Contraindication to MRI\r\n* Cardiac pacemaker or defibrillator\r\n* Surgically implanted electrical devices such as spinal stimulation devices or intracranial stimulation devices, cochlear implants, the presence of metallic foreign bodies in the orbits, and incompatible old mechanical heart valves and aneurysm clips Have septal aneurysm or other heart aneurysm. Patients with pacemakers, aneurysm clips, neurostimulators, cochlear implants, metal in ocular structures, history of being a steel worker, or other incompatible implants which makes MRI safety an issue are excluded Patients with pacemakers, non-titanium aneurysm clips, neurostimulators, cochlear implants, non-titanium metal in ocular structures, history of being a steel worker, or other incompatible implants which makes MRI safety an issue are excluded Have implanted electronic devices or implants with metal parts in the immediate vicinity of a lesion Patients who are not suitable to undergo MRI or use gadolinium contrast due to:\r\n* Claustrophobia\r\n* Presence of metallic objects or implanted medical devices in body (i.e. cardiac pacemaker, aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants)\r\n* Sickle cell disease\r\n* Renal failure\r\n* Reduced renal function, as determined by creatinine clearance < mL/min based on a serum creatinine level obtained within days prior to registration Has implanted medical device(s) that pose a high risk for colonization and/or cannot be easily removed (e.g., prosthetic joints, artificial heart valves, pacemakers, orthopedic screw(s), metal plate(s), bone graft(s), or other exogenous implant(s)). Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial heart, valves with steel parts, metal fragments, shrapnel, bullets, tattoos near the eye, or steel implants Ferromagnetic objects such as jewelry or metal clips in clothing For patients with localized prostate cancer contraindication to MRI:\r\n* Patients weighing > kilograms (weight limit for the scanner tables)\r\n* Allergy to MR contrast agent\r\n* Patients with pacemakers, cerebral aneurysm clips, shrapnel injury or implantable electronic devices Patients unable to undergo MRI exams (i.e. patients with non-compatible devices such as cardiac pacemakers, other implanted electronic devices, metallic prostheses, or ferromagnetic prostheses [e.g. pins in artificial joints and surgical pins/clips], or unable to receive gadolinium for MRI, as per the standard UM Department of Radiology MRI screening criteria) Patients who cannot undergo magnetic resonance imaging (MRI) or single photon emission computed tomography (SPECT) for any reason including due to obesity or to having certain metal in their bodies (specifically pacemakers, infusion pumps, metal aneurysm clips, metal prostheses, joints, rods, or plates) Metal in the body (except dental fillings) e.g., pacemaker, infusion pump, metal aneurysm clip, metal prosthesis, joint, rod or plate. Patients with a contraindication to MRI such as implanted metal devices or foreign bodies or severe claustrophobia Contraindication for contrast-enhanced MRI as defined by the standard operating procedures of the Department of Radiology at University of Texas (UT) Southwestern; briefly, these include medically unstable; cardiac pacemaker; intracranial clips, metal implants; metal in the eyes; pregnant or nursing; claustrophobia; and impairment of the renal function with estimated glomerular filtration rate (eGFR) < mL/min/. m^; patients with one or more of these contraindications but eligible to undergo contrast-enhanced CT can participate in this study and will not receive an MRI MRI MONITORING SUB-STUDY: Implanted prosthetic heart valves, pacemaker, neuro-stimulation devices, surgical clips (hemostatic clips) or other metallic implants Patients with one or more of the following contraindications for MRI and/or MRI contrast agents such as:\r\n* Severe claustrophobia\r\n* Aversion to MRI\r\n* Metallic fragments, clips or devices in the brain, eye, and/or spinal canal in which movement in the bore of the magnet may damage sensitive tissues, unless deemed to be safe by the manufacturer; note: metallic fragments, clips or devices outside the brain, eye, and/or spinal canal may be safe if deemed by the manufacturer; caution is needed to determine safety for each patient that may have the following conditions: cardiac pacemaker; heart valve replacement, venous umbrella, being a sheet-metal worker or welder; aneurysm surgery, renal or aortic clips, prosthetic devices such as middle ear, eye, joint, or penile implants, joint replacement, hearing aid, neurostimulator, insulin pump, intrauterine devices (IUD), shunts/stents/metal mesh/coil implants, metal plate/pin/screw/wires, or any other metal implants, and permanent eyeliner and/or eyebrows Standard contraindications to MRI: for example, MRI non-compatible cardiac pacemakers, intracranial clips, foreign metal objects in the body and others as defined in the University of Texas (UT) Southwestern Institutional MRI Safety Policy Patients with pacemakers, ferro-magnetic aneurysm clips, metal infusion pumps, metal or shrapnel fragments or certain types of stents The patient has implanted medical device(s) that pose a high risk for colonization and/or cannot be easily removed (e.g., prosthetic joints, artificial heart valves, pacemakers, orthopedic screw(s), metal plate(s), bone graft(s), or other exogenous implant[s]); NOTE: More common devices and prosthetics which include arterial and venous stents, dental and breast implants and venous access devices (e.g. Port-a-Cath or Mediport) are permitted; the study chair must be contacted prior to consenting any subject who has any other device and/or implant Known contraindication to enhanced MRI and computed tomography (CT), including but not limited to:\r\n* Presence of metal objects within the body such as a cardiac pacemaker, implanted cardiac defibrillator, brain aneurysm clips, cochlear implant, ocular foreign body, or shrapnel\r\n* History of immediate or delayed hypersensitivity reaction or other contraindication to contrast agents including but not limited to gadolinium and iodine Any contraindication to MRI (i.e. patients with pacemakers or other metal implanted medical devices) Intracranial aneurysm clips (except Sugita) or other metallic objects Intra- orbital metal fragments that have not been removed Presence of metallic objects such as artificial joints, inner ear (cochlear) implants, brain aneurysm clips, pacemakers, and metallic foreign bodies in the eye or other body areas that would prevent use of MRI imaging Has implanted medical device(s) that pose a high risk for colonization and/or cannot be easily removed (e.g., prosthetic joints, artificial heart valves, pacemakers, orthopedic screw(s), metal plate(s), bone graft(s), or other exogenous implant(s)). NOTE: More common devices and prosthetics which include arterial and venous stents, dental and breast implants, and venous access devices (e.g., Port-a-Cath or Mediport) are permitted. Sponsor must be contacted prior to consenting any subject who has any other device and/or implant Subjects who have implanted medical devices that pose high risks for colonization and cannot be easily removed (e.g. artificial heart valves, pacemakers, prosthetic joints, orthopedic screw(s), metal plate(s)) if infection occurs. Other common devices such as venous access devices (e.g. Port-a-Cath or Mediport) may be permitted as well as arterial and venous stents and dental and breast implants that were placed more than months prior to first dose of study drug. Patients whose physical dimensions cannot be accommodated in the MRI scanner or patients with contraindications to MRI imaging such as pacemakers, non-compatible aneurysm clips, shrapnel and other internal ferromagnetic objects Implanted medical devices that pose high risks for colonization and cannot be easily removed (e.g., artificial heart valves, pacemakers, prosthetic joints, orthopedic screw(s), metal plate(s)) if infection occurs. Other common devices such as venous access devices (e.g., Port-a-Cath or Mediport) may be permitted as well as arterial and venous stents and dental and breast implants that were placed more than months prior to first dose of study drug. Patients not suitable for cardiac MRI; contraindications include:\r\n* Intracranial metal, pacemakers, defibrillators, functioning neurostimulator devices, or other implanted electronic devices\r\n* Ferromagnetic cerebral aneurysm clips, or other intraorbital/intracranial metal\r\n* Allergy to gadolinium or other severe drug allergies\r\n* Claustrophobia\r\n* Congestive heart failure (New York Heart Association [NYHA] class III or IV)\r\n* Significant valvular disease, or significant pulmonary disease requiring supplemental oxygen therapy Has implanted medical device(s) that pose a high risk for colonization and/or cannot be easily removed (e.g., prosthetic joints, artificial heart valves, pacemakers, orthopedic screw(s), metal plate(s), bone graft(s), or other exogenous implant(s)). NOTE: More common devices and prosthetics which include arterial and venous stents, dental and breast implants, and venous access devices (e.g., Port-a-Cath or Mediport) are permitted. Sponsor must be contacted prior to consenting any subject who has any other device and/or implant. Has implanted medical device(s) that pose a high risk for colonization and/or cannot be easily removed (e.g., prosthetic joints, artificial heart valves, pacemakers, orthopedic screw(s), metal plate(s), bone graft(s), or other exogenous implant(s)). NOTE: More common devices and prosthetics which include arterial and venous stents, dental and breast implants, and venous access devices (e.g., Port-a-Cath or Mediport) are permitted. Sponsor must be contacted prior to consenting any subject who has any other device and/or implant. Patients who cannot undergo MRI or single-photon emission computed tomography (SPECT) due to obesity or to having certain metal in their bodies (specifically pacemakers, infusion pumps, metal aneurysm clips, metal prostheses, joints, rods, or plates) Subjects who have implanted medical devices that pose high risks for colonization and cannot be easily removed (e.g., artificial heart valves, pacemakers, prosthetic joints, orthopedic screw(s), metal plate(s)) if infection occurs; other common devices such as venous access devices (e.g., Port-a-Cath or Mediport) may be permitted as well as arterial and venous stents and dental and breast implants Has implanted medical device(s) that pose a high risk for colonization and/or cannot be easily removed (e.g., prosthetic joints, artificial heart valves, pacemakers, orthopedic screw(s), metal plate(s), bone graft(s), or other exogenous implant(s)). NOTE: More common devices and prosthetics which include arterial and venous stents, dental and breast implants, and venous access devices (e.g., Port-a-Cath or Mediport) are permitted. Sponsor must be contacted prior to consenting any subject who has any other device and/or implant. Patient has implanted medical device(s) that pose a high risk for colonization and/or cannot be easily removed (e.g., prosthetic joints, artificial heart valves, pacemakers, orthopedic screw(s), metal plate(s), bone graft(s), or other exogenous implant(s)); NOTE: more common devices and prosthetics which include arterial and venous stents, dental and breast implants and venous access devices (e.g., Port-a-Cath or Mediport) are permitted; sponsor must be contacted prior to consenting any subject who has any other device and/or implant Known contraindication to MRI (e.g., severe claustrophobia, intracranial aneurysm clips, intraocular metallic foreign body, cardiac pacemaker); an extensive screening questionnaire will be completed by the subject as part of standard OHSU MRI safety measures 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) Implanted metal or metal devices that make a MRI scan prohibitive, history of claustrophobia or other condition that would make a MRI scan prohibitive Patients with heart stents or metal implants such as pacemakers, automatic defibrillators, cochlear implants, aneurysm clips, vena cava clips and skull plates (metal implants for orthopedic repair, e.g. pins, clips, plates, cages, joint replacements are allowed) Patients with heart stents or metal implants such as pacemakers, automatic defibrillators, aneurysm clips, vena cava clips and skull plates; (metal implants for orthopedic repair, e.g. pins, clips, plates, cages, joint replacements are allowed as are central venous access devices) Conditions that would preclude from successfully scanning subjects in magnetic resonance imaging (MRI):\r\n* Claustrophobia (this would make lying in the scanner very uncomfortable)\r\n* Having a pacemaker, aneurysm clips, neurostimulators, cochlear implants, metal in eyes, steel worker, or other implants\r\n* History of seizures\r\n* History of head injuries resulting in loss of consciousness > minutes Existing implantable medical electronic devices, life-supporting medical devices, and medical monitoring devices \r\n* Note: metal implants for orthopedic repair, e.g. pins, clips, plates, cages, joint replacements are allowed as are central venous access devices Patients with heart stents or metal implants such as pacemakers, automatic defibrillators, cochlear implants, aneurysm clips, vena cava clips and skull plates; (metal implants for orthopedic repair, e.g. pins, clips, plates, cages, joint replacements are allowed) For the subset of participants undergoing neuroimaging:\r\n* Medical history or devices which make an MRI unsafe or uncomfortable (e.g., magnetic rods or pins, metal plates or screws, pacemaker) EXCLUSION - PATIENT: Presence of MRI unsafe devices or objects which would make having an MRI unsafe, as per institutional clinical protocol. MRI unsafe devices or objects for the purposes of exclusion include but are not limited to certain intracranial aneurysm clips, cardiac pacemaker, and implantable defibrillator devices, metallic heart valve, or coronary artery stents, breast tissue expanders, bio or neurostimulators, pellets and bullets, ocular implants and devices, otologic and cochlear implants; other devices or metallic objects may be deemed unsafe for MRI at the radiologists discretion Participants with intracranial clips, metal implants or external clips within mm of the head Participants who have had a metal injury to the eye Women with aneurysm clips that don't allow for MRI Those with ferromagnetic cerebral aneurysm clips or other intraorbital/intracranial metal; pacemakers, defibrillators, functioning neurostimulator devices, non-compatible MRI tissue expanders or breast implants, or other implanted non-compatible MRI devices CONTROL (HEALTHY) GROUP: Those with ferromagnetic cerebral aneurysm clips or other intraorbital/intracranial metal; pacemakers, defibrillators, functioning neurostimulator devices or other implanted non-compatible MRI devices Patients with ferromagnetic cerebral aneurysm clips or other intraorbital/intracranial metal; pacemakers, defibrillators, functioning neurostimulator devices or other implanted electronic devices Risk for hazard due to magnetic fields such as metal in the body surgically or accidentally (e.g., pacemaker, cochlear implants, aneurysm clips, intravascular stents or coils, spinal shunt, injury involving bullets, shrapnel or metal implanted in their body, etc) Risk for hazard due to magnetic fields such as metal in the body surgically or accidentally (e.g., pacemaker, cochlear implants, aneurysm clips, intravascular stents or coils, spinal shunt, injury involving bullets, shrapnel or metal implanted in their body, etc) Patients with ferromagnetic cerebral aneurysm clips or other intraorbital/intracranial metal; pacemakers, defibrillators, functioning neurostimulator devices or other implanted electronic devices Suitable to undergo MRI and receive the contrast agent gadolinium (exclusions follow):\r\n* No history of untreatable claustrophobia\r\n* No presence of metallic objects or implanted medical devices in body (i.e., cardiac pacemaker, aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants)\r\n* No history of sickle cell disease\r\n* No contraindication to intravenous contrast administration\r\n* No known allergy-like reaction to gadolinium or moderate or severe allergic reactions to one or more allergens as defined by the American College of Radiology (ACR); patient may be eligible if willing to undergo pre-treatment as defined by the institution's policy and/or ACR guidance\r\n* No findings consistent with renal failure, as determined by glomerular filtration rate (GFR) < \r\nmL/min/. m^ based on a serum creatinine level obtained within days prior to registration\r\n* Weight lower than that allowable by the MRI table Patients with a metal heart valve, surgical clips, a pacemaker or any other indwelling metal device that might interfere with MRI Patients with a metal heart valve, surgical clips, a pacemaker or any other indwelling metal device that might interfere with MRI Patients who are not suitable to undergo MRI or PET or use gadolinium contrast due to:\r\n* Claustrophobia\r\n* Presence of metallic objects or implanted medical devices in body (i.e. cardiac pacemaker, aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants); the craniotomy patients will all have titanium but this is MRI compatible\r\n* Sickle cell disease\r\n* Renal failure\r\n* Reduced renal function, as determined by creatinine clearance < mL/min based on a serum creatinine level obtained within days prior to registration Patients with contra-indications for contrast enhanced magnetic resonance (MR) exam, including:\r\n* Cardiac pacemaker or pacemaker wiring in situ\r\n* Cerebral clips or metal artificial cardiac valves\r\n* Ossicle prosthesis\r\n* Conditions that could produce a dangerous situation in the presence of a strong magnetic field: line metallic implants, shrapnel, inability to lie still, and conditions that can worsen inside confined spaces (severe claustrophobia, psychosis)\r\n* Acute or chronic severe renal disease as determined by glomerular filtration rate (GFR) < ml/min/. m^\r\n* Pregnancy or breastfeeding Subjects with any type of pacemaker, cerebral aneurysm clips, shrapnel injury, or other implanted electronic devices or metal not compatible with MRI Patients who are not suitable to undergo MRI or use gadolinium contrast due to:\r\n* Claustrophobia\r\n* Presence of metallic objects or implanted medical devices in body (i.e. cardiac pacemaker, aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants)\r\n* Sickle cell disease\r\n* Renal failure\r\n* Reduced renal function, as determined by creatinine clearance < mL/min based on a serum creatinine level obtained within days prior to registration Any contraindication to undergoing MRI (e.g., pacemakers, cochlear implants, shrapnel injuries, or other types of metal or electric devices in the body, severe claustrophobia, cataract surgery with certain ocular implants [the following ocular implant models from Bausch & Lomb are considered unsafe for MRI: intraocular lens, models A, P, S, P, P, P, P, , B, M, P, PC, R, M, P, EXP D]) Pacemakers, electronic stimulation, metallic foreign bodies and devices and/or other conditions that are not MR safe, which include but are not limited to: \r\n* Electronically, magnetically, and mechanically activated implants\r\n* Ferromagnetic or electronically operated active devices metallic splinters in the eye\r\n* Ferromagnetic hemostatic clips in the central nervous system (CNS) or body\r\n* Cochlear implants\r\n* Other pacemakers\r\n* Insulin pumps and nerve stimulators\r\n* Non-MR safe lead wires prosthetic heart valves (if dehiscence is suspected)\r\n* Non ferromagnetic stapedial implants\r\n* Pregnancy\r\n* Claustrophobia that does not readily respond to oral medication No contra-indication to MR including severe claustrophobia, incompatible aneurysm clips or cardiac pacemaker Contraindication to MRI (i.e. pacemakers, aneurysm clips, or shrapnel fragments) Presence of MRI-incompatible metallic objects or implanted medical devices in the body (including but not limited to: non-MRI compatible metal objects, cardiac pacemaker, aneurysm clips, artificial heart valves with steel parts, metal fragments in the eye or central nervous system) Patients with ferromagnetic or otherwise non-MRI compatible aneurysm clips Patients who are no suitable to undergo MRI or use gadolinium contrast due to:\r\n* Claustrophobia\r\n* Presence of metallic objects or implanted medical devices in body (i.e. cardiac pacemaker, aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants)\r\n* Sickle cell disease\r\n* Renal failure\r\n* Reduced renal function, as determined by creatinine clearance < mL/min based on a serum creatinine level obtained within days prior to registration Any condition for which a MRI procedure is contraindicated including presence of metallic material in the body, such as pacemakers, non-MRI compatible surgical clips, shrapnel; pregnant or breast-feeding women are excluded Patients with metal devices in the body including, but not limited to metallic joint prostheses, artificial heart valves, pacemakers, and cochlear implants Have implanted prosthetic heart valves, pacemaker, neuro-stimulation devices, surgical clips (hemostatic clips) or other metallic implants Subjects who are unable to tolerate or are not eligible for MR imaging (claustrophobia, metal implantable devices such as pacemaker, aneurysm clips, etc) Contraindication to MRI:\r\n* Patients weighing more than weight limit for the scanner tables\r\n* Allergy to magnetic resonance (MR) contrast agent\r\n* Patients with pacemakers, cerebral aneurysm clips, shrapnel injury or implantable electronic device Standard MRI exclusion criteria will also be applied, including pacemakers and metal clips located in the patient Contraindication to MRI scanning, such as surgery that involves metal clips or wires or metal prostheses which might be expected to cause tissue damage or produce image artifacts Patients with ferromagnetic or otherwise non-MRI compatible aneurysm clips Cardiac pacemaker and metal devices (as specified in a separate MRI Informed consent) Contra-indications to MRI and/or PET/MRI:\r\n* Electrical implants such as cardiac pacemakers or perfusion pumps\r\n* Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants\r\n* Ferromagnetic objects such as jewelry or metal clips in clothing\r\n* Pregnant subjects\r\n* Pre-existing medical conditions including a likelihood of developing seizures or claustrophobic reactions Patients unable to tolerate MRI (patients with pacemakers, cerebral aneurysm clips, shrapnel injuries, or other implantable electronic devices or metal not compatible with MRI) Patients unable to undergo magnetic resonance (MR) exams are not eligible (i.e. patients with non?compatible devices such as cardiac pacemakers, other implanted electronic devices, metallic prostheses, or ferromagnetic prostheses, pins in artificial joints and surgical pins/clips) Intracranial metal, pacemakers, defibrillators, functioning neurostimulator devices, or other implanted electronic devices Ferromagnetic cerebral aneurysm clips, or other intraorbital/intracranial metal Subjects that have vascular or aneurysm clips, or metallic staples from a surgical procedure Subjects that may have shrapnel imbedded in their bodies, such as from war wounds, metal workers and machinists (metallic fragments in or near eyes), severe auto accident victims Aneurysmal clips Any patient with a metallic MRI incompatible implant, including cardiac pacemakers, neural pacemakers, aneurysmal clips, shrapnel, cochlear implants or ferrous surgical clips Patients with ferromagnetic or otherwise non-MRI compatible aneurysm clips Presence of pacemaker, intracranial aneurysm clip, bladder stimulator, cochlear implant or metal near eyes or near pelvis that would create excessive imaging artifact Subjects with a contraindication to an MRI including those with a pacemaker, ferromagnetic aneurysm clip, or cochlear implants Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants ferromagnetic objects such as jewelry or metal clips in clothing Non-removable hearing aid or dentures, metal intrauterine device (IUD), surgical aneurysm clips, cardiac pacemaker, prosthetic heart valve, neurostimulator, implanted pumps, cochlear implants, metal rods, plates or screws, surgery leaving implanted materials, metal injury to eye, metallic tattoos anywhere on the body, tattoos near the eye and transdermal patches Participants with contraindications to MRI (i.e., implanted metal including pacemakers, cerebral spinal fluid shunts, aneurysm clips, artificial heart valves, ear implants or metal/foreign objects in the eyes and those with a history of claustrophobia), injuries to the eyes with metal without X-ray documentation that metal was removed Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial heart, valves with steel parts, metal fragments, shrapnel, bullets, tattoos near the eye, or steel implants Ferromagnetic objects such as jewelry or metal clips in clothing Patients who are claustrophobic or have other contraindications to MRI, such as implanted pacemaker device vascular clips, surgical clips, prosthetic valves, pacemakers, otologic implants Those with contraindications for MRI such as ferromagnetic cerebral aneurysm clips or other intracranial metal, pacemakers, defibrillators, functioning neurostimulator devices or other implanted electronic devices MRI-incompatible metallic implants, embedded metallic objects, implanted biomedical devices e.g., cardiac pacemakers Normal MRI exclusion criteria will apply, including those on the following list; a standard MRI safety form will be used to identify potential conditions warranting exclusion\r\n* Electrical implants such as cardiac pacemakers or perfusion pumps\r\n* Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial heart, valves with steel parts, metal fragments, shrapnel, bullets, tattoos near the eye, or steel implants\r\n* Ferromagnetic objects such as jewelry or metal clips in clothing\r\n* Claustrophobia\r\n* History of seizures\r\n* Diabetes Patients who have presence of a known contraindication to MRI\r\n* Pacemaker\r\n* Aneurysmal clips\r\n* Metal implants in field of view \r\n* Pregnant\r\n* Age and mental status wherein he/she is unable to cooperate for MRI study Any condition for which a MRI procedure is contraindicated including presence of metallic material in the body, such as pacemakers, non- MRI compatible surgical clips, shrapnel, etc The standard exclusion criteria for MRI exams will apply which include patients with pacemakers, non-compatible intra-cranial vascular clips, inner ear implants, and severe claustrophobia All patients who are contraindicated for MR imaging in general; contraindications include:\r\n* Electrical implants such as cardiac pacemakers or perfusion pumps\r\n* Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants\r\n* Ferromagnetic objects such as jewelry or metal clips in clothing\r\n* Pregnant subjects\r\n* Pre-existing medical conditions including a likelihood of developing seizures or claustrophobic reactions, and any greater than normal potential for cardiac arrest. Inability to undergo MRI with gadolinium contrast or PET imaging due to:\r\n* Claustrophobia\r\n* Presence of metallic objects or implanted medical devices in body (i.e. cardiac pacemaker, aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, tattoos near the eye, or steel implants)\r\n* Sickle cell disease\r\n* Renal failure\r\n* Reduced renal function, as determined by creatinine clearance < mL/min based on a serum creatinine level obtained within days prior to registration Have permanently implanted prosthetic heart valves, pacemaker, neuro-stimulation devices, surgical clips (hemostatic clips) or other metallic implants Not suitable to undergo MRI or gadolinium-based contrast agent because of: \r\n* Severe claustrophobia not relieved by oral anxiolytics per institutional standard practice\r\n* Presence of MRI-incompatible metallic objects or implanted medical devices in body (including, but not limited to: non-MRI compatible metal objects, cardiac pacemaker, aneurysm clips, artificial heart valves with steel parts, or metal fragments in the eye or central nervous system)\r\n* Renal failure, as determined by glomerular filtration rate (GFR) < mL/min/. m^ based on a serum creatinine level obtained within hours prior to enrollment\r\n* Weight greater than that allowable by the MRI table, per local institutional practice Patients who are contraindicated for MRI or gadolinium contrast agents due to:\r\n* Claustrophobia\r\n* Presence of metallic objects or implanted medical devices in body (i.e., cardiac pacemaker, aneurysm clips, surgical clips, prostheses, skin staples, implanted prostheses, artificial heart valves with steel parts, metal fragments, shrapnel, or other metal implants that would contraindicate MRI)\r\n* Sickle cell disease\r\n* Renal failure with estimated GFR < mL/min/. m^ based upon serum creatinine\r\n* Weight greater than pounds (lbs) (the weight limit for the MRI) Subjects who have any type of biomedical implant, device and/or ferromagnetic material that can be displaced, perturbed, or otherwise malfunction due to mechanical, electronic, or magnetic means; these items may include:\r\n* Metallic fragments or shrapnel (such as from war wounds)\r\n* Cerebral aneurysm clips, biopsy marker clips\r\n* Vascular access ports (as are used with intravenous chemotherapy)\r\n* Cochlear implants, pacemakers, neurostimulators, biostimulators, and electronic infusion pumps\r\n**Implanted materials other than those verified as being rated magnetic resonance [MR] Safe or MR Conditional will not be allowed on study Patients who have any type of bioimplant activated by mechanical, electronic, or magnetic means (e.g., cochlear implants, pacemakers, neurostimulators, biostimulators, electronic infusion pumps, etc), because such devices may be displaced or malfunction Patients who have cerebral aneurysm clips Patients who may have shrapnel imbedded in their bodies (such as from war wounds), metal workers and machinists (potential for metallic fragments in or near the eyes) Subjects who have any type of bioimplant activated by mechanical, electronic, or magnetic means (e.g., cochlear implants, pacemakers, neurostimulators, biostimulators, electronic infusion pumps, etc.), because such devices may be displaced or malfunction Subjects who have cerebral aneurysm clips Subjects who may have shrapnel imbedded in their bodies (such as from war wounds), metal workers and machinists (potential for metallic fragments in or near the eyes) Patient with a contraindication to MRI (e.g., pacemaker, aneurysm clip, severe claustrophobia, infusion pumps, cochlear implants metallic or others according to the imaging site standard practice) Subjects with pacemakers, cerebral aneurysm clips, shrapnel injury, or other implanted electronic devices or metal not compatible with MRI No contra-indication to MR including severe claustrophobia, incompatible aneurysm clips or cardiac pacemaker Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial heart, valves with steel parts, metal fragments, shrapnel, bullets, tattoos near the eye, or steel implants Presence of pacemakers, aneurysm clips, artificial heart valves, ear implants, metal fragments or foreign objects in the eyes, skin of body that would preclude obtaining an MRI as part of the initial study evaluation Women with MRI/magnetic resonance angiogram (MRA) contraindications such as a cardiac pacemaker, aneurysm clip, cochlear implants, and metal in the eyes Contraindications for MRI (such as claustrophobia, pacemaker, non MR-compatible artificial heart valves, cochlear implants, surgical clips in the brain, metal fragments in eye) Braces or metal heart valves that may interfere with MRI, surgical clips, a pacemaker, piercings that cannot be removed, or any other indwelling metal device that might interfere with MRI