The Consistence of Dynamic Contrast-Enhanced MRI and Filter-Exchange Imaging in Measuring Water Exchange Across the Blood-Brain Barrier in High-Grade Glioma

Abstract

Background: Water exchange across blood-brain barrier (BBB) (WEX_BBB ) is an emerging biomarker of BBB dysfunction with potential applications in many brain diseases. Several MRI methods have been proposed to measure WEX_BBB , but evidence remains scarce whether different methods can produce comparable WEX_BBB .

Purpose: To explore whether dynamic contrast-enhanced (DCE)-MRI and vascular water exchange imaging (VEXI) could produce comparable WEX_BBB in high-grade glioma (HGG) patients.

Study type: Prospective cross-sectional.

Subjects: 13 HGG patients (58.4 ± 9.4 years, 9 females, 4 WHO III and 9 WHO IV).

Field strength/sequence: A 3 T, spoiled gradient-recalled-echo DCE-MRI and VEXI containing two pulsed-gradient spin-echo blocks separated by a mixing block.

Assessments: The enhanced tumor and contralateral normal-appearing white matter (cNAWM) volume-of-interests (VOIs) were drew by two neuroradiologists. And whole-brain NAWM and normal-appearing gray matter (NAGM) without tumor-affected regions were segmented by automated segmentation algorithm in FSL.

Statistical tests: Student's t-test was used to evaluate parameters difference between cNAWM and tumor, NAGM and NAWM, respectively. The correlation between vascular water efflux rate constant (k_bo ) from DCE-MRI and apparent exchange rate across BBB (AXR_BBB ) from VEXI was evaluated by Pearson correlation. P < 0.05 was considered statistically significant.

Results: Compared with cNAWM, both k_bo and AXR_BBB were significantly reduced in tumor (k_bo = 3.50 ± 1.18 sec^-1 vs. 1.03 ± 0.75 sec^-1 ; AXR_BBB = 3.54 ± 1.11 sec^-1 vs. 1.94 ± 1.04 sec^-1 ). Both k_bo and AXR_BBB showed significantly higher values in NAWM than NAGM (k_bo = 3.50 ± 0.59 sec^-1 vs. 2.10 ± 0.56 sec^-1 ; AXR_BBB = 3.35 ± 0.77 sec^-1 vs. 2.07 ± 0.52 sec^-1 ). The VOI-averaged k_bo and AXR_BBB were also linearly correlated in tumor, NAWM, and NAGM (r = 0.59).

Data conclusion: DCE-MRI and VEXI showed comparable and correlated WEX_BBB in HGG patients, suggesting that the consistence and reliability of these two MRI methods in measuring WEX_BBB .

Evidence level: 2.

Technical efficacy: Stage 1.

Keywords: blood-brain barrier; brain; dynamic contrast-enhanced magnetic resonance imaging (MRI); high-grade glioma; vascular water-exchange imaging; water exchange.