Cardiac Imaging Tests

ByThomas Cascino, MD, MSc, Michigan Medicine, University of Michigan;

Michael J. Shea, MD, Michigan Medicine at the University of Michigan

Reviewed ByJonathan G. Howlett, MD, Cumming School of Medicine, University of Calgary

Reviewed/Revised Modified May 2026

v931781

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Chest Radiography in Cardiac Diagnosis
Computed Tomography (CT) in Cardiac Diagnosis
Cardiac Magnetic Resonance Imaging (MRI)
Radionuclide Imaging

Cardiac imaging tests can delineate cardiac structure and function. Standard imaging tests include:

Echocardiography
Chest radiography
Computed tomography (CT) and CT angiography
Magnetic resonance imaging (MRI) and MR angiography
Radionuclide imaging

Echocardiography is discussed separately.

Standard CT and MRI have limited application because the heart constantly beats, but faster CT and magnetic resonance techniques can provide useful cardiac images if the rhythm is regular and the heart rate is controlled; sometimes patients are given a medication (eg, a beta-blocker) to slow the heart rate during imaging.

In ECG gating, the image recording (or reconstruction) is synchronized with the electrocardiogram (ECG), providing information from several cardiac cycles that can be used to create single images of selected points in the cardiac cycle. CT gating is a form of ECG gating that uses the ECG to trigger the x-ray beam at the desired portion of the cardiac cycle, exposing the patient to less radiation than gating that reconstructs information from only the desired portion of the cardiac cycle (gated reconstruction) and does not interrupt the x-ray beam.

Chest Radiography in Cardiac Diagnosis

Chest radiographs are often useful as a starting point in a cardiac diagnosis. They are often performed in the evaluation of symptoms that might be cardiac in origin (eg, chest pain) and can provide valuable anatomic information, although additional tests are almost always required for precise characterization of cardiac structure and function. Posteroanterior and lateral views provide a gross view of atrial and ventricular size and shape, pulmonary vasculature, bronchial anatomy, and aortic arch-sidedness. A chest radiograph should always be performed when a diagnosis of heart failure is considered.

Chest Radiograph (Prosthetic Heart Valve)

Image

Signs of left atrial enlargement include a visible density of the left atrium in the right hemithorax (blue arrow, double-density sign), increased (> 7 cm) distance between the left atrial edge in the right hemithorax and the left mainstem bronchus, a convexity along the upper left heart border caused by enlargement of the left atrial appendage (red arrow), and widening of the carina with increased separation between the left and right mainstem bronchi. Signs of left ventricular enlargement include an obvious enlargement of the cardiac silhouette and leftward and inferior displacement of the left heart border.

ZEPHYR/SCIENCE PHOTO LIBRARY

Computed Tomography (CT) in Cardiac Diagnosis

CT may be used to evaluate for pericarditis, congenital cardiac disorders (especially abnormal arteriovenous connections), disorders of the great vessels (eg, aortic aneurysm, aortic dissection), cardiac tumors, acute pulmonary embolism, chronic pulmonary thromboembolic disease, and arrhythmogenic right ventricular cardiomyopathy. Noncontrast CT can be used to look for coronary artery calcification; the calcium load is sometimes used to refine estimates of cardiac risk. The use of CT to evaluate most other cardiac conditions, particularly those involving blood vessels, requires a radiopaque contrast agent, which may limit its use in patients with renal impairment. When used to image blood vessels specifically, CT with contrast is termed CT angiography and is often ECG-gated.

Coronary CT angiography (CCTA), a noninvasive alternative to coronary angiography, relies on multidetector CT technology. CCTA, is especially used for patients with chest pain and a low to intermediate probability of acute coronary syndrome (1). When used with beta-blockade to slow the heart rate and nitroglycerin to dilate the coronary arteries, it is up to 97% sensitive for significant obstructive coronary artery disease (). When used with beta-blockade to slow the heart rate and nitroglycerin to dilate the coronary arteries, it is up to 97% sensitive for significant obstructive coronary artery disease (2). Radiation levels are reasonable (1 to 10 mSv, compared with average annual background radiation exposure of 3.6 mSv) with current imaging protocols, including prospective ECG-gating (3). However, the presence of high-density calcified plaques creates imaging artifacts that interfere with interpretation. CCTA can be combined with a noninvasive estimate of fractional flow reserve (FFR), an important parameter in evaluating the functional hemodynamic significance of coronary lesions, and which otherwise requires invasive assessment in the cardiac catheterization laboratory (4).

Cardiac CT Angiogram

Image

Cross sectional view of a cardiac CT angiogram shows the left ventricle and the left anterior descending coronary artery.

LIVING ART ENTERPRISES, LLC/SCIENCE PHOTO LIBRARY

Abnormal CT of the Heart

Noncontrast CT Showing Coronary Artery Calcification

This image shows dense coronary calcifications in the left main (red arrow) and left anterior descending coronary artery (green arrow).

This image shows dense coronary calcifications in the left main (red arrow) and left anterior descending coronary arter

Cardiac CT (3D Scan of Prosthetic Heart Valve)

This is an oblique view of the left side, looking toward the front of the chest (left). The prosthetic heart valve (white) is visible at center, where the aorta (upper center) meets the heart (lower center). The stitches used to close the chest are visible at upper left. The 3D appearance is achieved through computerized reconstruction of multiple single-plane images.

This is an oblique view of the left side, looking toward the front of the chest (left). The prosthetic heart valve (whi

ZEPHYR/SCIENCE PHOTO LIBRARY

Noncontrast CT Showing Coronary Artery Calcification

This image shows dense coronary calcifications in the left main (red arrow) and left anterior descending coronary artery (green arrow).

This image shows dense coronary calcifications in the left main (red arrow) and left anterior descending coronary arter

Cardiac CT (3D Scan of Prosthetic Heart Valve)

This is an oblique view of the left side, looking toward the front of the chest (left). The prosthetic heart valve (whi

ZEPHYR/SCIENCE PHOTO LIBRARY

Contrast CT Showing Normal Coronary Arteries

Contrast CT Showing Normal Coronary Arteries – Slide 1

This contrast CT shows normal coronary arteries. The left main is indicated by the red arrow. The left anterior descending and left circumflex arteries are indicated by the green and blue arrows respectively and the right coronary artery is indicated by the purple arrow. (Not all arteries are seen in all images.) In this image, the origin of the left coronary artery is visible.