Computed tomographic angiography (CTA) uses a computerized analysis of x-ray images (enhanced by contrast material injected into a peripheral vein) to visualize the blood flow in arterial and venous structures throughout the body. Magnetic resonance angiography (MRA) uses magnetic resonance imaging (MRI) technology to detect, diagnose, and aid in the treatment of disorders affecting blood vessels.  This document addresses the use of CTA and MRA for the evaluation and imaging of vessels in the head and neck.

Note: Please see the following documents for other uses of CTA or MRA:

• CG-RAD-09 CTA/MRA of the Thorax, Abdomen and Extremities
• CG-RAD-14 CT/MRI of the Spine (Cervical, Thoracic, Lumbar)
• RAD.00035 Contrast-Enhanced Cardiac Computed Tomography Angiography (CTA) and Cardiac Magnetic Resonance Angiography (MRA)
• RAD.00055 MR Angiography (MRA) of the Spinal Canal

Note: Radiation exposure should be taken into account when considering the use of this technology. Follow-up scanning should be limited to organ or area of interest.

Note: CTA/MRA may be performed as the result of abnormalities found on CT or MR studies that require additional clarification, or when other imaging techniques such as Duplex ultrasonography studies do not provide adequate information and the results will be used in treatment planning. 

Medically Necessary:

I.  Vascular Disease and Anomalies

Computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) is considered medically necessary for the following indications:

• Evaluation of suspected occlusive/stenotic disorders of cerebral arteries and precerebral arteries causing transient ischemic attack [TIA] and cerebral vascular accident CVA when other imaging does not provide adequate information and the results may alter patient management.
• Suspect stenoses or other abnormalities of the vertebrobasilar system in patients with symptoms highly suggestive of vertebrobasilar syndrome (binocular vision loss, [positional] vertigo, dysarthria, diplopia) when the results may alter patient management.
• Suspected or known disease of the cranial or neck vessels including aneurysm, arteriovenous malformation, dissection, intramural hematoma, subarachnoid hemorrhage (SAH) or dural arterial fistula.
• For follow-up every 2 years after treatment of SAH treated with coils.  Current evidence shows that a follow-up CTA/MRA is beneficial every two (2) years after SAH treatment with coils. 
• Suspected thrombotic disease of the major vessels or dural sinus.
• Traumatic vascular injury.
• Subarachnoid, subdural, intracerebral hemorrhage secondary to trauma or cerebral aneurysm, or arteriovenous malformation (AVM) (Symptoms include recent onset of severe unexplained headache, alteration in cognitive status, or other focal neurological defect e.g., loss of vision).  Used to identify source of hemorrhage.
• Congenital anomalies of the cerebral or carotid circulation.
• Vascular abnormalities associated with sickle cell disease in children.
• Evaluation of sudden onset headaches during and/or after exertional activities.
• Evaluation of suspected dural sinus obstruction and /or invasion.
• Follow-up for:
  • Known AVM.
  • Known non-ruptured intracranial aneurysm that is greater than 3 mm in size.
• Pre-operative surgical planning of the resection of AVMs or aneurysms when the results may alter patient management.
• Pre-procedure planning prior to percutaneous vascular intervention for aneurysms or AVMs.

NOTE:  

• Current evidence does not support routine follow-up CTA/MRA after SAH in individuals treated with techniques other than coils.  The use of follow-up studies in these instances may be reviewed on a case-by-case basis.
• Current evidence does not support CTA/MRA screening when there is a genetic predisposition for subarachnoid hemorrhage (SAH) or the development of aneurysms.  Use of CTA/MRA screening in these instances may be reviewed on case-by-case basis.

II.  Tumors

Computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) is considered medically necessary for the evaluation for the following indications:

• Evaluation of pulsatile tinnitus in patients with signs or symptoms suggestive of a vascular lesion
• Evaluation of cerebral arteriovenous neoplasm, hemangioma.
• Pre operative planning to define the vascular supply of intracranial or glomus tumors.
• Evaluation of suspected dural sinus obstruction and /or invasion.

Clinical Considerations:

• Clinical situations may influence whether a CTA/MRA is suitable for pregnant women and children.
• Absolute and relative contraindications for scans requiring administration of intravascular contrast material may include
  • Documented allergy from prior contrast administration or a history of atopy.
  • Impaired renal function, when considering an enhanced CT with intravascular iodinated contrast agents.
  • Multiple myeloma.
• Contraindications for MRA imaging may include situations where individuals who:
  • Had placement of metal devices within the body. However, for those who have small amounts of implanted metal not located in the imaging area, an open MRA may be appropriate.
  • Who have intracranial surgical clips, that are not compatible with the use of MRI, placed for an aneurysm.
  • Who have conditions requiring external devices for care (e.g., portable O2 tank).
  • Are claustrophobic; an open MRA may be appropriate.
• CTA/MRA of the brain is not appropriate as a screening tool (i.e., asymptomatic patients without a previous diagnosis or specific clinical indication).

Place of Service:  Ambulatory, Outpatient Facility or Inpatient. Note, this guideline was intended to address the use of these studies in the outpatient setting

The following codes for treatments and procedures applicable to this guideline are included below for informational purposes.  Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy.  Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

Magnetic resonance angiography (MRA) of the brain is a noninvasive technique for imaging vascular anatomy and pathology without utilizing ionizing radiation and generally without the use of contrast agents. It is based on magnetic resonance imaging (MRI). MRA employs special imaging pulse sequences that emphasize the motion of blood relative to surrounding stationary tissue, with the goal of minimizing the signal from tissue and enhancing the signal from moving blood. The technique used in MRA allows for short repetition times, resulting in rapid image acquisition and reduced signal from background tissue. MRA may be used as an adjunct to Doppler ultrasonography or as an alternative to invasive catheter-based conventional angiography. In surgical planning, the MRA provides a three-dimensional rendering of vascular anatomy.  MRA data can be acquired on standard MRI scanners.

Computed tomography angiography (CTA) is an examination that uses x-rays to visualize blood flow in arterial structures supplying the brain. CTA combines the use of x-rays with computerized analysis of the images. Beams of x-rays are passed from a rotating device through the area of interest from several different angles creating cross-sectional images, which then are assembled by computer into a three-dimensional picture of the area being studied. Compared to catheter angiography, which involves injecting contrast material into an artery, CTA is much less invasive because the contrast material is injected intravenously. CTA can be done on conventional CT scanning equipment. Spiral (helical) CT scanners, with continuous gantry rotation and patient table movement, allow for image acquisition during the period of optimal intravascular contrast enhancement.

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Government Agency, Medical Society, and Other Authoritative Publications:

1. American College Of Radiology. ACR Practice Guideline for the performance of pediatric and adult cerebrovascular magnetic resonance angiography (MRA). 2005.  Available at:
   http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines.aspx. Accessed on December 06, 2007.
2. American College of Radiology. ACT Appropriateness Criteria,^™ Cerebrovascular Disease. 2006. Available at:
   http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx.   Accessed on December 07, 2007.
3. Centers for Medicare and Medicaid Services. National Coverage Determination for Magnetic Resonance Angiography (MRA). NCD #220.3. Effective July 1, 2003. Available at: http://www.cms.hhs.gov/mcd/index_list.asp?list_type=ncd. Accessed on December 06, 2007.
4. Hayes, Inc. Medical Technology Directory. Computed Tomography Angiography for Acute Ischemic Stroke. Hayes Inc. Lansdale, PA. February 9, 2005.  Search updated January 28, 2007.
5. Hayes, Inc. Medical Technology Directory. Computed Tomography Angiography for Intracerebral Aneurysm and Subarachnoid Hemorrhage. Hayes Inc. Lansdale, PA. February 11 2005.  Search updated January 29, 2007.

Aneurysms
Arteriovenous Malformation (AVM)
Cerebral Arteries
Computed Tomographic Angiography (CTA)
Magnetic Resonance Angiography (MRA)