Transkull focal lesions in cat brain produced by ultrasound

Focused ultrasound has been used for focal modifications of brain tissue and in preliminary studies of the application of ultrasonic techniques for tissue modification in human stereotaxic neurosurgery; however, the technique has been seriously compromised by the necessity of removal of intervening skull. Such removal was necessary to avoid distortion and extremely large attenuation of the ultrasonic beam which resulted from passage through bone. Recent studies have shown that under proper conditions focal beams of ultrasound can be transmitted with tolerable and attenuation through skull, suggesting the possibility of transkull lesion production in brain. This report describes the acoustical parameters and histological features of focal brain lesions produced in 10 craniectomized cats with intense focal ultrasonic beams which first had passed through a formalin-fixed human skull overlay. The histological appearance of these lesions produced to date is similar to that produced previously without intervening skull.