Researches on neurosonology of the author performed for 30 years or more are reviewed with episodes of humor that have made him urge to work on ultrasound, both in practice and at laboratory. The postoperative follow-up study with the aid of echodiagnosis of A-mode and of B-mode tomography afforded an accurate and simple method to find the regression and growth of malignant processes of surgery and neurosurgery after treatment, and those results were supported by basic studies of ultrasonic absorption coefficient of human brains and live organs. Pulsatile echoencephalography was studied by the analysis of time factors with a lot of result, which revealed potentials of differentiating occluded locations of cerebral arterial occlusive diseases, as well as of determining the state of brain death. The author has also achieved basic studies and applications of ultrasonic destruction of malignant tumors by making a comparison with the radiation therapy.
My experiences and episodes on clinical application of ultrasound for about thirty years were described. About the development of A-mode echoencephalography in Japan, the establishement of Japan Soiety of Ultrasonics in Medicine, the beginning of intraoperatieve use of B-mode in brain surgery in ultrasonic medicine in Japan, and other affairs followed about ultrasonic medicine in my life, were introduced here briefly.
I have developed three methods to measure the degree of arteriosclerosis non-invasively and quantitatively. (1) Pulse wave velocity (PWV) : PWV has become very useful in solving the following PWV problems: To neglect the effect of vasomoter activity, PWV was measured at aorta; also as PWV depended on blood pressure, a corrected blood pressure nomogram was made; and PWV was estimated from good correlation with the grade of pathological changes (γ=0.86) . (2) Ultrasonic quantitative flow measurement system (QFM) : QFM which can measure absolute carotid flow volume was developed to diagnose carotid and cerebral arteriosclerosis. It was found that flow volume decreased with aging and on the involved side in ischemic cerebrovascular disease. (3) Simulation method: To measure cerebral arteriosclerosis, a simulation method was developed. Parameters Rp, Cp indicating the degree of cerebral arteriosclerosis were calculated by feeding (a) carotid phasic flow volume measured using QFM, and (b) the carotid pressure wave into the simulation model of the carotid and cerebral vascular system. By pathological study, Rp was clarified as correlating well with lumen narrowing (γ=0.78), and Cp with the wall thickness ratio (γ=-0.61) . QFM and simulation method was of great use in estimating cerebral arteriosclerosis quantitatively.
A-mode of ultrasound sonography has been attempted for diagnostic purpose of cerebro-vascular disease in the 1960s. Recently. in the 1970s, the introduction of the CT scanner has allowed progress in the aspiration surgery via burr hole for hypertensive intracerebral hemorrhage. At the same time, it is looked again of usefullness of ultrasonotomography combined with aspiration technique. Hematoma aspiration under hand-controled ultrasound sonography seems to be available to remove the hematoma by observating the real-time change of picture on echogram. The correlation between aspiration rate, operative method, timing of operation and echographic findings was mentioned. The conclusion was obtained that hematoma aspiration under ultrasound guidance is considered beneficial to remove the hematoma with less brain damage. This method should be more widespread in surgery because of its accuracy and simplicity.
In 1959, I had an opportunity of meeting the late Prot. Dr. Shigeo Satomura who had devised the Doppler ultrasonic technique first in the world. Since then, I have been investigating the clinical applications of this technique for around thirty years. In this paper, my studies in the field were reviewed with some comments on episodes.