title: Ultrasound-induced thermal elevation in clotted blood and cranial bone.
abstract: Ultrasound thermal effects have been hypothesized to contribute to ultrasound-assisted thrombolysis. To explore the thermal mechanism of ultrasound-enhanced thrombolysis with recombinant tissue plasminogen activator (rt-PA) for the treatment of ischemic stroke, a detailed investigation is needed of the heating produced in skull, brain and blood clots. A theoretical model is developed to provide an estimate for the worst-case scenario of the temperature increase in blood clots and on the surface of cranial bone exposed to 0.12- to 3.5-MHz ultrasound. Thermal elevation was also assessed experimentally in human temporal bone, human clots and porcine clots exposed to 0.12 to 3.5-MHz pulsed ultrasound in vitro with a peak-to-peak pressure of 0.25 MPa and 80% duty cycle. Blood clots exposed to 0.12-MHz pulsed ultrasound exhibited a small temperature increase (0.25 degrees C) and bone exposed to 1.0-MHz pulsed ultrasound exhibited the highest temperature increase (1.0 degrees C). These experimental results were compared with the predicted temperature elevations.
authors.affiliation: Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH 45267-0586, USA.
authors.forename: Volodymyr
authors.initials: V
authors.lastname: Nahirnyak
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Mast
authors.forename: Christy K
authors.initials: CK
authors.lastname: Holland
mesh_terms: D000818:Animals; D001777:Blood Coagulation; D003131:Combined Modality Therapy; D006361:Heating; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D011994:Recombinant Proteins / Q000627:therapeutic use; D020521:Stroke / Q000628:therapy*; D034421:Sus scrofa; D013696:Temperature; D013701:Temporal Bone / Q000502:physiology*; D015912:Thrombolytic Therapy; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*; D014464:Ultrasonic Therapy
chemical_list: D011994:Recombinant Proteins; D010959:Tissue Plasminogen Activator