Multicentric cancer in the same breast as diagnosed by clinical examination, mammography, ultrasound; magnetic resonance imaging (MRI) or pathologic assessment, not amenable to excision with negative margins with a single lumpectomy Baseline imaging: Patients must be able to tolerate CT or magnetic resonance (MR) imaging including contrast agents as required for the treatment and the protocol At least one lesion that can be accurately measured in two dimensions utilizing mammogram, ultrasound, or magnetic resonance imaging (MRI) images to define specific size and validate complete clinical and pathologic response Patients must have T3/4 or N+ disease by magnetic resonance imaging (MRI) or endoscopic ultrasound Ability to tolerate magnetic resonance imaging (MRI). Patients not able to have a magnetic resonance imaging (MRI) (due to pacemaker, claustrophobia, etc.) Patients must have measurable (defined by at least 1 cm x 1 cm) contrast-enhancing disease by magnetic resonance imaging (MRI) imaging within 21 days of starting treatment Able to undergo a magnetic resonance imaging (MRI) scan and receive gadolinium-based contrast Contraindication to magnetic resonance imaging (MRI) For patients who have received prior cranial radiation, no increase in corticosteroid dose in the week prior to the baseline brain magnetic resonance imaging (MRI) Patients must have a baseline evaluation including history and physical examination with neurological evaluation and magnetic resonance imaging (MRI) of the brain (with and without gadolinium-based contrast), all completed within 30 days prior to initiation of treatment Participants with known spinal or distant metastases; patients with ependymoma, medulloblastoma or germinoma must have metastatic workup including spine magnetic resonance imaging (MRI) to rule out metastases Evidence of disease activity as outlined (e.g. gadolinium enhancement on magnetic resonance imaging of the brain or clinical progression) 1-6 definitive intracranial lesions must be present on magnetic resonance imaging (MRI) of the brain Cytologically-confirmed LMD or radiologically detectable LMD defined as either/or:\r\n* A measurable lesion on contrast-enhanced magnetic resonance imaging (MRI) of either the brain or total-spine > 3 mm that has not been radiated within the last 3 months prior to commencement of study therapy\r\n* Positive CSF cytology Five-twenty intracranial lesions must be present on magnetic resonance imaging (MRI) of the brain Experienced first unequivocal progression of tumor by magnetic resonance imaging (MRI) [as assessed via Radiologic Assessment in Neuro-Oncology (RANO) criteria within 3 months from the last dose of TMZ. Optic pathway tumors, including chiasmatic-hypothalamic, tumor without histologic confirmation; patients with chiasmatic lesions with or without contiguous extension of tumor into other regions of the visual pathways demonstrated on contrast magnetic resonance imaging (MRI) will be eligible for study without histopathologic confirmation with or without NF-1 Patient must have magnetic resonance imaging (MRI) confirming progressive disease Presence of T1 gadolinium (Gd)–enhancing lesions (on magnetic resonance imaging [MRI]) suggestive of high-grade glioma Inability to undergo magnetic resonance imaging (MRI) evaluation for treatment planning and follow-up Multicentric breast cancer in the ipsiltateral breast as diagnosed by clinical exam, mammogram, ultrasound or magnetic resonance imaging (MRI) Patients must have measurable disease (in 2-dimensions) on magnetic resonance imaging (MRI) scan of brain and/or spine to assess preliminary evidence of response Patients must be able to have magnetic resonance imaging (MRI) scans Myometrial invasion > 50% or evidence of nodal or metastatic disease on baseline magnetic resonance imaging (MRI) (MRI only to be done for EC patients) or tumor size > 2 cm on MRI or pelvic ultrasound Histologically proven adenocarcinoma of the lower rectum (lower border =< 6 cm from anal verge as assessed by pelvic magnetic resonance imaging [MRI]). Is able to have magnetic resonance imaging (MRI) with contrast of the brain Documented first or second recurrence of glioblastoma (GBM) by diagnostic biopsy or contrast enhanced magnetic resonance imaging (MRI) performed within 21 days of randomization per Response Assessment for NeuroOncology (RANO) criteria. Brain magnetic resonance imaging (MRI) (or CT if contraindication to MRI) within the last 60 days showing no evidence of metastatic disease Is unable (due to existent medical condition) or unwilling to have a contrast enhanced magnetic resonance imaging (MRI) of brain Phase I patients must have measurable contrast-enhancing disease (defined as at least 1 cm x 1 cm) by magnetic resonance imaging (MRI) imaging within 21 days prior to starting treatment (patients may have gross total resection, but should have measurable disease post-operatively); patients must be able to undergo MRI of the brain with gadolinium Patients must be able to undergo magnetic resonance imaging (MRI) scan with gadolinium contrast for treatment planning Meet eligibility requirements for SRS: able to get magnetic resonance imaging (MRI), lesion must not be abutting optic apparatus or brainstem, and must be able to be secured and positioned in a stereotactic U-frame mask Patients who cannot safely undergo magnetic resonance imaging (MRI) due to non-MRI compatible pacemaker, or other reason Patient can’t have magnetic resonance imaging (MRI) scan Patients with absolute contraindication to magnetic resonance imaging (MRI) imaging are not eligible for the study Have an enhancing mass on magnetic resonance imaging (MRI) amenable to > 90% resection of contrast-enhancing tumor (as determined by the neurosurgeon pre-operatively) and histological diagnosis of glioblastoma from a prior stereotactic biopsy Patients with inability to complete brain magnetic resonance imaging (MRI) studies with contrast A magnetic resonance (MR) scan must be obtained within 30 days of enrollment and must demonstrate an enhancing mass without significant mass effect; tumors must be less than approximately 32 cc in total volume, as assessed by the principal investigator (PI) based on pre-enrollment magnetic resonance imaging (MRI); the lesion must be stereotactically accessible Participants must have locally advanced rectum cancer where primary resection without chemoradiotherapy (CRT) is unlikely to achieve clear margins as defined by magnetic resonance imaging (MRI), with no metastatic disease, as assessed by independent review. Unifocal tumor =< 2 cm based on contrast-enhanced prone-breast magnetic resonance imaging (MRI) As defined on magnetic resonance imaging (MRI), target lesion must be at least 10 mm distance from skin (defined as volume encompassing first 3 mm from breast surface) The primary tumor must be measurable by an imaging modality prior to treatment; this imaging modality is to be repeated after completion of 4 cycles of paclitaxel and prior to surgery; such imaging modalities may include ultrasound, computed tomography (CT), mammography, or magnetic resonance imaging (MRI); MRI will be the preferred imaging modality if available; all imaging will be performed per standard of care at the discretion of the treating physicians Be able to undergo a brain magnetic resonance imaging scan Patients with untreated/active brain metastases as documented by magnetic resonance imaging (MRI) within 2 months of study enrollment Able to undergo brain magnetic resonance imaging (MRI) with and without contrast without requiring general anesthesia Patients unable to undergo magnetic resonance imaging (MRI) of the spine Chest imaging (x-ray, CT or magnetic resonance imaging [MRI]) negative for metastasis no more than 6 weeks prior to the date of RPLND Magnetic resonance imaging (MRI) findings consistent or with a histologically confirmed newly diagnosed GBM that has not been treated and would benefit from further surgical resection Creatinine within normal institutional limits OR according to institutional magnetic resonance imaging (MRI) policy Subjects must have suspected high grade glioma by magnetic resonance imaging (MRI) Medical contraindication to undergoing magnetic resonance (MR) imaging A contrast-enhanced magnetic resonance imaging (MRI) scan showing >= 4 treatable brain metastases Patient must be able have a magnetic resonance imaging (MRI) of the brain for treatment planning Patients with evidence of metastatic spinal disease by magnetic resonance imaging (MRI) are NOT eligible for either Stratum Contraindication to magnetic resonance (MR) imaging Histologically confirmed systemic malignancy with gadolinium contrast-enhanced magnetic resonance imaging (MRI) scan demonstrating 1-5 newly diagnosed intraparenchymal brain metastases Patients must have measurable lesion in the brain or spine that is >= 3 mm seen on magnetic resonance imaging (MRI) with contrast; NOTE: contrasted pre-treatment MRI scan must be obtained =< 21 days prior to stereotactic radiosurgery treatment Quantification of the degree of epidural spinal cord compression as grade 1C, 2, or 3 by magnetic resonance imaging (MRI), with and without contrast sequences; axial T2 sequence is encouraged but not required Stage IV metastatic disease with intracranial disease visible with magnetic resonance image (MRI) Any contraindication to MRI (i.e. patients with pacemakers or other metal implanted medical devices); an MRI safety questionnaire is required prior to magnetic resonance (MR) imaging No evidence of extraprostatic disease on 3T multiparametric pelvic magnetic resonance imaging (MRI) Radiographic evidence by magnetic resonance imaging (MRI) of brain metastasis (if patient is unstable to tolerate contrast, an MRI without contrast is acceptable) Diagnosis of biopsy proven stage I-IIIB (cT1-3, N0-2, M0) adenocarcinoma of the rectum; staging must also be based on multidisciplinary evaluation including magnetic resonance imaging (MRI) and/or endorectal ultrasound Presence of any contraindications to magnetic resonance imaging (MRI) scanning Patients must have disease that can be measured and followed by mammogram and/or breast ultrasound (in special cases a dedicated breast magnetic resonance imaging [MRI] may be clinically indicated); the target lesion must not have been previously irradiated Patient has no contraindications to magnetic resonance imaging (MRI) scanning with intravenous contrast Rectal cancer originally staged as T1, T2, or T3, node negative (N0) or node positive (N1, N2) by pelvic magnetic resonance imaging (MRI) Inability to undergo magnetic resonance imaging Eligible for contrasted magnetic resonance imaging (MRI) on initial evaluation with glomerular filtration rate (GFR) >= 60 ml/min; a diagnostic MRI ordered within 60 days of diagnosis will be considered an acceptable alternative and will not be repeated Magnetic resonance imaging (MRI) is required for radiation treatment planning on this study; a diagnostic MRI performed within 60 days of obtaining consent is acceptable and will not be repeated; subjects who have not had a diagnostic MRI will be required to have a research treatment planning MRI with contrast ordered by a radiation oncologist; these subjects must have a glomerular filtration rate (GFR) >= 60 ml/min Surgery: at least 2 weeks following surgery including brain and spine provided post-operative magnetic resonance imaging (MRI) shows no active bleeding Imaging by magnetic resonance imaging (MRI), ultrasound and/or mammogram and physical exam to document lesions size must be performed within 30 days of study entry Able to undergo brain magnetic resonance imaging (MRI) with and without contrast Centrally located tumors with radiographic evidence (CT or magnetic resonance imaging [MRI]) of local invasion of major blood vessels Unable to undergo magnetic resonance imaging (MRI) imaging Prospective participant is unable to undergo a magnetic resonance imaging (MRI) with contrast agent Gross disease must be unifocal on mammogram (mammo)/magnetic resonance imaging (MRI) imaging If consenting to participate in the optional PET/MR imaging sub-study, the patient must be able to tolerate PET/magnetic resonance imaging (MRI) with intravenous contrast administration and must complete the applicable MRI screening evaluation form Eligibility for stereotactic radiosurgery using magnetic resonance imaging (MRI) targeting: The decision to treat with stereotactic radiosurgery will be made by a consensus of the radiation oncology, neurosurgery and neuro-oncology providers or their alternates at the weekly Brain Tumor or Stereotactic Radiosurgery Tumor Conferences; all patients must have no restrictions to obtaining MRI with and without paramagnetic contrast Any contraindication to MRI (i.e. patients with pacemakers or other metal implanted medical devices); an MRI safety questionnaire is required prior to magnetic resonance (MR) imaging Residual lesion must be >= 1.0 cm in diameter as determined by magnetic resonance imaging (MRI) Measurable disease on magnetic resonance imaging (MRI) scan Patients must have had a bilateral diagnostic mammogram within 6 months of registration, and may also have a targeted sonography of the breast and/or ipsilateral axilla and magnetic resonance imaging (MRI) if clinically indicated Patients must have bilateral mammogram and/or breast magnetic resonance imaging (MRI) within 3 months of diagnosis of their breast cancer Any contraindication for undergoing magnetic resonance imaging (MRI) All patients must have greater than 3 but less than or equal to 15 metastatic lesions seen on a contrast enhancing magnetic resonance imaging (MRI) scan obtained not less than one month prior to study enrollment; patients who are found to have up to 20 metastatic lesions at the time of treatment planning (on volumetric MRI once the head frame is in place) may still participate in the trial Consensus of diagnosis must be reached by a multidisciplinary pediatric neuro-oncology team by considering both clinical evidence and magnetic resonance imaging (MRI) presentation; tissue diagnosis is not required There must be measurable disease on magnetic resonance imaging (MRI) Evidence of a new intracranial or intratumoral hemorrhage that is larger than a punctuate size on baseline magnetic resonance imaging (MRI) obtained within 14 days prior to study registration Imaging studies: brain magnetic resonance imaging (MRI) before start of protocol therapy; images must include T1, T1 with gadolinium, T2, and fluid attenuated inversion recovery (FLAIR) sequences Inability to tolerate periodic magnetic resonance imaging (MRI) scans or gadolinium contrast Newly diagnosed brain metastases (four or fewer by postcontrast magnetic resonance imaging [MRI] obtained within six weeks of study entry) Contraindication to magnetic resonance imaging (MRI) contrast agents There must be measurable contrast-enhancing progressive or recurrent GBM (single or multiple lesions) by magnetic resonance imaging (MRI) imaging with an interval of greater than or equal to 6 months between recurrence and completion of prior radiotherapy; while there is no defined maximum tumor volume for eligibility in this study, patients with diffuse, multifocal recurrences may be excluded at the discretion of the study principle investigator (PI); there must be an MRI performed within 4 weeks prior to any therapy Patients are excluded if they are unable to obtain a Magnetic resonance imaging (MRI) scan for any other reason. Contraindication for undergoing magnetic resonance imaging (MRIs) Contraindication to magnetic resonance imaging (MRI), including presence of a pacemaker or aneurysm clip, severe claustrophobia, a known reaction to gadolinium contrast, or body weight exceeding 300 pounds (lbs) Inability or unwillingness to have magnetic resonance imaging (MRI) scans performed (e.g. cardiac pacemaker-dependent) Patients must have magnetic resonance imaging (MRI) within 21 days of starting treatment; patients must be able to tolerate MRI Participants with prior therapy that included interstitial brachytherapy or stereotactic radiosurgery must have confirmation of progressive disease based upon nuclear imaging, magnetic resonance (MR) spectroscopy, perfusion imaging or histopathology Inability to undergo magnetic resonance (MR) imaging to assess disease status Patients must be able to undergo magnetic resonance imaging (MRI) of the brain with gadolinium Patients must meet both of the first two conditions, OR the third:\r\n* Clinical findings consistent with a presumed new diagnosis of diffuse midline glioma (DMG) in the opinion of the treating neuro-oncologist, AND\r\n* Brain magnetic resonance imaging (MRI) findings consistent with a new diagnosis of DMG based on multidisciplinary consensus after review of imaging \r\n* OR, recurrent DMG requiring tumor resection or biopsy Documented recurrence by diagnostic biopsy or contrast enhanced magnetic resonance imaging (MRI) performed within 28 days of entry in to the trial as per Response Assessment Criteria for High-Grade Gliomas (RANO) criteria Patients must have histologically or cytologically confirmed malignancy (not leukemia or lymphoma); there must be metastatic brain disease apparent on magnetic resonance imaging (MRI) which offers a medical indication for brain radiation Magnetic resonance imaging (MRI) performed within 4 weeks of trial enrollment Arm 1 patients must have measurable (defined by at least 1 cm x 1 cm) contrast-enhancing disease by magnetic resonance imaging (MRI) imaging within 21 days of starting treatment Patients who cannot undergo brain magnetic resonance imaging (MRIs) If applicable, patients must be off bevacizumab therapy for 30 days before the baseline magnetic resonance imaging (MRI) is obtained Radiologically confirmed metastatic brain lesion by magnetic resonance imaging (MRI) Patient is unable to undergo a magnetic resonance imaging (MRI) Contraindication for magnetic resonance imaging (MRI) Spinal compression or structurally unstable bone lesions suggesting impending pathologic fractures based on clinical findings and/or magnetic resonance imaging (MRI) >1 focal lesions detected by functional imaging including PET/CT and/or whole body magnetic resonance imaging (MRI) AND have measurable disease by protein electrophoresis analyses as defined by the following: A histologically proven, clinically significant lesion visible on mpMRI (magnetic resonance imaging) that is accessible to PRX302 transperineal injection. Cohort A: Histologically confirmed metastatic non-small cell lung cancer (all histologic subtypes allowed) with radiographic evidence by magnetic resonance imaging (MRI) of at least one measurable brain lesion as defined by Response Assessment in Neuro-Oncology (RANO) criteria that does not require corticosteroids for symptomatic control Documented recurrence by diagnostic biopsy or contrast enhanced magnetic resonance imaging (MRI) performed within 28 days of entry in to the trial as per Response Assessment in Neuro-Oncology (RANO) criteria Patients must have undergone an evaluation by magnetic resonance imaging (MRI) within 35 days of completing radiation and must also be within 7 days prior to registration; MRI must NOT demonstrate tumor progression, but patients with imaging changes consistent with pseudo-progression, stable neurologic function and not needing corticosteroid treatment are eligible Histologically confirmed primary invasive adenocarcinoma of the breast with the size of the primary tumor being at least 1 cm on imaging by either mammography, ultrasound or breast magnetic resonance imaging (MRI) Centrally located tumors with radiographic evidence (CT or magnetic resonance imaging [MRI]) of local invasion of major blood vessels Documentation of mammogram, ultrasound and magnetic resonance imaging (MRI) of the ipsilateral breast all performed within 42 days prior to registration Absence > 1 focal lesions on magnetic resonance imaging (MRI) studies No centrally located tumors with radiographic evidence (CT or magnetic resonance imaging [MRI]) of local invasion of major blood vessels Patients unable to obtain magnetic resonance imaging (MRI) for any reason (e.g., due to pacemaker, ferromagnetic implants, claustrophobia, extreme obesity) At least one recurrent or progressive brain metastasis(es) from any solid primary tumor that is visible on magnetic resonance imaging (MRI) as assessed by the patient’s treating physician Inability to undergo magnetic resonance imaging Patients with newly diagnosed DIPG, who undergo a biopsy are eligible; patients with disseminated disease are not eligible, and magnetic resonance imaging (MRI) of the spine must be performed if disseminated disease is suspected by the treating physician Clinical stage II-IIIC (T2-4 N0-3 M0) by mammogram, ultrasound or magnetic resonance imaging (MRI) There must be documented progression or recurrence of disease by magnetic resonance imaging (MRI) imaging or cerebrospinal fluid (CSF) studies since completion of last tumor-directed medical therapy; patients may have had surgical resection or radiation of tumor, and need not have measurable or evaluable disease at study entry Phase Ib and II: surgical candidates, with moderate to high-risk pathologically-confirmed rectal cancer (stage cT3-4N0 or cT1-4N+); clinical staging by endoscopic ultrasound (EUS) or magnetic resonance imaging (MRI) is permitted Inability or unwillingness to have magnetic resonance imaging (MRI) scans performed (e.g. cardiac pacemaker-dependent) Patient who is unable to undergo magnetic resonance imaging (MRI) brain and spine with gadolinium contrast. No increase in corticosteroid dose in the week prior to the baseline brain magnetic resonance imaging (MRI) Patient must be able to tolerate CT or magnetic resonance (MR) imaging including contrast agents as required for their treatment and the protocol Patients must have measurable disease, defined as at least one vestibular schwannoma (VS) > 0.4 ml (on volumetric analysis) that can be accurately measured by contrast-enhanced cranial magnetic resonance imaging (MRI) scan with fine cuts through the internal auditory canal (3 mm slices, no skip) Patients must have unequivocal evidence of tumor progression by magnetic resonance imaging (MRI) performed no longer than 28 days prior to study registration Able to undergo brain magnetic resonance imaging (MRI) with and without contrast Patients must have a baseline evaluation including history and physical examination with neurological evaluation and magnetic resonance imaging (MRI) of the brain (with and without gadolinium-based contrast), all completed within 30 days prior to initiation of treatment Patients with greater than 9 discrete metastases on magnetic resonance imaging (MRI) Diagnostic imaging: Baseline magnetic resonance imaging (MRI) of the brain and spinal axis with gadolinium and prior to any chemotherapy is required; if surgical resection is performed, a post operative MRI is required; if the patient receives chemotherapy prior to radiation, a post-chemotherapy MRI of the brain is required; if spinal involvement was seen on initial MRI and prior to chemotherapy, a MRI of the spine is required after chemotherapy and prior to radiation Patients with untreated central nervous system (CNS) metastases; patients should have a head CT/magnetic resonance imaging (MRI) within 28 days prior to treatment initiation; patients with previously excised/gamma knifed solitary or oligometastases and controlled disease are eligible Patients must be able to undergo an magnetic resonance imaging (MRI) scan Patients must have MS using McDonald criteria supported by characteristic magnetic resonance imaging (MRI) changes Patients must agree to undergo repeat clinical neurological examinations and brain magnetic resonance imaging (MRI) with appropriate contrast after every other cycle of chemotherapy Patients must be able to undergo a pre-surgical magnetic resonance imaging (MRI) brain Patients meeting the following exclusion criteria will be excluded from the magnetic resonance imaging (MRI) portion only: \r\n* Metallic implant, e.g. pacemaker, defibrillator \r\n* Unmanageable claustrophobia \r\n* High risk for nephrogenic systemic fibrosis Patients with >= 5 measurable brain metastases on a diagnostic-quality contrast-enhanced magnetic resonance imaging (MRI) obtained within 30 days prior to registration Contraindication to magnetic resonance (MR) imaging, such as implanted metal devices or foreign bodies, severe claustrophobia, or contraindications to contrast agent administration No brain metastases detected by magnetic resonance imaging (MRI). Patients must have measurable disease on magnetic resonance imaging (MRI) that has progressed after prior therapy; progressive disease (PD) will be defined as a >= 25% increase in the sum of the products of greatest perpendicular diameters of all measurable disease over the smallest sum observed (since treatment started) on gadolinium magnetic resonance imaging (Gd-MRI), the appearance of new lesions on scan, or clinical or neurologic worsening despite stable disease on the last 2 scans Contraindication to magnetic resonance imaging Patients must have measurable contrast-enhancing disease by magnetic resonance imaging (MRI) imaging within 21 days of starting treatment; patient must be able to undergo MRI of the brain with gadolinium Brain magnetic resonance imaging (MRI) documenting CR must be obtained within 30 days of study enrollment Patients with extraocular disease evident on magnetic resonance imaging (MRI) (extension into the optic nerve), massive choroidal/uveal invasion (grade IIC or IID per ARET0332) or disease outside the globe evident on MRI or physical examination would also be excluded Documentation by magnetic resonance (MR) of a gadolinium-enhancing intraparenchymal mass consistent with malignant glioma Medical contraindication to undergoing magnetic resonance (MR) imaging Known allergies against contrast agents required for magnetic resonance imaging (MRI) of intracranial lesions, or other contraindications for MRI, i.e., pacemaker A cardiac T2* <10 ms by magnetic resonance imaging (MRI). Patients must have magnetic resonance imaging (MRI) within 21 days of starting treatment Patients must be able to undergo brain or spine magnetic resonance imaging (MRI) scans with intravenous gadolinium, based on tumor location(s) within 14 days prior to registration Phlebotomy-dependent participants with splenomegaly by magnetic resonance imaging (MRI) or computerized tomography (CT) imaging (? 450 cubic centimeters [cm^3]) or without splenomegaly (< 450 cm^3, unpalpable, or prior splenectomy) Patient is able to be assessed by periodic dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) scan Patients must have measurable progressive or recurrent disease by magnetic resonance imaging (MRI) within 2 weeks of starting treatment Unable to undergo brain magnetic resonance imaging (MRI) Patients must have a magnetic resonance imaging (MRI) scan performed within 14 days prior to initial protocol treatment In patients with CNS tumors or known CNS metastases, evidence of intracranial or intratumoral hemorrhage of more than punctuate size and/or more than 3 foci of punctuate hemorrhage on baseline magnetic resonance imaging (MRI) obtained within 14 days prior to study registration No contraindications for magnetic resonance imaging (MRI) (e.g., unsafe MRI implanted devices, shrapnel, history of metal fragments in eyes, neurostimulators, excessive size and weight, claustrophobia) A diagnostic contrast-enhanced magnetic resonance imaging (MRI) of the brain must be performed within 28 days prior to registration Patients at institutions that elect to utilize central imaging review to confirm eligibility must be pre-registered prior to submission of these images; images should be submitted as soon as possible after the pre-registration magnetic resonance imaging (MRI) is obtained; turnaround time for this review will be =< 72 business hours after receipt of images by the Imaging and Radiation Oncology Core (IROC) Patients must be receiving magnetic resonance imaging (MRI) scans at University of California San Francisco (UCSF) Stable dose of corticosteroids for >= 5 days prior to baseline magnetic resonance imaging (MRI) Confirmed primary brain tumor diagnosis via magnetic resonance imaging (MRI) and their neuro-oncologist Magnetic resonance imaging (MRI)-incompatible head or neck tattoos Additional exclusion criteria include participation in a scheduled resistance exercise program within 1 month of study entry; metal implants or other contraindications for the magnetic resonance imaging (MRI); history of diabetes, chronic renal disease characterized by a creatinine clearance of less than 30, uncontrolled hypertension; and a vitamin D status (25(OH)D) of > 32ng/mL Patients unable to undergo magnetic resonance imaging (MRI) of the spine Contraindication to magnetic resonance (MR) imaging such as implanted metal devices or foreign bodies For the subset of participants who will undergo magnetic resonance imaging (MRI), ability to withstand lying down in small area (MRI scanner) for 50 minutes Subjects should have breast and axillary imaging with breast magnetic resonance imaging (MRI) (preferred) or breast and axillary ultrasound (US) within 4 weeks prior to treatment initiation Acute ischemic stroke within the prior four weeks, defined as a new neurologic deficit(s) with magnetic resonance imaging (MRI) evidence of acute ischemia in a referable location, and no clinical or radiologic indication of a non-cerebrovascular mimic, such as a brain metastasis, as the etiology of the deficit(s) Contraindication to magnetic resonance (MR) imaging, such as implanted metal devices or foreign bodies, severe claustrophobia, or contraindications to contrast agent administration Immediate need for magnetic resonance imaging (MRI) Participant had a breast magnetic resonance imaging (MRI) that was performed after the diagnosis of ADH but before surgical excision. Participants with non- magnetic resonance (MR) compatible objects or implants that would make MRI a contraindication Screening contrast-enhanced magnetic resonance imaging (MRI) or 99mTc-sestamibi based imaging of the breast(s) within the prior 12 months or planned within the next two years Patients who are thought to have a breast magnetic resonance imaging (MRI) within 1 year prior to the study Arm 2 patients must have lymph node, soft tissue, or visceral metastatic disease measuring >= 1 cm, or bone metastases, documented by prior CT or magnetic resonance imaging (MRI) imaging; Arm 2 patients may have hormone-sensitive or castrate-resistant disease and may be receiving treatment with hormonal or other therapies Previous CT scan, magnetic resonance imaging/magnetic resonance cholangiopancreatography (MRI/MRCP) or EUS of the abdomen in the past three years Serious medical illness unsuitable for the magnetic resonance (MR) scanner based on best clinical judgment Must have a negative mammogram or negative breast magnetic resonance imaging (MRI) within 1 year of protocol-required baseline core biopsy\r\n* Patients positive for BRCA mutations must have a negative breast MRI within 1 year of protocol-required baseline core biopsy Patients with breast implants are usually permitted to have an magnetic resonance imaging (MRI); check with the MRI technician to confirm Patients must have measurable, supratentorial contrast-enhancing progressive or recurrent glioblastoma or gliosarcoma by magnetic resonance imaging (MRI) imaging within 21 days of starting treatment; patient must be able to tolerate MRIs Histologically proven diagnosis of solid tumor malignancy and Magnetic Resonance (MR) imaging documenting brain lesions. More than 1 focal lesion >=5 millimeter (mm) in diameter by magnetic resonance imaging (MRI) Patients must have a biopsy marker placed within the tumor bed with imaging confirmation (preferably mammogram but ultrasound or magnetic resonance imaging [MRI] is acceptable) of marker placement prior to neoadjuvant chemotherapy Clinical stage I grade 1-2 endometrial cancer also eligible with deep myoinvasion >= 50% shown on preoperative (preop) magnetic resonance imaging (MRI) and/or elevated preop cancer antigen (CA)-125 > 35 U/ml Patients with no contra-indications to magnetic resonance (MR) imaging Patient is not able to undergo magnetic resonance (MR) imaging due to any contraindication to MRI based on departmental MR questionnaire (e.g. past gadolinium allergies, failure of metallic screening, claustrophobia, inability to lay flat for duration of the study, inability to hold breath, etc.) Diagnostic CT or magnetic resonance imaging (MRI) scan within 2 months of study entry No contra-indications to magnetic resonance imaging (MRI), including permanent pacemaker, implantable device, aneurysm clip, or severe claustrophobia (for patients planning to be imaged on PET/magnetic resonance [MR] scanner) Patients who have presence of a known contradiction to MRI\r\n* Pacemaker\r\n* Aneurysm clips\r\n* Patients with implants that are contradicted for magnetic resonance (MR) imaging will be excluded\r\n* Pregnant\r\n* Age and mental status wherein he/she is unable to cooperate for MRI study Patient agrees to undergo, prior to the procedure, magnetic resonance imaging (MRI, within 14 days and preferably with 3 days of the planned procedure) with perfusion, diffusion and spectroscopic imaging. Be able to undergo magnetic resonance (MR) imaging Any contraindication to the use of contrast and/or general guidelines for magnetic resonance (MR) imaging as per standard Department of Radiology imaging guidelines Contraindication for magnetic resonance imaging Patient must have a solid tumor with a short-axis greater than or equal to 1 cm (by CT, magnetic resonance imaging (MRI), ultrasonography or mammography) to allow reliable PET imaging. Patients must be able to tolerate magnetic resonance (MR) imaging required by protocol Implanted devices, metallic hazards or other conditions presenting a contraindication to 3Tesla cardiac magnetic resonance imaging (MRI) Diagnostic CT or magnetic resonance imaging (MRI) performed within 30 days prior to the 68Ga-RM2 PET Contraindication to magnetic resonance imaging (MRI). Contraindication to magnetic resonance (MRI) imaging, as determined through review of the University of California, San Francisco (UCSF) MRI screening form by study investigator Scheduled for magnetic resonance imaging (MRI) fusion/transrectal ultrasound (TRUS) biopsy, followed by histology At least 2 metastatic soft tissue or osseous lesions identified on conventional imaging (CT, magnetic resonance imaging [MRI] or bone scan) Standard gadolinium-enhanced magnetic resonance imaging (MRI) changes that are considered indeterminate for tumor progression versus (vs.) treatment-related changes by the neuroradiologist or clinician within 24 weeks of completion of radiation Patients with non-magnetic resonance imaging (MRI) compatible implanted metallic foreign bodies are excluded from this study Patients whose lung tumors are being monitored by magnetic resonance (MR) imaging as part of standard clinical care Diagnosis of HCC with one or more of the following:\r\n* Liver mass (>= 1 cm) with arterial phase contrast enhancement and early washout on subsequent phases by CT or magnetic resonance imaging (MRI)\r\n* Suggestive imaging findings plus alpha-feto protein (AFP) > 200 mg/dL; or\r\n* Tumor confirmed by arteriography Allergy or relative contraindications to magnetic resonance imaging (MRI) contrast agents Patients with the most recent abdominal magnetic resonance (MR) study obtained within 3 months +/- 1 week No contraindications to magnetic resonance imaging (MRI) Suspected first recurrence of a glioblastoma tumor by clinical measures and/or magnetic resonance imaging (MRI) Patients with a known diagnosis of central nervous system (CNS) malignancy, including metastases, with known enhancement on magnetic resonance (MR) who are otherwise eligible to undergo MRI Adult patients who require monitored anesthesia for magnetic resonance imaging (MRI) scanning Magnetic resonance imaging (MRI) or transrectal doppler ultrasound demonstrating at least one target lesion Presence of a genetic disorder other than NF1 that effects cognition or is associated with magnetic resonance (MR) imaging abnormalities (e.g. tuberous sclerosis) CT/magnetic resonance imaging (MRI) scan must be obtained within 4 weeks prior to study entry Patients with reoccurrence of brain tumor\r\n* The principal investigator or co-principal investigator (PI) must review magnetic resonance imaging (MRI) and CT findings based on the radiologic assessment provided they meet the following imaging criteria (as established in the clinical trial 09-177) OR Any contraindication to baseline MRI based on departmental magnetic resonance (MR) questionnaire, or inability to cooperate for an MRI scan Inability to undergo a magnetic resonance imaging (MRI) or PET scan (e.g., claustrophobia or metal implant) Patient must not have any contra-indications to MRI imaging including implanted medical devices and metal objects which may be adversely affected by MRI imaging; all subjects will be required to complete a standard MRI screening form prior to imaging Able to tolerate magnetic resonance (MR) imaging required by protocol, to be performed at an American College of Radiology Imaging Network (ACRIN)-qualified facility and scanner Previous MRI imaging of the prostate The subject has concordant magnetic resonance imaging (MRI)/1H MRSI findings from a magnetic resonance (MR) staging exam at UCSF performed prior to the 13C MRSI exam performed in this study with investigational medicinal product (IMP), or is willing to undergo MRI/1H MRSI in connection with the study exam Diagnostic quality abdominal imaging (CT or magnetic resonance imaging [MRI]) within the past 45 days Unable to receive or tolerate magnetic resonance imaging (MRI) scan after evaluation of MRI screening form Inability to undergo magnetic resonance imaging (i.e. those patients with automated implantable cardioverter defibrillators [AICD]/pacemakers) Participants requiring conscious sedation for magnetic resonance (MR) imaging Expected to undergo magnetic resonance imaging (MRI) within two weeks following the study procedure DCIS must be >= 1 cm based on extent of calcifications, presence of a mass on ultrasound OR enhancement on magnetic resonance imaging (MRI) OR