Significant increase in detection of prostate cancer recurrence following radical prostatectomy with an early imaging acquisition protocol with ¹⁸F-fluorocholine positron emission tomography/computed tomography.

PURPOSE: To highlight a new imaging acquisition protocol during (18)F-fluorocholine PET/CT in patients with biochemical recurrence after RP.

METHODS: A total of 146 patients with PSA levels between 0.2 and 1 ng/ml with negative conventional imaging who did not receive salvage treatment were prospectively enrolled. Imaging acquisition protocol included an early dynamic phase (1-8 min), a conventional whole body (10-20 min), and a late phase (30-40 min). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were measured. Univariable and multivariable analyses were performed to identify independent predictors of positive PET/CT.

RESULTS: The median trigger PSA was 0.6 ng/ml (IQR 0.43-0.76). Median PSA doubling time (PSA DT) was 7.91 months (IQR 4.42-11.3); median PSA velocity (PSAV) was 0.02 ng/ml per month (IQR 0.02-0.04). Overall, (18)F-fluorocholine PET/CT was positive in 111 of 146 patients (76 %). Out of 111 positive examinations, 80 (72.1 %) were positive only in the early dynamic phase. Sensitivity, specificity, PPV, NPV, and accuracy were 78.9, 76.9, 97.2, 26.3, and 78.7 %, respectively. At multivariable logistic regression, trigger PSA ≥ 0.6 ng/ml [odds ratio (OR) 3.13; p = 0.001] and PSAV ≥ 0.04 ng/ml per month (OR 4.95; p = 0.004) were independent predictors of positive PET/CT. The low NPV remains the main limitation of PET/CT in this setting of patients.

CONCLUSIONS: The increased sensitivity, thanks to the early imaging acquisition protocol, makes (18)F-fluorocholine PET/CT an attractive tool to detect prostate cancer recurrences in patients with a PSA level <1 ng/ml.