Locally advanced prostate cancer: Three-dimensional magnetic resonance spectroscopy to monitor prostate response to therapy

Purpose: To correlate results of three-dimensional magnetic resonance spectroscopic imaging (MRSI) with prostate-specific antigen (PSA) levels and time since external beam irradiation (EBRT) in patients treated with long-term hormone therapy (HT) and EBRT for locally advanced disease to verify successful treatment by documenting the achievement of metabolic atrophy (MA). Methods and Materials: Between 2006 and 2008, 109 patients were consecutively enrolled. MA was assessed by choline and citrate peak area-to-noise-ratio 1.5:1 or choline signal-to-noise-ratio >5:1. To test the strength of association between MRSI results and the time elapsed since EBRT (TEFRT), PSA levels, Gleason score (GS), and stage, logistic regression (LR) was performed. p value 2 years. MA was detected in 54.1% of patients of group 1, 88.9% of group 2, and in 94.5% of group 3 (100% when PSA nadir was reached). CM was detected in 50% of patients with reached PSA nadir in group 1. Local relapse was found in 3 patients previously showing CM at long TEFRT. Conclusion: MA detection, indicative of successful treatment because growth of normal or abnormal cells cannot occur without metabolism, increases with decreasing PSA levels and increasing time on HT after EBRT. This supports long-term HT in advanced prostate cancer. Larger study series are needed to assess whether MRSI could predict local relapse by detecting CM at long TEFRT.