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Updated: Dec 15, 2025
Diffusion Imaging in the Rat Cervical Spinal Cord
Published on: April 7, 2015
Application of a stretched-exponential model for morphometric analysis of accelerated diffusion-weighted 129Xe MRI of
Alexei V Ouriadov1,2,3,4, Matthew S Fox5,6, Andras A Lindenmaier7,8
1Department of Physics and Astronomy, Western University, London, ON, Canada. aouriado@uwo.ca.
Objective:
Diffusion-weighted, hyperpolarized 129Xe MRI is useful for the characterization of microstructural changes in the lung. A stretched exponential model was proposed for morphometric extraction of the mean chord length (Lm) from diffusion-weighted data. The stretched exponential model enables accelerated mapping of Lm in a single-breathhold using compressed sensing. Our purpose was to compare Lm maps obtained from stretched-exponential model analysis of accelerated versus unaccelerated diffusion-weighted 129Xe MRI data obtained from healthy/injured rat lungs.
Material And Methods:
Lm maps were generated using a stretched-exponential model analysis of previously acquired fully sampled diffusion-weighted 129Xe rat data (b values = 0 … 110 s/cm2) and compared to Lm maps generated from retrospectively undersampled data simulating acceleration factors of 7/10. The data included four control rats and five rats receiving whole-lung irradiation to mimic radiation-induced lung injury. Mean Lm obtained from the accelerated/unaccelerated maps were compared to histological mean linear intercept.
Results:
Accelerated Lm estimates were similar to unaccelerated Lm estimates in all rats, and similar to those previously reported (< 12% different). Lm was significantly reduced (p < 0.001) in the irradiated rat cohort (90 ± 20 µm/90 ± 20 µm) compared to the control rats (110 ± 20 µm/100 ± 15 µm) and agreed well with histological mean linear intercept.
Discussion:
Accelerated mapping of Lm using a stretched-exponential model analysis is feasible, accurate and agrees with histological mean linear intercept. Acceleration reduces scan time, thus should be considered for the characterization of lung microstructural changes in humans where breath-hold duration is short.
Insights
Accelerated 129Xe MRI using a stretched exponential model accurately maps lung microstructure mean chord length (Lm). This method is feasible for characterizing lung changes, even in short human breath-holds.
Area of Science:
- Pulmonary imaging and diagnostics
- Advanced MRI techniques
- Quantitative lung morphometry
Background:
- Hyperpolarized 129Xe MRI enables detailed lung microstructural characterization.
- The stretched exponential model is used to extract mean chord length (Lm) from diffusion-weighted data.
- Accelerated imaging with compressed sensing can reduce scan times for Lm mapping.
Purpose of the Study:
- To compare Lm maps derived from accelerated versus unaccelerated diffusion-weighted 129Xe MRI.
- To validate the accuracy of accelerated Lm mapping against histological data.
- To assess the feasibility of accelerated Lm mapping in healthy and injured rat lungs.
Main Methods:
- 129Xe MRI data from healthy and irradiated rats were analyzed using a stretched exponential model.
- Lm maps were generated from both fully sampled and retrospectively undersampled (7/10 acceleration) data.
- Mean Lm values were compared between accelerated and unaccelerated maps and with histological mean linear intercept.
Main Results:
- Accelerated Lm estimates closely matched unaccelerated estimates (<12% difference).
- Significantly reduced Lm was observed in irradiated rats (90 ± 20 µm) compared to controls (110 ± 20 µm).
- Lm values from accelerated mapping showed good agreement with histological measurements.
Conclusions:
- Accelerated Lm mapping using the stretched exponential model is accurate and feasible.
- This technique effectively characterizes lung microstructural changes, including those induced by radiation injury.
- Reduced scan times make accelerated 129Xe MRI suitable for clinical applications, especially in patients with limited breath-hold capacity.
