Spatial profiling of in vivo diffusion-weighted MRI parameters in the healthy human kidney

• Published in: Magma (New York, N.Y.) Vol. 37; no. 4; pp. 671 - 680
• Main Authors: Gilani, Nima, Mikheev, Artem, Brinkmann, Inge M., Kumbella, Malika, Babb, James S., Basukala, Dibash, Wetscherek, Andreas, Benkert, Thomas, Chandarana, Hersh, Sigmund, Eric E.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.08.2024
• Subjects: Adult; Algorithms; Anisotropy; Basic Science - Diffusion; Biomedical Engineering and Bioengineering; Computer Appl. in Life Sciences; Diffusion Magnetic Resonance Imaging - methods; Diffusion Tensor Imaging - methods; Female; Health Informatics; Healthy Volunteers; Humans; Image Processing, Computer-Assisted - methods; Imaging; Kidney - diagnostic imaging; Kidney Medulla - diagnostic imaging; Male; Medicine; Medicine & Public Health; Microcirculation; Middle Aged; Motion; Radiology; Research Article; Solid State Physics; Young Adult; DTI; Microvasculature; IVIM; Microstructure; MRI; Renal imaging
• ISSN: 1352-8661; 0968-5243; 1352-8661
• DOI: 10.1007/s10334-024-01159-6

Objective Diffusion-weighted MRI is a technique that can infer microstructural and microcirculatory features from biological tissue, with particular application to renal tissue. There is extensive literature on diffusion tensor imaging (DTI) of anisotropy in the renal medulla, intravoxel incoherent motion (IVIM) measurements separating microstructural from microcirculation effects, and combinations of the two. However, interpretation of these features and adaptation of more specific models remains an ongoing challenge. One input to this process is a whole organ distillation of corticomedullary contrast of diffusion metrics, as has been explored for other renal biomarkers. Materials and methods In this work, we probe the spatial dependence of diffusion MRI metrics with concentrically layered segmentation in 11 healthy kidneys at 3 T. The metrics include those from DTI, IVIM, a combined approach titled “REnal Flow and Microstructure AnisotroPy (REFMAP)”, and a multiply encoded model titled “FC-IVIM” providing estimates of fluid velocity and branching length. Results Fractional anisotropy decreased from the inner kidney to the outer kidney with the strongest layer correlation in both parenchyma (including cortex and medulla) and medulla with Spearman correlation coefficients and p -values ( r , p ) of (0.42, <0.001) and (0.37, <0.001), respectively. Also, dynamic parameters derived from the three models significantly decreased with a high correlation from the inner to the outer parenchyma or medulla with ( r , p ) ranges of (0.46–0.55, <0.001). Conclusions These spatial trends might find implications for indirect assessments of kidney physiology and microstructure using diffusion MRI.