Clinical application of 18F-FDG PET/CT on tumor staging and tumor thrombus grading of renal cell carcinoma

Abstract

Objective To investigate the value of 18F-FDG PET/CT in the phasing and grading of renal cell carcinoma (RCC) complicated with vena cava tumor thrombus (VCTT). Methods From December 2011 to September 2015, a total of 72 patients (52 males, 20 females, age: 36-74 years) were enrolled in this retrospectively study. All patients underwent 18F-FDG PET/CT and contrast-enhanced CT studies, and were diagnosed as RCC. The RCC patients combined with VCTT were classified by Mayo-level. Wilcoxon rank sum test was used to compare the grading of VCTT by PET/CT and contrast-enhanced CT. NM staging on abdominal area level was performed and the results were compared with χ2 test. Results VCTT was identified in 18 RCC patients and the grading results by PET/CT were as follows: 9 cases in Level 0, 4 cases in Level Ⅰ, 2 cases in Level Ⅱ, 1 case in Level Ⅲ, and 2 cases in Level Ⅳ. When evaluated by PET/CT, 20 cases were in N0M0, 21 were in N1M0, 9 were in N0M1, and 22 were in N1M1. NM staging results by contrast-enhanced CT were as follows: 50 cases in N0M0, 10 in N1M0, 10 in N0M1, and 2 in N1M1. In addition, 2 N1 and 2 M1 were found by the whole body PET/CT. The classification results of VCTT and staging of abdominal level by PET/CT were significantly better than those by contrast-enhanced CT (z=-2.462, P<0.05; χ2 =32.806, P<0.01). Conclusion 18F-FDG PET/CT is not only valuable for detecting primary RCC and local metastasis, but also useful for finding where the VCTT extends, which is conducive to therapeutic planning and further clinical treatment. Key words: Carcinoma, renal cell; Neoplasm staging; Tomography, emission-computed; Tomography, X-ray computed; Deoxyglcose