18F‐choline and/or 11C‐acetate positron emission tomography: detection of residual or progressive subclinical disease at very low prostate‐specific antigen values (<1 ng/mL) after radical prostatectomy

Abstract

OBJECTIVES To assess the value of positron emission tomography (PET)/computed tomography (CT) with either ¹⁸F‐choline and/or ¹¹C‐acetate, of residual or recurrent tumour after radical prostatectomy (RP) in patients with a prostate‐specific antigen (PSA) level of 18F‐choline (group A) and 11 with ¹¹C‐acetate (group B), in 20 consecutive patients (two undergoing PET/CT scans with both tracers). The median (range) PSA level before PET/CT was 0.33 (0.08–0.76) ng/mL. Endorectal‐coil magnetic resonance imaging (MRI) was used in 18 patients. Nineteen patients were eligible for evaluation of biochemical response after salvage radiotherapy. RESULTS There was abnormal local tracer uptake in five and six patients in group A and B, respectively. Except for a single positive obturator lymph node, there was no other site of metastasis. In the two patients evaluated with both tracers there was no pathological uptake. Endorectal MRI was locally positive in 15 of 18 patients; 12 of 19 responded with a marked decrease in PSA level (half or more from baseline) 6 months after salvage radiotherapy. CONCLUSIONS Although ¹⁸F‐choline and ¹¹C‐acetate PET/CT studies succeeded in detecting local residual or recurrent disease in about half the patients with PSA levels of 18F‐choline and/or ¹¹C‐acetate PET with optimal spatial resolution might be needed for patients with a high risk of distant relapse after RP even at low PSA values.