Application of Diffusion Weighted Imaging in Prostate Cancer Bone Metastasis: Detection and Therapy Evaluation

Background: Bone metastasis is one of the most common complications of Prostate Cancer (PCa). The detection of distal bone metastasis at the time of initial PCa diagnosis is valuable for the determination of therapeutic methods and for the prognosis of PCa. Many current therapeutic methods target PCa bone metastasis, but no uniform evaluation standard for therapeutic efficacy has been established; in addition, traditional therapeutic evaluation standards that rely on changes in the measured tumor volume are quite controversial. In clinical practice, the volumes of some tumors often change nonsignificantly at the early stage of therapy (especially targeted therapy), while the volumes of other tumors, such as metastatic bone lesions, are difficult to measure. Diffusion-Weighted Imaging (DWI) not only reflects the diffusion characteristics of tissues but can also allow the analysis of microstructural and functional changes in tissues. Therefore, DWI is suitable for evaluations of early responses to tumor therapy. Objective: This study mainly reviews the principle of DWI and its progress in the detection and therapy evaluation of PCa bone metastasis. Methods: PubMed was searched to identify eligible articles up to December 26, 2020. The keywords of the analysis included DWI, PCa, bone metastasis, therapeutic response, targeted therapy, Bone Scintigraphy (BS), Positron Emission Tomography/Computed Tomography (PET/CT) and metastatic Castration-Resistant Prostate Cancer (mCRPC). Results: This review based on collected articles achieved an imaging biomarker for detection and therapy evaluation of PCa bone metastasis. Conclusion: DWI is a promising imaging method for the detection and therapeutic evaluation of PCa bone metastases.