Abdominal MRI on a Commercial 0.55T System: Initial Evaluation and Comparison to Higher Field Strengths

Anupama Ramachandran; Hero K Hussain; Vikas Gulani; Lauren Kelsey; Mishal Mendiratta-Lala; Jacob Richardson; Maria Masotti; Nancy Dudek; Joel Morehouse; Kathleen Ropella Panagis; Katherine Wright; Nicole Seiberlich

doi:10.1016/j.acra.2024.01.018

Abdominal MRI on a Commercial 0.55T System: Initial Evaluation and Comparison to Higher Field Strengths

Acad Radiol. 2024 Feb 5:S1076-6332(24)00018-7. doi: 10.1016/j.acra.2024.01.018. Online ahead of print.

Affiliations

¹ Department of Radiology, University of Michigan, Ann Arbor, MI 48109.
² Department of Biostatistics, University of Michigan, Ann Arbor, Michigan.
³ Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan.
⁴ Department of Radiology, University of Michigan, Ann Arbor, MI 48109. Electronic address: nse@med.umich.edu.

PMID: 38320946
DOI: 10.1016/j.acra.2024.01.018

Abstract

Rationale and objectives: This study aims to assess the quality of abdominal MR images acquired on a commercial 0.55T scanner and compare these images with those acquired on conventional 1.5T/3T scanners in both healthy subjects and patients.

Materials and methods: Fifteen healthy subjects and 52 patients underwent abdominal Magnetic Resonance Imaging at 0.55T. Images were also collected in healthy subjects at 1.5T, and comparison 1.5/3T images identified for 28 of the 52 patients. Image quality was rated by two radiologists on a 4-point Likert scale. Readers were asked whether they could answer the clinical question for patient studies. Wilcoxon signed-rank test was used to test for significant differences in image ratings and acquisition times, and inter-reader reliability was computed.

Results: The overall image quality of all sequences at 0.55T were rated as acceptable in healthy subjects. Sequences were modified to improve signal-to-noise ratio and reduce artifacts and deployed for clinical use; 52 patients were enrolled in this study. Radiologists were able to answer the clinical question in 52 (reader 1) and 46 (reader 2) of the patient cases. Average image quality was considered to be diagnostic (>3) for all sequences except arterial phase FS 3D T1w gradient echo (GRE) and 3D magnetic resonance cholangiopancreatography for one reader. In comparison to higher field images, significantly lower scores were given to 0.55T IP 2D GRE and arterial phase FS 3D T1w GRE, and significantly higher scores to diffusion-weighted echo planar imaging at 0.55T; other sequences were equivalent. The average scan time at 0.55T was 54 ± 10 minutes vs 36 ± 11 minutes at higher field strengths (P < .001).

Conclusion: Diagnostic-quality abdominal MR images can be obtained on a commercial 0.55T scanner at a longer overall acquisition time compared to higher field systems, although some sequences may benefit from additional optimization.

Keywords: 0.55T; Abdominal imaging; Low-field MRI.