This study will test the feasibility of using novel/existing imaging technologies focused on hypoxia measurements to determine "response to therapy" in pediatric soft tissue sarcomas as a pilot study. Specifically, the investigators will compare the sensitivity of Blood Oxygen Level Dependent [BOLD], Diffusion-Weighted [DW] MRI and Magnetic Resonance Spectroscopy (MRS) with that of conventional MRI to detect measurement changes between the start and completion of neoadjuvant therapy ("response to therapy") in children and adolescents (6-18 years) with suspicion of sarcoma tumors. Clinicians and scientists may use results of the proposed hypoxia-imaging surrogate markers to adjust/modify therapeutic schemes to patients on a personalized basis.

Inclusion Criteria:

• Referred with a confirmed or suspected sarcoma tumor (rhabdomyosarcoma [RMS] or non-rhabdomyomatous sarcoma) presenting with an extra-osseous component;
• Candidate for neoadjuvant therapy that will consist of standard systemic chemotherapy with or without radiation therapy

Exclusion Criteria:

• Patients with general contraindications for an MRI scan (metal foreign body, pacemaker, inability to tolerate an examination without sedation);
• Patients with a known immunodeficiency/sickle cell disease/collagen vascular disease/another malignancy;
• Patients with no clinical indication for neoadjuvant therapy prior to surgery;
• Patients with chronic pulmonary disease;
• Patients with other diagnosis confirmed after initial suspicion of RMS or non-RMS.

No IPD data will be shared with other researchers