Cardiac imaging

A physician may recommend cardiac imaging to support a diagnosis of a heart condition. Medical specialty professional organizations discourage the use of routine cardiac imaging during pre-operative assessment for patients about to undergo low or mid-risk non-cardiac surgery because the procedure carries risks and is unlikely to result in the change of a patient's management. Stress cardiac imaging is discouraged in the evaluation of patients without cardiac symptoms or in routine follow-ups. ==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. Transthoracic echocardiography (TTE) Transthoracic echocardiography (TTE) uses ultrasonic waves for continuous heart chamber and blood movement visualization. It is the most commonly used imaging tool for diagnosing heart problems, as it allows non-invasive visualization of the heart and the blood flow through the heart, using a technique known as Doppler. TTE is commonly used to evaluate patients with coronary artery disease. Stress echocardiography is used to diagnose coronary artery disease and assess myocardial viability. 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. 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. 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. 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. ==Magnetic resonance imaging (MRI)==

Magnetic resonance imaging visualizes the heart by detecting hydrogen atoms using superconducting magnets, particularly those attached to water and fat molecules. These hydrogen atoms possess a property known as nuclear spin. Although the direction of this spin is usually random, the spin can be aligned using a powerful magnetic field. Cardiovascular magnetic resonance (MR) technology is able to measure the size, shape, function, and tissue characteristics of the heart in a single session. It is also commonly used to determine ventricular function and for the evaluation of structural heart disease. Other metal structures such as artificial valves and coronary stents are generally not problematic. However, MR is less widely available and may be more difficult for patients to tolerate than other noninvasive modalities, requiring physician monitoring for complex cases. Recent development in deep learning and convolutional neural network techniques have made it possible to analyze and quantify some aspects of cardiac MRI automatically. 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. 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. This is achieved through the use of thin slices and high-resolution scanning, as well as the addition of electrocardiogram (ECG) gating or triggering to capture a motion-free image. Standard CT scans are acquired in either Axial or Helical modes, while CCT adds the ECG gating dimension to these modes to capture images of the heart. This severity can be presented as Agatston score or Coronary Artery Calcium (CAC) score. The CAC score is an independent marker of risk for cardiac events, cardiac mortality, and all-cause mortality. In addition, it provides additional prognostic information to other cardiovascular risk markers. ==Nuclear medicine imaging==

Positron emission tomography (PET) Positron emission tomography (PET) is a nuclear medicine imaging methodology that tracks positron emitting radioisotopes. PET enables visual image analysis of multiple different metabolic chemical processes and is thus one of the most flexible imaging technologies. Cardiology uses are growing very slowly due to technical and relative cost difficulties. Most uses are for research, not clinical purposes. Appropriate radioisotopes of elements within chemical compounds of the metabolic pathway being examined are used to make the location of the chemical compounds of interest visible in a PET image. 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. PET scanners detect these gamma rays to produce images showing the location of the positrons and the metabolic processes in the body. The two scanners are located in the same machine, but they do not perform scans at the same time. A CT scan is typically done first, followed by a PET scan. The accuracy of the test depends on the technical quality of the study, and interpreting the results requires knowledge of the physics and technical aspects of the procedure. ==Associated invasive cardiac imaging techniques==

Coronary catheterization Coronary catheterization uses pressure monitoring and blood sampling through a catheter inserted into the heart through blood vessels in the leg or wrist to determine the functioning of the heart, and, following injections of radiocontrast dye, uses X-ray fluoroscopy, typically at 30 frames per second, to visualize the position and volume of blood within the heart chambers and arteries. Coronary angiography is performed during a cardiac catheterization and used to determine the patency and configuration of the coronary artery lumens. 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. Fractional flow reserve 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==