# Overcoming Low‐Field Limitations: High‐Quality Ex Vivo Soft Tissue Imaging with Compact MRI Systems

## TL;DR

Researchers developed a protocol to improve soft tissue imaging quality using low-field MRI systems, making high-quality imaging more accessible and affordable.

## Contribution

A practical framework for optimizing low-field MRI systems to achieve high-quality ex vivo soft tissue imaging.

## Key findings

- Optimized imaging protocols significantly enhance SNR and tissue contrast in low-field MRI.
- Standardized sample preparation with Gd-DTPA and Fluorinert or agarose improves imaging outcomes.
- The 3D-GRE sequence with adjusted parameters enables high-resolution imaging in 13 hours.

## Abstract

High‐field magnetic resonance imaging (MRI) scanners have been the primary choice for high‐quality soft tissue imaging, but use remains limited by high costs, complex siting requirements, and infrastructure demands. In contrast, preclinical MRI scanners with a low‐field permanent magnet are increasingly being adopted in research due to their lower cost, portability, and ease of installation. However, their reduced intrinsic signal‐to‐noise ratio (SNR) and limited pulse sequence availability constrain their use for high‐quality ex vivo soft tissue characterization. To overcome these limitations, we established an optimized imaging protocol using a compact 1‐Tesla permanent‐magnet preclinical MRI system for high‐quality ex vivo soft tissue imaging. A 25‐mm (length) × 23‐mm (diameter) coil was employed to image both human and animal soft tissue samples. Protocol optimization focused on four key parameters, namely the number of excitations (NEX), repetition time (TR), echo time (TE), and slice thickness, using a 3D gradient‐echo (3D‐GRE) acquisition sequence. Increasing the NEX enhances the SNR through signal averaging, extending the TR further improves the SNR, reducing the TE provides improved tissue contrast, and thinner slices improve image resolution. A typical 3D‐GRE MRI scan using the imaging protocol takes 13 hr. The approach also incorporates standardized ex vivo sample preparation, including staining with gadolinium diethylenetriaminepentaacetic acid to enhance tissue contrast, and background proton signal suppression and sample immobilization with Fluorinert or agarose. Collectively, these optimizations substantially improve the performance of low‐field permanent‐magnet MRI scanners for high‐quality soft tissue imaging. This set of protocols provides a practical framework for researchers to expand the capabilities of low‐field MRI systems, enabling more widespread access to advanced tissue characterization methods that support disease research and therapeutic development. © 2026 The Author(s). Current Protocols published by Wiley Periodicals LLC.

Basic Protocol 1: Tissue sample preparation with Gd‐DTPA and Fluorinert

Alternate Protocol: Tissue sample preparation with Gd‐DTPA and agarose

Basic Protocol 2: High‐quality sample imaging with 1‐Tesla compact MRI