Diagnostic potential of PET/CT using a 68Ga-labelled prostate-specific membrane antigen ligand in whole-body staging of renal cell carcinoma: initial experience

Purpose To evaluate the diagnostic potential of whole-body PET/CT using a Ga-68-labelled PSMA ligand in renal cell carcinoma (RCC). Methods Six patients with histopathologically proven RCC underwent Ga-68-PSMA PET/CT. Each PET/CT scan was evaluated in relation to lesion count, location and dignity. SUVmax was measured in primary tumours and PET-positive metastases. Tumour-to-background SUVmax ratios (TBRSUVmax) were calculated for primary RCCs in relation to the surrounding normal renal parenchyma. Metastasis-to-background SUVmax ratios (MBRSUVmax) were calculated for PET-positive metastases in relation to gluteal muscle. Results Five primary RCCs and 16 metastases were evaluated. The mean SUVmax of the primary RCCs was 9.9 +/- 9.2 (range 1.7 - 27.2). Due to high uptake in the surrounding renal parenchyma, the mean TBRSUVmax of the primary RCCs was only 0.2 +/- 0.3 (range 0.02 - 0.7). Eight metastases showed focal Ga-68-PSMA uptake (SUVmax 9.9 +/- 8.3, range 3.4 - 25.6). The mean MBRSUVmax of these PET-positive metastases was 11.7 +/- 0.2 (range 4.4 - 28.1). All PET-negative metastases were subcentimetre lung metastases. Conclusion Ga-68-PSMA PET/CT appears to be a promising method for detecting RCC metastases. However, no additional diagnostic value in assessing the primary tumour was found.