New respiratory gating technique for whole heart cine imaging: Integration of a navigator slice in steady state free precession sequences

Abstract

Purpose: To evaluate the performance of a slice navigator sequence integrated into a b-SSFP sequence for obtaining real time respiratory self-gated whole heart cine imaging. Materials and Methods:In this work, we present a novel and robust approach for respiratory motion detection by integrating a slice navigator sequence into a balanced steady state free precession (b-SSFP) sequence, while maintaining the steady state. The slice navigator sequence is integrated into consecutive repetition times (TRs) of a b-SSFP sequence to excite and read out a navigator slice. We performed several phantom experiments to test the performance of the slice navigator sequence. Additionally, the method was evaluated in five volunteers and compared with breathing signals obtained from conventional pencil beam navigator sequence. Finally, the navigator slice was used to obtain whole heart MR cine images. Results:The breathing signals detected by the proposed method showed an excellent agreement with those obtained from pencil beam navigators. Moreover, the technique was capable of removing respiratory motion artifacts with minimal distortion of the steady state. Image quality comparison showed a statistical significant improvement from a quality score of 2.1 obtained by the nonrespiratory gated images, compared to a quality score of 3.4 obtained by the respiratory gated images. Conclusion:This novel method represents a robust approach to estimate breathing motion during SSFP imaging. The technique was successfully applied to acquire whole heart artifact-free cine images.

Retrospective reconstruction of cardiac cine images from golden‐ratio radial MRI using one‐dimensional navigators

“…To avoid steady‐state free precession (SSFP) banding artifacts we performed all measurements with a FLASH‐based sequence. It is, however, conceivable that the techniques described in this study are also applicable with a SSFP sequence because navigator acquisition, golden‐ratio–based rotation, and data combination from multiple gating windows can also be combined with refocused SSFP acquisition.…”

Retrospective motion gating in cardiac MRI using a simultaneously acquired navigator

“…However, the signal changes from respiratory motion depend on the orientation of the navigator slice. Cross‐correlation between projection data has been used to measure the absolute motion displacement in previous free‐breathing techniques, but this method could be applied to projection data containing only in‐plane motions along the readout dimension. In other words, the orientation of the readout dimension must be parallel to the head‐to‐feet direction.…”

“…Therefore, the navigator signals must be acquired such that there is one navigator signal to multiple image signals, but this scheme leads to disturbance of the steady‐state condition of bSSFP. In order to preserve the steady state during a scan, a new respiratory gating technique has been proposed, in which the acquisitions of navigator signals are integrated into a bSSFP imaging sequence …”

Imaging in population science: cardiovascular magnetic resonance in 100,000 participants of UK Biobank - rationale, challenges and approaches

“…The CMR protocol is subject to modifications before, during and immediately after the pilot phase, but it is not likely to be changed subsequently during the main phase of the study. Examples of opportunities for modification include automated plane finding algorithms or full 3D volumetric acquisition of the heart [33]. CMR feature tracking, which is similar to echocardiographic speckle tracking, tracks regional myocardial features throughout the cardiac cycle.…”