Imaging of renal cell carcinoma in patients with acquired cystic disease of the kidney: comparison 11C-choline and FDG PET/CT with dynamic contrast-enhanced CT

To evaluate renal cell carcinoma (RCC) findings in acquired cystic disease of the kidney (ACDK) shown by 11C-choline and FDG PET/CT, and contrast-enhanced CT. Six ACDK patients with 7 RCCs underwent 11C-choline and FDG PET/CT, and contrast-enhanced CT before nephrectomy. Findings obtained with 3 imagings were evaluated and sensitivity detecting RCC was compared using 3-point grading scale (negative, equivocal, positive). The equivocal scale used for SUVmax ranged from 2.0 to 3.0 for PET/CT and a peak enhancement value ranging from 20 to 30 HU was used for CT. The histopathologic subtypes of 7 RCCs were clear-cell (n = 4) and ACD-associated RCC (n = 3). The negative/equivocal/positive grading results were 0/0/7 for 11C-choline-PET/CT, 0/3/4 for FDG-PET/CT, and 2/2/3 for CT. Three equivocal cases by FDG-PET/CT were 2 clear-cell RCCs and 1 ACD-associated RCC. CT of 3 ACD-associated RCCs showed negativity for 2 and equivocality for 1. Sensitivity defining equivocal interpretation as negative for 11C-choline-PET/CT, FDG-PET/CT, and CT was 100% (7/7), 57.1% (4/7), and 42.9% (3/7). 11C-choline-PET/CT was more sensitive to detect RCC in ACDK as compared to FDG-PET/CT and contrast-enhanced CT in our series. FDG-PET/CT may be limited for detecting clear-cell RCC, while CT may have difficulty with detection of ACD-associated RCC.