Characterizing coronary motion and its effect on MR coronary angiography—Initial experience

Abstract

Purpose: To characterize coronary artery motion as a prescan procedure to select the optimum scan setting that will produce high-resolution images. Materials and Methods:A 2D real-time scan was used to image the major coronary arteries during breath-holding and free-breathing conditions. With the use of the 2D images, motion displacement of each artery was measured along three axes. Motion data obtained from a computer simulation were used to estimate point-spread functions (PSFs) associated with different high-resolution spiral acquisition strategies, including real-time, cardiac-gated, and respiratory-gated acquisitions. The simulation output determined the optimum acquisition and scan parameters that would produce the highest-spatial-resolution images of the coronary arteries. The effects of heart rate (HR), extended breath-holding, and number of slices per heart cycle were also investigated.Results: Substantial variations in coronary motion occur among individuals, which directly influences the optimum parameters for a high-resolution scan. Lower HRs and longer breath-holds yield substantially increased spatial resolution. The maximum number of slices per heart cycle can also be determined to minimize slice-to-slice distortion. Conclusion:The results suggest that to obtain high-resolution coronary images, one should perform a prescan coronary-motion characterization for each individual so that the scan parameters can be optimized before data acquisition.

Cardiovascular magnetic resonance artefacts

“…During cardiac motion, the coronaries have been shown to shift position from 5 to 20 mm [45], therefore the imaging window is limited to mid-diastole when the heart is relatively still. Often the cardiac timing is adjusted according to the coronary movement assessed from a long-axis cine.…”

Repositioning precision of coronary arteries measured on X-ray angiography and its implications for coronary MR angiography

“…These findings have implications for coronary MRI and coronary computed tomography angiography in which the repositioning precision is of fundamental importance, because image data are acquired during multiple consecutive cardiac cycles. In particular, these two periods have to be taken into consideration for the adequate choice of the position of the acquisition window in the cardiac cycle for optimized image quality. In this study, we wanted to exploit the use of a peak‐systolic acquisition window to assess its performance for coronary MRA.…”

“…Electrocardiogram (ECG) triggering is thus needed to always acquire the different k ‐space segments during the same exact period in the cardiac cycle. Several studies have investigated the best position of this acquisition period in the cardiac cycle by using the coronary velocity as an indicator of relative coronary quiescence . For this purpose, different imaging modalities including x‐ray coronary angiography or MRI were exploited.…”

Prospective respiratory motion correction for coronary MR angiography using a 2D image navigator

“…CMRA is highly susceptible to respiratory motion artifacts because of the long scan duration, particularly for whole‐heart examinations, which typically have to be performed during free breathing. Several studies have investigated respiration induced coronary motion along the foot–head (FH), left–right (LR), and anterior–posterior directions throughout the respiratory cycle (1–7). Although the principal motion component is in the FH direction, the displacement magnitude in the LR or anterior–posterior direction has high subject specific variability and can contribute to increased motion artifacts in CMRA (8).…”