Free‐Breathing 3D Cardiac MRI Using Iterative Image‐Based Respiratory Motion Correction

Abstract

Respiratory motion compensation using diaphragmatic navigator (NAV) gating with a 5 mm gating window is conventionally used for free-breathing cardiac MRI. Due to the narrow gating window, scan efficiency is low resulting in long scan times, especially for patients with irregular breathing patterns. In this work, a new retrospective motion compensation algorithm is presented to reduce the scan time for free-breathing cardiac MRI that increasing the gating window to 15 mm without compromising image quality. The proposed algorithm iteratively corrects for respiratory-induced cardiac motion by optimizing the sharpness of the heart. To evaluate this technique, two coronary MRI datasets with 1.3 mm3 resolution were acquired from 11 healthy subjects (7 females, 25±9 years); one using a NAV with a 5 mm gating window acquired in 12.0±2.0 minutes and one with a 15 mm gating window acquired in 7.1±1.0 minutes. The images acquired with a 15 mm gating window were corrected using the proposed algorithm and compared to the uncorrected images acquired with the 5 mm and 15 mm gating windows. The image quality score, sharpness, and length of the three major coronary arteries were equivalent between the corrected images and the images acquired with a 5 mm gating window (p-value>0.05), while the scan time was reduced by a factor of 1.7.

An iterative approach to respiratory self‐navigated whole‐heart coronary MRA significantly improves image quality in a preliminary patient study

“…In this study, we have investigated the differences in respiratory patterns between a group of volunteers and patients with suspected or confirmed CAD. Consistent with earlier reports , we found that end‐exp is the most frequently occurring respiratory position at least in our sub‐group of healthy adult volunteers. However, the average respiratory pattern of our patient cohort included a higher frequency of intermediate respiratory positions located in‐between end‐exp and end‐insp (see Figure b,d).…”

“…This particular SN implementation was successfully tested in both volunteers and patients . It has recently been established that end‐expiration (end‐exp) as a respiratory reference position in self‐navigated coronary MRA may be most promising in terms of image quality in healthy adult subjects with regular breathing patterns. However, in the case of more irregular respiration and respiratory drift as often occurring in patients , this may no longer apply and alternative strategies may thus be needed.…”

4D respiratory motion‐compensated image reconstruction of free‐breathing radial MR data with very high undersampling

“…In case of radial kspace acquisitions, streak artifacts arise from azimuthal undersampling. To overcome these limitations, motioncompensated (MoCo) image reconstruction has been proposed (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). In contrast to gating, 100% of the measured data are employed for the reconstruction of each individual phase.…”

Faster 3D saturation-recovery based myocardial T1 mapping using a reduced number of saturation points and denoising

“…Nevertheless, it was still dependent on the efficiency of the diaphragmatic navigator and its unpredictable scan time, which can severely drop in patients with irregular breathing patterns. Alternative motion compensation techniques, such as image-based navigation and selfnavigation (26)(27)(28), will be investigated in future studies to achieve 100% respiratory scan efficiency and consequently to further accelerate the scan, which can provide more comfort to the patient and reduce the risk of introducing additional bulk motion artifacts associated with long scans.…”