18F-FDG PET/CT in the follow-up of asymptomatic RCC patients after surgery : Can substitute conventional imaging?

Objectives The aim of this study is to evaluate the clinical usefulness of 18F-FDG PET/CT for the postoperative surveillance in the renal cell carcinoma (RCC) patients in terms of detectability of the recurrence comparing with conventional imaging.

Methods Three hundred forty-four RCC patients who underwent surgery and postoperative surveillance from 2003 June to 2015 December in Seoul National University Bundang hospital were retrospectively included. None of the patients exhibited specific symptom suggesting recurrence. All abnormal lesions suggesting recurrence or metastasis were certificated with pathological confirmation or clinical follow-up. The sensitivity, specificity, positive predictive value and accuracy of 18F-FDG PET/CT were analyzed. Conventional imaging was consisted of contrast-enhanced abdominopelvic CT and in case of advanced staging, chest CT was added with scheduled surveillance protocol.

Results Thirty-nine patients (11.6 %) developed recurrence. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 18F-FDG PET/CT were 92.3 %, 97 %, 80 %, 99.0 % and 96.5% in detecting recurrence. On the other hand, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of conventional imaging including chest CT were 89.7%, 97.7%, 83.3%, 98.7% and 96.8%. 18F-FDG PET/CT did not exhibited significant difference with the conventional imaging (McNemar test, p=1.000). Additionally, FDG PET/CT found secondary malignancy in 6 patients (1.8%).

Conclusions In the surveillance of RCC, 18FDG PET/CT exhibited good diagnostic performance in the asymptomatic RCC patients after surgery. 18FDG PET/CT exhibited no significant difference to the conventional imaging. 18FDG PET/CT could be useful diagnostic modality in the follow-up for RCC patients, considering characteristic of hematogenous metastasis of RCC and low radiation exposure to the conventional imaging, especially in case of combined chest CT and abdominopelvic CT.

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