A tissue-equivalent upper abdominal phantom.

The first prototypes of an abdominal phantom have been constructed. The phantom is intended for eventual use in training diagnostic ultrasound personnel and in demonstrating commercial equipment. It is constructed from plastics believed to be stable and approximately tissue-equivalent at room temperature. Abdominal structures are formed from a dispersion of a polystyrene butadiene plastic in mineral oil. Polyvinyl chloride particles are incorporated to provide the desired attenuation coefficients and scattering levels. B-scans of the phantom produced realistic images, although problems associated with scanning technique and somewhat high phantom attenuation were noted. Very useful phantoms should result from relatively simple improvements in construction techniques.

Evaluation of fetal intracranial anatomy by static and real-time ultrasound.

Improvements in ultrasound technology have now made possible detailed visualization of fetal intracranial anatomy. Structures such as the midbrain, thalami, and lateral ventricles can be routinely imaged. Measurements of the ratio between lateral ventricular width and cerebral hemispheric width demonstrate a steady decrease from a mean of 56% at 15 wk gestation to 28% at term reflecting the relatively more rapid growth of the cerebral hemispheres as compared with the cerebral ventricles. Application of this new ultrasound data greatly facilitates accurate and consistent biparietal diameter estimations and early diagnosis of fetal hydrocephalus and other fetal cranial anomalies. This article describes the axial fetal cranial anatomy as demonstrated sonically and includes a table for normal fetal ventricular size at various gestational ages, based on evaluation of 196 normal fetuses. Some of the more common fetal cranial anomalies amenable to ultrasound diagnosis in utero are discussed.

B-mode echoencephalography in the normal and high risk infant.

Commercially available high resolution, contact, gray scale imaging systems can now dependably visualize the normal and abnormal ventricular system as well as some other intracranial structures in all newborns. On 25 normal infants and 41 high risk infants, 135 B-mode echoencephalograms were performed. The technique for obtaining these scans is described. The normal lateral ventricle at the midbody in term infants is 0.9--1.3 cm wide (mean, 1.1 cm). Normal ratio of lateral ventricle to hemisphere is 28% (range, 24%--30%). High risk premature infants have a ratio of 31% (range, 24%--34%). The demonstration of hydrocephalus and cystic intracranial masses is reliable and the correlation with computed tomography is excellent. Postoperative or high risk infants can be repeatedly evaluated without radiation, at a lower cost, and more rapidly with ultrasound than with computed tomography. Ventricular size can be closely monitored and shunt failure detected at any early stage.