Comparison of readout-segmented and conventional single-shot for echo-planar diffusion-weighted imaging in the assessment of kidney interstitial fibrosis.

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 mm ³ , 10 b-values). The cortico-medullary difference for each DW parameter from a monoexponential fit (ΔADC) or, segmented biexponential fit (ΔD, ΔD*, ΔF _p ) 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 R ² 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 R ² comparison) with fibrosis than ss-EPI ΔADC (RESOLVE R ²  = 0.65, P = 5.9 × 10 ^-9 , ss-EPI R ²  = 0.29, P = 8.9 × 10 ^-4 ). ΔD (RESOLVE) was correlated (moderately) with fibrosis (R ²  = 0.29, P = 9.2 × 10 ^-4 ); however, ΔD* and ΔF _p did not show, in our population, a significant correlation with interstitial fibrosis (0.01 < R ² < 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.
Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1631-1640.
(© 2017 International Society for Magnetic Resonance in Medicine.)