MR imaging of vertebral metastases at 0.2 Tesla: clinical evaluation of T1-weighted opposed-phase gradient-echo imaging.

The purpose of this study was to evaluate clinically T1-weighted spin-echo imaging (T1-SE) and T1-weighted opposed-phase gradient-echo (T1-opposed GRE) in medical examinations for vertebral metastases using 0.2 Tesla MRI. Twenty-one patients (9 males and 12 females, 105 vertebrae) with non-neoplastic lesions were assigned to the normal group (Group N), whereas 27 patients (16 males and 11 females, 133 vertebrae) with malignant metastatic vertebral lesions were assigned to the metastatic group (Group M). Using quantitative analysis, the contrast to noise ratio (CNR) for bone marrow to muscle in the region of interest (ROI) defined by the operator were determined with both groups, whereas the CNR for lesion to bone marrow was determined with Group M. In the subjective analysis, 275 vertebrae of 27 patients in Group M were evaluated. There were significant differences in the Group M between CNR values, T1-SE and T1-opposed GRE. The evaluation by T1-SE image alone was rated as 85.0% for sensitivity, 99.3% for specificity, respectively. On the other hand, evaluation rate only by T1-opposed GRE was 98.5% for sensitivity, 82.4% for specificity, respectively. T1-opposed GRE image is an effective tool for 0.2 Tesla MRI to examine metastatic bone marrow tumors. These findings indicate the necessity of both T1-SE and T1-opposed GRE in diagnostic imaging of vertebral metastases using 0.2 Tesla MRI.