Basic Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Radiol. Oct 28, 2020; 12(10): 231-246
Published online Oct 28, 2020. doi: 10.4329/wjr.v12.i10.231
Cardiac functional magnetic resonance imaging at 7T: Image quality optimization and ultra-high field capabilities
El-Sayed H Ibrahim, V Emre Arpinar, L Tugan Muftuler, Jadranka Stojanovska, Andrew S Nencka, Kevin M Koch
El-Sayed H Ibrahim, V Emre Arpinar, Andrew S Nencka, Kevin M Koch, Department of Radiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States
L Tugan Muftuler, Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI 53226, United States
Jadranka Stojanovska, Department of Radiology, University of Michigan, Ann Arbor, MI 48109, United States
Author contributions: Ibrahim EH helped with study design, experiments, image and data analysis, results interpretation, and manuscript writing; Arpinar VE helped with experiments, image and data analysis, and manuscript revision; Muftuler LT helped with study design, experiments, and manuscript revision; Stojanovska J helped with results interpretation and manuscript revision; Nencka AS helped with results interpretation and manuscript revision; Koch KM helped with results interpretation and manuscript revision; and all authors read and approved the final manuscript.
Supported by The Daniel M. Soref Charitable Trust, Center for Imaging Research, Medical College of Wisconsin, United States.
Institutional review board statement: This study was conducted with approval from Medical College of Wisconsin Institutional Review Board, and informed consent was obtained from scanned human subjects.
Conflict-of-interest statement: The authors have no conflicts-of-interest to report.
Data sharing statement: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: El-Sayed H Ibrahim, PhD, Associate Professor, Department of Radiology, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226, United States. eibrahim@mcw.edu
Received: July 17, 2020
Peer-review started: July 17, 2020
First decision: September 21, 2020
Revised: September 27, 2020
Accepted: October 13, 2020
Article in press: October 13, 2020
Published online: October 28, 2020
Processing time: 103 Days and 11.6 Hours
Abstract
BACKGROUND

7T cardiac magnetic resonance imaging (MRI) introduces several advantages, as well as some limitations, compared to lower-field imaging. The capabilities of ultra-high field (UHF) MRI have not been fully exploited in cardiac functional imaging.

AIM

To optimize 7T cardiac MRI functional imaging without the need for conducting B1 shimming or subject-specific tuning, which improves scan efficiency. In this study, we provide results from phantom and in vivo scans using a multi-channel transceiver modular coil.

METHODS

We investigated the effects of adding a dielectric pad at different locations next to the imaged region of interest on improving image quality in subjects with different body habitus. We also investigated the effects of adjusting the imaging flip angle in cine and tagging sequences on improving image quality, B1 field homogeneity, signal-to-noise ratio (SNR), blood-myocardium contrast-to-noise ratio (CNR), and tagging persistence throughout the cardiac cycle.

RESULTS

The results showed the capability of achieving improved image quality with high spatial resolution (0.75 mm × 0.75 mm × 2 mm), high temporal resolution (20 ms), and increased tagging persistence (for up to 1200 ms cardiac cycle duration) at 7T cardiac MRI after adjusting scan set-up and imaging parameters. Adjusting the imaging flip angle was essential for achieving optimal SNR and myocardium-to-blood CNR. Placing a dielectric pad at the anterior left position of the chest resulted in improved B1 homogeneity compared to other positions, especially in subjects with small chest size.

CONCLUSION

Improved regional and global cardiac functional imaging can be achieved at 7T MRI through simple scan set-up adjustment and imaging parameter optimization, which would allow for more streamlined and efficient UHF cardiac MRI.

Keywords: Magnetic resonance imaging; High-field; Cardiac function; Cine; Tagging; Strain

Core Tip: The capabilities of ultra-high-field magnetic resonance imaging (MRI) have not been fully exploited in cardiac functional imaging. In this study, we provide results from phantom and in vivo scans using a multi-channel transceiver modular coil to optimize 7T cardiac MRI functional imaging without the need for conducting B1 shimming or subject-specific system tuning. The results showed that improved regional and global cardiac functional imaging can be achieved at 7T MRI through simple scan set-up adjustment and imaging parameter optimization, which would allow for more streamlined and efficient ultra-high-field cardiac MRI with access to more information and details compared to lower-field imaging.