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

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, Pelvis 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:

A. Congenital Heart Disease

• For evaluation of suspected congenital heart disease in individuals whose echocardiogram is technically limited or non-diagnostic; or
• For initial evaluation of complex congenital heart disease in individuals who have undergone echocardiography; or
• For evaluation of complex congenital heart disease in individuals who are less than one year post surgical correction; or
• For evaluation of complex congenital heart disease in individuals who have new or worsening symptoms; or
• For evaluation of complex congenital heart disease in individuals with a change in physical examination; or
• To assist in surgical planning for individuals with complex congenital heart disease; or
• For surveillance in asymptomatic individuals with complex congenital heart disease who have not had cardiac MRI or cardiac CT within the preceding year.

B. Cardiac and paracardiac mass (including bronchogenic cysts, vascular lesions, metastases or thrombus) when suspected by transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) is limited or is not feasible

C. 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:

A. Aneurysm and Dissection

• Thoracic or aortic dissection or thoracoabdominal aneurysm for any of the following:
  • Suspected dissection; or
  • Suspected aneurysm; or
  • Confirmed dissection or aneurysm with new or worsening symptoms; or
  • Confirmed aortic dissection when surgical repair is anticipated (to assist in preoperative planning); or
  • Surveillance of stable individuals with confirmed thoracic aneurysm or dissection that have not undergone imaging within the preceding 12 months.

B. 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 other pleural collection (e.g., hemothorax, empyema or chylothorax);or
• Undiagnosed systemic illness presenting as fever of unknown origin after initial evaluation for other causes; or
• Unexplained weight loss exceeding 10% of desirable body weight over a short time interval, after initial evaluation for other causes.

C. Anatomic Abnormalities

• Structural abnormalities including mass of or within the chest, chest wall or pleura; or
• Evaluation of known or suspected congenital thoracic anomalies; or
• Thoracic outlet syndrome; or
• Penetrating atherosclerotic aortic ulcer; or
• Traumatic aortic injury; or
• Other abnormalities of the aorta or other thoracic vessels (e.g., vasculitis).

D. 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; or
• Hilar or mediastinal lymphadenopathy; or
• For evaluation of known or suspected post-operative complications.

III. Pulmonary Indications
CT of the thoracic cavity is considered medically necessary for any of the following pulmonary indications:

A. Evaluation of Known or Suspected Malignancy

• Sputum cytology positive for malignancy; or
• Pulmonary nodule or mass, surveillance of stable nodules for up to 2 years at approximately 6 month intervals; or
• Surveillance of previously diagnosed cancer; or
• Staging lung cancer.

 B. 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 individuals 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).

 C. Evaluation of Signs or Symptoms

• Individuals 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; or
• Cough persisting more than 3 weeks, with normal chest x-ray, unresponsive to medical treatment and after evaluation for other causes (e.g., diagnostic investigation or therapeutic trial of treatment for post nasal drainage, asthma, gastroesophageal reflux and medication effects); or
• Cough in an immunosuppressed individual (e.g., HIV, after organ or bone marrow transplant, or on immunosuppressive medications); or
• Fever of unknown origin or weight loss, unexplained, following standard work-up including chest x-ray.

D. 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; or
• Hyperlucent lung lesions in pediatric individuals; or
• Pulmonary sequestration.

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 individuals; or
• As a technique to evaluate the coronary arteries; or
• When 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 for CT heart and thoracic cavity except where specified above as medically necessary.

Magnetic Resonance Imaging 

Medically Necessary 

I. Cardiac Indications
MRI of the heart is considered medically necessary for any of the following indications:

A. 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.

B. 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.

C. Congenital Heart Disease

• For evaluation of suspected congenital heart disease in individuals whose echocardiogram is technically limited or non-diagnostic; or
• For initial evaluation of complex congenital heart disease in individuals who have undergone echocardiography; or
• For evaluation of complex congenital heart disease in individuals who are less than one year post surgical correction; or
• For evaluation of complex congenital heart disease in individuals who have new or worsening symptoms; or
• For evaluation of complex congenital heart disease in individuals with a change in physical examination; or
• To assist in surgical planning for individuals with complex congenital heart disease; or
• For surveillance in asymptomatic individuals with complex congenital heart disease who have not had cardiac MRI or cardiac CT within the preceding year.

 D. Intra-Cardiac and Para-Cardiac Masses and Tumors

• Suspected cardiac or para-cardiac mass (thrombus, tumor, etc.) suggested by transthoracic echocardiography, transesophageal echocardiography, blood pool imaging or contrast ventriculography and there has not been a cardiac MRI or CT within the preceding 60 days; or
• Established cardiac or para-cardiac mass (thrombus, tumor, etc.) in individuals who are clinically unstable and there has not been a cardiac MRI or CT within the preceding year; or
• Established cardiac or para-cardiac mass (thrombus, tumor, etc.) in individuals who are clinically stable for annual follow-up evaluation; or
• Follow-up evaluation of individuals with established cardiac or para-cardiac mass (thrombus, tumor, etc.) after treatment (chemotherapy, radiation therapy, thrombolysis, anticoagulation or surgery) and there has not been a cardiac MRI or CT within the preceding 60 days.

E. 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.

F. Evaluation of individuals with suspected arrhythmogenic right ventricular dysplasia

G. Evaluation of Pericardial Conditions

• Suspected pericardial constriction; or
• Suspected congenital pericardial disease; or
• Suspected pericardial effusion (including hemopericardium) in individuals who have undergone echocardiography deemed to be technically suboptimal in evaluation of the effusion; or
• In individuals whose echocardiogram shows a complex pericardial effusion (loculated, containing solid material).

H. Evaluation of myocarditis

I. Valvular Heart Disease

II. Thoracic Indications
MRI of the chest is considered medically necessary for any of the following thoracic indications:

A. Aneurysm and Dissection

• Thoracic or aortic dissection or thoracoabdominal aneurysm for any of the following:
  • Suspected dissection; or
  • Suspected aneurysm; or
  • Confirmed dissection or aneurysm with new or worsening symptoms; or
  • Confirmed aortic dissection when surgical repair is anticipated (to assist in preoperative planning).
  • Surveillance of stable individuals with confirmed thoracic aneurysm or dissection that have not undergone imaging within the preceding 12 months.

B. Other

• Posterior mediastinal mass; 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:

A. Evaluation of Known or Suspected Malignancy

• Suspected sulcus (Pancoast) tumor after chest x-ray; or
• Surveillance of previously diagnosed cancer; or
• Staging lung cancer.

B. Other

• To differentiate mediastinal and hilar mass lesions from vascular structures, particularly in individuals 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 individuals; or
• As a technique to evaluate the coronary arteries; or
• When 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 for MRI heart and thoracic cavity 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.

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 individual. 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 individuals may be appropriate in those instances when early detection of disease has been shown to change management or improve member outcomes. Cancer staging is one example. Individuals 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^®], 2010). 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 individuals with colorectal cancer, will prompt evaluation for pulmonary metastases. Finally, CT surveillance for individuals 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 individuals 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 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
  • Whose condition requires external devices for care (e.g., portable oxygen tank)
  • 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. Isselbacher EM. Thoracic and abdominal aortic aneurysms. Circulation. 2005; 111(6):816-828.
7. Kearon C. Diagnosis of pulmonary embolism. CMAJ. 2003; 168(2):183-194.
8. Kimura F, Sakai F, Sakomura Y, et al. Helical CT features of arrhythmogenic right ventricular cardiomyopathy. Radiographics. 2002; 22(5):1111-1124.
9. Kuhlman JE. Thoracic imaging in heart transplantation. J Thorac Imaging. 2002; 17(2):113-121.
10. Parker MS, Hui FK, Camacho MA, et al. Female breast radiation exposure during CT pulmonary angiography. AJR. 2005; 185(5):1228-1233.
11. van Klaveren RJ, Oudkerk M, Prokop M, et al. Management of lung nodules detected by volume CT scanning. N Engl J Med. 2009; 361(23):2221-2229.

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 January 04, 2010.
2. American College of Radiology. ACR Appropriateness Criteria^®. Available at: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx. Accessed on January 13, 2010.
   • Acute Chest Pain — Suspected Aortic Dissection (2008)
   • Blunt Chest Trauma — Suspected Aortic Injury (2009)
   • Metastatic Bone Disease (2009)
   • Primary Bone Tumors (2009)
   • Screening for Pulmonary Metastases (2008)
   • Solitary Pulmonary Nodule (2008)
   • Suspected Congenital Heart Disease in the Adult (2007)
3. American College of Radiology. Practice guideline: Available at: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines.aspx Accessed on January 13, 2010.
   • Practice guideline for the performance of computed tomography (CT) for the detection of pulmonary embolism in adults (2005)
   • Practice guideline for the performance of pediatric and adult thoracic computed tomography (CT) (2008)
4. 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: Computerized Tomography. NCD# 220.1. Effective March 12, 2008.
   • Centers for Medicare and Medicaid Services. National Coverage Determination: Magnetic Resonance Imaging (MRI). NCD #220.2. Effective September 28, 2009.
5. 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.
6. 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.
7. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology™. Non-small cell lung cancer. (2010) Available at: http://www.nccn.org/professionals/physician_gls/PDF/nscl.pdf. Accessed on January 04, 2010.
8. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology™. Small cell lung cancer. (2010) Available at: http://www.nccn.org/professionals/physician_gls/PDF/sclc.pdf. Accessed on January 04, 2010.
9. Nickoloff EL, Alderson PO. Radiation exposures to patients from CT: reality, public perception, and policy. AJR. 2001; 177(2):285–287.
10. 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