This pilot study successfully translated a previously developed LF MRI canine cadaver brain protocol for in vivo application and compared the acquired images with paired 1.5 T MRI images from 21 different canine patients, representing the first in vivo usage and evaluation of a 0.05 T MRI in a clinical veterinary context.
Abstract
ABSTRACT Prohibitive costs associated with high-field MRI systems have resulted in reduced access in resource-limited areas with consequential healthcare inequities. This has renewed interest in purposefully designed low-field (LF) systems that, despite inherently lower signal-to-noise ratios, have advantages in terms of cost, portability, and accessibility. This pilot study successfully translated a previously developed LF (0.05 T) MRI canine cadaver brain protocol for in vivo application and compared the acquired images with paired 1.5 T images from 21 different canine patients. The visibility of 15 anatomic features was ordinarily scored (scale 1–3) on transverse T1-weighted post-contrast (21/21 patients) and T2-weighted (17/21 patients) sequences. Lateral ventricles were easily visualized (89.3%–100% scored 3/3) across all sequence‒system combinations, with T2-weighted sequences also providing good identification of the mesencephalic aqueduct (56.3%–100%), fourth ventricle (77.1%–100%), and thalamus (68.8%–100%). Absolute visual grading characteristics (VGC) analysis confirmed comparable performance of the LF system to the 1.5 T MRI for these features, a particularly relevant finding given the system's originally intended application for pediatric hydrocephalus neuroimaging in resource-limited areas. This study represents the first in vivo usage and evaluation of a 0.05 T MRI in a clinical veterinary context.
The recent developments in ultra-low-field brain MRI are reviewed, which enable imaging in open environments and demonstrate initial clinical applicability in point-of-care settings, and future developments are envisioned to address the current limitations of image quality and contrast in ultra-low-field brain MRI systems.
Ed X. Wu, Yujiao Zhao, Yilong Liu et al.· Stroke· 1 citation
Qualitative similarities between volume measurements in adults and the questions of reproducibility through test-retest reliability and external validity using recent software updates to the Hyperfine Swoop system constitute a crucial foundation for the clinical utility of 64 mT MRI in monitoring brain volume loss over time.
M. Stockbridge, Rex Wang, V. Neal et al.· Aperture Neuro· 0 citations
Background: Low-field MRI (LF-MRI) widens neuroimaging access in resource-limited settings but suffers low signal-to-noise ratio (SNR), reduced resolution and artefacts. We developed and validated a deep-learning framework for image normalisation and noise reduction to elevate 0.35T brain MRI toward high-field quality, and tested whether it improves clinically significant lesion detection.
Methods: In a multicentre retrospective diagnostic-accuracy study (STARD 2015), 450 adults underwent non-contrast 0.35T brain MRI (T1W, T2W, FLAIR) across three private tertiary centres in Palembang, Indonesia. Images were enhanced with a CycleGAN incorporating Vision-Transformer blocks. Three blinded neuroradiologists scored a 5-point Likert scale and recorded lesion presence; paired 1.5T MRI was the reference standard. Sensitivity, specificity, AUC and likelihood ratios were computed with 95% CIs; tests compared by McNemar and DeLong; agreement by Fleiss kappa.
Results: AI enhancement improved all quality metrics (e.g., T1W PSNR 22.15 to 28.45 dB; SSIM 0.71 to 0.89; all p<0.001). For lesion detection, AI-enhanced LF-MRI achieved sensitivity 93.9% (95% CI 89.4-96.6), specificity 91.1% (87.1-94.0) and AUC 0.94 (0.91-0.97) versus 78.3%, 81.1% and 0.81 for original images (DeLong p<0.001; McNemar p<0.001). LR+ rose to 10.56 and LR- fell to 0.067. Inter-reader agreement was almost perfect (Fleiss kappa 0.78-0.85).
Conclusions: A CycleGAN-with-transformer framework substantially improved objective quality and diagnostic performance of 0.35T brain MRI toward high-field standards with almost-perfect reader agreement. Pending prospective and external validation, AI enhancement is a low-cost route to more equitable neuroimaging.
Rachmat Hidayat, Linda Purnama· Sriwijaya Journal of Radiol...· 0 citations
Magnetic resonance imaging has limitations in definitively diagnosing canine brain diseases due to overlapping lesion morphologies. Magnetic resonance spectroscopy (MRS) can complement conventional MR imaging by evaluating brain metabolites at a molecular level, though voxels under 1 cm3 have not been routinely evaluated in veterinary medicine. This study evaluated the usefulness of single-voxel spectroscopy (SVS) using small-sized voxels (0.125 cm3) by comparing it with multi-voxel spectroscopy (MVS). Both techniques were performed on the white matter and gray matter of the frontoparietal lobe, the caudate nucleus, and the thalamus in seven healthy beagle dogs using a 1.5T system. Brain metabolite concentrations and their ratios to creatine were compared. SVS had a significantly shorter mean acquisition time (4.79 ± 0.29 min) than MVS (11.64 ± 0.23 min). No significant differences were observed in metabolite concentrations or ratios between SVS and MVS following multiplicity correction, confirming no statistically significant discrepancies between the two protocols. No significant differences were found between the left and right hemispheres. While small-voxel SVS is technically feasible and reduces scan time, these findings represent protocol-specific descriptive data in a small sample of healthy dogs and do not establish clinical reference values or diagnostic accuracy.
Jong-Bong Lee, Gunha Hwang, Seokmin Lee et al.· Veterinary Sciences· 0 citations
This within-subject study compared non-contrast renal MRA (NC-MRA) at 1.5 T, 3 T and 5 T via comprehensive quantitative and subjective imaging assessments, and further explored imaging disparities between standard and high-resolution 5 T sequences.
Thirty-nine healthy volunteers underwent standardized same-day non-contrast MRA scans across the three magnetic field strengths; both standard and high-resolution protocols were implemented on the 5 T scanner. Quantitative parameters including apparent signal-to-noise ratio (aSNR), apparent contrast-to-noise ratio (aCNR) and vessel sharpness were calculated using the erector spinae muscle as the local noise reference, an approach intended to reduce g-factor related noise bias between different scanners. Two senior radiologists performed subjective image scoring independently as blinded readers. All images were fully anonymized by removing scanner and sequence identifiers, and the presentation order of image datasets was randomly rearranged for each reviewer to minimize potential reading bias.
Statistically significant inter-group differences were detected for all quantitative indicators (all
p
< 0.05). The 5 T standard protocol yielded the highest median aSNR and aCNR values, while the 5 T high-resolution sequence achieved optimal vessel sharpness and clearer visualization of distal subsegmental renal branches. Both 5 T protocols were superior to 1.5 T and 3 T sequences in terms of artifact suppression, vascular contour delineation and subjective diagnostic confidence.
The two tested 5 T NC-MRA protocols were associated with improved image-quality metrics and artifact scores in healthy volunteers. These findings provide quantitative baseline data for normal renal vasculature and support further clinical validation of NC-MRA protocols in patients with renal artery disease or contraindications to gadolinium-based contrast agents.
Anjie Xie, Min Li, Jia-Qi Wang et al.· BMC Medical Imaging· 0 citations
BACKGROUND
Conventional phased-array torso coils used for abdominal MRI are relatively heavy and inflexible, potentially affecting patient comfort and technologist workflow.
OBJECTIVE
To compare image quality, patient experience, and technologist experience using a recently United States Food and Drug Administration-cleared flexible, lightweight, blanket-like torso coil versus a conventional torso coil for pediatric abdominal MRI.
MATERIALS AND METHODS
In this prospective institutional review board-approved study, 20 pediatric patients (7 years-old to 18 years-old) undergoing routine clinical outpatient abdominal MRI were imaged on the same 1.5-T system using both a conventional torso coil and a flexible blanket-like torso coil (Smart Fit TorsoCardiac; Philips Healthcare). After standard clinical imaging, selected sequences were repeated following coil exchange. Five pediatric radiologists independently evaluated paired image sets for subjective signal-to-noise ratio (SNR) and coil-related artifacts. Objective image quality was assessed using organ- and tissue-based SNR estimates and contrast-to-noise ratio (CNR) measurements. Patients and MRI technologists completed questionnaires regarding comfort, usability, and examination experience.
RESULTS
All 20 patients (median age, 15 years; 55% female) underwent imaging with both coils. Radiologists rated the novel coil as similar to the conventional coil for subjective SNR across all three sequences under study; coil-related artifacts were uncommon (2% of assessments for all sequences evaluated). Objective analysis showed no significant image-based SNR differences for most sequences, although the flexible coil demonstrated higher liver SNR on axial diffusion-weighted imaging (adjusted P=0.01). CNR did not differ between coils. Patients reported greater comfort and less anxiety with the flexible coil; 55% preferred it for future MRI examinations versus 20% for the conventional coil. Technologists also favored the flexible coil, with 70% expressing an overall preference.
CONCLUSION
The flexible blanket-like torso coil provided image quality similar to a conventional coil and was generally preferred by patients and MRI technologists.
J. Dillman, Jean A. Tkach, R. P. Guillerman et al.· Pediatric Radiology· 0 citations