Single breath-hold diffusion-weighted imaging of the abdomen

Area of Science:

• Magnetic Resonance Imaging
• Abdominal Imaging
• Diffusion-Weighted Imaging

Background:

• Diffusion-weighted imaging (DWI) is a powerful MRI technique for assessing tissue microstructure.
• Obtaining high-quality abdominal DWI with full organ coverage, especially for kidneys, in a single breath-hold remains a challenge.
• Accurate measurement of apparent diffusion coefficients (ADCs) is crucial for understanding renal physiology and pathology.

Purpose of the Study:

• To develop and validate a novel DWI technique for generating high-quality abdominal images and isotropic ADC maps.
• To achieve full organ coverage, including kidneys, within a single breath-hold period.
• To assess the feasibility of measuring anisotropic diffusion in renal tissues.

Main Methods:

• Employed an asymmetric, spin-echo, single-shot EPI readout with high-performance gradients.
• Acquired DWI and reference images in 12 healthy subjects, measuring signal-to-noise ratio (SNR) in liver, spleen, pancreas, and kidneys.
• Utilized single-axis diffusion encoding in orthogonal directions in six patients to evaluate renal anisotropic diffusion.

Main Results:

• The technique produced high-quality abdominal DWI and ADC maps with favorable resolution compared to previous methods.
• Achieved high SNR values, ranging from 27.0 (liver) to 44.1 (kidneys) for DWI.
• Demonstrated significantly different ADCs between renal medulla (2091 x 10⁻⁶ mm²/s) and cortex (2580 x 10⁻⁶ mm²/s) (P = 4.22 x 10⁻¹⁰), with moderate anisotropy in the renal medulla (AI = 0.129).

Conclusions:

• Single-shot SE EPI DWI enables high-quality abdominal imaging and ADC mapping with full organ coverage in a single breath-hold.
• Significant differences in ADCs between renal medulla and cortex were confirmed.
• Renal medulla exhibits moderate anisotropic diffusion, suggesting potential for advanced tissue characterization.