Tissue characterization with gray level histogram width and assessment of fetal lung immaturity

Abstract

Purpose: The aims are to clarify the reproducibility of gray level histogram width (GLHW) in ultrasound machines and to demonstrate tissue character of fetal organs and tissues in B‐mode image.Methods: The GLHW is calculated manually and automatically with the ROM provided by Aloka, and the values are compared among six Aloka, each one of Toshiba, Yokogawa and Kretz 503D wuth use of RMI phantoms. Clinically, the placenta, fetal brain periventricular echodensity (PVE), fetal lung and liver, those of preterm fetuses with the refernece to stable microbubbles of amniotic fluid, and meconium stained amniotic fluid are studied.Results: No influence of clinical gain control, image depth, STC, 1 cm2 or more ROI or 1000 or more pixels is confirmed. GLHW is large in high image contrast, but it is easily compensated. Some own values are corrected and standardized. GLHW is reproducible among machines. Clinically, GLHW is large in grade III placenta, the value is large in fetal brain PVE and it is large in meconium stained fluid. Normal fetal lung GLHW is low and lower than fetal liver before 30 weeks of pregnancy, fetal GLHW is 31% or less in the group of five or less stable microbubbles with 90% sensitivity and 80% specificity. In gynecology, GLHW is high and coefficient of variation is low in multiple ROIs of ovarian malignancy. GLHW is large in hyperplastic endometrium. Adult organs and tissues are of interest particularly in hepatic diseases.Conclusion: GLHW is reproducible in ultrasound machines, and it is useful in tissue characterization. It is possible to assess fetal lung immaturity with GLHW.