Aims: Magnetic resonance imaging (MRI) is an effective method for evaluating the spine in patients with a high risk of metastatic disease. The aim of this study was to compare MRI spine with radionuclide bone scan in detecting spinal metastases for staging prostate cancer patients.
Materials and methods: A cohort of 99 patients with locally advanced prostate cancer at high risk of skeletal metastasis (prostate-specific antigen>10 ng/ml, composite Gleason score>or=8) or equivocal findings on bone scan were included in the retrospective study, and their MRI spine and bone scans were analysed.
Results: Ten patients were detected to have definite spinal metastasis by bone scan, whereas 12 patients had definite skeletal metastasis by MRI spine. Compared with the 'gold standard', derived from clinical and radiological follow-up, the sensitivities for radionuclide bone scan and that for MRI spine for detecting skeletal metastasis were 71.4 and 85.7%, respectively (P=0.023), whereas the specificities were 96.5 and 97.7%, respectively (P=0.95). Of the 34 individual metastatic lesions in the spine, 15 were concordantly positive on both scans, whereas five lesions were positive only by bone scan and 11 positive only by MRI. The addition of MRI spine in the staging for prostate cancer resulted in a change of stage and management plan in seven (7%) patients.
Conclusion: MRI spine has comparable specificity and slightly better sensitivity than bone scan to detect spinal metastasis from prostate cancer.