Amide Proton Transfer MRI Could Be Used to Evaluate the Pathophysiological Status of White Matter Hyperintensities

Abstract

Background: The pathophysiology of white matter hyperintensities (WMH) remains unclear, investigations of amide proton transfer (APT) signals in WMH disease may provide relevant pathophysiological information.

Purpose: To evaluate the APT signals differences and heterogeneity of WMH and adjacent normal-appearing white matter (NAWM) at different Fazekas grades and different locations.

Study type: Prospective.

Population: In all, 180 WMH patients (age, 40-76; male/female, 77/103) and 59 healthy controls (age, 42-70; male/female, 23/36).

Field strength/sequence: A 3 T; 3D fluid-attenuated inversion recovery (FLAIR), 3D APT-weighted (APTw).

Assessment: The mean APTw values (APTw_mean ) and the APTw signals heterogeneity (APTw_max-min ) among different grades WMH and NAWM and the APTw_mean of the same grade deep WMH (DWMH) and paraventricular WMH (PWMH) were calculated and compared. Regions of interests were delineated on WMH lesions, NAWM and healthy white matter.

Statistical tests: One-way analysis of variance (ANOVA); independent sample t test; Chi-square test. Significance level: P < 0.05.

Results: APTw_mean among different grade WMH (from grade 0 to 3, 0.58 ± 0.14% vs. 0.29 ± 0.23% vs. 0.37 ± 0.24% vs. 0.61 ± 0.22%, respectively) were significantly different except between grade 1 and 2 (P = 0.27) and between grade 0 and 3 (P = 0.97). The differences in APTw_mean between WMH and NAWM were significant (WMH vs. NAWM from grade 1 to 3, 0.29% ± 0.23% vs. 0.55% ± 0.27%; 0.37% ± 0.24% vs. 0.59% ± 0.22%; 0.61% ± 0.22% vs. 0.42% ± 0.24%, respectively). Lower APTw_mean values were found only in grade 3 NAWM than other grades NAWM and controls. The APTw_max-min values of grade 1-3 WMH (0.38% ± 0.27% vs. 0.51% ± 0.31% vs. 0.67% ± 0.34%, respectively) were significantly different. Higher APT_mean values were found only in grade 2 PWMH (0.47% ± 0.22% vs. 0.32% ± 0.24%).

Data conclusion: Significant differences of APT signals were found in WMH of different Fazekas grades and different locations.

Evidence level: 2 TECHNICAL EFFICACY: Stage 3.

Keywords: Fazekas scale; amide proton transfer; cerebral small vessel disease; normal-appearing white matter; white matter hyperintensities; white matter hyperintensity penumbra.