Safety Validation of Repeated Blood–Brain Barrier Disruption Using Focused Ultrasound

• Published in: Ultrasound in medicine & biology Vol. 42; no. 2; pp. 481 - 492
• Main Authors: Kobus, Thiele, Vykhodtseva, Natalia, Pilatou, Magdalini, Zhang, Yongzhi, McDannold, Nathan
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.02.2016
• Subjects: Animals; Blood-Brain Barrier - pathology; Blood-Brain Barrier - physiology; Blood-Brain Barrier - radiation effects; Blood–brain barrier disruption; Focused ultrasound; High-Energy Shock Waves; Histologic evaluation; Magnetic resonance guidance; Multiple sessions; Radiation Dosage; Radiology; Rats; Rats, Sprague-Dawley; Safety study; Sonication - methods; Safety study; Focused ultrasound; Blood–brain barrier disruption; Multiple sessions; Magnetic resonance guidance; Histologic evaluation
• ISSN: 0301-5629; 1879-291X; 1879-291X
• DOI: 10.1016/j.ultrasmedbio.2015.10.009

The purpose of this study was to investigate the effects on the brain of multiple sessions of blood–brain barrier (BBB) disruption using focused ultrasound (FUS) in combination with micro-bubbles over a range of acoustic exposure levels. Six weekly sessions of FUS, using acoustical pressures between 0.66 and 0.80 MPa, were performed under magnetic resonance guidance. The success and degree of BBB disruption was estimated by signal enhancement of post-contrast T1-weighted imaging of the treated area. Histopathological analysis was performed after the last treatment. The consequences of repeated BBB disruption varied from no indications of vascular damage to signs of micro-hemorrhages, macrophage infiltration, micro-scar formations and cystic cavities. The signal enhancement on the contrast-enhanced T1-weighted imaging had limited value for predicting small-vessel damage. T2-weighted imaging corresponded well with the effects on histopathology and could be used to study treatment effects over time. This study demonstrates that repeated BBB disruption by FUS can be performed with no or limited damage to the brain tissue.