Single voxel 1 H magnetic resonance spectroscopy in the diagnosis of musculoskeletal mass lesions

Introduction: In vivo magnetic resonance spectroscopy (MRS) is an established technique for evaluation of malignant tumors in brain, breast, prostate, etc., However, its efficacy in the diagnosis of musculoskeletal (MSK) mass lesions is yet to be established. We present our experience with MRS of these lesions. Materials and Methods: Magnetic resonance imaging (MRI), dynamic contrast-enhanced MRI and single-voxel ¹ H MRS was performed in 30 consecutive patients with histologically proven benign and malignant MSK tumors/mass lesions each, on a 1.5-T magnetic resonance scanner. MRS was performed with echo times (TE) of 40, 135 and 270 ms. A clearly identifiable peak at 3.2 ppm in at least two of the three spectra acquired at the three TE was taken as positive for choline. MRS imaging and enhancement patterns were compared in these two groups and were analyzed by a Radiologist blinded to the histopathological findings. Results: Ages of patients in the malignant age group ranged from 2 to 65 years (M: F - 19:11) while that of patients in the benign group ranged from 7 months to 56 years (M: F - 17:13). There were two patients with Type I curve, 18 with Type II curve and 10 with Type III curve on dynamic contrast enhanced images in the malignant group while there were no patients with Type I curve, 5 with Type II curve and 25 with Type III curve in the benign group. The sensitivity of MRS for predicting malignancy was 60%, specificity was 93.33%, positive predictive value was 90%, negative predictive value was 70% and accuracy was 76.66%. Conclusion: MRS is a promising technique for evaluation of MSK mass lesions. The accuracy at present remains low. We recommend that it be used as an adjunct to routine MRI.