(MRI-CA, MRCA) The noninvasive imaging of the coronary arteries using magnetic resonance imaging of the heart.
For cardiac MRI-CA, high performance machines are necessary with minimum 40mT/m and 300μsec slew rate.
2D and 3D acquisition are used for fast gradient echo sequences with techniques for minimizing cardiac and respiratory motion and suppressing the high signal of pericardial fat. The optimal sequences seem to be trueFISP, Balanced FFE or FIESTA with SMASH and SENSE techniques. Respiratory motion is minimized for 3D acquisitions by using respiratory gating, especially using navigator echoes (Navigator Technique) to track diaphragmatic and cardiac movement. Optimization of MR technique can provide mapping of long segments of the coronary arteries.
Blood pool agents are being applied to improve the reliability of coronary MR angiography. The major current clinical indication is the identification of coronary artery anomalies because the diagnostic accuracy's for identifying haemodynamically significant stenoses are variable depending of the image quality.

See also Magnetic Resonance Angiography, and Cardiac MRI.

(MRI-CA) Coronary angiography with dobutamine stress tagging (MR images are taken after the heart has been stressed by using a medication called dobutamine). Investigational noninvasive imaging as a diagnostic tool for evaluating stenosis, anatomy and flow effects in coronary arteries with dobutamine stress.

For Ultrasound Imaging (USI) see Stress Echocardiogram at Medical-Ultrasound-Imaging.com.

Cardiovascular MR imaging includes the complete anatomical display of the heart with CINE imaging of all phases of the heartbeat. Ultrafast techniques make breath hold three-dimensional coverage of the heart in different cardiac axes feasible. Cardiac MRI provides reliable anatomical and functional assessment of the heart and evaluation of myocardial viability and coronary artery disease by a noninvasive diagnostic imaging technique.
Cardiovascular MRI offers potential advantages over radioisotopic techniques because it provides superior spatial resolution, does not use ionizing radiation, has no imaging orientations constraints and contrast resolution better than echocardiography. It also offers direct visualization and characterization of atherosclerotic plaques and diseased vessel walls and surrounding tissues in cardiovascular research.
MRI perfusion approaches measure the alteration of regional myocardial magnetic properties after the intravenous injection of contrast agents and assess the extent of injury after a myocardial infarction and the presence of myocardial viability with a technique based on late enhancement. Extracellular MRI contrast agents, like Gd-DTPA, accumulate only in irreversibly damaged myocardium after a time period of at least 10 minutes.
This type of patients may also have an implanted cardiac stent, bypass or a cardiac pacemaker and special caution should be observed on the MRI safety and the contraindications. While a number of coronary stents have been tested and reported to be MRI compatible, coronary stents must be assessed on an individual basis, with the medical team weighing the risks and benefits of the MRI procedure.

Cardiac MRI overview:

Cardiovascular MRI has become one of the most effective noninvasive imaging techniques for almost all groups of heart and vascular disease.

Short name: B22956, generic name: Gadocoletic acid, chemical compound: Gadocoletic acid trisodium salt, central moiety: Gd, phase: II
A blood pool agent for magnetic resonance coronary angiography and first pass myocardial perfusion imaging under development (Bracco Diagnostics Inc). The small molecules of gadolinium-based B22956 are bound after injection to large human serum albumin molecules in coronary vessels with the result of high vessel/muscle contrast.

(DENSE) Displacement Encoding with Stimulated Echoes is a functional cardiac MRI pulse sequence, used to create maps of myocardial displacement with high resolution.
The DENSE magnitude images produce black blood images to show better myocard-blood contrast and to reduce motion artifacts.

See also Myocardial Late Enhancement, Spin Tagging, Coronary Angiography with D-Tagging, Cardiovascular Imaging, and Black Blood MRA.