Detection of ventricular landmarks by two dimensional ultrasonography.

Visualization of the brain's midline structures or of an intracranial mass lesion and detection of ventricular landmarks are the main goals of the ultrasonic (US) techniques in clinical neurology. While investigating the structures in the mid-sagittal plane of the head responsible for the midline echo by A-mode or unidimensional techniques (see Fig. 1), Gordon (1959), and de Vlieger and Ridder (1959) reported a double echo corresponding to the fissure of the third ventricle and a single echo at a higher level corresponding to the septum pellucidum. This was confirmed by Jeppsson (1960) in infants, and by ter Braak, Crezee, Grandia, and de Vlieger (1961), using simultaneous US and pneumoencephalography (PEG). An experimental confirmation of these data was given by Lithander (1961) who introduced a needle indicator in proximity to the reflecting interfaces on excised brains. Ford and Ambrose (1963) described the behaviour of the A-mode echoes arising from the walls of the third ventricle in relation to air study and curved interfaces. Most recently Feuerlein and Dilling (1967) studied the range of the width of the third ventricle in normal subjects at different ages by A-scans. The possibility of detecting other landmarks of the ventricular system was suggested also by Tanaka, Kikuchi, and Uchida (1961) and experimentally by Lithander (1961), who could identify the A-echoes arising from the lateral wall of the occipital horns and of the portion of the anterior horns just anterior to the foramen of Monroe. Ambrose (1963) suggested a technique for localizing the walls of the lateral ventricles by A-scan. A more systematic search for specific landmarks pertaining to the lateral ventricular system was carried out by Ford and McRae (1966) with unidimensional techniques. These authors investigated the possibility of detecting the lateral walls of the anterior horns and the ultrasonic findings were