Characterization of Hyperpolarized Pyruvate MRI Reproducibility

Inclusion Criteria: * Patients with history of histologically-confirmed malignant solid tumor (histology confirmed by MSKCC Department of Pathology.) NOTE: An exception will be made for patients with brain lesions. Patients identified by a radiologist to have a brain lesion with high suspicion for neoplasm given MRI features will be enrolled, prior to histological confirmation. * Disease measurable or evaluable as defined by RECIST 1.1, a mass of greater than 1cm in the long axis and/or other tumor response criteria from an MSKCC IRB-approved clinical research protocol. NOTE: Study patients do not need to be participating in an MSKCC approved clinical trial prior to study recruitment. * Negative serum or urine pregnancy test for female patients of childbearing age and potential (as defined by MSKCC Standards \& Guidelines), from assays obtained \< 2 weeks prior to study enrollment. * This study will include only patients with sarcoma, prostate, breast, brain, metastatic or pancreatic cancer. In the future other patient groups may be included through amendment of this protocol. Exclusion Criteria: * Inability or refusal to have at least one peripheral intravenous line for intravenous access (as applicable to the day of \[1-13C\] pyruvate injection) * Breast-feeding * Refusal or inability to tolerate the scanning procedure (e.g., due to claustrophobia) * Hepatic: from assays obtained within 3-4 weeks prior to study enrollment. For each patient, the upper limit of normal (ULN) value for a particular assay will be defined by the normal reference values of the laboratory that performed the assay * Bilirubin \> 1.5 x (ULN) * AST/ALT \>2.5 x ULN * Albumin \< 3 g/dl * GGT \> 2.5 x ULN if Alkaline phosphatase \> 2.5 x ULN. * Renal: Creatinine \>1.5 x ULN or creatinine clearance \< 60 mL/min, from assays obtained within 3-4 weeks prior to study enrollment * Acute major illness (e.g., unstable cardiovascular condition, etc.) * Standard MRI exclusion criteria will also be applied, including pacemakers and metal clips located in the patient.