Cardiac imaging
Cardiac imaging | |
---|---|
ICD-10-PCS | B2 |
MeSH | D057791 |
Cardiac imaging refers to minimally invasive imaging of the heart using
Indications
A physician may recommend cardiac imaging to support a diagnosis of a heart condition.
Echocardiography
Echocardiography is regularly utilized to diagnose, manage, and monitor patients with suspected or established heart ailments, making it a highly prevalent diagnostic imaging technique in cardiology due to its speed and efficiency.[3]
Transthoracic echocardiography (TTE)
TTE is commonly used to evaluate patients with coronary artery disease.[4] Stress echocardiography is used to diagnose coronary artery disease and assess myocardial viability.[4]
Transesophageal Echocardiography (TEE)
Transesophageal echocardiography is an invasive procedure that involves inserting a flexible probe with an ultrasound transducer into the esophagus, providing closer access to the heart and surrounding structures.[5] This procedure allows for better imaging of the aorta, pulmonary artery, heart valves, atria, atrial septum, left atrial appendage, and coronary arteries. It can also be used during cardiac surgery to monitor the patient and assess the success of surgical interventions.[5] TTE can visualize non-dilated coronary arteries and measure coronary artery flow using harmonic imaging, contrast agents, and high-frequency transducers. This noninvasive and low-cost method can help diagnose and manage patients with suspected or confirmed CAD by demonstrating pathologic coronary artery flow patterns at rest and with pharmacological stress.[6]
Transesophageal echocardiography creates clearer images of the heart and surrounding blood vessels than traditional transthoracic echocardiography (TTE). TEE is especially useful for patients with obesity or chronic obstructive pulmonary disease (COPD) who may have difficulty obtaining high-quality images using TTE.[5]
However, TEE has several disadvantages, including the need for a team of medical personnel to perform the procedure, the necessity of the patient to follow specific guidelines before the procedure, longer procedure time, and potential discomfort for the patient requiring general anesthesia. TEE is also limited by available anatomy and may require a second procedure, such as esophagogastroduodenoscopy, to visualize the anatomy for safety.[5]
Additionally, TEE has some risks associated with it, such as esophageal perforation and adverse reactions to medication.[5]
3D Echocardiography
3D TEE is a technology developed to improve upon the limitations of 2D tomography. With the introduction of the matrix TEE probe, 3D TEE can collect real-time 3D images that provide a comprehensive view of the heart structures, leading to better understanding and decision making during cardiac procedures. The technique acquires a volumetric data set and displays it in custom orientations, allowing for greater depth and understanding of heart structures compared to 2D echocardiography.[7]
Contrast Echocardiography
The introduction of ultrasound contrast agents for contrast echocardiography has significantly improved the usefulness of echocardiography in diagnosing and assessing coronary artery disease.[8] Ultrasound contrast is used for assessing left ventricular ejection fraction at rest and during stress echocardiography. Contrast echocardiography can simultaneously assess regional myocardial function and perfusion, allowing for the non-invasive diagnosis of coronary artery disease. It has several advantages compared to other non-invasive imaging techniques, such as being performed without radiation exposure and potential nephrotoxicity. Contrast echocardiography requires intravenous administration of an ultrasound contrast agent during contrast specific ultrasound imaging.[8]
Magnetic resonance imaging (MRI)
Cardiovascular magnetic resonance (MR) technology is able to measure the size, shape, function, and tissue characteristics of the heart in a single session.[11] It is also commonly used to determine ventricular function and for the evaluation of structural heart disease.[12] It is more reproducible than echocardiography with less inter-observer variability, allowing for more precise reference ranges to better distinguish health from disease.[11] Additionally, MR lacks ionizing radiation and does not have any known long-term effects, making it safe for repeated imaging.[13]
Additional benefits from cardiac MRI include the ability to detect scar within the heart using late gadolinium enhancement, and identify other abnormalities of the heart muscle itself such as infiltration with iron or
Recent development in deep learning and convolutional neural network techniques have made it possible to analyze and quantify some aspects of cardiac MRI automatically.[15] The use of cardiac MRI is projected to increase through greater availability of scanners and more widespread knowledge about its clinical application.
Computed tomography (CT)
Computed tomography (CT) provides simultaneous evaluation of multiple systems.[12] A downside to CT scans are that they subject the patient to ionizing radiation, but technological improvements are lessening the amount. CT is best employed in low-to-intermediate-risk patients and is often used when other noninvasive tests are equivocal or abnormal. The Wells' score for pulmonary embolism or the Diamond-Forrester chest pain criteria and Thrombolysis in Myocardial Infarction (TIMI) score can help select appropriate patients for CT.[12]
Coronary Computed Tomography Angiography (CCTA)
Gated Cardiac CT (CCT)
Coronary CT calcium scan
A
Nuclear medicine imaging
Positron emission tomography (PET)
PET tracers emit positrons, which are nearly identical to negatively charged electrons, but have the opposite charge and are considered antimatter. When a positron and an electron come close together, they annihilate each other, producing two gamma rays that travel in opposite directions.[21] PET scanners detect these gamma rays to produce images showing the location of the positrons and the metabolic processes in the body.[21] The accuracy of the image depends on the initial speed of the emitted positron, which affects the ability of the scanner to define the position of radioactive atoms in the body.[21]
PET/CT Scans
Most new PET scanners are combined with a
PET/MRI Scans
PET/MRI systems combine the capabilities of positron emission tomography (PET) and magnetic resonance imaging (MRI) to provide both functional and morphological information in various clinical applications.[22] Cardiac MRI can produce complementary data to increase accuracy and reproducibility to PET scans, especially in systemic diseases, inflammatory processes, assessing risk of atherosclerotic plaque rupture, and stem cell tracking.[22] PET/MRI systems come in two types: tandem, in-line systems where two imagers share a patient transport system for sequential acquisitions, and integrated systems where both scanners operate simultaneously. The latter has some performance limitations, but it may be essential in some applications, such as cardiac perfusion and metabolism.[22] PET/MRI is still in its early stages, and more work is needed to establish it as a widespread and cost-effective clinical tool for cardiac imaging.[22]
Single photon emission computed tomography (SPECT)
Associated invasive cardiac imaging techniques
Coronary catheterization
Intravascular ultrasound
Intravascular ultrasound, also known as a percutaneous echocardiogram is an imaging methodology using specially designed, long, thin, complex manufactured catheters attached to computerized ultrasound equipment to visualize the lumen and the interior wall of blood vessels.
FFR
Fractional flow reserve (FFR) examines the pressure drop across the stenosis in suspected ischemic coronary artery that may require percutaneous coronary intervention (PCI) or coronary artery bypass surgery.
References
- ABIM Foundation, American Society of Nuclear Cardiology, archived from the original(PDF) on 2012-04-16, retrieved August 17, 2012, citing
- Hendel, R. C.; Berman, D. S.; Di Carli, M. F.; Heidenreich, P. A.; Henkin, R. E.; Pellikka, P. A.; Pohost, G. M.; Williams, K. A.; American College of Cardiology Foundation Appropriate Use Criteria Task Force; American Society of Nuclear Cardiology; American College Of, R.; American Heart, A.; American Society of Echocardiology; Society of Cardiovascular Computed Tomography; Society for Cardiovascular Magnetic Resonance; Society Of Nuclear, M. (2009). "ACCF/ASNC/ACR/AHA/ASE/SCCT/SCMR/SNM 2009 Appropriate Use Criteria for Cardiac Radionuclide Imaging". Journal of the American College of Cardiology. 53 (23): 2201–2229. PMID 19497454.
- Fleisher, L. A.; Beckman, J. A.; Brown, K. A.; Calkins, H.; Chaikof, E. L.; Fleischmann, K. E.; Freeman, W. K.; Froehlich, J. B.; Kasper, E. K.; Kersten, J. R.; Riegel, B.; Robb, J. F.; Smith Jr, S. C.; Jacobs, A. K.; Adams, C. D.; Anderson, J. L.; Antman, E. M.; Buller, C. E.; Creager, M. A.; Ettinger, S. M.; Faxon, D. P.; Fuster, V.; Halperin, J. L.; Hiratzka, L. F.; Hunt, S. A.; Lytle, B. W.; Nishimura, R.; Ornato, J. P.; Page, R. L.; Riegel, B. (2007). "ACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery". Journal of the American College of Cardiology. 50 (17): e159–e241. PMID 17950140.
- Hendel, R. C.; Berman, D. S.; Di Carli, M. F.; Heidenreich, P. A.; Henkin, R. E.; Pellikka, P. A.; Pohost, G. M.; Williams, K. A.; American College of Cardiology Foundation Appropriate Use Criteria Task Force; American Society of Nuclear Cardiology; American College Of, R.; American Heart, A.; American Society of Echocardiology; Society of Cardiovascular Computed Tomography; Society for Cardiovascular Magnetic Resonance; Society Of Nuclear, M. (2009). "ACCF/ASNC/ACR/AHA/ASE/SCCT/SCMR/SNM 2009 Appropriate Use Criteria for Cardiac Radionuclide Imaging". Journal of the American College of Cardiology. 53 (23): 2201–2229.
- ABIM Foundation, American College of Cardiology, retrieved 10 February 2014
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