OBJECTIVE:To determine whether single photon emission computed tomography (SPECT) is useful in the detection of prostate cancer bone metastases in the lumbar vertebrae. METHODS:Thirty-nine patients (12 with benign prostatic hyperplasia, 27 with prostate cancer) were considered and submitted to bone SPECT. All of them had increased uptake in lumbar vertebrae on bone scintigraphy. In those with prostate cancer, definitive diagnosis of bone metastases was established by magnetic resonance imaging (MRI). SPECT axial images were classified into five accumulation patterns: mosaic, large hot, diffuse, peripheral, and articular (or pediculate). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of bone SPECT were calculated. RESULTS:Overall, 116 vertebral lesions (49 metastatic, 67 degenerative) were studied. Mosaic, large hot and diffuse patterns were more frequently associated with metastatic lesions (84.2%, 70.3%, and 63.1% of the cases, respectively). On the other hand, peripheral and articular (or pediculate) patterns were mostly ascribed to degenerative lesions (100% and 87.5% of the cases, respectively). Sensitivity, specificity, PPV and NPV of bone SPECT were 95.9% (47/49), 73.1% (49/67), 72.3% (47/65), and 96.1% (49/51), respectively. CONCLUSIONS:Bone SPECT provides better accuracy than bone scintigraphy in differential diagnosis of lumbar vertebral lesions from prostate cancer.