Background: Presently grade is the most important factor used to decide the soft tissue sarcoma (STS) management. But it is always very difficult to assign a pathologic grade as discordance rate is 30-40%, even among experienced sarcoma pathologists. Again histopathology has the disadvantages of being invasive, subjective, and insensitive to tumor heterogeneity. This emphasizes the need for an objective and accurate assessment of histologic type and grade of sarcoma. The aim of this study is to evaluate the correlation of in vivo PMRS findings with preoperative biopsy results and final histopathological findings of different types of soft tissue sarcomas. Patients and Methods:- PMRS Study was performed at 1.5 Tesla MRI machine with a surface body coil appropriate for the location and size of the lesions in 20 patients. Single-voxel (SVS) study has been done in 10 cases and chemical shift imaging (CSI) study characterised the heterogeneity of the tumor in 10 cases by using point - resolved spectroscopic sequence (PRESS) acquision technique with echo time TR=2000 / TE = 30,135 & 270 mseconds. The choline peak, identified at 3.2 ppm in spectra was considered for malignancy. Finally MRS results, preoperative biopsy and histopathologic findings were correlated and p < 0.001, considered being significant. Results and Discussion:- Thirteen patients presented with the disease for the first time where as 7 patients presented with suspected recurrences and / or residual disease. Nine patients have been diagnosed as malignant and 8 as benign & no residual disease where as 3 cases have not been diagnosed properly in preoperative period. But in MRS study, Choline peak (> 3.2 ppm) was found in 12 out of 12 patients with malignant soft tissue tumours where as four patient with benign and four treated patients with no residual disease did not show any choline. In vivo spectroscopy shows sensitivity, specificity,positive predictive value, negative predictive value and accuracy of 100% each where as preoperative biopsy shows 75%, 100%, 100%, 72.7% and 85% respectively. Conclusion:-In vivo PMRS study can differentiate the malignant from benign soft tissue tumor, tumour heterogeneity (especially CSI) and tumour activity in recurrent and / or residual soft tissue sarcoma preoperatively. This may be a good adjunct to clinical and pathological diagnosis to tailor the treatment of STS and further major study is required to validate it for routine clinical use.

[Proc Amer Assoc Cancer Res, Volume 47, 2006]