Systematic Reviews
Copyright ©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Radiol. Jan 28, 2024; 16(1): 20-31
Published online Jan 28, 2024. doi: 10.4329/wjr.v16.i1.20
From strength to precision: A systematic review exploring the clinical utility of 7-Tesla magnetic resonance imaging in abdominal imaging
Arosh S Perera Molligoda Arachchige, Ana Claudia Teixeira de Castro Gonçalves Ortega, Federica Catapano, Letterio S Politi, Michael N Hoff
Arosh S Perera Molligoda Arachchige, Ana Claudia Teixeira de Castro Gonçalves Ortega, Faculty of Medicine, Humanitas University, Pieve Emanuele 20072, Milan, Italy
Federica Catapano, Letterio S Politi, Department of Biomedical Sciences, Humanitas University, Pieve Emanuele 20072, Milan, Italy
Federica Catapano, IRCCS Humanitas Research Hospital, Rozzano 20089, Milan, Italy
Letterio S Politi, Department of Neuroradiology, IRCCS Humanitas Research Hospital, Rozzano 20089, Milan, Italy
Michael N Hoff, Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA 94143, United States
Author contributions: All authors contributed equally to this work; Perera Molligoda Arachchige AS designed the research study; Perera Molligoda Arachchige AS and Teixeira de Castro Gonçalves Ortega AC performed the research; Catapano F and Politi LS revised the final draft; All authors analyzed the data and wrote the manuscript; Hoff MN supervised the study, revised the final draft; All authors have read and approved the final manuscript.
Conflict-of-interest statement: All the authors have no conflicts of interest to declare.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
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: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Michael N Hoff, PhD, Professor, Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, San Francisco, California CA 94143, United States. michael.hoff2@ucsf.edu
Received: October 16, 2023
Peer-review started: October 16, 2023
First decision: November 9, 2023
Revised: December 6, 2023
Accepted: December 25, 2023
Article in press: December 25, 2023
Published online: January 28, 2024
Abstract
BACKGROUND

After approval for clinical use in 2017 early investigations of ultra-high-field abdominal magnetic resonance imaging (MRI) have demonstrated the feasibility as well as diagnostic capabilities of liver, kidney, and prostate MRI at 7-Tesla. However, the elevation of the field strength to 7-Tesla not only brought advantages to abdominal MRI but also presented considerable challenges and drawbacks, primarily stemming from heightened artifacts and limitations in Specific Absorption Rate, etc. Furthermore, evidence in the literature is relatively scarce concerning human studies in comparison to phantom/animal studies which necessitates an investigation into the evidence so far in humans and summarizing all relevant evidence.

AIM

To offer a comprehensive overview of current literature on clinical abdominal 7T MRI that emphasizes current trends, details relevant challenges, and provides a concise set of potential solutions.

METHODS

This systematic review adheres to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A PubMed search, utilizing Medical Subject Headings terms such as "7-Tesla" and organ-specific terms, was conducted for articles published between January 1, 1985, and July 25, 2023. Eligibility criteria included studies exploring 7T MRI for imaging human abdominal organs, encompassing various study types (in-vivo/ex-vivo, method development, reviews/meta-analyses). Exclusion criteria involved animal studies and those lacking extractable data. Study selection involved initial identification via title/abstract, followed by a full-text review by two researchers, with discrepancies resolved through discussion. Data extraction covered publication details, study design, population, sample size, 7T MRI protocol, image characteristics, endpoints, and conclusions.

RESULTS

The systematic review included a total of 21 studies. The distribution of clinical 7T abdominal imaging studies revealed a predominant focus on the prostate (n = 8), followed by the kidney (n = 6) and the hepatobiliary system (n = 5). Studies on these organs, and in the pancreas, demonstrated clear advantages at 7T. However, small bowel studies showed no significant improvements compared to traditional MRI at 1.5T. The majority of studies evaluated originated from Germany (n = 10), followed by the Netherlands (n = 5), the United States (n = 5), Austria (n = 2), the United Kingdom (n = 1), and Italy (n = 1).

CONCLUSION

Further increase of abdominal clinical MRI field strength to 7T demonstrated high imaging potential, yet also limitations mainly due to the inhomogeneous radiofrequency (RF) excitation field relative to lower field strengths. Hence, further optimization of dedicated RF coil elements and pulse sequences are expected to better optimize clinical imaging at high magnetic field strength.

Keywords: 7-Tesla magnetic resonance imaging, Abdominal, Prostate, Kidney, Renal, Pancreas, Hepatobiliary, Liver, Small bowel

Core Tip: At 7T non-enhanced T1w imaging, especially time-of-flight magnetic resonance angiography, excels in liver vessel assessment, outperforming both steady-state free precession and T2-weighted TSE techniques. Additionally, 7T magnetic resonance spectroscopy (MRS), particularly 31P-MRS, provides valuable insights into hepatic energy metabolism in non-alcoholic fatty liver disease/non-alcoholic steatohepatitis. In pancreatic evaluation, 7T magnetic resonance imaging (MRI) holds promise for tumor characterization. Renal 7T MRI demonstrates potential for reducing contrast use, and prostate imaging explores metabolomic profiles and multi-voxel MRS for cancer detection. Imaging the small bowel at 7T currently offers no significant advantages. Despite challenges 7T MRI holds promise for advancing abdominal diagnostics.