CMS Pub. 100-03, ch. 1, § 220.2

A. General

1. Method of Operation

Magnetic Resonance Imaging (MRI), formerly called nuclear magnetic resonance (NMR), is a non-invasive

method of graphically representing the distribution of water and other hydrogen-rich molecules in the human

body. In contrast to conventional radiographs or computed tomography (CT) scans, in which the image is

produced by x-ray beam attenuation by an object, MRI is capable of producing images by several

techniques. In fact, various combinations of MRI image production methods may be employed to emphasize

particular characteristics of the tissue or body part being examined. The basic elements by which MRI

produces an image are the density of hydrogen nuclei in the object being examined, their motion, and the

relaxation times, and the period of time required for the nuclei to return to their original states in the main,

static magnetic field after being subjected to a brief additional magnetic field. These relaxation times reflect

the physical-chemical properties of tissue and the molecular environment of its hydrogen nuclei. Only

hydrogen atoms are present in human tissues in sufficient concentration for current use in clinical MRI.

Magnetic Resonance Angiography (MRA) is a non-invasive diagnostic test that is an application of MRI. By

analyzing the amount of energy released from tissues exposed to a strong magnetic field, MRA provides

images of normal and diseased blood vessels, as well as visualization and quantification of blood flow

through these vessels.

2. General Clinical Utility

Overall, MRI is a useful diagnostic imaging modality that is capable of demonstrating a wide variety of soft-tissue lesions with contrast resolution equal or superior to CT scanning in various parts of the body.

Among the advantages of MRI are the absence of ionizing radiation and the ability to achieve high levels of

tissue contrast resolution without injected iodinated radiological contrast agents. Recent advances in

technology have resulted in development and Food and Drug Administration (FDA) approval of new

paramagnetic contrast agents for MRI which allow even better visualization in some instances. Multi-slice

imaging and the ability to image in multiple planes, especially sagittal and coronal, have provided flexibility

not easily available with other modalities. Because cortical (outer layer) bone and metallic prostheses do not

cause distortion of MR images, it has been possible to visualize certain lesions and body regions with greater

certainty than has been possible with CT. The use of MRI on certain soft tissue structures for the purpose of

detecting disruptive, neoplastic, degenerative, or inflammatory lesions has now become established in

medical practice.

Phase contrast (PC) and time-of-flight (TOF) are some of the available MRA techniques at the time these

instructions are being issued. PC measures the difference between the phases of proton spins in tissue and

blood and measures both the venous and arterial blood flow at any point in the cardiac cycle. TOF measures

the difference between the amount of magnetization of tissue and blood and provides information on the

structure of blood vessels, thus indirectly indicating blood flow. Two-dimensional (2D) and three-dimensional (3D) images can be obtained using each method.

Contrast-enhanced MRA (CE-MRA) involves blood flow imaging after the patient receives an intravenous

injection of a contrast agent. Gadolinium, a non-ionic element, is the foundation of all contrast agents

currently in use. Gadolinium affects the way in which tissues respond to magnetization, resulting in better

visualization of structures when compared to un-enhanced studies. Unlike ionic (i.e., iodine-based) contrast

agents used in conventional contrast angiography (CA), allergic reactions to gadolinium are extremely rare.

Additionally, gadolinium does not cause the kidney failure occasionally seen with ionic contrast agents.

Digital subtraction angiography (DSA) is a computer-augmented form of CA that obtains digital blood flow

images as contrast agent courses through a blood vessel. The computer “subtracts” bone and other tissue

from the image, thereby improving visualization of blood vessels. Physicians elect to use a specific MRA or

CA technique based upon clinical information from each patient.

B. Nationally Covered MRI and MRA Indications

1. MRI

Although several uses of MRI are still considered investigational and some uses are clearly contraindicated

(see subsection C), MRI is considered medically efficacious for a number of uses. Use the following

descriptions as general guidelines or examples of what may be considered covered rather than as a restrictive

list of specific covered indications. Coverage is limited to MRI units that have received FDA premarket

approval, and such units must be operated within the parameters specified by the approval. In addition, the

services must be reasonable and necessary for the diagnosis or treatment of the specific patient involved.

a. Effective November 22, 1985, MRI is useful in examining the head, central nervous system, and

spine. Multiple sclerosis can be diagnosed with MRI and the contents of the posterior fossa are

visible. The inherent tissue contrast resolution of MRI makes it an appropriate standard diagnostic

modality for general neuroradiology.

b. Effective November 22, 1985, MRI can assist in the differential diagnosis of mediastinal and

retroperitoneal masses, including abnormalities of the large vessels such as aneurysms and dissection.

When a clinical need exists to visualize the parenchyma of solid organs to detect anatomic disruption

or neoplasia, this can be accomplished in the liver, urogenital system, adrenals, and pelvic organs

without the use of radiological contrast materials. When MRI is considered reasonable and

necessary, the use of paramagnetic contrast materials may be covered as part of the study. MRI may

also be used to detect and stage pelvic and retroperitoneal neoplasms and to evaluate disorders of

cancellous bone and soft tissues. It may also be used in the detection of pericardial thickening.

Primary and secondary bone neoplasm and aseptic necrosis can be detected at an early stage and

monitored with MRI. Patients with metallic prostheses, especially of the hip, can be imaged in order

to detect the early stages of infection of the bone to which the prosthesis is attached.

c. Effective March 22, 1994, MRI may also be covered to diagnose disc disease without regard to

whether radiological imaging has been tried first to diagnose the problem.

d. Effective March 4, 1991, MRI with gating devices and surface coils, and gating devices that

eliminate distorted images caused by cardiac and respiratory movement cycles are now considered

state of the art techniques and may be covered. Surface and other specialty coils may also be

covered, as they are used routinely for high resolution imaging where small limited regions of the

body are studied. They produce high signal-to-noise ratios resulting in images of enhanced anatomic

detail.

2. MRA (MRI for Blood Flow)

Currently covered indications include using MRA for specific conditions to evaluate flow in internal carotid

vessels of the head and neck, peripheral arteries of lower extremities, abdomen and pelvis, and the chest.

Coverage is limited to MRA units that have received FDA premarket approval, and such units must be

operated within the parameters specified by the approval. In addition, the services must be reasonable and

necessary for the diagnosis or treatment of the specific patient involved.

a. Head and Neck

Effective April 15, 2003, studies have proven that MRA is effective for evaluating flow in internal

carotid vessels of the head and neck. However, not all potential applications of MRA have been shown

to be reasonable and necessary. All of the following criteria must apply in order for Medicare to provide

coverage for MRA of the head and neck:

• MRA is used to evaluate the carotid arteries, the circle of Willis, the anterior, middle or

posterior cerebral arteries, the vertebral or basilar arteries or the venous sinuses;

• MRA is performed on patients with conditions of the head and neck for which surgery is

anticipated and may be found to be appropriate based on the MRA. These conditions include,

but are not limited to, tumor, aneurysms, vascular malformations, vascular occlusion or

thrombosis. Within this broad category of disorders, medical necessity is the underlying

determinant of the need for an MRA in specific diseases. The medical records should clearly

justify and demonstrate the existence of medical necessity; and

• MRA and CA are not expected to be performed on the same patient for diagnostic purposes

prior to the application of anticipated therapy. Only one of these tests will be covered

routinely unless the physician can demonstrate the medical need to perform both tests.

b. Peripheral Arteries of Lower Extremities

Effective April 15, 2003, studies have proven that MRA of peripheral arteries is useful in determining

the presence and extent of peripheral vascular disease in lower extremities. This procedure is non-invasive and has been shown to find occult vessels in some patients for which those vessels were not

apparent when CA was performed. Medicare will cover either MRA or CA to evaluate peripheral

arteries of the lower extremities. However, both MRA and CA may be useful in some cases, such as:

• A patient has had CA and this test was unable to identify a viable run-off vessel for bypass.

When exploratory surgery is not believed to be a reasonable medical course of action for this

patient, MRA may be performed to identify the viable runoff vessel; or

• A patient has had MRA, but the results are inconclusive.

c. Abdomen and Pelvis

i. Pre-operative Evaluation of Patients Undergoing Elective Abdominal Aortic Aneurysm (AAA)

Repair

Effective July 1, 1999, MRA is covered for pre-operative evaluation of patients undergoing elective

AAA repair if the scientific evidence reveals MRA is considered comparable to CA in determining

the extent of AAA, as well as in evaluating aortoiliac occlusion disease and renal artery pathology

that may be necessary in the surgical planning of AAA repair. These studies also reveal that MRA

could provide a net benefit to the patient. If preoperative CA is avoided, then patients are not

exposed to the risks associated with invasive procedures, contrast media, end-organ damage, or

arterial injury.

ii. Imaging the Renal Arteries and the Aortoiliac Arteries in the Absence of AAA or Aortic

Dissection

Effective July 1, 2003, MRA coverage is expanded to include imaging the renal arteries and the

aortoiliac arteries in the absence of AAA or aortic dissection. MRA should be obtained in those

circumstances in which using MRA is expected to avoid obtaining CA, when physician history,

physical examination, and standard assessment tools provide insufficient information for patient

management, and obtaining an MRA has a high probability of positively affecting patient

management. However, CA may be ordered after obtaining the results of an MRA in those rare

instances where medical necessity is demonstrated.

d. Chest

i. Diagnosis of Pulmonary Embolism

Current scientific data has shown that diagnostic pulmonary MRAs are improving due to recent

developments such as faster imaging capabilities and gadolinium-enhancement. However, these

advances in MRA are not significant enough to warrant replacement of pulmonary angiography in

the diagnosis of pulmonary embolism for patients who have no contraindication to receiving

intravenous iodinated contrast material. Patients who are allergic to iodinated contrast material

face a high risk of developing complications if they undergo pulmonary angiography or computed

tomography angiography. Therefore, Medicare will cover MRA of the chest for diagnosing a

suspected pulmonary embolism when it is contraindicated for the patient to receive intravascular

iodinated contrast material.

ii. Evaluation of Thoracic Aortic Dissection and Aneurysm

Studies have shown that MRA of the chest has a high level of diagnostic accuracy for pre-operative

and post-operative evaluation of aortic dissection of aneurysm. Depending on the clinical

presentation, MRA may be used as an alternative to other non-invasive imaging technologies, such as

transesophageal echocardiography and CT. Generally, Medicare will provide coverage only for

MRA or for CA when used as a diagnostic test. However, if both MRA and CA of the chest are

used, the physician must demonstrate the medical need for performing these tests.

While the intent of this policy is to provide reimbursement for either RA or CA, the Centers for

Medicare & Medicaid Services (CMS) is also allowing flexibility for physicians to make appropriate

decisions concerning the use of these tests based on the needs of individual patients. CMS

anticipates, however, low utilization of the combined use of MRA and CA. As a result, CMS

encourages the Medicare Administrative Contractors (MACs) to monitor the use of these tests and,

where indicated, require evidence of the need to perform both MRA and CA.

C. Contraindications and Nationally Non-Covered Indications

1. Contraindications

The MRI is not covered when the following patient-specific contraindications are present:

MRI is not covered for patients with cardiac pacemakers or with metallic clips on vascular aneurysms unless

the Medicare beneficiary meets the provisions of the following exceptions:

Effective July 7, 2011, the contraindications will not apply to pacemakers when used according to the FDA-approved labeling in an MRI environment, or

Effective February 24, 2011, CMS believes that the evidence is promising although not yet convincing that

MRI will improve patient health outcomes if certain safeguards are in place to ensure that the exposure of

the device to an MRI environment adversely affects neither the interpretation of the MRI result nor the

proper functioning of the implanted device itself. We believe that specific precautions (as listed below)

could maximize benefits of MRI exposure for beneficiaries enrolled in clinical trials designed to assess the

utility and safety of MRI exposure. Therefore, CMS determines that MRI will be covered by Medicare

when provided in a clinical study under section 1862(a)(1)(E) (consistent with section 1142 of the Social

Security Act (the Act)) through the Coverage with Study Participation (CSP) form of Coverage with

Evidence Development (CED) if the study meets the criteria in each of the three paragraphs below:

The approved prospective clinical study of MRI must, with appropriate methodology, address one or more

aspects of the following questions:

1. Do results of MRI in implanted permanent pacemaker (PM)/implantable cardioverter defibrillator (ICD)

beneficiaries with implanted cardiac devices affect physician decision making related to:

a. Clinical management strategy (e.g., in oncology, toward palliative or curative care)?

b. Planning of treatment interventions?; or

c. Prevention of unneeded diagnostic studies or interventions, or preventable exposures?

2. Do results of MRI in PM/ICD beneficiaries with implanted cardiac devices affect patient outcomes

related to:

a. Survival?

b. Quality of life?; or

c. Adverse events during and after MR scanning?

In addition, the prospective clinical study of MRI must include safety criteria for all participants. Such

required safety measures for such studies, as further explained in guidance documents from professional

societies must include, but are not limited to:

1. MRI should be done on a case-by-case and site-by-site basis.

2. MRI scan sequences, field intensity, and field(s) of exposure should be selected to minimize risk to the

patient while gaining needed diagnostic information for diagnosis or for managing therapy.

3. MRI scanning should be done only if the site is staffed with individuals with the appropriate radiology

and cardiology knowledge and expertise on hand.

4. Implanted device patients who are candidates for recruitment for an MRI clinical study should be

advised that life-threatening arrhythmias might occur during MRI and serious device malfunction might

occur, requiring replacement of the device.

5. Radiology and cardiology personnel and a fully stocked crash cart should be readily available throughout

the procedure in case a significant arrhythmia develops during the examination that does not terminate

with the cessation of the MRI study. The cardiologist should be familiar with the patient’s arrhythmia

history and the implanted device. A programmer that can be used to adjust the device as necessary

should be readily available.

6. All such patients should be actively monitored for cardiac and respiratory function throughout the

examination. At a minimum, ECG and pulse oximetry should be used. Visual and verbal contact with

the patient must be maintained throughout the MRI scan. The patient should be instructed to alert the

MRI staff on hand to any unusual sensations, pains, or to any problems.

7. At the conclusion of the examination, the cardiologist should examine the device to confirm that the

function is consistent with its pre-examination state.

8. Follow-up should include a check of the patient’s device at a time remote (1-6 weeks) after the scan to

confirm appropriate function.

9. If the implanted device manufacturer has indicated additional safety precautions appropriate for safe

MRI performance, these must be included in the study protocol.

The clinical study must adhere to the following standards of scientific integrity and relevance to the

Medicare population:

a. The principal purpose of the research study is to test whether a particular intervention potentially

improves the participants’ health outcomes.

b. The research study is well supported by available scientific and medical information or it is intended

to clarify or establish the health outcomes of interventions already in common clinical use.

c. The research study does not unjustifiably duplicate existing studies.

d. The research study design is appropriate to answer the research question being asked in the study.

e. The research study is sponsored by an organization or individual capable of executing the proposed

study successfully.

f. The research study is in compliance with all applicable Federal regulations concerning the protection

of human subjects found at 45 CFR Part 46. If a study is regulated by the FDA, it must be in

compliance with 21 CFR Parts 50 and 56.

g. All aspects of the research study are conducted according to appropriate standards of scientific

integrity (see http://www.icmje.org).

h. The research study has a written protocol that clearly addresses, or incorporates by reference, the

standards listed here as Medicare requirements for CED coverage.

i. The clinical research study is not designed to exclusively test toxicity or disease pathophysiology in

healthy individuals. Trials of all medical technologies measuring therapeutic outcomes as one of the

objectives meet this standard only if the disease or condition being studied is life threatening as

defined in 21 CFR §312.81(a) and the patient has no other viable treatment options.

j. The clinical research study is registered on the www.ClinicalTrials.gov website by the principal

sponsor/investigator prior to the enrollment of the first study subject.

k. The research study protocol specifies the method and timing of public release of all pre-specified

outcomes to be measured, including release of outcomes if outcomes are negative or study is

terminated early. The results must be made public within 24 months of the end of data collection. If

a report is planned to be published in a peer reviewed journal, then that initial release may be an

abstract that meets the requirements of the International Committee of Medical Journal Editors

(http://www.icmje.org). However, a full report of the outcomes must be made public no later than

three (3) years after the end of data collection.

l. The research study protocol must explicitly discuss subpopulations affected by the treatment under

investigation, particularly traditionally underrepresented groups in clinical studies, how the inclusion

and exclusion criteria effect enrollment of these populations, and a plan for the retention and

reporting of said populations in the trial. If the inclusion and exclusion criteria are expected to have a

negative effect on the recruitment or retention of underrepresented populations, the protocol must

discuss why these criteria are necessary.

m. The research study protocol explicitly discusses how the results are or are not expected to be

generalizable to the Medicare population to infer whether Medicare patients may benefit from the

intervention. Separate discussions in the protocol may be necessary for populations eligible for

Medicare due to age, disability, or Medicaid eligibility.

Consistent with section 1142 of the Act, the Agency for Healthcare Research and Quality supports clinical

research studies that CMS determines meet the above-listed standards and address the above-listed research

questions.

• MRI during a viable pregnancy is also contraindicated at this time.

• The danger inherent in bringing ferromagnetic materials within range of MRI units generally

constrains the use of MRI on acutely ill patients requiring life support systems and monitoring

devices that employ ferromagnetic materials.

• In addition, the long imaging time and the enclosed position of the patient may result in

claustrophobia, making patients who have a history of claustrophobia unsuitable candidates for MRI

procedures.

2. Nationally Non-Covered Indications

CMS has determined that MRI of cortical bone and calcifications, and procedures involving spatial

resolution of bone and calcifications, are not considered reasonable and necessary indications within the

meaning of section 1862(a)(1)(A) of the Act, and are therefore non-covered.

D. Other

Effective June 3, 2010, all other uses of MRI or MRA for which CMS has not specifically indicated

coverage or non-coverage continue to be eligible for coverage through individual MAC discretion.