Description
Computed tomography angiography (CTA) generates images of the arteries that can be evaluated for evidence of stenosis, occlusion, or aneurysms. It is used to evaluate the arteries of the abdominal aorta and the renal arteries. CTA uses ionizing radiation and requires the administration of iodinated contrast agent, which is a potential hazard in patients with impaired renal function. Abdominal CTA is not used as a screening tool, e.g., evaluation of asymptomatic patients without a previous diagnosis.

Cross-sectional imaging (liver ultrasound with Doppler, CT or MRI) should be completed no more than a month prior to the transjugular intrahepatic portosystemic shunt (TIPS) to assess for vascular patency and look for hepatic masses or other problems that could complicate the procedure.

Post-procedure, an ultrasound of the liver is conducted a day after to assess shunt patency. Hepatic encephalopathy (HE) is the most common complication and usually occurs 2 – 3 weeks after insertion of TIPS. Unique complications may include intravascular hemolysis and infection of the shunt. Other complications can include capsule puncture, intraperitoneal bleed, hepatic infarction, fistula, hematobilia, thrombosis of stent, occlusion, or stent migration and may require cross-sectional imaging.

Follow-up and maintenance imaging if complications suspected include Doppler ultrasound to assess shunt velocity. If asymptomatic sonogram performed at 4 weeks post placement, then every 6 months to a year. The gold standard for shunt patency is portal venography, usually reserved if concern for shunt occlusion.

General Information

• It is an expectation that all patients receive care/services from a licensed clinician. All appropriate supporting documentation, including recent pertinent office visit notes, laboratory data, and results of any special testing must be provided. If applicable: All prior relevant imaging results and the reason that alternative imaging cannot be performed must be included in the documentation submitted.
• Where a specific clinical indication is not directly addressed in this guideline, medical necessity determination will be made based on widely accepted standard of care criteria. These criteria are supported by evidence-based or peer-reviewed sources such as medical literature, societal guidelines and state/national recommendations.
   

OVERVIEW
CTA and Renal Artery Stenosis: Renal artery stenosis is the major cause of secondary hypertension. It may also cause renal insufficiency and end-stage renal disease. Atherosclerosis is one of the common causes of this condition, especially in older patients with multiple cardiovascular risk factors and worsening hypertension or deterioration of renal function. CTA is used to evaluate the renal arteries and detect renal artery stenosis.

NF1 may present with hypertension due to renal artery stenosis in children. All young patients (< 30 year) with hypertension should be clinically screened for secondary causes of hypertension,
including NF1, so that renal revascularization can be offered before permanent end organ damage has occurred.²⁶

Abdominal Aneurysms and general guidelines for follow-up: The normal diameter of the suprarenal abdominal aorta is 3.0 cm and that of the infrarenal is 2.0 cm. Aneurysmal dilatation of the infrarenal aorta is defined as diameter ≥ 3.0 cm or dilatation of the aorta ≥ 1.5x the normal diameter.²⁷ Evaluation of AAA can be accurately made by ultrasound. Ultrasound can detect and size AAA, with the advantage of being relatively inexpensive, noninvasive, and not requiring iodinate contrast. The limitations are that overlying bowel gas can obscure findings and the technique is operator dependent. CT is used when US is inconclusive or insufficient. When there are suspected complications, complex anatomy and/or surgery is planned, CTA/MRA is preferred.

MRI/CT and acute hemorrhage: MRI is not indicated and MRA/MRV (MR Angiography/Venography) is rarely indicated for evaluation of intraperitoneal or retroperitoneal hemorrhage, particularly in the acute setting. CT is usually the study of choice due to its availability, speed of the study, and less susceptibility to artifact from patient motion. Advances in technology have allowed conventional CT to not just detect hematomas but also the source of acute vascular extravasation. In special cases finer vascular detail to assess the specific source vessel responsible for hemorrhage may require the use of CTA. CTA in diagnosis of lower gastrointestinal bleeding is such an example.²⁸

MRA/MRV is often utilized in non-acute situations to assess vascular structure involved in atherosclerotic disease and its complications, vasculitis, venous thrombosis, vascular congestion, or tumor invasion. Although some of these conditions may be associated with hemorrhage, it is usually not the primary reason why MRI/MRA/MRV is selected for the evaluation. A special condition where MRI may be superior to CT for evaluating hemorrhage is to detect an underlying neoplasm as the cause of bleeding.²⁹

IMPORTANT NOTE
Abdomend/pelvis CTA and lower extremity CTA runoff requests: Only one authorization request is required, using CPT Code 75635 Abdominal Arteries CTA. This study provides for imaging of the abdomen, pelvis and both legs. The CPT code description is CTA aorto-iliofemoral runoff; abdominal aorta and bilateral ilio-femoral lower extremity runoff.

Policy
IMPORTANT NOTE
When vascular imaging of the aorta and both legs, i.e., CTA aortogram and runoff is desired (sometimes incorrectly requested as Abd/Pelvis CTA & Lower Extremity CTA Runoff), only one authorization request is required, using CPT Code 75635 Abdominal Arteries CTA. This study provides for imaging of the abdomen, pelvis, and both legs. The CPT code description is CTA aorto-iliofemoral runoff; abdominal aorta and bilateral ilio-femoral lower extremity runoff.

When separate requests for CTA abdomen and CTA Pelvis are encountered for processes involving both the abdomen and pelvis (but do NOT need to include legs/runoff), they need to be resubmitted as a single Abdomen/Pelvis CTA, using CPT 74174 (to avoid unbundling). Otherwise, the exam should be limited to the appropriate area (i.e., Abdomen OR Pelvis) that includes the area of concern.

INDICATIONS FOR ABDOMEN CT ANGIOGRAPHY/CT VENOGRAPHY (CTA/CTV)
Abdominal Aortic Disease
Abdominal Aortic Aneurysm
Asymptomatic known or suspected abdominal aortic aneurysms when prior ultrasound is inconclusive or insufficient AND a reason CTA is needed rather than CT has been provided, such as complex vascular anatomy or suspected complications.

• Symptomatic known or suspected Abdominal Aortic Aneurysm^1,2
  • Symptoms may include:
    • Abrupt onset of severe sharp or stabbing pain in the chest, back or abdomen
    • Acute abdominal or back pain with a pulsatile or epigastric mass
    • Acute abdominal or back pain and at high risk for aortic aneurysm and/or aortic syndrome (risk factors include hypertension, atherosclerosis, prior cardiac or aortic surgery, underlying aneurysm, connective tissue disorder (e.g., Marfan syndrome, vascular form of Ehlers-Danlos syndrome, Loeys- Dietz syndrome), and bicuspid aortic valve³

Aortic Syndromes

• For initial diagnosis of suspected and follow-up of known aortic syndromes, including aortic dissection, intramural hematoma and penetrating atherosclerotic ulcer.
• Frequency for follow up is as clinically indicated

Postoperative Follow-Up of Aortic Repair
Follow-up for post-endovascular repair (EVAR) or open repair of AAA¹ or abdominal extent of iliac artery aneurysms at the following intervals (CT preferred for routine follow up):

• • • If type II endoleak or sac enlargement is seen at any point in time (US not needed):
      • Monitor every 6 months x 2 years, then annually (does not require US)
• Routine follow up after open repair of AAA when a reason CTA is needed rather than CT has been provided such as complex vascular anatomy or suspected complications:⁽²⁾
  • Within 1 year postoperatively then
  • Annually monitor with ultrasound
    • When US is abnormal or insufficient CT/MR can be used to monitor annually
  • Every 5 years monitor with CT/MR
• If symptomatic or imaging shows increasing or new findings related to stent graft – more frequent imaging may be needed as clinically indicated
• Suspected complications such as: new onset lower extremity claudication, ischemia, or reduction in ABI after aneurysm repair.

Renal Artery Stenosis
In a patient with hypertension unrelated to recent medication use AND prior abnormal or inconclusive ultrasound AND any of the following:^4,5,6

• Onset of hypertension prior to the age of 30 without a family history of hypertension and when there is suspicion of fibromuscular dysplasia or a vasculitis
• Failure to obtain adequate blood pressure control on 3 antihypertensive medications, including one diuretic
• Recurrent episodes of sudden onset of congestive heart failure (also known as cardiac disturbance syndrome; may have normal left ventricular function)
• Renal failure of uncertain cause with normal urinary sediment and < 1 g of urinary protein per day
• Coexisting diffuse atherosclerotic vascular disease, especially in heavy smokers
• Acute elevation of creatinine after initiation of an angiotensin converting enzyme inhibitor (ACE inhibitor) or angiotensin receptor blocker (ARB)
• Malignant or difficult to control hypertension and unilateral small kidney size (noted on prior imaging)
• New onset of difficult to control or labile hypertension after age 55
• Abdominal bruit lateralizing to one side of the abdomen
• Diagnosis of a syndrome with a higher risk of vascular disease, such as neurofibromatosis⁷ and Williams syndrome⁸

Other Vascular Abnormalities

• Initial evaluation of inconclusive vascular findings on prior imaging
• For evaluation or monitoring of non-aortic large vessel or visceral vascular disease when ultrasound is inconclusive, and finding is limited to the abdomen^9,10,11,12
  • Includes abnormalities such as aneurysm, dissection, arteriovenous malformations (AVM), vascular fistula, intramural hematoma, compression syndromes and vasculitis involving any of the following: inferior vena cava, superior/inferior mesenteric, celiac, hepatic, splenic or renal arteries/veins
• Suspected complications of known aneurysm as evidenced by clinical findings such as new onset of abdominal pain, and finding is limited to the abdomen

Venous Disease
Suspected venous thrombosis (including renal vein thrombosis and/or portal venous thrombosis) if previous studies (such as ultrasound) have not resulted in a clear diagnosis and location of disease is confined to the abdomen¹³

Evaluation of Tumor

• When needed for clarification of vascular invasion from tumor (including suspected renal vein thrombosis)¹⁴
• Prior to Y90 treatment¹⁵

Pre-Operative Evaluation and/or Pre-Procedural Evaluation

• Evaluation of transjugular intrahepatic portosystemic shunt (TIPS) when Doppler ultrasound indicates suspected complications^16,17,18
• Evaluation prior to interventional vascular procedures for luminal patency versus restenosis due to conditions such as atherosclerosis, thromboembolism, and intimal hyperplasia
• Evaluation of vascular anatomy prior to solid organ transplantation
• Evaluation prior to endovascular aneurysm repair (EVAR) and imaging of the pelvis is not needed
• Evaluation of anatomy (lower pole crossing vessel) prior to UPJ (ureteropelvic junction) obstruction surgery
• Prior to Y90 treatment¹⁵

Post-Operative Evaluation and/or Post-Procedural Evaluation
Unless otherwise specified within the guideline:

• Follow-up study may be needed to help evaluate a patient’s progress after treatment, procedure, intervention, or surgery. Documentation requires a medical reason that clearly indicates why additional imaging is needed for the type and area(s) requested.
• Evaluation of endovascular/interventional abdominal vascular procedures for luminal patency versus restenosis due to conditions such as atherosclerosis, thromboembolism, and intimal hyperplasia
• Evaluation of post-operative complications, e.g., pseudoaneurysms, related to surgical bypass grafts, vascular stents, and stent-grafts in abdomen

Genetics and Rare Diseases

• Marfan syndrome:¹⁹
  • At diagnosis and then every 3 years
  • More frequently (annually) if EITHER: history of dissection, dilation of aorta beyond aortic root OR aortic root/ascending aorta are not adequately visualized on TTE (i.e. advanced imaging is needed to monitor the thoracic aorta)^2,20
• Williams Syndrome:⁸
  • When there is concern for vascular disease (including renal artery stenosis) based on abnormal exam or imaging findings (such as diminished pulses, bruits or signs of diffuse thoracic aortic stenosis)
• Neurofibromatosis Type 1 (NF-1):⁷
  • Development of hypertension (including concern for renal artery stenosis)
• For other syndromes and rare diseases not otherwise addressed in the guideline, coverage is based on a case-by-case basis using societal guidance

Combination Studies
Abdomen CT and Abdomen CTA

• When needed for clarification of vascular invasion from tumor (including renal vein thrombosis)

Abdomen CT (or MRI) and Abdomen CTA (or MRA) and PET

• Prior to Y90 treatment¹⁵

Chest/Abdomen CTA

• Evaluation of extensive vascular disease involving the chest and abdominal cavities when pelvic imaging is not needed
• Significant post-traumatic or post-procedural vascular complications when pelvic imaging is not needed

Chest and Abdomen or Abdomen and Pelvis CTA

• Evaluation prior to endovascular aneurysm repair (EVAR) when thoracic involvement is present
• Evaluation prior to Transcatheter Aortic Valve Replacement (TAVR)²¹
• Marfan syndrome:⁽¹⁹⁾
  • At diagnosis and every 3 years
  • More frequently (annually) if EITHER: history of dissection, dilation of aorta beyond aortic root OR aortic root/ascending aorta are not adequately visualized on TTE (i.e., advanced imaging is needed to monitor the thoracic aorta)^2,20
• Williams Syndrome⁸
  • When there is concern for vascular disease (including renal artery stenosis) based on abnormal exam or imaging findings (such as diminished pulses, bruits or signs of diffuse thoracic aortic stenosis)
• Acute aortic dissection²²
• Significant post-traumatic or post-procedural vascular complications reasonably expected to involve the chest, abdomen and pelvis

Further Evaluation of Indeterminate Findings on Prior Imaging
Unless follow-up is otherwise specified within the guideline

• For initial evaluation of an inconclusive finding on a prior imaging report that requires further clarification
• One follow-up exam of a prior indeterminate MR/CT finding to ensure no suspicious interval change has occurred. (No further surveillance unless specified as highly suspicious or change was found on last follow-up exam)

BACKGROUND
Contraindications and Preferred Studies
Contraindications and reasons why a CT/CTA cannot be performed may include: impaired renal function, significant allergy to IV contrast, pregnancy (depending on trimester).
Contraindications and reasons why an MRI/MRA cannot be performed may include: impaired renal function, claustrophobia, non-MRI compatible devices (such as non- compatible defibrillator or pacemaker), metallic fragments in a high-risk location, patient exceeds weight limit/dimensions of MRI machine.

Abdominal Aneurysms
General Guidelines for Follow-Up
The normal diameter of the suprarenal abdominal aorta is 3.0 cm and that of the infrarenal is
2.0 cm. Aneurysmal dilatation of the infrarenal aorta is defined as diameter ≥ 3.0 cm or dilatation of the aorta ≥ 1.5x the normal diameter. Ultrasound can detect and size AAA, with the advantage of being relatively inexpensive, noninvasive, and not requiring iodinate contrast. CT is used when US is inconclusive or insufficient. When there are suspected complications, complex anatomy and/or surgery is planned, CTA/MRA is preferred.
 

References

17. Dariushnia S R, Haskal Z J, Midia M, Martin L G, Walker T G et al. Quality Improvement Guidelines for Transjugular Intrahepatic Portosystemic Shunts. J Vasc Interv Radiol. 2016; 27: 1-7. 10.1016/j.jvir.2015.09.018.
18. Farsad K, Kolbeck K. Clinical and radiologic evaluation of patients before TIPS creation. AJR Am J Roentgenol. Oct 2014; 203: 739-45. 10.2214/ajr.14.12999.
19. Dietz H. FBN1-Related Marfan Syndrome [Updated 2022 Feb 17]. GeneReviews® [Internet]. 2022.
20. Weinrich J M, Lenz A, Schön G, Behzadi C, Molwitz I et al. Magnetic resonance angiography derived predictors of progressive dilatation and surgery of the aortic root in Marfan syndrome. PLOS ONE. 2022; 17: true. https://doi.org/10.1371/journal.pone.0262826.
21. Hedgire S S, Saboo S S, Galizia M S, Aghayev A, Bolen M A et al. ACR Appropriateness Criteria® Preprocedural Planning for Transcatheter Aortic Valve Replacement: 2023 Update. Journal of the American College of Radiology. 2023; 20: S501 - S512. 10.1016/j.jacr.2023.08.009.
22. Kicska G, Hurwitz Koweek L, Ghoshhajra B, Beache G, Brown R et al. ACR Appropriateness Criteria® Suspected Acute Aortic Syndrome. Journal of the American College of Radiology. 2021; 18: S474 - S481. 10.1016/j.jacr.2021.09.004.

Coding Section

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive. 

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community, and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies, and accredited national guidelines.

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