AUTHORS: Friedli I, Crowe LA, de Perrot T, Berchtold L, Martin P-Y, de Seigneux S, Vallée J

Journal of Magnetic Resonance Imaging, 46(6): 1631-1640, December 2017

ABSTRACT

Purpose: 

To compare readout-segmented echo-planar imaging (EPI) (RESOLVE) to single-shot EPI (ss-EPI) diffusion-weighted imaging (DWI) for the assessment of renal interstitial fibrosis.

Materials and methods: 

A phantom, eight healthy volunteers (under 30 years to avoid age-fibrosis related) and 27 chronic kidney disease (CKD) patients (scheduled for kidney biopsy) were scanned (at 3T) with ss-EPI and 5-shot RESOLVE DWI (resolution: 2 × 2 × 5 mm3 , 10 b-values). The cortico-medullary difference for each DW parameter from a monoexponential fit (ΔADC) or, segmented biexponential fit (ΔD, ΔD*, ΔFp ) were compared between both sequences. A fibrosis threshold of 40% was defined to separate all 35 subjects into low and high fibrosis groups. The linear relationship between DW parameters and percentage fibrosis (up to 80%) from Masson trichrome was assessed with the Pearson product-moment correlation coefficient. Fisher Z-transform was used for R2 correlation comparison.

Results: 

A coefficient of variation between ADCs of 3% was measured between both sequences in the phantom. In healthy volunteers, no significant difference was measured for all DW parameters. Both sequences separated low to high level of fibrosis with a significant decrease of ΔADC (RESOLVE P = 3.1 × 10-6 , ss-EPI P = 0.003) and ΔD (RESOLVE P = 8.2 × 10-5 , ss-EPI P = 0.02) in the high level of fibrosis. However, RESOLVE ΔADC had a stronger negative correlation (P = 0.04 for R2 comparison) with fibrosis than ss-EPI ΔADC (RESOLVE R2 = 0.65, P = 5.9 × 10-9 , ss-EPI R2 = 0.29, P = 8.9 × 10-4 ). ΔD (RESOLVE) was correlated (moderately) with fibrosis (R2 = 0.29, P = 9.2 × 10-4 ); however, ΔD* and ΔFp did not show, in our population, a significant correlation with interstitial fibrosis (0.01 < R2 < 0.08).

Conclusion: 

ΔADC derived from both sequences correlated with fibrosis. ΔADC from RESOLVE showed better correlation with fibrosis than ΔADC from ss-EPI and therefore has potential to monitor CKD.

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