Does T1- and diffusion-weighted magnetic resonance imaging give value-added than bone scintigraphy in the follow-up of vertebral metastasis of prostate cancer?

PURPOSE To evaluate the effectiveness of limited Magnetic Resonance (MR) images including T1- and diffusion-weighted image (DWI) for monitoring vertebral metastasis in patients with prostate cancer. MATERIALS AND METHODS From July 2014 to November 2016, patients diagnosed with spinal metastasis from prostate cancer using 99mTc bone scintigraphy were enrolled. Regardless of the primary local therapy, the changes in spinal metastasis were followed up using bone scan and biparametric MR (T1+DWI). All tests were followed up for more than 3 months. RESULTS Among the 14 follow-ups of 10 patients, 6 and 10 (including all progressed cases on bone scan) follow-ups were determined to show progressive disease using bone scan and biparametric MR, respectively. Otherwise, we could have predicted neurologic sequela earlier using biparametric MR. Examination time for biparametric MR was 15 minutes, and it was 4 hours for bone scan, respectively. CONCLUSIONS Although bone scan has been considered the standard test for bony metastasis in men with prostate cancer, limited MR including T1 and DWI has an additional benefit in monitoring spinal metastasis in patients who are already diagnosed as having spinal metastasis. The limited MR is more sensitive in detecting progressive disease. In addition, it can reduce neurologic complications caused by spinal metastasis.