This is a pilot study to determine the diagnostic value of dynamic contrast enhancing MRI (DCE-MRI) in soft tissue sarcoma for assessment of tumor radiographic changes in vascular permeability and microvessel density before and after preoperative radiotherapy.

All patients have biopsy proven soft tissue sarcoma and undergo preoperative radiotherapy. Dynamic contrast-enhancing MRI T1-weight DCE-MRI will cover the whole tumor and involved lymph nodes if indicated. DCE-MRI is obtained before radiation starts and 4 weeks after RT completes. Blood volume images are estimated by using general Toft model, by which the blood flow was corrected for vascular permeability and perfusion. These images are geometrically co-registered with post-Gd T1-weighted MR images and pre-op RT routine MRI images are fused with the treatment planning CT.

Routine and DCE-MRI will be evaluated in each patient to determine the gross tumor volume. The quantitative parameters are determined on DCE-MRI for quantitative parameters in blood flow and permeability in the region of interest. Dynamic images are converted into color maps reflecting Ktrans, kep, Ve, and mean value of each parameter.

Inclusion Criteria:

1. Pathologically confirmed soft tissue sarcoma.
2. Age ≥ 18.
3. ECOG 0-1.
4. Able to receive preoperative radiotherapy followed by surgical resection.
5. Able to provide treatment consent forms that conforms to federal and institutional guidelines.
6. Have adequate kidney function for safe administration of gadolinium contrast, as determined by current Department of Radiology MRI guidelines.
7. Creatinine clearance either by 24 hour collection or nomogram:

Creatinine clearance (CC) > 50 ml/min is determined by 24 hour collection or nomogram: CC male = (140 - age) x (wt. in kg)/(Serum Cr mg/dl) x 72 CC female = 0.85 x (CC male)

Exclusion Criteria:

1. Patients have claustrophobia, iron or metal in the MRI scan site or pacemaker which are contraindicated for MRI scan.
2. patients have pacemaker or defibrillator and contraindicated to MRI images
3. Patients are allergic to gadolinium IV contrast.
4. Patients have acute or chronic renal insufficiency and contraindicated to gadolinium contrast enhancing MRI.
5. Patient had previous radiation to the same disease site.
6. Patient had chemotherapy prior to preoperative radiotherapy.
7. Patients that are pregnant. Patients that may become pregnant must have a negative pregnancy test prior to enrolling.