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Model‐free leakage index estimation of the blood‐brain barrier using dual dynamic susceptibility contrast MRI acquisition
Author(s) -
Jin Seokha,
Cho Hyung Joon
Publication year - 2021
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.4570
Subject(s) - evans blue , extravasation , blood–brain barrier , leakage (economics) , dynamic contrast enhanced mri , nuclear medicine , biomedical engineering , magnetic resonance imaging , chemistry , nuclear magnetic resonance , medicine , pathology , radiology , physics , central nervous system , economics , macroeconomics
Pharmacokinetic K 2 mapping from dynamic susceptibility contrast (DSC)‐MRI can be a sensitive technique for evaluating the vascular permeability of the subtly damaged blood‐brain barrier (BBB) in ischemic regions. However, the K 2 values of ischemic lesions depend upon the selection of the intact BBB reference region. As previous observations suggest that the Δ R 2 * curve of pre‐loaded DSC‐MRI is not significantly affected by the extravasation of contrast agent, dual DSC‐MRI acquisitions can be performed to derive the BBB leakage index from the voxel‐wise reference input function for ischemic regions. This study aims to demonstrate the robustness of such model‐free leakage index estimation in ischemic brains. By configuring the relationship between dual Δ R 2 * curves of the intact contralateral brain, the deviation of the measured Δ R 2 * curve from the unloaded DSC‐MRI with respect to the non‐deviated Δ R 2 * curve in the pre‐loaded DSC‐MRI can be quantified as the BBB leakage index. Such model‐free leakage index values from rats with transient middle carotid artery occlusion (tMCAO) ( n = 17) and normal controls ( n = 3) were evaluated and compared with conventional K 2 values with multiple reference regions. Inter‐subject leakage index values were also compared with the corresponding Δ T 1 map. Evans‐blue‐stained images were used to validate the leakage index. For the tMCAO group, leakage index values correlated well with Δ T 1 (Pearson's r = 0.828). The hyperintense area on the leakage index map matched well with the corresponding Evans‐blue‐stained area (Dice correlation = 0.626). The slopes of the scatter‐plot from the leakage index (0.97‐1.00) were observed to be more robust against changes in the reference region than those from conventional K 2 values (0.94‐1.07). In a subtly damaged BBB tMCAO model, model‐free evaluation of vascular permeability using dual DSC‐MRIs would provide a consistent measure of inter‐subject vascular permeability.