MRI anatomy of the heart

Planning scan planes

Strictly sequential planes are used to obtain standard cardiac projections.

The base plane is the vertical long axis (Vertical long axis, VLA). It is planned using axial slices and oriented to intersect the mitral valve and the cardiac apex. Based on the obtained VLA, the horizontal long axis (Horizontal long axis, HLA) is established, intersecting the same structures perpendicularly.

Next, short-axis (Short-axis, SA) slices are generated. They run strictly perpendicular to the HLA at various ventricular levels (e.g., basal or mid-ventricular). These exact axes serve as the foundation for acquiring classic chamber projections:

• Four-chamber (Four-chamber): captures both ventricles, left and right atria.
• Two-chamber (Two-chamber): an isolated plane for the left ventricle, perpendicular to the four-chamber view.
• Three-chamber (Three-chamber): demonstrates the left ventricle, aorta, and left ventricular outflow tract.

Imaging modes and body axes

Two main groups of pulse sequences are used in cardiac imaging:

• «Black-blood» (Black-blood): provides a static anatomical picture. Blood appears dark, which allows for a clear view of the chamber walls and pericardium. However, this mode is not suitable for volume and ejection fraction calculations.
• «Bright-blood» (Bright-blood / SSFP): so-called cine-MRI, where circulating blood gives a bright signal. These are multiphase images necessary for quantitative contractility analysis and dynamic evaluation of the valvular apparatus.

Classic anatomical body axes—axial (transverse), coronal, and sagittal—are used to assess the great vessels, pericardium, and mass lesions. For instance, the axial plane is optimal for examining the ascending and descending aorta, venae cavae, and pulmonary veins. Furthermore, planimetric measurement of the right ventricle on axial slices is often more accurate than on the short axis.

Anatomy of the atria and ventricles

MRI allows for a detailed study of the morphology of each cardiac chamber.

Atria: The right atrium (RA) has a broad triangular appendage; the superior and inferior venae cavae, as well as the coronary sinus, empty into it. The left atrium (LA) features a narrow tubular appendage and receives four pulmonary veins.

Ventricles have distinct anatomical differences:

Valvular apparatus and pericardium

The normal pericardium is visualized due to contrast with epicardial fat as a low MR-signal structure on T1-weighted scans. Normally, its thickness is less than 4 mm.

Atrioventricular valves are controlled by papillary muscles (there are normally three in the RV: anterior, posterior, and septal; two larger ones in the LV) and tendinous cords (chordae tendineae). Papillary muscles are clearly visualized on any sequence, but thin chordae tendineae and the membranous part of the interventricular septum are difficult to visualize due to limited spatial resolution.

Semilunar valves (aortic and pulmonary) are best evaluated using targeted cine-MRI slices.

Class and exam questions

What else to study on this topic

• Anatomy and imaging planes of the right ventricular outflow tract (RVOT)
• MRI appearance of the aortic valve in normal and bicuspid disease
• Clinical application of cardiac CT: indications and ECG-gating features
• Visualization and evaluation of coronary arteries using computed tomography

Other topics in the «Chest Radiology» section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.