Two cases of oligometastatic castration‐resistant prostate cancer detected by diffusion‐weighted whole‐body imaging with background body signal suppression

INTRODUCTION: Treatment for oligometastasis in prostate cancer has changed from systemic therapy to metastatic lesion‐targeted therapy. Early detection of metastatic lesions and assessment of the treatment response have become very important. Therefore, we started to perfume assessments with whole‐body magnetic resonance imaging, especially diffusion‐weighted imaging with background body signal suppression, as a modality to detect metastasis in patients with prostate cancer. CASE PRESENTATION: We encountered two cases of castration‐resistant prostate cancer in which oligometastasis was detected by diffusion‐weighted imaging with background body signal suppression. Metastasis‐directed therapy was initiated for to treat the lesions in each case. The treatment was effective for disease control and symptom relief. Diffusion‐weighted imaging with background body signal suppression could detect new lesions at an early phase and delineate changes in lesions immediately after therapy. CONCLUSION: Diffusion‐weighted imaging with background body signal suppression enables early decision‐making for metastasis‐directed therapy compared with conventional imaging modalities. Further, metastasis‐directed therapy targeting oligometastatic lesions detected by diffusion‐weighted imaging with background body signal suppression may improve patients’ overall survival and quality of life.