Assessing 3DQLayers for Quantitative Cortico-Medullary Gradient Measurements using Ex-Vivo Renal Tissue

Motivation: Renal function is driven by cortico-medullary gradients in physiology. Tools to quantitatively study MRI measures of such biological gradients across the whole kidney are highly desirable. Goal(s): To assess/validate cortical-medullary gradient measurements using high-resolution quantitative-MRI (qMRI) of ex-vivo transplant kidneys. Approach: To use '3DQLayers' to segment the kidney into 3D depth-based layers from the renal surface to study the cortico-medullary gradients in qMRI measures. To compare on ex-vivo renal tissue the result of 3DQLayers to standard tissue region-of-interest (ROI) analysis which excludes biological information. Results: Quantitative cortico-medullary gradients were measured in T1, T2, T2*, ADC and MTR maps. Renal cortex thickness was measured. Impact: This work demonstrates the application of '3DQLayers', software to study depth-dependent renal cortico-medullary gradients in quantitative MRI measures. 3DQLayers is demonstrated in high resolution ex-vivo tissue and shown to provide improvements over traditional region-of-interest based analysis methods.