Magnetic resonance imaging for detection of prostate cancer metastatic to bone

The diagnosis of prostate cancer metastatic to bone currently is made with plain x-rays, radionuclide bone scans, and acid and alkaline phosphatases. We used magnetic resonance imaging (MRI) in 18 patients with known prostate cancer to resolve conflicting evidence of metastases found on bone scans, plain films and serum enzyme determinations. Of 8 bone scans interpreted as positive MRI was read as negative for metastatic disease in 2. Of 5 negative bone scans 1 MRI study was interpreted as positive. All 5 equivocal bone scans demonstrated no osseous lesions on MRI. In addition, in 6 patients with evidence of bone metastases the serial MRI scans following hormonal therapy demonstrated radiographic and clinical improvement. We conclude that MRI is helpful in the diagnosis of metastatic prostate cancer when other radiographic examinations are enigmatic and that MRI can be used to determine the response to hormonal treatment.