Whole-Body Diffusion-Weighted MRI Compared With 18F-NaF PET/CT for Detection of Bone Metastases in Patients With High-Risk Prostate Carcinoma

OBJECTIVE. The purpose of this study was to evaluate the accuracy of whole-body diffusion-weighted MRI (DWI) and F-18-NaF PET/CT for detection of bone metastases in patients with high-risk prostate cancer. SUBJECTS AND METHODS. Both patient-and lesion-based analyses were performed on 49 consecutive patients (median age, 67 years; age range, 57-80 years) with recently diagnosed high-risk prostate cancer. All patients underwent bone scintigraphy, whole-body MRI including DWI and F-18-NaF PET/CT before treatment. Bone scintigraphy, conventional MR images, and follow-up images were used as the standard of reference to evaluate F-18-NaF PET/CT and DWI. RESULTS. On patient-based analysis, five patients had skeletal metastases on reference imaging that both DWI and F-18-NaF PET/CT could verify, and F-18-NaF PET/CT and DWI showed false-positive findings in four and one patient, respectively. With lesion-based analysis, F-18-NaF PET/CT and DWI showed nine and five true-positive lesions, zero and four false-negative lesions, and seven and two false-positive lesions, respectively. Two patients with uncountable bone metastases were analyzed separately. In these patients, F-18-NaF PET/CT showed more bone metastases than did DWI. CONCLUSION. We believe F-18-NaF PET/CT is a sensitive modality for detection of bone metastases caused by prostate cancer. Whole-body DWI shows a higher specificity but lower sensitivity than F-18-NaF PET/CT. Future studies with a larger patient cohort along with analyses of costs and clinical availability are needed before implementation of these methods can be considered.