It was verified form the anatomical studies and the clinical applications that the quantitative and phasic blood flow velocity of the mid size to large arteries and veins in the cranium could be measured by our improved TCT (two dimensional echoencephalography) and the color TCDT.
[Anatomical study] From the examination of the thickness of the bone, the ultrasonic bony window on the temple is about 33mm in height and about 54mm in width calculated as the mean value of 55 skulls. The window has an adequate size for applring a conventional electric sector scan probe.
[TCT application] The power-increased TCT at 2.4MHz could supply the sector image of the brain st the horizontal, coronal and arbitrary planes through the temple, in which clinoid processes, venticles, the brain stem, the optical shiasma and the other structures could be shown. Simultaneously MCA, PCA, ACA and veins were captured and the phasic velocity sonograms of those vessels were recorded with ECG by the duplex method. Each artery flow and vein flow showed the well-known pulsatile flow pattern and the steady flow pattern respectivery. The pulsatile patternvanished on the MCA by the CCA compression test, and the steady flow increased rapidly on the superior petrosal vein by the varusarva test. Such phenomena on the cerebral circulation could be detected at the desired vessel on the TCT image.
[TCDT application] Although the desired vessel could be reasonably detected on TCT images by well trained clinicians, it is inadequate for calculating the quantitative velocity of the vessel and for reading the angle between the ultrasonic beam and the three dimensional flow direction. The reason is that the resolution of the ultrasonic image is inadequate to indicate the long axis view of the desired vessel and the length of the view is too short to read the angle. Even though the resolution was not improved by the color TCDT, the TCDT image made it easy to recognize the existence of the vessel in TCT image and to detect the beam angle of the vessel. By means of the TCDT image, the quantitative velocity could be measured at most of the large arteries and veins. And even on the MCA, the differences in the velocity could be quantified from the angle difference on the proximal and the peripheral.
Quantitative and various hemodynamic analyses for the intracranial circulation will be performed based upon true velocity information on the rather large arteries and veins measured by the color TCDT.
