PET/CT or PET/MRI in Measuring Tumors in Patients Undergoing Clinical Imaging or With Newly Diagnosed Breast Cancer

Inclusion Criteria: * \[Cohorts 1 and 2\] Female patients who are referred by their physician to have a clinical PET/CT * \[Cohort 3\] Patients referred for clinical breast dynamic contrast-enhanced (DCE)-MRI for recently diagnosed breast cancer * Normal kidney function for subjects that will receive magnetic resonance (MR) contrast agent as part of their clinical imaging * For subjects for whom MR contrast agent is to be administered, University Hospitals (UH) policy 8.17.26 will be applied * The following guidelines will be followed when a patient or patient representative responds "yes" to questions on the MRI history sheet 'Are you on dialysis, history of kidney failure, end stage renal disease, chronic liver disease, or are you a peri-liver transplant patient': * The patient must have a serum creatinine value available within three (3) weeks prior to the injection of gadolinium * Calculate an estimated glomerular filtration rate (eGFR) based on serum creatinine; if the eGFR is less than 30 the attending radiologist must discuss the risks and benefits of administering gadolinium with the referring physician and patient; the collective judgment of the patient, radiologist and referring physician must be in agreement to proceed with the injection of gadolinium * Calculated eGFR in range of 31-59 requires the judgment of the attending radiologist whether to discuss gadolinium administration with referring physician and patient or whether to directly use or hold the contrast agent * If an eGFR is greater than 60, gadolinium may be administered without further physician or patient discussion * Gadolinium administration is limited to single dose at 0.1mmol/kg; Omniscan should not be used * Technologist will document radiologist decision to administer gadolinium on the MRI history sheet; radiologist will document decision and consultation with the referring physician and patient in the MRI report * PERITONEAL DIALYSIS PATIENTS: * No gadolinium will be administered unless the patient has been scheduled for hemodialysis within 24 hours following the injection of gadolinium; technologist will determine eGFR and follow above guidelines; dialysis will be scheduled by the referring physician * HEMODIALYSIS PATIENTS: * No gadolinium will be administered unless the patient has been scheduled for hemodialysis within 24 hours following the injection of gadolinium; no determination of eGFR is necessary; radiologist will assume eGFR less than 30 and follow above guidelines; dialysis will be scheduled by the referring physician * Ability to provide informed consent Exclusion Criteria: * Subjects who do not meet all of the above inclusion criteria * Subjects unwilling or unable to sign the informed consent form * Subjects who are cognitively impaired and thus unable to give informed consent * Subjects unable to undergo MR scanning due to exclusion via University Hospitals Case Medical Center (UHCMC) MR restrictions (e.g. certain implanted metallic or electronic devices) * Subjects who are pregnant * Subjects that are too large to fit comfortably into the PET/MR on the breast coil; for cohort 1 only we will accept a maximum of 10 subjects that are too large for the PET/MRI to acquire a prone PET/CT but without the paired PET/MR