Journal of Diagnostic Medical Sonography

Quality assurance is the routine monitoring of diagnostic imaging equipment to insure proper and consistent performance. Quality assurance programs have proven beneficial by producing high quality images consistently as well as by reducing costs because fewer repeat examinations are necessary. The purpose of this article is to describe a quality assurance program for real-time ultrasound equipment in terms of testing procedures and practical performance limits.

The use of ultrasound as a guidance tool for chorionic villi sampling for prenatal diagnosis in the first trimester is discussed. Three sampling techniques used in the first trimester are reviewed: endoscopy, blind aspiration, and the combination of endoscopy and aspiration with ultrasound guidance. A review of the literature found that ultrasound guidance provided the highest success rate in obtaining chorionic villi for chromosomal analysis and enzyme determination. Concerns regarding proper scanning technique for localizing the implantation site for sampling are discussed.

Both computerized tomography (CT) and sonography are important imaging techniques in patients with major renal infections. Sonography should be performed as the initial screening examination to exclude pyonephrosis or a large renal or perirenal abscess. In patients who continue to have persistent sepsis without adequate explanation by sonography, CT should be performed to characterize the nature of the renal inflammatory process.

Ultrasound tissue characterization is the effort to derive from the ultrasound signal quantitative information which relates to and provides information about normal and diseased states. Two subjects in this research effort that are currently undergoing investigation and preliminary clinical application are scattering and attenuation. By quantifying backscatter amplitude, the "echogenicity" of diseased organs can be determined more precisely than by visual inspection. Obtaining some measurement of the spatial distribution of scatterers should serve as an approximate indicator of "tissue texture" and yield clinically useful information about normal and diseased tissue structure. Attenuation, estimated by measuring the change in frequency or amplitude as the ultrasound beam traverses tissue, may also prove valuable by providing another measurable parameter for the development of a given tissue's "acoustic profile." The successful implementation into clinical practice of these and other ultrasound tissue characterization measurements will extend and augment the diagnostic capabilities of ultrasound imaging.

Cervical pregnancy is one of the rarest types of ectopic gestation but one of the most serious because of the potential for extensive hemorrhage and perforation of the cervical wall. The clinical symptoms, sonographic appearance, and sonographic differentials are described and discussed.