5% [7/8]) than in the pelvicalyceal system (PPV, 50% [8/16]). CT urography failed to depict four tumors. CONCLUSION: Our data confirm that CT urography has utility in the surveillance of upper tract tumors. Urothelial thickening is an important radiologic sign of tumor, especially in the pelvicalyceal system.