Quantification of sonographic echogenicity with grey-level histogram width: a clinical tissue characterization

Grey-level histogram width (GLHW) values obtained by common sonographic devices were large in echogenic image and small in less echoic parts. The Aloka UIP-100 computer system, SSD-680, and Toshiba SSA-270A sonographs showed GLHW values not significantly different when tested with RMI-412 phantom with the device contrast set at the lowest level. No influence on the GLHW value was observed by the changes of device gain, STC or image depth in the range of clinical practice. Device contrast control influenced the value. Although two sonographs showed significant differences from UIP-100, they were easily corrected by a small factor. Normal ranges of GLHW values of the placenta were obtained every 2 weeks, from 20 to 41 weeks, in 222 normal pregnancies measured by old scanners. GLHW values of normal pregnancies measured by the new Aloka and Toshiba machines were distributed within the normal ranges, and those of Grannum Grade III abnormally echogenic placenta were greater than the upper normal range. GLHW is a reproducible value among commercial ultrasonic devices, and the value is useful in clinical practice. Manual and automated GLHW values were identical.