Diagnostic Potential of PET/CT Using a Ga-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-labelled PSMA ligand in renal cell carcinoma (RCC).

Methods: Six patients with histopathologically proven RCC underwent Ga-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 (TBR) were calculated for primary RCCs in relation to the surrounding normal renal parenchyma. Metastasis-to-background SUVmax ratios (MBR) 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 TBR of the primary RCCs was only 0.2 ± 0.3 (range 0.02 - 0.7). Eight metastases showed focal Ga-PSMA uptake (SUVmax 9.9 ± 8.3, range 3.4 - 25.6). The mean MBR 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-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.