Ultrasound and Imaging

Diagnostic sonograms, ultrasound in 3D and 4D included, are among the studies Candace Cooley has performed and interpreted, and this index gathers the entries on how those images are made and read. The National Institute of Biomedical Imaging and Bioengineering explains that a transducer sends sound at frequencies above the range of human hearing into the body and builds an image from the echoes returned at boundaries between tissues, and that although most probes sit on the skin, some are placed inside the body, including in the vagina, to sharpen the image.¹

The obstetric history is short. A history of the obstetric and gynecologic ultrasound machine dates the first two dimensional scanner, the diasonograph built by Ian Donald and Tom Brown, to 1958; it stood eight feet tall, took up nearly a third of the scanning room and produced slow static images without real grayscale.² In pregnancy the uses are practical. MedlinePlus lists working out the stage a pregnancy has reached, taking measurements and checking for problems, and notes that a probe placed in the vagina is more likely early in pregnancy.³

The five entries are How Medical Ultrasound Works, Transvaginal Ultrasound, Obstetric Ultrasound, Three and Four Dimensional Ultrasound and Ian Donald and the Early Obstetric Scans. The bone density scan has its own entry, Dual Energy X Ray Absorptiometry.