This document addresses the use of computed tomography (CT) and magnetic resonance imaging (MRI) for evaluation, diagnosis, and management of conditions of the thorax, including the heart, lungs, mediastinum, and great vessels. This document applies to the use of these studies in the outpatient setting.

In most clinical settings, a CT or MRI is not the initial imaging study. These studies are most often performed after a chest x-ray or echocardiogram has identified some abnormality and the additional information obtained will be used in clinical decision making. Additionally, almost all indications for MRI or CT are based either on clinical signs or symptoms.

This document does not address CT angiography (CTA), a method of imaging veins and arteries. Indications for CTA are addressed in other documents as noted below.

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

• CG-RAD-09 CTA/MRA of the Thoracic Cavity, Abdomen and Extremities
• RAD.00001 Computed Tomography to Detect Coronary Artery Calcification
• RAD.00035 Coronary Artery Imaging: Contrast-Enhanced Coronary Computed Tomography Angiography (CCTA) and Coronary Magnetic Resonance Angiography (MRA)
• RAD.00043 CT Scans with or without Computer Assisted Detection (CAD) for Lung Cancer Screening

Computed Tomography

Medically Necessary

I. Cardiac Indications

CT of the heart is considered medically necessary for any of the following indications:

1. Congenital heart disease; or
2. Cardiac and paracardiac mass (including bronchogenic cysts, vascular lesions, metastases or thrombus) when suspected by transthoracic echocardiography (TTE) and transesophageal echocardiography is limited or is not feasible; or
3. Suspected pericarditis, when transthoracic echocardiography is non-diagnostic; or
4. Evaluation of cardiac anatomy, including pulmonary veins and aneurysm:
   • Evaluation of pulmonary vein anatomy prior to radiofrequency ablation for atrial fibrillation; or
   • Pulmonary mapping prior to biventricular pacemaker placement; or
   • Evaluation of cardiac aneurysm or pseudoaneurysm.

II. Thoracic Indications

CT of the thoracic cavity is considered medically necessary for any of the following thoracic indications:

1. Aneurysm and Dissection
   • Thoracic or aortic dissection or thoracoabdominal aneurysm for any of the following:
     • Suspected dissection or aneurysm; or
     • Confirmed dissection or aneurysm with new or worsening symptoms; or
     • Surveillance of stable patients with confirmed thoracic aneurysm or dissection who have not undergone imaging within the preceding 6 months.
2. Evaluation of Signs or Symptoms
   • Hoarseness or vocal cord weakness, suggestive of recurrent laryngeal nerve injury; or
   • Mediastinal widening or mass or hilar enlargement when identified by chest x-ray; or
   • Persistent, undiagnosed pleural effusion; or
   • Undiagnosed systemic illness presenting as fever of unknown origin or significant unexplained weight loss after initial evaluation for other causes. 
3. Anatomic Abnormalities
   • Structural abnormalities including mass of or within the chest, chest wall or pleura as evidenced by chest x-ray; or
   • Evaluation of known or suspected congenital thoracic anomalies; or
   • Thoracic outlet syndrome; or
   • Other abnormalities of the aorta or other thoracic vessels (e.g., vasculitis).
4. Other
   • Chest trauma; or
   • Unexplained or recurrent pneumothorax; or
   • Diaphragmatic hernia or unexplained elevation or immobility of diaphragm; or
   • Suspected thymoma or a history of myasthenia gravis; or
   • Superior vena cava syndrome; or
   • Asbestos related lesions of the lung and pleura; or
   • Evaluation of tracheobronchial lesion; or
   • Preoperative evaluation prior to thoracic surgery. 

III. Pulmonary Indications

CT of the thoracic cavity is considered medically necessary for any of the following pulmonary indications:

1. Evaluation of Known or Suspected Malignancy
   • Sputum cytology positive for malignancy with normal chest x-ray; or
   • Pulmonary nodule or mass:
     • Surveillance of stable nodules for up to 2 years; or
   • Surveillance of previously diagnosed cancer; or
   • Staging lung cancer.
2.  Infection or Inflammatory Conditions (suspected or known)
   • Complications of acute respiratory infection (e.g., lung abscess or emphysema after chest x-ray); or
   • Pneumonia refractory to medical treatment of adequate duration (at least 4 weeks) or suspected to be secondary to obstruction; or
   • Recurrent pneumonia in the same location within 6 months, to evaluate for obstructive etiology; or
   • Evaluation of patients with chest infections or inflammatory processes which are not complications of acute respiratory infections:
     • Abscess; or
     • Bronchiectasis; or
     • Mediastinitis; or
     • Sternal infections (a known complication of cardiac surgery). 
3. Evaluation of Signs or Symptoms
   • Patients with suspected pulmonary embolus; or
   • Bullous emphysema, infiltrates, interstitial disease, or pleural changes after chest x-ray and with unexplained clinical findings; or
   • Hemoptysis of suspected bronchopulmonary etiology and normal chest x-ray; or
   • Chronic cough, with normal chest x-ray, unresponsive to medical treatment and after evaluation for other causes (e.g., post nasal drainage, cough, asthma, gastroesophageal reflux and medication effects); or
   • Fever of unknown origin or weight loss, unexplained, following standard work-up including chest x-ray.
4. Other
   • Sarcoidosis, for diagnosis, after chest x-ray and with unexplained clinical findings and for periodic follow-up; or
   • Evaluation of interstitial lung disease or pulmonary fibrosis; or
   • Evaluation of pneumoconiosis; or
   • Asbestos related lesions of the lung and pleura; or
   • Trauma. 

Not Medically Necessary

CT of the thoracic cavity or heart is considered not medically necessary for any of the following:

• As a screening exam in asymptomatic patients; or
• As a technique to evaluate the coronary arteries; or
• When the above criteria are not met.

Magnetic Resonance Imaging 

Medically Necessary 

I. Cardiac Indications

MRI of the heart is considered medically necessary for any of the following indications:

1. Following a myocardial infarction (MI) when prior imaging studies are indeterminate, discordant, or technically suboptimal for any of the following indications:
   • To assess the viability of the infarcted myocardium using delayed hyperenhancement (contrast studies); or
   • To assess left ventricular function; or
   • To assess function of cardiac valves; or
   • To assess ventricular septal defects (VSD); or
   • To delineate pericardial effusions.
2. For suspected cardiomyopathy when echocardiography is limited or not feasible, secondary to the following indications, including but not limited to:
   • Cardiotoxic therapies; or
   • Sarcoidosis, amyloidosis, hemochromatosis; or
   • Hypertrophic obstructive cardiomyopathy (HOCM); or
   • Duchenne or Becker muscular dystrophy.
3. Congenital heart disease including the great vessels
4. Cardiac and paracardiac mass (including bronchogenic cysts, vascular lesions, metastases or thrombus) when suspected by transthoracic echocardiography (TTE), and transesophageal echocardiography is limited or is not feasible
5. Evaluation of cardiac anatomy, including pulmonary veins and aneurysm
   • Evaluation of pulmonary vein anatomy prior to radiofrequency ablation for atrial fibrillation; or
   • Pulmonary mapping prior to biventricular pacemaker placement; or
   • Evaluation of cardiac aneurysm or pseudoaneurysm.
6. Evaluation of patients with suspected arrhythmogenic right ventricular dysplasia
7. Evaluation of pericarditis, when transthoracic echocardiography (TTE) is non-diagnostic

II. Thoracic Indications

MRI of the chest is considered medically necessary for any of the following thoracic indications:

1. Aneurysm and Dissection
   • Thoracic or aortic dissection or thoracoabdominal aneurysm for any of the following:
     • Suspected dissection or aneurysm; or
     • Confirmed dissection or aneurysm with new or worsening symptoms; or
     • Surveillance of stable patients with confirmed thoracic aneurysm or dissection who have not undergone imaging within the preceding 6 months. 
2. Other
   • Posterior mediastinal mass; or
   • Tracheobronchial tree prior to endobronchial laser photoresection; or
   • Other abnormalities of the aorta or other thoracic vessels (e.g., vasculitis); or
   • Suspected thymoma or a history of myasthenia gravis; or
   • Thoracic outlet syndrome; or
   • Superior vena cava syndrome; or
   • Brachial plexus injury or plexopathy; or
   • Developmental anomalies of the thoracic vasculature.

III. Pulmonary Indications

MRI of the chest is considered medically necessary for any of the following pulmonary indications:

1. Evaluation of Known or Suspected Malignancy
   • Sputum cytology positive for malignancy with normal chest x-ray; or
   • Suspected sulcus (Pancoast) tumor after chest x-ray; or
   • Pulmonary nodule or mass:
     • Surveillance of stable nodules for up to 2 years; or
   • Surveillance of previously diagnosed cancer; or
   • Staging lung cancer. 
2. Other
   • To differentiate mediastinal and hilar mass lesions from vascular structures, particularly in patients with a history of allergy to iodinated CT contrast material or at risk for other complications from contrast media

Not Medically Necessary

MRI of the thoracic cavity or heart is considered not medically necessary for any of the following:

• As a screening exam in asymptomatic patients; or
• As a technique to evaluate the coronary arteries; or
• When the above criteria are not met.

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.

Computed tomography (CT), sometimes called CAT scan, is a diagnostic tool that uses special x-ray equipment to obtain image data from different angles around the body, then uses computer processing of the information to show a cross-section of body tissues and organs. The CT requires less time than MRI and can be performed in acute settings where advanced monitoring and life support is needed for an unstable patient. Newer scanners have improved image quality and scanning time at the price of increased radiation exposure, in particular during chest CT procedures. This results in significant radiation exposure to the breast and thyroid glands. When such imaging procedures are ordered in females of reproductive age the risk of carcinogenesis is of concern. It has been estimated that radiation dose to the breast from a CT is equivalent to seven to ten two-view mammograms, thus this technology must be used with caution (Parker, 2005).

Magnetic resonance imaging (MRI) is a diagnostic technique that uses a cylindrical magnet and radio waves to produce high quality multiplanar images of organs and structures within the body without x-rays or radiation. The body's hydrogen atoms react to the magnetic field and pulses of radio waves. This reaction is changed to an image by a computer. CT and MRI are valuable imaging techniques most often used when preliminary diagnostics or symptoms suggest an abnormal condition requiring further analysis.

In general, signs, symptoms, and results of initial imaging with either chest x-ray or echocardiography will prompt consideration of either CT or MRI. However, imaging in asymptomatic patients may be appropriate in those instances when early detection of disease has been shown to change patient management or improve patient outcomes. Cancer staging is one example. Patients with tumors at high risk for pulmonary metastases are typically evaluated with a chest CT to rule out metastatic disease, particularly when definitive surgical resection of the primary site is considered. CT surveillance to detect early recurrence of lung cancer or tumors at high risk for pulmonary metastases is also recommended in practice guidelines from the National Comprehensive Cancer Network^® ([NCCN^®], 2008). Pulmonary metastases are most commonly associated with colorectal, breast, kidney, testicular and bone cancer and melanoma. In some instances routine surveillance is recommended at defined intervals, in other instances rising levels of tumor markers, such as CEA in patients with colorectal cancer, will prompt evaluation for pulmonary metastases. Finally, CT surveillance for patients with thoracic aneurysms is also undertaken to identify unstable aneurysms that require intervention. The intervals for surveillance are not based on controlled trials, but in the case of cancer, the intervals are based on the natural history of disease. For patients with thoracic aneurysm, the surveillance interval is based on the interval recommended for abdominal aortic aneurysms.

The following are examples of clinical situations where the choice between MRI and CT scans may be related to specific patient characteristics:

• Clinical situations may influence whether CT or MRI is suitable for pregnant women and children

• Relative and absolute contraindications for scans requiring administration of intravascular contrast material may include individuals:
  • Who have a documented allergy from prior contrast administration or a history of atopy
  • Who have impaired renal function, when considering an enhanced CT with intravascular iodinated contrast agents
  • Who have multiple myeloma
• Contraindications for MRI include individuals:
• Who have a pacemaker or implantable cardioverter-defibrillator (ICD)
• Who have intracranial surgical clips, which are not compatible with the use of MRI, that have been placed for an aneurysm
• Who have had placement of other non-MRI compatible devices within the body

• Additional considerations and possible contraindications for MRI may also include individuals:
  • Who have 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 MRI may be appropriate
  • For whose condition requires external devices for care (e.g., portable oxygen tank)
  • For individuals who are claustrophobic, an open MRI may be appropriate

Peer Reviewed Publications:

1. Brenner DJ, Hall EJ. Computed tomography--an increasing source of radiation exposure. N Engl J Med. 2007; 357(22):2277-2284.
2. 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.
3. Erasmus JJ, McAdams HP, Donnelly LF, Spritzer CE. MR imaging of mediastinal masses. Magn Reson Imaging Clin N Am. 2000; 8(1):59-89.
4. Gutierrez FR, Siegel MJ, Fallah JH, Poustchi-Amin M. Magnetic resonance imaging of cyanotic and noncyanotic congenital heart disease. Magn Reson Imaging Clin N Am. 2002; 10(2):209-235.
5. Haramati LB, White CS. MR imaging of lung cancer. Magn Reson Imaging Clin N Am. 2000; 8(1):43-57.
6. Kearon C. Diagnosis of pulmonary embolism. CMAJ. 2003; 168(2):183-194.
7. Kimura F, Sakai F, Sakomura Y, et al. Helical CT features of arrhythmogenic right ventricular cardiomyopathy. Radiographics. 2002; 22(5):1111-1124.
8. Kuhlman JE. Thoracic imaging in heart transplantation. J Thorac Imaging. 2002; 17(2):113-121.
9. Parker MS, Hui FK, Camacho MA, et al. Female breast radiation exposure during CT pulmonary angiography. AJR. 2005; 185(5):1228-1233.

Government Agency, Medical Society, and Other Authoritative Publications:

1. American Academy of Pediatrics Section on Cardiology and Cardiac Surgery. Cardiovascular health supervision for individuals affected by Duchenne or Becker muscular dystrophy. Pediatrics. 2005; 116(6):1569-1573. Available at: http://aappolicy.aappublications.org/cgi/content/full/pediatrics;116/6/1569. Accessed on June 26, 2009.
2. American College of Radiology. ACR Appropriateness Criteria^®. Expert Panel on Thoracic Imaging documents. (2005) Available at: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/TableofContents.aspx. Accessed on June 26, 2008.
3. American College of Radiology. ACR Appropriateness Criteria^®. Bone Tumors. (2005) Available at: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/ExpertPanelonMusculoskeletalImaging/BoneTumorsDoc4.aspx. Accessed on June 26, 2009.
4. American College of Radiology. ACR Appropriateness Criteria^®. Metastatic Bone Disease. (2005) Available at: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/ExpertPanelonMusculoskeletalImaging/MetastaticBoneDiseaseDoc14.aspx. Accessed on June 26, 2009.
5. Centers for Medicare and Medicaid Services. National Coverage Determination: Computerized Tomography. NCD# 220.1. Effective March 12, 2008. Available at: http://www.cms.hhs.gov/MCD/viewncd.asp?ncd_id=220.1&ncd_version=2&basket=ncd%3A220%2E1%3A2%3AComputed+Tomography. Accessed on June 26, 2009.
6. Centers for Medicare and Medicaid Services. National Coverage Determination: Magnetic Resonance Imaging (MRI). NCD #220.2. Effective March 22, 1994. Available at: http://www.cms.hhs.gov/MCD/viewncd.asp?ncd_id=220.2&ncd_version=1&basket=ncd%3A220%2E2%3A1%3AMagnetic+Resonance+Imaging+%28MRI%29. Accessed on June 26, 2009.
7. Desch CE, Benson AB, Somerfield MR, et al. Colorectal Cancer Surveillance: 2005 Update of an American Society of Clinical Oncology Practice Guideline. J Clin Oncol. 2005; 23(33):8512-8519.
8. Hendel RC, Patel Mr, Kramer CM, Poon M. ACCF/ACR/SCCT/SCMR/ ASNC/NASCI/SCAI/SIR Appropriateness Criteria for Cardiac Computed Tomography and Cardiac Magnetic Resonance Imaging: A Report of the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group, American College of Radiology, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, American Society of Nuclear Cardiology, North American Society for Cardiac Imaging, Society for Cardiovascular Angiography and Interventions, and Society of Interventional Radiology. J Am Coll Cardiol. 2006; 48(7):1-23.
9. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology™. Non-small cell lung cancer. (2008) Available at: http://www.nccn.org/professionals/physician_gls/PDF/nscl.pdf. Accessed on June 26, 2009.
10. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology™. Small cell lung cancer. (2008) Available at: http://www.nccn.org/professionals/physician_gls/PDF/sclc.pdf. Accessed on June 26, 2009.
11. Nickoloff EL, Alderson PO. Radiation exposures to patients from CT: reality, public perception, and policy. AJR. 2001; 177(2):285–287.
12. Zipes DP, Camm AJ, Borggrefe M, et al ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/ American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). J Am Coll Cardiol. 2006; 48:247–346.

Aorta
Chest
Computed Tomography (CT)
Heart
Magnetic Resonance Imaging (MRI)
Mediastinum
Thoracic/Aortic Dissection
Thoracoabdominal Aneurysm
Vena Cava Syndrome