Clinical role of F-18 fluorodeoxyglucose positron emission tomography for diagnosis and staging of renal tumours

Abstract

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Objectives: The role of F-18 fluorodeoxyglucose positron emission tomography (FDG PET) in renal cell carcinoma remains to be clearly defined. The sensitivity, specificity and accuracy of FDG PET to detect renal cell carcinomas and a distant metastatic disease were compared with other established imaging modalities, including computerized tomography (CT), chest PA, and bone scan.

Methods: FDG PET and conventional imaging including CT, chest PA and bone scan were performed in 71 patients with primary renal tumours and/or metastatic diseases. Radical nephrectomy and metastatectomy were performed. The results of FDG PET were compared with the conventional imaging and postoperative histopathological diagnoses.

Results: Of seventy-one patients, the postoperative histopathological diagnoses were renal cell carcinomas in 67, leiomyosarcoma in 1, and benign renal tumours in 3. FDG PET scans showed positive in 41, equivocal and false negative in 15 and 20. Considering equivocal findings as negative, true positive (TP), true negative (TN), false positive (FP), and false negative (FN) cases were 41, 3, 0, and 27 on FDG PET, respectively. On CT scans, TP, TN, FP, FN were 66, 1, 2, 2. FDG PET showed lower sensitivity (60.3%), but higher specificity (100%) than CT scans (97.1%, 33.3%) in diagnosis of primary renal mass. However, in diagnosis of metastatic lesions, FDG PET showed sensitivity of 100% (14 of 14) and specificity of 100% (57 of 57) among the 71 metastatic sites in 14 patients with distant metastasis (lung mets in 6, bone mets in 6, adrenal mets in 1, and brain mets in 1). the sensitivity and specificity of conventional imaging including CT scans for the metastatic lesions were 64.3% and 96.0% (p<0.01, McNemar test). FDG PET was more sensitive, specific, and accurate than CT in the evaluation of distant metastases.

Conclusions: FDG PET was complementary to conventional imaging in the initial diagnosis of renal cell carcinomas and superior to CT scans in evaluating the metastasis.