Magnetic resonance imaging enhanced by superparamagnetic iron oxide particles: usefulness for distinguishing between focused ultrasound-induced blood-brain barrier disruption and brain hemorrhage.
OBJECTIVE
To investigate the usefulness of a fully flow-compensated heavy T2*-weighted imaging enhanced by superparamagnetic iron oxide (SPIO) particles for distinguishing between focused ultrasound-induced disruption of blood-brain barrier (BBB) and brain hemorrhage.


METHODS
Focused ultrasound (frequency: 1.5 MHz) was used to induce disruption of the BBB in 39 rats. Two T2*-weighted images were obtained before and after SPIO administration. Preenhanced T2*-weighted images were used to detect hemorrhage. Detection of BBB disruption was performed on SPIO-enhanced images. Thirty-four rats were sacrificed after magnetic resonance (MR) scanning for histological confirmation of brain lesions. The remaining five animals were followed up for 35 days. Prussian blue staining was performed on histological sections to detect SPIO particles in the brain.


RESULTS
After SPIO injection the areas of BBB disruption in rat brain were significantly enlarged. The area of mismatch between the T2*-weighted images indicated a safe region where BBB opening occurred without hemorrhagic complications. In the longitudinal study, removal of SPIO occurred at a faster rate in hemorrhagic areas, albeit being closer to that occurring in the liver. The presence of SPIO was confirmed by Prussian blue staining in brain parenchyma and capillary endothelial cells in areas of BBB disruption.


CONCLUSIONS
T2*-weighted images-either with and without SPIO enhancement-may differentiate focused ultrasound-induced BBB disruption from brain hemorrhage.
Liu
Hao-Li
HL
Department of Electrical Engineering, Chang-Gung University, Taiwan.
Hsu
Po-Hong
PH
Chu
Po-Chun
PC
Wai
Yau-Yau
YY
Chen
Jin-Chung
JC
Shen
Chia-Rui
CR
Yen
Tzu-Chen
TC
Wang
Jiun-Jie
JJ
D000818:Animals; D001812:Blood-Brain Barrier / Q000000981:diagnostic imaging / Q000473:pathology* / Q000528:radiation effects*; D002543:Cerebral Hemorrhage / Q000175:diagnosis*; D003287:Contrast Media; D005290:Ferric Compounds; D007089:Image Enhancement / Q000379:methods*; D008280:Magnetics; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013010:Sonication / Q000379:methods*; D014464:Ultrasonic Therapy / Q000379:methods*; D014463:Ultrasonography
D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide