The Localization of Brain Tumors by Ultrasonic Techniques

Abstract

T ~E pathology and symptomology of brain tumors are now well understood. Diagnosis is sometimes assisted by air studies, a r te r iographyand electroencephalography. Ultrasonic examinat ion is a simple diagnostic technique, and has part icular value in the advanced stages of brain tumor when ar ter iography or air studies are inadvisable. The application of u l t rasound for the purpose of diagnosis in the neurosurgical field has been repor ted since 1950.1-7,9-a2 Dussik, 6 and Huer t e r and Bol t la have tried to obtain a picture of the ventricles by a transmission method of u l t rasound called hyperphonography. However , the picture of the ventricles was not as clear as a pneumoencephalogram. Recent ly the reflection method of ul trasound (echo) has been chiefly employed. Since 195~, we have been utilizing the reflection method of u l t rasound in the diagnosis of brain tumors . This pape r summarizes our results. the t ransmi t ted pulse can be measured. By analysis of these ultrasonic echoes, correct diagnosis can be made. To establish the accuracy of the refle.ction of the ultrasonic wave and the difference in acoustic impedance between brain t umor tissue and normal brain tissue, we conducted the following experiments with fresh tissue. The appara tus used to measure veloci ty of sound in fresh tissue is shown in Fig. 1.* To make measurements the device was first clamped on the sample, than immersed in degassed water. Using a microscope on the films, the distance of the reflecting surface from the s tar t ing point of the t r ansmi t t ed pulse in each of the mater ia ls was compared. The density of the sample was measured b y a solution of copper sulphate. The results of these experiments are shown in Tab le 1. I t will be seen tha t the acoustic impedance of brain t umor tissue is greater t han t h a t of normal brain tissue. Thus it is theoret ical ly possible tha t the border between brain tissue and tumor tissue will cause a reflection.