Neuronavigation-guided focused ultrasound-induced blood-brain barrier opening: a preliminary study in swine.
OBJECTIVE
FUS-induced BBB opening is a promising technique for noninvasive and local delivery of drugs into the brain. Here we propose the novel use of a neuronavigation system to guide the FUS-induced BBB opening procedure and investigate its feasibility in vivo in large animals.


METHODS
We developed an interface between the neuronavigator and FUS to allow guidance of the focal energy produced by the FUS transducer. The system was tested in 29 swine by more than 40 sonication procedures and evaluated by MR imaging. Gd-DTPA concentration was quantitated in vivo by MR imaging R1 relaxometry and compared with ICP-OES assay. Brain histology after FUS exposure was investigated using H&E and TUNEL staining.


RESULTS
Neuronavigation could successfully guide the focal beam, with precision comparable to neurosurgical stereotactic procedures (2.3 ± 0.9 mm). A FUS pressure of 0.43 MPa resulted in consistent BBB opening. Neuronavigation-guided BBB opening increased Gd-DTPA deposition by up to 1.83 mmol/L (a 140% increase). MR relaxometry demonstrated high correlation with ICP-OES measurements (r(2) = 0.822), suggesting that Gd-DTPA deposition can be directly measured by imaging.


CONCLUSIONS
Neuronavigation provides sufficient precision for guiding FUS to temporally and locally open the BBB. Gd-DTPA deposition in the brain can be quantified by MR relaxometry, providing a potential tool for the in vivo quantification of therapeutic agents in CNS disease treatment.
Department of Neurosurgery, Chang-Gung University and Memorial Hospital, Taoyuan, Taiwan.
K-C
KC
Wei
H-C
HC
Tsai
Y-J
YJ
Lu
H-W
HW
Yang
M-Y
MY
Hua
M-F
MF
Wu
P-Y
PY
Chen
C-Y
CY
Huang
T-C
TC
Yen
H-L
HL
Liu
D000818:Animals; D001812:Blood-Brain Barrier / Q000033:anatomy & histology* / Q000528:radiation effects / Q000601:surgery*; D005240:Feasibility Studies; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D038361:Neuronavigation / Q000379:methods*; D010865:Pilot Projects; D013552:Swine