Pulse sequence and timing of contrast-enhanced MRI for assessing blood-brain barrier disruption after transcranial focused ultrasound in the presence of hemorrhage.
OBJECTIVE
To optimize the timing of contrast-enhanced magnetic resonance imaging (MRI) that best indicates blood-brain barrier (BBB) disruption induced by focused ultrasound (FUS) along with an ultrasound contrast agent (UCA) and to verify that the contrast-enhanced spin-echo MRI sequence can indicate the degree and location of BBB disruption in the presence of hemorrhage better than a gradient-echo sequence.


METHODS
Sonication was applied to 12 rat brains with four different doses of UCA to cause variable degrees of hemorrhage. Two imaging sequences were performed to acquire T1-weighted (T1W) images at two time-points after the administration of a T1-shortening contrast agent. The contrast enhancement at the sonicated regions was quantified and correlated against Evans blue (EB) staining.


RESULTS
The spin-echo T1W images at 10 minutes post-contrast enhancement showed the best correlation with EB staining in both quantity of EB extravasation (r = 0.812; P < 0.01) and spatial distribution (r = 0.528, P < 0.01). This capability was more robust than the gradient-echo sequence.


CONCLUSIONS
Our results suggest that contrast-enhanced T1W spin-echo sequence acquired in the early phase post-contrast enhancement should be considered to monitor the degree and location of BBB disruption under the possibility of hemorrhage induced by FUS.
Center for Optoelectronic Biomedicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
Jun-Cheng
JC
Weng
Sheng-Kai
SK
Wu
Feng-Yi
FY
Yang
Win-Li
WL
Lin
Wen-Yih Isaac
WY
Tseng
D000818:Animals; D001812:Blood-Brain Barrier / Q000473:pathology*; D001921:Brain / Q000473:pathology; D003287:Contrast Media / Q000494:pharmacology; D005070:Evans Blue / Q000494:pharmacology; D006470:Hemorrhage / Q000473:pathology*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013010:Sonication; D013997:Time Factors; D014463:Ultrasonography / Q000379:methods
D003287:Contrast Media; D005070:Evans Blue