Diffusion-weighted Renal MRI at 9.4\u2009Tesla Using RARE to Improve Anatomical Integrity

Joāo Dos Santos Periquito,Kathleen Cantow,Katharina Paul,Thoralf Niendorf,Erdmann Seeliger,Thomas Gladytz,Yiyi Ji,Bert Flemming,Dirk Grosenick,Till Huelnhagen,Sonia Waiczies,Min-Chi Ku,Andreas Pohlmann

doi:10.1038/s41598-019-56184-6

Abstract

Diffusion-weighted magnetic resonance imaging (DWI) is a non-invasive imaging technique sensitive to tissue water movement. By enabling a discrimination between tissue properties without the need of contrast agent administration, DWI is invaluable for probing tissue microstructure in kidney diseases. DWI studies commonly make use of single-shot Echo-Planar Imaging (ss-EPI) techniques that are prone to suffering from geometric distortion. The goal of the present study was to develop a robust DWI technique tailored for preclinical magnetic resonance imaging (MRI) studies that is free of distortion and sensitive to detect microstructural changes. Since fast spin-echo imaging techniques are less susceptible to B0 inhomogeneity related image distortions, we introduced a diffusion sensitization to a split-echo Rapid Acquisition with Relaxation Enhancement (RARE) technique for high field preclinical DWI at 9.4 T. Validation studies in standard liquids provided diffusion coefficients consistent with reported values from the literature. Split-echo RARE outperformed conventional ss-EPI, with ss-EPI showing a 3.5-times larger border displacement (2.60 vs. 0.75) and a 60% higher intra-subject variability (cortex = 74%, outer medulla = 62% and inner medulla = 44%). The anatomical integrity provided by the split-echo RARE DWI technique is an essential component of parametric imaging on the way towards robust renal tissue characterization, especially during kidney disease.

Highlights

Diffusion-weighted magnetic resonance imaging (DWI) is a non-invasive imaging technique sensitive to tissue water movement
We acquired experimental data to validate that the diffusion parameters measured with the DW Split-echo Rapid Acquisition with Relaxation Enhancement (RARE) are correct, to assess the geometric fidelity of the images, and to detail the diffusion parameters obtained in healthy rat kidneys
In this work we demonstrate the feasibility of DW Split-echo RARE for renal diffusion weighted imaging (DWI) in small rodents at 9.4 T

Summary

Introduction

Diffusion-weighted magnetic resonance imaging (DWI) is a non-invasive imaging technique sensitive to tissue water movement. To facilitate the standardization and validation of renal DWI, consensus-based technical recommendations are currently being developed by an international, multidisciplinary group of renal imaging researchers as part of the European Cooperation in Science and Technology (COST) action ‘PARENCHIMA’ (www.renalmri.org) This is motivated by the relevance of renal DWI having been demonstrated in numerous preclinical and clinical studies with applications such as AKI13, characterization of renal masses[14], tumors[15,16,17,18], lesions[19,20] and cysts[21], as www.nature.com/scientificreports well as the assessment of renal fibrosis[22,23,24,25], allograft pathophysiology[26,27], diabetic nephropathy[28], and functional changes in AKI and CKD29,30. Semi-automated ROI analysis techniques, such as concentric object analysis[32,33] or the morphology-based ROI-placement[34,35] can be severely compromised by geometric distortions

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