White D N
Can Med Assoc J. 1966 Jan 22;94(4):180-9.
The technique of A-scan echoencephalography is criticized in so far as it lacks objectivity and reproducibility. In the author's laboratory, the M-echo, being of higher amplitude than other intracranial echoes, is distinguished from other echoes by an averaging technique-a time exposure. Double transmission pulses indicate the theoretical position of echoes from the true mid-line and superimposition of far-side echoes ensures that the transducers are correctly aligned.The very considerable difficulties in identifying the anatomical structures giving rise to other echoes seen within the skull are outlined. They are largely due to variations in the reflected energy, depending upon the shape and orientation and position of the various interfaces with respect to the ultrasonic beam.Despite these difficulties and limitations, A-scan echoencephalography appears to have an important part to play as a simple, safe and quick form of neurological examination, if the technique can be made truly objective.
A 型超声脑回波描记术因缺乏客观性和可重复性而受到批评。在作者的实验室中，M 波比其他颅内回波的振幅更高，通过平均技术（时间曝光）将其与其他回波区分开来。双发射脉冲指示来自真正中线的回波的理论位置，远侧回波的叠加确保换能器正确对齐。文中概述了识别颅骨内其他所见回波的解剖结构时存在的巨大困难。这些困难主要是由于反射能量的变化，这取决于各种界面相对于超声束的形状、方向和位置。尽管存在这些困难和局限性，但如果该技术能够真正做到客观，A 型超声脑回波描记术似乎可以作为一种简单、安全且快速的神经学检查方法发挥重要作用。
