Bone marrow diseases of the spine: differentiation with T1 and T2 relaxation times in MR imaging.

Forty-two patients underwent magnetic resonance (MR) imaging for a variety of lesions in the vertebral body. A 0.15-T MR system was employed. Twenty-six patients were found to have malignant metastatic lesions (group 1); 16 had nonneoplastic lesions (group 2). The ability to differentiate between the two groups with MR imaging was evaluated. With the longer spin-echo repetition time, the image was variable in both groups. All malignant metastatic lesions appeared as low-intensity areas on T1-weighted images, but 50% of the nonneoplastic lesions also appeared this way. The mean T1 for group 1 was longer than that for group 2, but not significantly so. However, there were significant differences in the ratios of T1 to T2 and of the T1 ratio to the T2 ratio (T1 ratio = T1 for affected vertebrae/T1 for normal vertebrae, T2 ratio = T2 for affected vertebrae/T2 for normal vertebrae). These ratios were therefore useful in distinguishing malignant metastatic from nonneoplastic lesions.