Computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) combine the use of computed tomography (CT) and magnetic resonance imaging (MRI) in conjunction with intravenously administered radio-opaque contrast material in order to visualize the anatomy and blood flow in arterial and venous vessels throughout the body. This document addresses the use of both CTA and MRA studies with contrast with or without specific computerized reconstruction of the images in the outpatient setting for the evaluation and imaging of vessels in the chest (excluding the coronary arteries), abdomen, and upper and lower extremities.

Note: CT and MRI of the heart are addressed in CG-RAD-15 and are not included in this document.

Note: Please see the following related documents for additional information:

• CG-RAD-08 CTA/MRA Head and Neck
• CG-RAD-15 CT/MRI of the Thoracic Cavity and Heart
• MED.00064 Transcatheter Ablation of Arrhythmogenic Foci in the Pulmonary Veins as a Treatment of Atrial Fibrillation (Radiofrequency and Cryoablation)
• RAD.00035 Coronary Artery Imaging: Contrast-Enhanced Coronary Computed Tomography Angiography (CCTA) and Coronary Magnetic Resonance Angiography (MRA)
• RAD.00055 MR Angiography (MRA) of the Spinal Canal

Medically Necessary:

1. Pulmonary Computed Tomographic Angiography
   Pulmonary CTA is considered medically necessary for any of the following:
   • Pulmonary embolism (PE) in individuals with suggestive clinical or radiographic findings; or
   • For the evaluation of candidates for pulmonary thromboendarterectomy; or
   • Pulmonary hypertension; or
   • Pulmonary arteriovenous malformation (AVM); or
   • Pulmonary sequestration; or
   • Localization of pulmonary veins in individuals with chronic or paroxysmal atrial fibrillation or flutter who meet criteria (Med.00064) for radiofrequency ablation and have undergone appropriate electrophysiology evaluation and re-evaluation of the pulmonary veins on one occasion following radiofrequency ablation; or
   • For individuals requiring pulmonary angiography but who have contraindications to conventional catheter-based pulmonary arteriography.
     
     
2. Pulmonary Magnetic Resonance Angiography
   Pulmonary MRA is considered medically necessary in individuals with suspected pulmonary embolism who meet all of the following criteria:
   • Pulmonary CTA and arteriography are contraindicated; and
   • Interpretation of a ventilation and perfusion (V/Q) study is limited.
     
     
3. Computed Tomographic Angiography or Magnetic Resonance Angiography of the Thoracic Cavity
   CTA or MRA of the thoracic cavity is considered medically necessary for any of the following:
   
   
   1. Evaluation of Thoracic Aorta: aneurysms, dissection, atheromatous disease, hematoma
      • Evaluation of thoracic aorta aneurysm
        • In individuals with suspected aortic aneurysm who have not undergone imaging of the thoracic aortic in the previous 60 days; or
        • In individuals with confirmed aneurysm with worsening symptoms; or
        • Prior to post-placement of a stent graft; or
        • Surveillance of confirmed aneurysm in individuals who have not undergone imaging of the thoracic aorta within the preceding 6 months; or
      • Evaluation of thoracic aorta dissection
        • In individuals with suspected aortic dissection; or
        • In individuals with confirmed aortic dissection with worsening symptoms or when surgical repair is anticipated; or
        • Surveillance of confirmed dissection in individuals who have not undergone imaging of the thoracic aorta within one year; or
      • Follow-up of repair of aneurysm or dissection
        • In individuals who have undergone surgical repair of aneurysm within the preceding year and have not undergone thoracic imaging within the preceding 6 months; or
        • Post-operative or post interventional vascular procedure for luminal patency versus re-stenosis (due to atherosclerosis, thromboembolism, intimal hyperplasia and other causes) as well as complications such as pseudoaneurysms, leaks, infection; or
      • Evaluation of atheromatous diseases such as penetrating ulcer and aortitis; or
      • Evaluation of hematoma.
        
        
   2. Evaluation of Anatomic Anomalies including:
      • Developmental anomalies; or
      • Congenital abnormalities of the great vessels and thoracic vasculature.
        
        
   3. Tumors
      • Vascular involvement from neoplasm.
        
        
   4. Other Signs, Symptoms or Conditions
      • Post-traumatic vascular injury; or
      • Suspected venous thrombosis or occlusion including superior vena cava syndrome; or
      • Subclavian steal syndrome; or
      • Thoracic outlet syndrome; or
      • Vasculitis; or
      • Non-invasive coronary arterial mapping, including internal mammary prior to repeat surgical revascularization; or
      • Identification of the source for embolism or occlusion (when the suspected source is the thoracic aorta or proximal arch arteries); or
      • Evaluation of pericardial conditions (i.e., pericardial effusion, constrictive pericarditis, or congenital pericardial disease).
        
        
4. Renal Computed Tomographic Angiography or Renal Magnetic Resonance Angiography
   CTA or MRA is considered medically necessary as part of the diagnostic evaluation for renal artery stenosis in any of the following:
   
   • Individuals with documented hypertension associated with any of the following clinical scenarios:
     • Abrupt onset; or
     • Accelerated progression; or
     • Onset of hypertension before age 30; or
     • Refractory to at least 3 conventional medications; or
     • Hypertension with renal failure or progressive renal insufficiency; or
   • Individuals with renal insufficiency that is either unexplained or induced by angiotensin-converting enzyme inhibitors; or
   • Individuals with unilateral small kidney (greater than 1.5 cm difference in size by ultrasound);
     or
   • Individuals with abdominal bruits, suspected to originate from the renal artery; or
   • Individuals with negative ultrasound and suspected accessory renal artery; or
   • Ultrasound suspicious for renal artery stenosis; or
   • Generalized arteriosclerotic occlusive disease with hypertension; or
   • Recurrent unexplained episodes of "flash" pulmonary edema.
     
     CTA or MRA of the renal artery is considered medically necessary for any of the following:
   • Planning for renal tumor resection; or
   • Surgical planning for kidney donor.
     
     
5. Abdominal, Pelvic or Lower Extremity Computed Tomographic Angiography or Magnetic Resonance Angiography
   CTA or MRA of the abdomen, pelvis or lower extremity is considered medically necessary for any of the following:
   
   
   1. Suspected Aortic Disease or Disease of the Major Branches of the Aorta
      • Aneurysm, intramural hematoma, or dissection of aorta and its branches; or
      • Occlusive disease of aorta and iliac arteries.
        
        
   2. Evaluation of Vasculature Anatomy Prior to Surgery
      • Prior to repair of abdominal aortic aneurysm (AAA) via surgery or stent placement; or
      • Pre-operative evaluation of known aortoiliac or lower extremity peripheral arterial disease, when there are contraindications to conventional arteriography and ultrasound has indicated significant disease, but was inconclusive regarding the pathology, in terms of whether it would be amenable to surgery; or
      • Evaluation of lower extremity claudication; or
      • Prior to hepatic procedures
        • Liver resection or liver transplantation; or
        • Chemoembolization; or
        • Insertion of a portal system shunt; or
      • Vascular anatomic delineation for other surgical and interventional procedures for vascular delineation prior to operative resection of an abdominal or pelvic neoplasm.
        
        
   3. Post Procedure Follow Up
      • Endovascular stent graft placement, abdominal aorta:
        • Initial baseline CTA less than 1 month post stent placement; or
        • Surveillance scans at 6 month intervals for 2 years; or
        • Following initial surveillance, yearly scans; or
        • Repeat imaging, based on symptoms; or
      • Evaluation of interventional vascular procedure for luminal patency versus re-stenosis (due to atherosclerosis, thromboembolism, intimal hyperplasia and other causes) as well as complications such as pseudoaneurysms related to:
        • Surgical bypass grafts; or
        • Vascular stents and stent-grafts; or
      • Suspected leak following abdominal aortic surgery.
        
        
   4. Other Signs, Symptoms or Diagnoses
      • Venous thrombosis or occlusion of the following, when an ultrasound is non-diagnostic:
        • Portal and mesenteric venous system; or
        • Systemic venous system, including inferior vena cava (IVC) thrombosis and hepatic vein thrombosis (Budd-Chiari syndrome); or
        • Renal vein thrombosis; or
        • Other major abdominal vessels; or
        • Mesenteric vein system; or
        • Ilio-femoral luminal thrombosis; or
      • Mesenteric or critical limb ischemia; or
      • Vasculitis; or
      • Vascular invasion or displacement by tumor; or
      • Traumatic vascular injury; or
      • Assessment of unexplained blood loss; or
      • Arterial entrapment syndrome; or
      • Venous compression, due to surrounding mass effect; or
      • Arterio-venous malformation or fistula; or
      • Pseudoaneurysm; or
      • Portal hypertension; or
      • Thromboembolic disease.
        
        
6. Upper Extremity Computed Tomographic Angiography or Magnetic Resonance Angiography
   CTA or MRA of the upper extremity is considered medically necessary for any of the following:
   
   
   1. Suspected Vascular Disease
      • Aneurysm, arteriovenous malformation (AVM), fistula, vasculitis, intramural hematoma; or
      • Arteriovenous malformation (AVM); or
      • Thromboembolic disease; or
      • Steno-occlusive disease; or
      • Arterial dissection.
        
        
   2. Pre and Post-operative Evaluation
      • Evaluation of luminal patency versus re-stenosis (due to atherosclerosis, thromboembolism, intimal hyperplasia and other causes) as well as complications such as pseudoaneurysms related to:
        • Surgical bypass grafts; or
        • Vascular stents and stent-grafts.
          
          
   3. Other Signs, Symptoms, or Diagnoses
      • Evaluation of a dialysis graft, following Doppler ultrasound; or
      • Vasculitis; or
      • Raynaud's syndrome; or
      • Vascular invasion or compression by neoplasm; or
      • Arterial entrapment syndrome.

Not Medically Necessary
CTA or MRA is considered not medically necessary for any of the following:

• As a screening exam in asymptomatic individuals; or
• When any of the above criteria are not met.

Repeat imaging of the same body part by the same or similar imaging technology, when there is no change in clinical status (e.g., deterioration), persistent diagnostic problem, or medical intervention which warrants interval re-assessment is considered not medically necessary except where specified above as medically necessary.

The following codes for treatments and procedures applicable to this document 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.

Coding Note:  For CT imaging of thoracic blood vessels (e.g., for pulmonary embolism) the appropriate code for CT imaging with contrast or CT angiography (CTA) should be used based on the actual study performed.  Coding rules indicate that for a study to be coded as a CT angiography, three-dimensional reconstruction post-processing of angiographic images and specialized interpretation of the images is required.  If this is not done, the CT with contrast imaging codes should be utilized; from a coding perspective, these codes include two-dimensional reconstruction of images after contrast (for example, reformatting an axial scan into the coronal plane).

CTA of the chest is indicated in the evaluation of individuals suspected of pulmonary embolism (PE). A variety of algorithms incorporating clinical factors, laboratory testing (D-dimer) and imaging are currently in clinical use. All existing data indicates that imaging studies are most useful with assessment of the underlying probability of a positive test based on clinical factors in conjunction with laboratory tests. In addition, risks such as radiation exposure or adverse reactions to contrast materials should be considered. Studies have shown CTA to be highly sensitive and specific and a medically necessary adjunct in clinical settings when there is sufficient suspicion of pulmonary embolus and a need for more definitive data exists. A meta-analysis by Moores and colleagues (2004) evaluated the use of CT of the pulmonary artery. This study involved 4,657 patients in 23 studies found to have negative CTA exams. In these patients with negative CTA exams, the 3-month rate of subsequent venous thromboembolic events was 1.4% and the 3-month fatality rate of pulmonary embolus was 51%. The authors noted that this compared favorably with conventional angiography. The radiographic techniques varied both across and within these studies, however, all studies used early generation CT technology and none of the studies used reconstruction algorithms for interpretation. Thus, while this may not be directly applicable to individuals with more sophisticated data acquisition methods, there is an assumption that newer technologies could improve overall outcomes.

Another more recent blinded, randomized controlled trial by Anderson and colleagues (2007) involved the comparison of V/Q scanning versus computed tomography pulmonary angiography (CTPA) in patients suspected of pulmonary embolus. In this study 1,417 patients were evaluated for PE. Those found to have a high probability of PE received further testing with either CTPA or V/Q scanning. As with other studies, the term CTPA was described as a radiographic procedure with axial images, rather than 3 dimensional imaging. The results found no significant difference between groups in the primary outcome of thromboembolism within 3 months of evaluation. However, the study did find that CTPA identified a greater number of thromboembolism diagnoses compared to V/Q scanning. The significance of this finding requires further evaluation, as it is unclear whether this is a result of better accuracy in finding true cases of PE, or that CTPA identifies a high number of false positives. Overall the authors report that "a strategy to rule out pulmonary embolism that used clinical probability assessment, D-dimer, and lower extremity ultrasound in conjunction with CTPA or V/Q scanning resulted in low and similar rates of venous thromboembolic events in 3 months follow-up in the 2 groups."

Although MRA is not widely utilized for detecting pulmonary emboli, it has proven valuable where contrast administration is contraindicated.

CTA and MRA are useful in a select group of individuals who are likely to have proximal renal artery stenosis associated with hypertension. If clinical findings strongly suggest the possibility of renovascular disease in these individuals, MRA or CTA should be performed. Both of these techniques are very accurate in diagnosing proximal renal artery lesions.

CTA or MRA is indicated in the diagnosis of aortic dissection and allows for the exclusion of other causes of mediastinal widening, detection of intraluminal and periaortic thrombus, and diagnosis of pleural effusions. Newer gadolinium-enhanced 3-dimensional MRA techniques permit rapid acquisition of MR angiograms of the thoracic and abdominal aorta and their branch vessels.

As noted in the Clinical Indications above, there are many indications where either MRA or CTA would be considered medically necessary. The choice between imaging technique can be based on individual circumstances as follows:

• The use of CT or MRI in children requires careful assessment of the risks, benefits and uses of the studies. Generally, children are more sensitive to radiation than adults and with their longer life expectancy there is a larger window of opportunity for incurring radiation damage
• 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:
  • 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
  • Have intracranial surgical clips placed for an aneurysm that are not compatible with the use of MRI
  • Have conditions requiring external devices for care (e.g., portable oxygen tank)
  • Are claustrophobic; an open MRA may be appropriate

Peer Reviewed Publications:

1. Anderson ER, Kahn SR, Rodger MA, et al. Computed tomographic pulmonary angiography vs ventilation-perfusion lung scanning in patients with suspected pulmonary embolism. JAMA. 2007; 298(23):2743- 2753.
2. Brenner DJ, Hall EJ. Computed tomography--an increasing source of radiation exposure. N Engl J Med. 2007; 357(22):2277-2284.
3. Carman TL, Olin JW, Czum J. Noninvasive imaging of the renal arteries. Urol Clin North Am. 2001 28(4): 815-826.
4. Einstein AJ, Henzlova MJ, Rajagopalan S. Estimating risk of cancer associated with radiation exposure from 64-slice computed tomography coronary angiography. JAMA. 2007; 298(3):317-323.
5. Garg K, Macey L. Helical CT scanning in the diagnosis of pulmonary embolism. Respiration. 2003; 70(3):231-237.
6. Koelemay MJ, Lijmer JG, Stoker J, et al. Magnetic resonance angiography for the evaluation of lower extremity arterial disease: a meta-analysis. JAMA. 2001; 285(10):1338-1345.
7. Met R, Bipat S, Legemate DA, et al. Diagnostic performance of computed tomography angiography in peripheral arterial disease: a systematic review and meta-analysis. JAMA. 2009; 301(4):415-424.
8. Moores LK, Jackson WL Jr, Shorr AF, Jackson JL.. Meta-Analysis: outcomes in patients with suspected pulmonary embolism managed with computed tomographic pulmonary angiography. Ann Intern Med. 2004; 141(11):866-874. 
9. Remy-Jardin M, Mastora I, Remy J. Pulmonary embolus imaging with multislice CT. Radiol Clin North Am. 2003; 41(3):507-519.
10. Soulez G, Pasowicz M, Benea G, et al. Renal artery stenosis evaluation: diagnostic performance of gadobenate dimeglumine-enhanced MR angiography--comparison with DSA. Radiology. 2008; 247(1):273-285.
11. Stein PD, Fowler SE, Goodman LR, et al. PIOPED II Investigators. Multidetector computed tomography for acute pulmonary embolism. N Engl J Med. 2006; 354(22):2317-2327.
12. Tatli S, Yucel EK, Lipton MJ. CT and MR imaging of the thoracic aorta: current techniques and clinical applications. Radiol Clin North Am. 2004; 42(3):565-585.

Government Agency, Medical Society, and Other Authoritative Publications:

1. American College of Radiology. ACR Appropriateness Criteria^®. Available at: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx. Accessed on January 04, 2010.
   • Acute Chest Pain—Suspected Aortic Dissection (2008)
   • Acute Chest Pain—Suspected Pulmonary Embolism (2006)
   • Renovascular Hypertension (2009)
2. Centers for Medicare and Medicaid Services. Available at: http://www.cms.hhs.gov/MCD/index_list.asp?list_type=ncd. Accessed on January 04, 2010.
   • National Coverage Determination: Magnetic Resonance Angiography (MRA). NCD #220.3. Effective July 1, 2003.
   • National Coverage Determination: Magnetic Resonance Imaging (MRI). NCD #220.0. Effective September 28, 2009.
3. Nickoloff EL, Alderson PO. Radiation exposures to patients from CT: reality, public perception, and policy. AJR. 2001; 177(2):285–287.

Angiography, Computed Tomographic
Angiography, Magnetic Resonance
Computed Tomographic Angiography
CTA/MRA, Extra-Cranial Vessels
Magnetic Resonance Angiography