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DESCRIPTIONContrast-enhanced computed tomographic angiography or CTA is a noninvasive imaging test that requires the use of intravenously administered contrast material and high-resolution, high-speed CT machinery to obtain detailed volumetric images of blood vessels. CTA can be applied to image blood vessels throughout the body; however, to apply CTA in the coronary arteries, several technical challenges must be overcome to obtain high-quality diagnostic images. First, very short image acquisition times are necessary to avoid blurring artifacts from the rapid motion of the beating heart. In some cases, premedication with beta-blocking agents is used to slow down the heart rate below about 60-65 beats per minute to facilitate adequate scanning, and electrocardiographic triggering or retrospective gating is used to obtain images during diastole when motion is reduced. Second rapid scanning is also helpful so that the volume of cardiac images can be obtained during breath-holding. Third, very thin sections (< 1mm) are important to provide adequate spatial resolution and high-quality 3D reconstruction and high-quality 3D reconstruction images.
Volumetric imaging permits multiplanar reconstruction (MPR) of cross-sectional images to display the coronary arteries. Curved MPR and thin-slab maximum intensity projections (MIPs) provide an overview of the coronary arteries, and volume-rendering techniques (VRT) provide a 3D anatomical display of the exterior of the heart. Quantification of coronary artery stenosis may be difficult given current techniques, though improvements in image reconstruction algorithms such as automatic vessel tracking are being developed.
Two different CT technologies can achieve high-speed CT imaging. Electron-beam CT (EBCT, also known as ultrafast CT) uses an electron gun rather than a standard x-ray tube to generate x-rays, thus permitting very rapid scanning, on the order of 50–100 milliseconds per image. Helical CT scanning (also referred to as spiral CT scanning) also creates images at greater speed than conventional CT by continuously rotating a standard x-ray tube around the patient so that data are gathered in a continuous spiral or helix rather than individual slices. Helical CT is able to achieve scan times of 500 milliseconds or less per image and use of partial ring scanning or post-processing algorithms may reduce the effective scan time even further.
Multidetector row helical CT scanning (MDCT) or multislice CT (MSCT) is a technological evolution of helical CT, which uses CT machines equipped with an array of multiple x-ray detectors that can simultaneously image multiple sections of the patient during a rapid volumetric image acquisition. Currently available MDCT machines may have 4, 8, 16, 32, 40 or 64 detectors. Diffusion of MDCT machines into the medical community has been occurring over the past several years.
Evaluation of obstructive coronary artery disease (CAD) involves quantifying arterial stenoses to determine whether hemodynamically significant stenosis is present. Symptomatic lesions with greater than 50%–75% diameter stenosis are generally considered significant and often result in revascularization procedures when viable myocardium is present. It has been suggested that CTA may be helpful to rule out the presence of CAD and to avoid invasive coronary angiography in patients with a very low clinical likelihood of significant CAD. Also of note is the increasing interest in exploring the role of nonsignificant plaques (i.e., those associated with less than 50% stenosis) because it is postulated that some of these plaques which are considered unstable may undergo rupture or erosion and lead to acute myocardial infarction. Cross-sectional angiographic imaging may visualize the presence and composition of these plaques and quantify the plaque burden better than conventional angiography, which only visualizes the vascular lumen. However, it is not yet well established how this information would be used to guide patient management.
The information sought from angiography after coronary artery bypass graft surgery may depend on the length of time since surgery. Bypass graft occlusion may occur during the early postoperative period; whereas, over the long term, recurrence of obstructive CAD may occur in the bypass graft, which requires a similar evaluation as CAD in native vessels.
Congenital coronary arterial anomalies (i.e., abnormal origination or course of a coronary artery) that lead to clinically significant problems are relatively rare lesions. Symptomatic manifestations may include ischemia or syncope. Clinical presentation of anomalous coronary arteries is hard to distinguish from other more common causes of cardiac disease; however, anomalous coronary artery is an important diagnosis to exclude, particularly in young patients who present with unexplained symptoms (e.g., syncope). There is no specific clinical presentation to suggest a coronary artery aneurysm.
CTA has several important limitations. The presence of dense arterial calcification or an intracoronary stent can produce significant beam-hardening artifacts and may preclude a satisfactory study. The presence of an uncontrolled rapid heart rate or arrhythmia hinders the ability to obtain diagnostically satisfactory images. Evaluation of the distal coronary arteries is generally more difficult than visualization of the proximal and midsegment coronary arteries due to greater cardiac motion and the smaller caliber of coronary vessels in distal locations.
The radiation delivered with 64-row MDCT is typically 8 to 20 mSv. CCA delivers about 4 to 8 mSv. Electrocardiographically (ECG)-controlled modulation of the x-ray beam during the cardiac cycle can reduce radiation exposure up to 50% by reducing exposure during nonimaging phases of the cardiac cycle. The effect of radiation exposure from CTA is not clearly understood and estimates of excess cancer risk have varied. It is estimated that estimated lifetime cancer risk associated with the radiation delivered from a single 64-row scan without dose modulation ranges from 1 in 143 in a 20-year-old woman to 1 in 3,261 for an 80-year-old man; with dose modulation, estimates decline to 1 in 219 and 1 and 5,017 respectively. It is estimated that a single CTA in a woman age 25 would result in 1 excess lifetime breast or lung cancer case per 200 to 333 individuals; in a 55-year-old woman, 1 case for every 500 to 1,000 scans. The EBCT using ECG triggering delivers the lowest dose (approximately 0.7 to 1.1 mSv with 3-mm sections).
POLICYContrast-enhanced computed tomographic angiography for evaluation of anomalous coronary arteries in symptomatic patients is considered medically necessary when conventional angiography is unsuccessful or equivocal and when the results will impact treatment.
Contrast-enhanced computed tomographic angiography for coronary artery evaluation is considered investigational for all other indications.
POLICY GUIDELINESInvestigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY3/31/2005: Approved by Medical Policy Advisory Committee (MPAC)
5/19/2005: Code Reference section completed
11/15/2005: HCPCS code S8093 added
11/22/2005: ICD9 diagnosis codes 401.0, 401.1, 401.9, 402.00, 402.01, 402.10, 402.11, 402.90, 402.91, 414.00 - 414.07, 423.8, 427.0, 427.1, 427.2, 427.31, 427.32, 427.41, 427.42, 427.5, 427.60, 427.61, 427.69, 427.81, 427.89, 427.9, 428.0, 428.1, 428.20 - 428.23, 428.30 - 428.33, 428.40 - 428.43, 428.9, 429.1, 429.2, 429.4, 440.0, 780.2, 780.71, 780.79, 785.0, 785.1, 785.3, 786.05, 786.50 - 786.52, 786.59, 794.31, V43.3, V45.81, V45.89, V58.89, V71.89, V71.9 added
5/31/2006: Coding updated. 0146T and 0151T added to policy
09/13/2006: Coding updated. ICD9 2006 revisions added to policy
10/27/2006: Medically necessary section added to policy statement
11/7/2006: Code reference section updated. ICD-9 diagnosis code 746.85 added to policy. ICD-9 diagnosis codes 401.0, 410.1, 401.9, 402.00-402.01, 402.10, 402.11, 402.90, 402.91, 423.8, 427.0-427.2, 427.31, 427.32, 427.41, 427.42,427.5, 427.60, 427.61, 427.69, 427.81, 427.89, 427.9, 428.0, 428.1, 428.20-428.23, 428.30-428.33, 428.40-428.43, 428.9, 429.1, 429.2, 429.4, 440.0, 780.2, 780.71, 780.79, 785.1, 785.3, 786.05, 786.50-786.52, 786.59, 794.31, V43.3, V45.86, V45.89, V58.89, V71.89, V71.9 deleted from policy
12/27/2006: Code reference section updated per the 2007 CPT revisions
1/30/2007: Code reference section reviewed and updated. CPT codes 0145T, 0148T, and 0150T added.
2/23/2007: Code reference section updated. CPT codes 71275, 0145T, 0150T, and 0151T removed from policy. CPT code 71275 removed from policy; not applicable for dates of service on 1-1-2007 and after.
02/27/2007: Code reference section updated. Non-covered table added. CPT code 0148T moved to the non-covered table. CPT codes 0147T and 0149T added to the non-covered table. CPT 71275 was re-added to the policy with a parenthetical note indicating that it is not appropriate to use this code to report CTAs for service dates on and after 1-1-2007. Specific codes have now been assigned for CTAs. ICD-9 codes 414.06 and 414.07 removed from policy.
10/9/2007: Code reference section reviewed. CPT 0151T added to non-covered table
12/17/2007: Coding updated. CPT/HCPCS 2008 revisions added to policy
2/18/08: Policy reviewed, no changes
8/22/2008: Code reference section reviewed. CPT 0148T moved to covered. CPT 0151T removed from policy
7/27/2009: Code reference section updated. Code 71275 removed from the covered table. The NOTE for code 71275 was revised and left as a heading for the covered codes table.
06/30/2010: Policy description updated regarding radiation exposure from the machines and the associated cancer risks. Medically necessary policy statement revised to add "in symptomatic patients." Added new CPT codes 75572, 75573, and 75574 to the Covered Codes table. Added new CPT code 75571 to the Non-Covered Codes table. Also added HCPCS code S8092 to the Non-Covered Codes table. Code section updated to indicate that the Category III CPT codes for CTA were deleted on 12/31/2009.
SOURCE(S)Blue Cross Blue Shield Association Policy # 6.01.43
This is not intended to be a comprehensive list of codes. Some covered procedure codes have multiple descriptions.
The code(s) listed below are ONLY covered if the procedure is performed according to the "Policy" section of this document.
This is not an all-inclusive list of non-covered procedure codes.
The code(s) listed below and ANY code not listed in the previous section are considered non-covered for this procedure.