Related Experiment Video
Updated: May 15, 2026
Magnetic Resonance Imaging Quantification of Pulmonary Perfusion using Calibrated Arterial Spin Labeling
Published on: May 30, 2011
Reliable assessment of perfusivity and diffusivity from diffusion imaging of the body
M Freiman1, S D Voss, R V Mulkern
1Computational Radiology Laboratory, Boston Children's Hospital, Harvard Medical School, MA, USA.
Abstract:
Diffusion-weighted MRI of the body has the potential to provide important new insights into physiological and microstructural properties. The intra-voxel incoherent motion (IVIM) model relates the observed DW-MRI signal decay to parameters that reflect perfusivity (D*) and its volume fraction (f), and diffusivity (D). However, the commonly used voxel-wise fitting of the IVIM model leads to parameter estimates with poor precision, which has hampered their practical usage. In this work, we increase the estimates' precision by introducing a model of spatial homogeneity, through which we obtain estimates of model parameters for all of the voxels at once, instead of solving for each voxel independently. Furthermore, we introduce an efficient iterative solver which utilizes a model-based bootstrap estimate of the distribution of residuals and a binary graph cut to generate optimal model parameter updates. Simulation experiments show that our approach reduces the relative root mean square error of the estimated parameters by 80% for the D* parameter and by 50% for the f and D parameters. We demonstrated the clinical impact of our model in distinguishing between enhancing and nonenhancing ileum segments in 24 Crohn's disease patients. Our model detected the enhanced segments with 91%/92% sensitivity/specificity which is better than the 81%/85% obtained by the voxel-independent approach.
Insights
This study introduces a new spatial homogeneity model to improve precision in diffusion-weighted MRI (DW-MRI) analysis. The enhanced intra-voxel incoherent motion (IVIM) model significantly boosts parameter accuracy for physiological insights.
Area of Science:
- Medical Imaging
- Biophysics
- Radiology
Background:
- Diffusion-weighted MRI (DW-MRI) offers insights into physiological and microstructural properties.
- The intra-voxel incoherent motion (IVIM) model quantifies perfusivity (D*), its volume fraction (f), and diffusivity (D).
- Voxel-wise IVIM fitting yields imprecise parameters, limiting clinical application.
Purpose of the Study:
- To enhance the precision of IVIM model parameter estimation in DW-MRI.
- To develop an efficient iterative solver for improved parameter accuracy.
- To validate the clinical utility of the enhanced IVIM model.
Main Methods:
- Introduced a spatial homogeneity model for simultaneous voxel parameter estimation.
- Developed an iterative solver using bootstrap residuals and binary graph cut for parameter updates.
- Evaluated performance through simulation experiments and clinical application in Crohn's disease patients.
Main Results:
- Reduced relative root mean square error by 80% for D* and 50% for f and D parameters in simulations.
- Achieved 91% sensitivity and 92% specificity in distinguishing ileum segments in Crohn's disease patients.
- Outperformed the voxel-independent approach (81%/85% sensitivity/specificity).
Conclusions:
- The proposed spatial homogeneity model significantly improves IVIM parameter precision.
- This enhanced IVIM analysis offers superior diagnostic performance for conditions like Crohn's disease.
- The method holds promise for advancing DW-MRI applications in clinical practice.
Related Concept Videos
01:17Assessment of Diffusion and Perfusion
The Role of Diffusion in Respiration
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. In the respiratory system, this principle...
01:24Magnetic Resonance Imaging
01:09Methods for Studying Drug Absorption: In situ
The Doluisio method involves perfusing a prepared segment of a rat's small intestine with a solution of radiolabeled drug and a non-absorbable marker. This helps to differentiate between absorbed and non-absorbed drug concentrations. The intestinal segment is connected at both ends using tubing and syringes,...