PT  - JOURNAL ARTICLE
AU  - R. Blankena
AU  - R. Kleinloog
AU  - B.H. Verweij
AU  - P. van Ooij
AU  - B. ten Haken
AU  - P.R. Luijten
AU  - G.J.E. Rinkel
AU  - J.J.M. Zwanenburg
TI  - Thinner Regions of Intracranial Aneurysm Wall Correlate with Regions of Higher Wall Shear Stress: A 7T MRI Study
AID  - 10.3174/ajnr.A4734
DP  - 2016 Jul 01
TA  - American Journal of Neuroradiology
PG  - 1310--1317
VI  - 37
IP  - 7
4099  - http://www.ajnr.org/content/37/7/1310.short
4100  - http://www.ajnr.org/content/37/7/1310.full
SO  - Am. J. Neuroradiol.2016 Jul 01; 37
AB  - BACKGROUND AND PURPOSE: Both hemodynamics and aneurysm wall thickness are important parameters in aneurysm pathophysiology. Our aim was to develop a method for semi-quantitative wall thickness assessment on in vivo 7T MR images of intracranial aneurysms for studying the relation between apparent aneurysm wall thickness and wall shear stress.MATERIALS AND METHODS: Wall thickness was analyzed in 11 unruptured aneurysms in 9 patients who underwent 7T MR imaging with a TSE-based vessel wall sequence (0.8-mm isotropic resolution). A custom analysis program determined the in vivo aneurysm wall intensities, which were normalized to the signal of nearby brain tissue and were used as measures of apparent wall thickness. Spatial wall thickness variation was determined as the interquartile range in apparent wall thickness (the middle 50% of the apparent wall thickness range). Wall shear stress was determined by using phase-contrast MR imaging (0.5-mm isotropic resolution). We performed visual and statistical comparisons (Pearson correlation) to study the relation between wall thickness and wall shear stress.RESULTS: 3D colored apparent wall thickness maps of the aneurysms showed spatial apparent wall thickness variation, which ranged from 0.07 to 0.53, with a mean variation of 0.22 (a variation of 1.0 roughly means a wall thickness variation of 1 voxel [0.8 mm]). In all aneurysms, apparent wall thickness was inversely related to wall shear stress (mean correlation coefficient, −0.35; P < .05).CONCLUSIONS: A method was developed to measure the wall thickness semi-quantitatively, by using 7T MR imaging. An inverse correlation between wall shear stress and apparent wall thickness was determined. In future studies, this noninvasive method can be used to assess spatial wall thickness variation in relation to pathophysiologic processes such as aneurysm growth and rupture.AWTapparent wall thicknessMPIR-TSEmagnetization-prepared inversion-recovery turbo spin-echoPC/magphase-contrast MR magnitude imagesPCMRphase-contrast MR imagingWSSwall shear stress