|Focus of CMR Sequences||Technical Detail||Example Images|
|Cine images: cardiac volumes, mass, and function||The SSFP sequence provides excellent contrast between the myocardium and the blood pool. The cardiac cycle is divided into 12 to 30 “phases.” Individual images of each of these phases are then stitched together to form a “cine” movie of the cardiac cycle.|
|Structure and tissue characterization||A family of sequences called short tau inversion recovery are used to enhance tissue characterization. These use multiple pulses to null the signal from the blood pool, creating a “black blood” effect and, thus, emphasizing signal properties from the myocardium. The sequences can be relatively T1- or T2-weighted. T1-weighting can assist in identification of fatty infiltration, such as in ARVC. T2-weighting is used to identify regions of myocardial edema in inflammation or ischemia.|
|Blood flow and velocity||Velocity-encoded sequences allow the quantification of flow across cardiac valves. They achieve this by using special gradient pulses that “sensitize” the images to flow in a precise and quantifiable manner, permitting the calculation of velocity and, hence, of bulk flow.|
|Myocardial perfusion||CMR is able to image the change in T1-weighted signal intensity of the myocardium during the passage of gadolinium contrast agent. Imaging is performed with each cardiac cycle (usually 3 to 6 short-axis slices). In regions where blood flow is normal, the myocardium appears bright as the gadolinium perfuses the capillaries, whereas dark areas represent ischemic myocardial regions of low perfusion.|
|LGE in regions of fibrosis or increased interstitial space||LGE-CMR uses the slow clearance of gadolinium from regions of increased interstitial space, classically fibrosis, infiltration, or cellular necrosis. The most validated sequence to assess this is a 2D-segmented inversion recovery fast gradient echo sequence. Images are acquired starting from 5 to 10 min after intravenous administration of a dose of 0.1 to 0.2 mmol/kg of gadolinium-DTPA. The TI (inversion recovery time) is adjusted to null the normal myocardium before acquiring a short-axis stack through the ventricles, as well as 4-, 2-, and 3-chamber image planes.|
A standard plan for CMR acquisition includes: 1) a scout; 2) black blood axials and coronals; 3) bSSFP cine images in specific cardiac planes (4-chamber shown); 4) black blood images; 5) perfusion images; 6) flows sequences; and 7) LGE images.
ARVC = arrhythmogenic right ventricular cardiomyopathy; bSSFP = balance steady-state free precession; CMR = cardiac magnetic resonance; DPTA = diethylenetriaminepentaacetic acid; LGE = late gadolinium enhancement; 2D = 2-dimensional.