Hemorrhage detection during focused-ultrasound induced blood-brain-barrier opening by using susceptibility-weighted magnetic resonance imaging.
High-intensity focused ultrasound has been discovered to be able to locally and reversibly increase the permeability of the blood-brain barrier (BBB), which can be detected using magnetic resonance imaging (MRI). However, side effects such as microhemorrhage, erythrocyte extravasations or even extensive hemorrhage may also occur. Although current contrast-enhanced T1-weighted MRI can be used to detect the changes in BBB permeability, its efficacy in detecting tissue hemorrhage after focused-ultrasound sonication remains limited. The purpose of this study is to investigate the feasibility of magnetic resonance susceptibility-weighted imaging (MR-SWI) for identifying possible tissue hemorrhage associated with disruption of the BBB induced by focused ultrasound in a rat model. The brains of 42 Sprague-Dawley rats were subjected to 107 sonications, either unilaterally or bilaterally. Localized BBB opening was achieved by delivering burst-mode focused ultrasound energy into brain tissue in the presence of microbubbles. Rats were studied by T2-weighted and contrast-enhanced T1-weighted MRI techniques, as well as by SWI. Tissue changes were analyzed histologically and the extent of apoptosis was investigated with the terminal deoxynucleotidyl transferase biotin-dUTP nick-end labeling method. The results demonstrated that SWI is more sensitive than standard T2-weighted and contrast-enhanced T1-weighted MRI techniques in detecting hemorrhages after brain sonication. Longitudinal study showed that SWI is sensitive to the recovery process of the damage and, therefore, could provide important and complementary information to the conventional MR images. Potential applications such as drug delivery in the brain might be benefited.
Liu
Hao-Li
HL
Department of Electrical Engineering, Chang-Gung University, Linkou, Taiwan.
Wai
Yau-Yau
YY
Chen
Wen-Shiang
WS
Chen
Jin-Chung
JC
Hsu
Po-Hong
PH
Wu
Xin-Yu
XY
Huang
Wen-Cheng
WC
Yen
Tzu-Chen
TC
Wang
Jiun-Jie
JJ
D000818:Animals; D001812:Blood-Brain Barrier / Q000293:injuries / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000175:diagnosis* / Q000209:etiology; D003287:Contrast Media; D004195:Disease Models, Animal; D005240:Feasibility Studies; D019786:Gadolinium DTPA; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012720:Severity of Illness Index; D014464:Ultrasonic Therapy / Q000009:adverse effects* / Q000379:methods
D003287:Contrast Media; D019786:Gadolinium DTPA