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Updated: Jun 5, 2025
In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging
Published on: September 2, 2016
Investigation of diffusion time dependence of apparent diffusion coefficient and intravoxel incoherent motion
Julia Stabinska1,2, Thomas Andreas Thiel3, Helge Jörn Zöllner2
1F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
Purpose:
To characterize the diffusion time (Δeff) dependence of apparent diffusion coefficient (ADC) and intravoxel incoherent motion-related parameters in the human kidney at 3 T.
Methods:
Sixteen healthy volunteers underwent an MRI examination at 3 T including diffusion-weighted imaging at different Δeff ranging from 24.1 to 104.1 ms. The extended mono-exponential ADC and intravoxel incoherent motion models were fitted to the data for each Δeff and the medullary and cortical ADC, (pseudo-)diffusion coefficients (D* and D) and flow-related signal fraction (f) were calculated.
Results:
When all the data were used for fitting, a significant trend toward higher ADC with increasing Δeff was observed between 24.1 and 104.1 ms (median and interquartile range: 2.38 [2.19, 2.47] to 2.84 [2.36, 2.90] × 10-3 mm2/s for cortex, and 2.28 [2.18, 2.37] to 2.82 [2.58, 3.11] × 10-3 mm2/s for medulla). In contrast, no significant differences in ADC were found when only the data acquired at b-values higher than 200 s/mm2 were used for fitting. When the intravoxel incoherent motion model was applied, cortical and medullary f increased significantly (cortex: 0.21 [0.15 0.27] to 0.37 [0.32, 0.49] × 10-3 mm2/s; medulla: 0.15 [0.13 0.29] to 0.41 [0.36 0.51] × 10-3 mm2/s). No significant changes in cortical and medullary D and D* were observed as diffusion time increased.
Conclusion:
Renal perfusion and tubular flow substantially contribute to the observed increase in ADC over a wide range of Δeff between 24 and 104 ms.
Insights
Renal perfusion and tubular flow significantly increase apparent diffusion coefficient (ADC) in the human kidney with longer diffusion times (Δeff). This highlights the impact of blood and fluid flow on diffusion MRI measurements.
Area of Science:
- Magnetic Resonance Imaging
- Renal Physiology
- Diffusion Tensor Imaging
Background:
- Diffusion MRI is crucial for assessing tissue microstructure.
- Understanding the influence of physiological processes like perfusion on diffusion measurements is essential for accurate interpretation.
- Kidney diffusion MRI is sensitive to changes in water diffusion and microcirculation.
Purpose of the Study:
- To investigate the impact of varying diffusion times (Δeff) on apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) parameters in the healthy human kidney at 3T.
- To quantify the contribution of perfusion and tubular flow to ADC values in the renal cortex and medulla.
Main Methods:
- 16 healthy volunteers underwent 3T MRI with diffusion-weighted imaging at multiple Δeff (24.1–104.1 ms).
- Extended mono-exponential ADC and IVIM models were applied to analyze cortical and medullary data.
- Calculated parameters included ADC, pseudo-diffusion coefficient (D*), diffusion coefficient (D), and fractional flow (f).
Main Results:
- ADC significantly increased with longer Δeff (24.1–104.1 ms) in both cortex and medulla when all b-values were used.
- No significant ADC changes were observed when fitting data only from b-values > 200 s/mm².
- The fractional flow (f) significantly increased with longer Δeff in both regions, while D and D* remained unchanged.
Conclusions:
- Renal perfusion and tubular flow significantly contribute to the observed increase in ADC across a wide range of diffusion times (24–104 ms).
- These findings emphasize the importance of considering physiological flow effects in diffusion MRI of the kidney.
- The study provides insights into the microstructural and microcirculatory properties of the healthy kidney using advanced diffusion MRI techniques.
