To determine if MRI imaging can be used to accurately determine if a sarcoma is responding to the type of chemotherapy being used.

The purpose of this study is to determine if MRI imaging can be used to accurately determine if a sarcoma is responding to the type of chemotherapy being used or if it is ineffective early on in the treatment; instead of finding this out 2-3 months later. If it is determined that MRI can accurately diagnose tumor response, medications can be switched early on potentially improv8ing the patients'chances of recovery.

Inclusion Criteria:

1. Biopsy proven primary bone or soft tissue tumor
2. No previous treatment for this malignancy
3. Will be given chemotherapy before having surgery or radiation on the tumor.
4. Are able to undergo a MRI examination
5. If your tumor measures at least 1/2 inch in length.

Exclusion Criteria:

1. Younger than 3 yrs. of age or need general anesthesia(sedation that puts you to sleep) to have a MRI performed.

2. History of Renal Failure

3. Are not able to have a MRI performed for any reason such as you have a pacemaker or other implanted device that may malfunction or move because of the magnetic field inside the MRI room and scanner.

4. Have any history of an allergic reaction to gadolinium based contrast agents (a medication injected in a vein that helps create clearer MRI images.

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