Biophysical Diffusion MRI Models Better Identify White Matter Tracts in Edema
by
, , , , , ,
Isaac E. Prentiss
1,†
,
Sasha Hakhu
1,†,
Jennapher Lingo VanGilder
1,
Parvathy Hareesh
1,
Andrew Hooyman
1,
Jason Yalim
2,
Justin Hines
3,
Gabe LaFond
3,
Edward Ofori
4,
Leslie C. Baxter
5
,
Yuxiang Zhou
3, 
Leland S. Hu
3,
Kurt G. Schilling
6 and
Scott C. Beeman
1,7,* 1
School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85287, USA
2
Research Computing, Arizona State University, Tempe, AZ 85287, USA
3
Department of Radiology, Mayo Clinic, Phoenix, AZ 85054, USA
4
College of Health Solutions, Arizona State University, Tempe, AZ 85287, USA
5
Department of Psychiatry and Psychology, Mayo Clinic, Phoenix, AZ 85054, USA
6
Department of Radiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
7
John Shufeldt School of Medicine and Medical Engineering, Arizona State University, Tempe, AZ 85287, USA
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Tomography 2026, 12(6), 78; https://doi.org/10.3390/tomography12060078
Submission received: 14 February 2026
/
Revised: 11 May 2026
/
Accepted: 19 May 2026
/
Published: 25 May 2026
(This article belongs to the Special Issue Imaging in Cancer Diagnosis)
Simple Summary
Brain tumors often cause nearby tissue to swell, and this swelling can hide the appearance of the bundles of nerve fibers, called white matter, that carry signals between different regions of the brain on standard MRI brain imaging. This makes it difficult for surgeons to know exactly where these fibers are when planning surgery. In this study, we tested whether more advanced diffusion MRI methods, which account for the way in which water moves around in different microscopic parts of the brain, could better identify white matter through the swelling. In five patients with benign meningioma tumors, the advanced methods better traced white matter pathways than standard methods. These findings suggest that newer diffusion MRI approaches may improve preoperative planning for brain surgery in regions affected by swelling.
Abstract
Background/Objectives: White matter (WM) tract detection is critical in the presurgical planning of tumor resection. However, standard-of-care imaging techniques including T1-weighted, T2-weighted, and Diffusion Tensor Imaging (DTI) often fail to identify WM tracts within edematous regions. In T1/T2-weighted imaging, edema increases extracellular water and reduces tissue contrast, and in diffusion-weighted imaging, edema elevates isotropic diffusion, reducing sensitivity to anisotropic diffusion along WM tracts. Advanced biophysical diffusion modeling techniques such as Neurite Orientation Dispersion and Density Imaging (NODDI) and the Standard Model (SM) address this limitation by compartmentalizing the diffusion signal into free-water, intra-neurite, and extra-neurite contributions. Here, we test if biophysical multi-compartment models can robustly identify WM tracts and recover tractography streamlines within edematous regions. Methods: In this study, we use multi-shell diffusion-weighted MRI data obtained from patients with meningiomas—a pathology allowing for isolation of the effects of edema without the confounding effects of tumor cell invasion. We compared FA from standard and free-water-corrected DTI, the orientation dispersion index (ODI) from NODDI, and P2 (a scalar descriptor of fiber orientation coherence) from the SM fODF in edematous and unaffected contralateral WM regions. As a proof of concept, we visually evaluated the tractography performance across models. Results: Our results show that (1 − ODI) and P2 values in edema remained close to within-subject contralateral measurements, contrasting with substantial reductions in FA and FW-FA. (1 − ODI) showed a small but statistically significant increase in edema (~8%, p = 0.02), while P2 was unchanged. Conclusions: These results highlight the potential of biophysical diffusion models for preoperative mapping in edema.
Keywords:
NODDI; SM; DTI; edema; diffusion MRI; white matter; tractography
