Study of single voxel 1H MR spectroscopy of bone tumors: differentiation of benign from malignant tumors.

OBJECTIVE: To evaluate the clinical application of single voxel (1)H MRS in the discrimination of benign and malignant bone tumors.

MATERIALS AND METHODS: Eighty-three patients (64 male, 19 female), presenting with a bone tumor, were examined on a 1.5 T MRI scanner. Using pathological results as a gold standard, there were 34 benign and 49 malignant tumors. After plain MRI scans, a 3D fast SPGR sequence was used for dynamic contrast-enhanced scanning. Dynamic images were transferred to the workstation, where the region of maximal enhancement was identified for prescription of the (1)H MRS sequence. Single-voxel (1)H MRS was then performed with the probe-p sequence, TR/TE = 1500/110 ms, VOI ranging from 14.4 mm × 7.3mm × 20.2mm to 27.9 mm × 25.5 mm × 20.1 mm, automatic shimming and water suppression, 15 min post-contrast. For control purposes, the 3rd lumbar spine vertebral body of six patients having lumbar disc herniation (LDH) without systemic disease was examined with (1)H MRS of normal bone marrow. The static contrast enhancement scan was used for these LDH patients. Conversion of raw MR signal to an MR spectrum was performed using SAGE 7. Cho/Lip (choline/lipids) peak height ratios were calculated. ROC curve analysis was used to determine the cut-off of Cho/Lip ratio for discrimination.

RESULTS: For malignant tumors, one resonance at 3.30-3.19 ppm attributed to choline and another at 1.14-1.55 ppm attributed to lipid were detected. With normal bone marrow and most benign tumors, no choline signal was detected. Choline was only found in six benign lesions. With a threshold for Cho/Lip peak height ratio of 0.2, the area under ROC curve was 0.819. The corresponding sensitivity and specificity of (1)H MRS were 76% and 88%.

CONCLUSIONS: Single voxel (1)H MRS can help in discriminating benign and malignant bone tumors.