Post-treatment MRI aspects of photodynamic therapy for prostate cancer.

OBJECTIVES: Photodynamic therapy is a new focal therapy for prostate cancer. METHODS: In this technique, a photosensitising agent is introduced intravenously, then activated by local laser illumination to induce tumour necrosis. Treatment efficacy is assessed by magnetic resonance imaging (MRI). RESULTS AND CONCLUSIONS: We illustrate specific post-treatment MRI aspects at early and late follow-up with pathological correlations. TEACHING POINTS: • Dynamic phototherapy is a new and promising focal therapy for prostate cancer. • One-week MRI shows increased volume of the treated lobe and large, homogeneous necrosis area. • Six-month MRI shows significant changes of the prostate shape and signal. • Six-month MRI becomes "base line" appearance for further follow-up or monitoring.