Ultrasound imaging-guided noninvasive ultrasound thrombolysis: preclinical results.
BACKGROUND
Catheter-based therapeutic ultrasound thrombolysis was recently shown to be effective and safe. The purpose of this work was to study the safety and efficacy of external high-intensity focused ultrasound thrombolysis guided by ultrasound imaging in experimental settings.


RESULTS
A therapeutic transducer was constructed from an acoustic lens and integrated with an ultrasound imaging transducer. In vitro clots were inserted into bovine arterial segments and sonicated under real-time ultrasound imaging guidance in a water tank. With pulsed-wave (PW) ultrasound, the total sonication time correlated with thrombolysis efficiency (r(2)=0.7666). A thrombolysis efficiency of 91% was achieved with optimal PW parameters (1:25 duty cycle, 200-micros pulse length) at an intensity (I(spta)) of >35+/-5 W/cm(2). Ultrasound imaging during sonication showed the cavitation field as a spherical cloud of echo-dense material. Within <2 minutes, the vessel lumen evidenced neither residual clot nor damage to the arterial wall. On serial filtration, 93+/-1% of the lysed clot became subcapillary in size (<8 microm). In vitro safety studies, however, showed arterial damage when an I(spta) of 45 W/cm(2) was used for periods of >/=300 seconds.


CONCLUSIONS
External high-intensity focused ultrasound thrombolysis using optimal PW parameters for periods of </=300 seconds appears to be a safe and effective method to induce thrombolysis. The procedure can be guided by ultrasound imaging, thereby allowing the monitoring of therapy.
Rosenschein
U
U
Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. urosenschein@angiosonics.co.il
Furman
V
V
Kerner
E
E
Fabian
I
I
Bernheim
J
J
Eshel
Y
Y
D000818:Animals; D002339:Carotid Arteries / Q000473:pathology; D002417:Cattle; D003131:Combined Modality Therapy; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D013552:Swine; D015912:Thrombolytic Therapy; D013927:Thrombosis / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology; D010959:Tissue Plasminogen Activator / Q000494:pharmacology*; D014465:Ultrasonics; D018084:Ultrasonography, Interventional / Q000379:methods*
D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator