Application of the ultrasonic Doppler method to medical diagnosis was first made in 1955 by Shigeo Satomura. At first he measured the small vibration and motion of the human body in the heart, the eye ball and blood vessels by the Doppler method with microwave and ultrasound. Accidentally in 1958 Satomura found Doppler noise of the blood stream in the process of measuring the microvibration of the blood vessel wall. The next clinical application of this ultrasonic flowmeter was developed by Satomura and Kaneko. Descriptions of the first report at the Society of Acoustics and medical meeting, the first paper in Japanese and English, the first equipment, recording system, the first commercial Doppler flowmeter, the naming of the ultrasonic blood rheograph and further studies on cerebral circulation were also provided in this paper.
In recent years brain ultrasonography has become a simple, useful and almost indispensable examina-tion for the neurological diagnosis of newborns and young infants. A pulsatility index (PI) calculated from the formula (S-D) /S for the cerebral arteries such as basilar artery (BA) or anterior cerebral artery (ACA) decreased at the stage of elevated intracranial pressure in the infants with acute encephalopathy and subdural hemorrhage. Using two-dimensional Doppler ultrasonography (color flow mapping system), the blood flow of BA or ACA was observed as a continuous line of warm color along the course of the arteries. To obtain PI of these arteries, the sampling site could be easily decided using this system. Brain ultrasonograms of 515 cases of 1-month-old infants whose birth weights were more than 2500gm. were observed at their health 1-month-examination. Subependymal cysts (SEC) were observed in 51 infants (9.9%), and choroid plexus cysts (CPC) in 31 infants (6.0%) . Since the rate of neonatal asphyxia was 15.7% in SEC, 0% in CPC and 1.9% in normal controls, SEC was correlated with neonatal asphyxia statically. SEC was suspected of subependymal hemorrhage (SEH) and the occurrence of SEH in mature neonates was indicated in this study.
Ultrasonic quantitative flow measurement system (QFM) was developed to measure an absolute flow volume of common carotid artery (CCA) noninvasively as one of the cerebral circulation tests. It is verified from the model experiment that the output is independent of the depth of vessel and the angle between beam and flow. Moreover, the accuracy is confirmed by the comparison with the electromag-netic flow meter; the error is less than ±7%. However, it is required for accurate and reproducible measurements to handle the probe properly to detect an adequate amplitude of wall echo and to set the gate position at the vessel inner surface echo. The following clinical results have been obtained: 1) There is no significant difference in CCA flow volume between right and left sides. 2) The mean value of male/female is 1.058. 3) The CCA flow volume is decreased with age: 8.98ml/s in 20s and 8.03ml/s in 70s. 4) Body position : The rapid standing from supine position decreases the CCA flow volume; the ratio ranged from -3.3% to -22.2%. 5) It is suspected that the CCA flow is independent of the blood pressure. 6) CCA flow volume in sleeping stage decreases 10% in REM and 20% in non-REM.
Comparison of Doppler flow parameters measured by pulsed Doppler method with angiographic findings was studied in 77 patients (121 common carotid arteries) . A RT-3600 scanner which employs a 5-MHz transducer in the Doppler mode, was used for the duplex studies. Duplex studies were performed after cerebral angiography. All patients had images of right and/or left common carotid artery obtained by digital subtraction angiography, and conventional cerebral angiography. The severity of atheroscler-osis was scored by angiographic findings : atheromatous plaque, wall irregularity, stenosis, tortousity, and so on. Systolic velocity, diastolic velocity, mean velocity, and pulsatility index were measured by the pulsed Doppler technique in the common carotid artery. The systolic velocity, diastolic velocity, and mean velocity showed negative currelations with the atherosclerotic score on angiograms, and the pulsatility index showed positive correlation with that on angiograms. Pulsatility index in patients with cerebral infarction in the examind internal carotid artery distribution was statistically significantly higher than that in patients having no ischemic lesions. It was thought that Doppler flow parameters, such as systolic velocity, diastolic velocity, mean velocity, and pulsatility index reflected well the severity of atherosclerosis, and Doppler ultrasound was a useful method for evaluating atherosclerosis and cerebral ischemic lesions.
The Ultrasound-guided biopsy method has many outstanding capabilities that the other brain biopsy techniques do not have, such as, taking aim at the target using puncture guide system, all performances taking place in the operating room without transportation to C.T. or M.R.I, room, and real-time visualization of the tomogram displaying the target and forceps during the biopsy procedure, etc. Recently, the authors devised a new brain biopsy technique with ultrasonic guidance through only a burr hole, using a small foot-print transducer 12mm in diameter, and special trocar with engraved scales on its surface. We believe that this new biopsy technique surpasses the traditional ones such as classic stereotaxic and C.T.-guided stereotaxic approaches, in many aspects. Two cases treated by this technique are presented.