Imaging of the Heart and Great Vessels

Worldwide, the most frequent cause of death is heart disease. Thus, the common conditions that are evaluated in healthcare facilities are often related to the heart or the cardiovascular system: hypertension, atherosclerotic disease, and heart failure. In radiologic terms, this region is likely the most frequently studied aspect of human anatomy in healthcare delivery settings. Multiple methods are used, including X-ray, CT, MRI, echocardiography, nuclear imaging, and angiography. Each test has its advantages and disadvantages and is obtained on the basis of the clinical presentation, acuity of symptoms, and risks and benefits to the patient. It is important to know the roles of imaging studies to help determine the proper treatment.

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Chest X-ray


  • Chest X-ray: most common imaging test to evaluate the heart and great vessels; usually the initial test before using more expensive diagnostic tools:
    • Shadows that form the cardiac silhouette allow for assessment of the size and shape of the heart and major vessels. 
    • Lung parenchymal findings also give information regarding pulmonary pathologies secondary to cardiac abnormalities (e.g., pulmonary edema). 
    • Also used in the evaluation of the mediastinum 
  • Positioning for specific views:
    • Posteroanterior (PA):
      • Board is against the anterior chest.
      • X-ray beams posterior → anterior direction through patient
    • Anteroposterior (AP):
      • Board is against the back. 
      • X-ray beams anterior → posterior direction through the patient
    • Lateral (from side):
      • Patient is upright.
      • Board is against the left or right side.
    • Lateral decubitus (from side while laying down): 
      • Patient is supine.
      • Board is against the side.
      • Usually left side down on table 
  • Penetration: degree to which radiation has passed through body, resulting in darker or lighter image
    • Good penetration:
      • Ribs are only faintly visible behind the heart. 
      • Vascular markings are nonprominent but clear. 
    • Underpenetration: film appears whiter and features are less apparent.
    • Overpenetration: film appears darker and features are less apparent. 


The following structures must be identified and checked for abnormalities in size or shape:

  • PA projection:
    • Structures:
      • Trachea: should be on the midline
      • Superior vena cava (SVC)
      • Ascending and descending aorta (aortic arch)
      • Pulmonary hilum (right and left)
      • Pulmonary artery
      • Right atrium (right heart border)
      • Left ventricle (left heart border)
    • To easily identify the structures on the left border in a cephalocaudal order, remember: 
      • 1st bump: aorta
      • 2nd bump: pulmonary artery
      • 3rd (the largest) bump: left ventricle
  • Lateral projection:
    • Retrosternal space
    • Right ventricle
    • Right hemidiaphragm
    • Aortic arch
    • Pulmonary hilum
    • Left ventricle
    • Left hemidiaphragm
    • Posterior cardiac space


  • On a plain chest film, heart size is quickly assessed calculating the cardiothoracic index (CI): the percentage of the chest diameter occupied by the heart. 
    • A normal CI is < 50%. 
    • However, this is reliable only on a PA projection taken upright.
  • An enlarged heart can be due to:
    • Cardiomegaly
    • Pericardial effusion (water-bottle heart): pericardial effusions must be ≥ 250 mL to be detectable on a chest X-ray.
    • Valvular disease
    • Congenital heart disease
    • Masses
Table: Artifactual causes of cardiac enlargement
RotationThe shadow of the heart appears bigger in the projection because of the rotation of the subject to either side.
Suboptimal inspirationThe diaphragm moves upward and compresses the heart.
Portable supine filmCardiac silhouette undergoes magnification because the cassette is placed in contact with the posterior aspect of the patient and the X-ray beam penetrates from the anterior aspect.
Pectus excavatumThe heart is compressed between the sternum and the spine.

Great vessels

  • In the PA and AP projections, the great vessels can be identified at either side of the mediastinal shadow. 
    • Right mediastinal margin (cephalocaudal):
      • SVC
      • Right pulmonary artery coinciding with the right pulmonary hilum
    • Left mediastinal margin (cephalocaudal):
      • Aorta
      • Left pulmonary artery coinciding with the left pulmonary hilum
  • In a lateral projection, only the shadow of the aorta can be distinguished.



  • Ultrasound principles are used in echocardiography to produce anatomical images of the heart and great vessels. 
  • Common indications:
    • Evaluation of ventricular function
    • Cardiomyopathy
    • Congenital heart disease
    • Valvular heart disease
    • Pericardial effusion
    • Cardiac masses
    • Proximal aortic disease
  • Echocardiography is likewise an essential tool in assessing the dynamic function of the heart in stress tests (exercise or dobutamine stress echocardiography).

Evaluation of the heart and great vessels

  • Transthoracic echocardiography (TTE):
    • More common; noninvasive
    • Uses a handheld transducer positioned on the chest to scan the heart
    • Provides the clinician with the ability to quickly assess the heart, especially in life-threatening situations
    • Allows for the rapid distinction between cardiac (e.g., pericardial effusion) and extracardiac (e.g., pulmonary embolus) causes of illness
  • Transesophageal echocardiography (TEE):
    • Improved image quality (especially posterior cardiac structures) because of the proximity of the esophagus to the heart
    • Because of TEE’s invasive nature, TTE often precedes TEE.
    • Commonly used in:
      • Evaluation for a cardiac source of embolus
      • Valvular assessment in cases of endocarditis 
      • Determination of left atrial appendage (LAA) thrombi in patients with atrial fibrillation 
  • Modalities:
    • 2-Dimensional: by undergoing complex processes (e.g., filtering, signal amplification), the signal received forms a cardiac image displayed on the monitor. 
    • M-mode: 
      • M = motion
      • Movement of the structures is graphically imaged over time by directing a linear beam of ultrasound at a single structure. 
    • Doppler:
      • Provides information regarding blood flow (hemodynamics)
      • Especially helpful in valvular and cardiac function assessment, as well as in evaluating intracardiac shunts
  • Interpretation includes:
    • Reason for the test
    • Quality of image
    • Rate and rhythm
    • Chamber sizes
    • Hypertrophy
    • Right ventricular function
    • Left ventricular systolic function:
      • Ejection fraction = (stroke volume [end diastolic volume – end systolic volume]/end diastolic volume) × 100
      • Wall motion
    • Left ventricular diastolic function
    • Valves
    • Mass or thrombus
    • Atrial or ventricular septal defect
    • Pericardium
    • Other findings can include aneurysms, pleural effusion, and incidental findings.

Cardiac scan


  • Cardiac scan: 
    • Also called heart scan or myocardial perfusion imaging
    • Detects variation in blood flow and myocardial extraction of radiotracers 
    • Materials: 
      • Isotopes: technetium-99m, thallium-201 
      • Radiopharmaceutical (radioisotope + organic molecule): sestamibi, teboroxime
  • Procedure:
    • In normal coronary arteries, significant arterial dilatation is seen in response to exercise/stress.
    • Stenotic areas do not show dilatation; thus, ischemia and ECG changes occur. 
    • In this test, stress is either:
      • Exercise-induced by running on a treadmill
      • Pharmacologically induced by injecting adenosine or dobutamine for those who cannot run 
  • Imaging is obtained both during stress and at rest.
  • Radiopharmaceuticals are injected when 85% of the maximum predicted heart rate (MPHR) is reached.
  • Indications:
    • Myocardial ischemia or MI evaluation
    • Wall-motion abnormalities: done by ECG-gated SPECT scan
    • Calculate left ventricular ejection fraction
  • Normal cardiac scan obtained in 3 different planes:
    • The top row of each set is performed under cardiac stress
    • Bottom row of each set is performed at rest
    • Normal flow to all aspects of the heart both at rest and during stress
Normal myocardial perfusion scan with thallium-201

Normal myocardial perfusion scan with thallium-201 for the rest images (bottom rows) and technetium-sestamibi for the stress images (top rows)

Image: “Nl mpi2” by Myohan. License: CC BY 3.0



  • Thoracic CT is very useful for studying the anatomy of the heart, great vessels, and mediastinum. 
  • The use of IV contrast allows for adequate visualization of the heart chambers and the venous and arterial anatomy. 
  • Even though a CT scan is usually displayed as slices, the image data can be manipulated to obtain a 3-dimensional reconstruction of the anatomy.
  • Cardiac CT, though, is associated with high dose of ionizing radiation, and use of contrast material carries a risk for renal failure.


  • Coronary CTA (CCTA):
    • For evaluation of the coronary arteries in cases of indeterminate stress tests
    • Characterizes coronary or cardiac anomalies, including location and patency of bypass grafts
    • Triple rule-out in emergency situations of atypical chest pain:
      • Atherosclerotic disease
      • Pulmonary embolism
      • Aortic dissection
  • Coronary artery calcium (CAC) scoring:
    • Noninvasive test that detects and quantifies CAC.
    • Generally recommended in asymptomatic adults ≥ 40 years of age with intermediate atherosclerotic cardiovascular disease risk
    • Requires a relatively low radiation dose (comparable to that for a screening mammography)
    • The amount of calcified plaque present in the epicardial coronary arteries, reported as the total calcium score (Agatston score):
      • No identifiable disease: 0 Agatston units
      • Mild disease: 1–99 Agatston units
      • Moderate disease: 100–399 Agatston units
      • Severe disease: ≥ 400 Agatston units 
    • Scoring provides guidance on further management (e.g., recommending aspirin and lipid-lowering agents).


Aortic CTA:

  • Contrast-enhanced CT can provide information on the thickness and composition of the vessel wall. 
  • Most common initial imaging for aortic dissection evaluation
  • Allows for:
    • Documentation of size and shape of aneurysms
    • Visualization of the true and false lumen in aortic dissection
    • Characterization of calcification and stenoses 
    • Visualization of the anatomy of congenital anomalies
    • Evaluation of vasculitis
  • Also useful to detect postoperative complications: 
    • Restenosis
    • Thrombosis
    • Endoleak after aneurysm repair

Pulmonary arteries

CT pulmonary angiography (CTPA):

  • Also called chest CT angiography with contrast
  • Most frequently used imaging to evaluate the pulmonary arteries
  • High sensitivity and specificity for pulmonary embolism
An axial cut of a chest CT scan visualizing the great vessels

An axial cut of a chest CT scan visualizing the great vessels
A: aorta
PA: pulmonary artery

Image by Hetal Verma.

Chest MRI


  • A thoracic MRI is for studying the heart and great vessels; it has greater definition of anatomy than CT. 
  • The function of MRI is based on the utilization of magnetic fields and radiofrequencies to generate 3-dimensional, high-fidelity images. 
  • Use is restricted to large medical centers because of its great cost and required operational expertise. 
  • MRI is often reserved for evaluation of complex thoracic pathology initially assessed with more accessible imaging methods (e.g., CT).
  • Contraindications: patients with metallic or electrical implants, devices, or foreign bodies that are not MRI-compatible. 


  • Cardiac MRI (CMR)
    • Single-plane 2-dimensional (2D) or multiple-plane 2D or 3-dimensional (3D) images can be obtained.
    • Can provide images of the heart going through a cardiac cycle 
    • Usual indications:
      • Congenital heart disease
      • Valvular dysfunction
      • Suspected intracardiac masses
      • Myocardial disease, including cardiomyopathy, ischemic heart disease, myocarditis
      • Pericardial disease (e.g., noncalcified constrictive pericarditis, pericardial tumor invasion)
      • Aortic abnormality (e.g., aneurysm, aortic dissection)
  • MRA:
    • Contrast-enhanced angiography
    • Can be used to identify anomalous coronary arteries as well as other blood vessels (aorta) and to monitor coronary artery aneurysms
Cardiac MRI images

Cardiac MRI images:
A: Cardiac MRI gradient echo sequence of the normal dimensions and function of the left ventricle
B: T2-weighted short τ inversion recovery sequence
C: Late gadolinium hyperenhancement sequence

Image: “Cardiac-MRI images” by Renilla González, A., et al. License: CC BY 2.0

Cardiac Catheterization and Angiography


  • Among the most commonly performed cardiovascular imaging tests
  • A catheter is introduced into a peripheral vessel such as the femoral or axillary vein or artery (catheterization) and is positioned in the region of interest:
    • Performed under fluoroscopic guidance
    • Contrast material is injected to confirm the location of the catheter and to highlight the cardiac structures for diagnostic evaluation (angiography).
  • Images are digitally recorded and stored and can be videotaped.
  • While complications are rare, the following can occur:
    • Bleeding/hematoma
    • Infection
    • MI
    • Stroke
    • Arrhythmia
    • Allergic reaction (to contrast agent)
    • Renal failure (due to contrast agent)

Evaluation of the heart and great vessels

  • Cardiac catheterization:
    • Diagnostic:
      • Defines the cardiac and coronary artery anatomy, cardiac function, and pulmonary arterial hemodynamics
      • Also used for endomyocardial biopsy and intravascular ultrasonography
    • Therapeutic:
      • For coronary artery disease therapy (percutaneous coronary intervention (PCI))
      • For valvuloplasty and valve replacement
  • Left heart catheterization: 
    • Coronary angiography to assess coronary arteries (gold standard)
    • Assessment includes the ventricular outflow tracts, left ventricular motion, ejection fraction, mitral valve, and aortic valve function. 
    • Aortic angiography evaluates the aortic structure and function (e.g., aortic dissection).
  • Right heart catheterization:
    • Checks right atrial and ventricular pressure
    • Assesses pulmonary artery pressure and pulmonary artery occlusion pressure
    • Pulmonary angiography can evaluate for pulmonary embolism (though this has been largely replaced by CTPA).

Clinical Correlation

Congestive heart failure

  • Congestive heart failure (CHF) refers to the inability of the heart to supply the body with normal cardiac output to meet metabolic needs.
  • Multiple causes, including ischemia/coronary artery disease, hypertension, valvular heart disease, and cardiomyopathy.
  • Types:
    • Heart failure with reduced ejection fraction (HFrEF) or systolic failure: left ventricle unable to contract normally
    • Heart failure with preserved ejection fraction (HFpEF) or diastolic failure (or diastolic dysfunction): left ventricle unable to normally relax to fill the ventricle with blood
  • Tests:
    • X-rays:
      • Initial test used in evaluating patients with symptoms of CHF (e.g., shortness of breath, orthopnea)
      • Gives information regarding any chamber enlargement or associated pulmonary congestion
    • Echocardiography:
      • Can confirm the diagnosis
      • Results include EF, associated structural and hemodynamic abnormalities which depend on the type and etiology of the heart failure (HF). 

Cardiomyopathy (CM)

  • Disorder in which the heart muscle is structurally and functionally impaired and is not due to coronary artery, valvular, or congenital heart disease or hypertension.
  • Types:
    • Dilated CM: dilated ventricle(s) associated with impaired contraction
    • Hypertrophic CM: hypertrophy of the left (and, occasionally, the right) ventricle (seen as increased wall thickness)
    • Restrictive CM: ventricles not dilated or hypertrophied but have impaired ventricular filling
    • Arrhythmogenic right ventricular CM: 
      • Genetic heart muscle disease 
      • Ventricular arrhythmias with fibrofatty tissue in the myocardium of the right ventricle
    • Unclassified
  • Tests (findings depend on the CM type):
    • Echocardiography: 1 of the initial tests for suspected cardiomyopathy, giving information on cardiac structure and function
    • Cardiac MRI provides assessment of:
      • Ventricular volumes and systolic function (ejection fraction)
      • Myocardial mass and wall thickness
      • Wall motion (in cine sequences)

Pulmonary embolism

  • A potentially fatal condition resulting from the mechanical obstruction of the pulmonary artery or its branches
  • Can be due to any material (such as thrombus, air, or fat) from anywhere in the body. 
  • CTPA:
    • 1st-choice diagnostic imaging method, especially in emergent settings
    • Highly sensitive in detecting pulmonary emboli (seen as filling defects)
    • Alternative diagnoses can be ruled out.
Pulmonary embolism

Pulmonary embolism:
Chest CT showing multiple filling defects of the principal branches (arrows) due to pulmonary embolism

Image: “Chest Spiral TC” by Serra W, De Iaco G, Reverberi C, Gherli T. License: CC BY 2.0

Aortic dissection

  • A condition in which the inner coat (tunica intima) of the aortic wall develops a fissure allowing blood to enter the media layer to form a secondary lumen.
  • CTA:
    • Most common initial test
    • Findings include:
      • Intimal flap with a false lumen (which is often larger than the true lumen)
      • Possible thrombus
      • Enlarged aorta 
    • An alternative is MRA.
  • TEE: 
    • For those with suspected ascending aortic involvement or for hemodynamically unstable patients
    • Requires skilled operators and patient sedation
  • Aortography: when initial tests are inconclusive.

Coronary artery disease

  • The most common type of heart disease, occurring when the coronary arteries narrow, usually due to the buildup of plaque (atherosclerosis)
  • As narrowing worsens, less blood can flow through the arteries, resulting in ischemia and cell death → MI
  • Multiple methods used:
    • Stress echocardiography: can be used with exercise or pharmacologic stress test
    • Cardiac scan (stress): 
      • Myocardial ischemia: areas of photopenia (i.e., decreased uptake) under stress that improves at rest
      • MI: persistent photopenia (i.e., decreased uptake) despite rest state
    • CT:
      • CAC scoring: screening for patients with moderate or intermediate risk
      • CTA: screening for those with indeterminate stress tests and/or ECGs
    • Cardiac catheterization and coronary angiography:
      • Both for diagnostic and therapeutic management of acute coronary syndrome (ST-segment elevation MI)
      • For evaluation of patients with chronic debilitating angina despite maximal medical therapy
      • When noninvasive testing suggests severe ischemic disease


  • Inflammatory disease of the interior cardiac lining that can be due to either infectious or noninfectious causes; primarily and most notably affects the valves
  • Echocardiography:
    • All patients with suspected infective endocarditis should undergo echocardiography.
    • Findings can include:
      • Vegetation
      • Abscess
      • New dehiscence of a prosthetic valve
    • TTE:
      • 1st diagnostic test
      • If images are inadequate, or complications are suspected (abscess, valvular abnormality needing cardiac surgery), TEE is performed.
Endocarditis transesophageal echocardiogram

A transesophageal echocardiogram shows the left atrium (LA), parts of the mitral valve (MV), the left ventricle (LV), the ascending aorta (AO), and a thickened aortic cusp (arrow), the last of which is highly suggestive of endocarditis.

Image: “A transesophageal echocardiogram” by Stöllberger C, Bastovansky A, Finsterer J. License: CC BY 2.0

Pericardial conditions

  • Pericardial effusion:
    • Accumulation of fluid in the pericardial cavity of the heart
    • Since the pericardium does not expand, after enough fluid accumulates under pressure, the cardiac filling becomes restricted → cardiac tamponade
  • Pericarditis:
    • Inflammation of the pericardium
    • Can be idiopathic or caused by a variety of conditions, including infection, previous MI, or systemic diseases
  • Tests:
    • Chest X-ray: initial test done showing enlargement of the heart (in effusion)
    • Echocardiography: 
      • Often normal in pericarditis
      • In pericardial effusion, pericardial fluid is seen as an echolucent space between the epicardium and the pericardium.
    • CMR and cardiac CT: help in quantification of pericardial fluid


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