Quantitative assessment of placental maturity by acoustic intensity histogram

ABSTRACT

Morphologic and sonographic changes appear progressively in the placenta as it matures with the advancing gestation. Ultrasonically these changes appear as 1-4 mm echogenic densities in the chorionic plate, placental substance, basal plate and in the intercotyledonary septa. On the basis of these changes placenta is classified into 4 grades from grade 0 to grade III. Ultrasonic placental grading system is a non invasive way to indirectly predict the placental functional maturity and fetal lung maturity. There is 100% correlation of grade III placenta with mature L/S ratio, 80% with grade II and 60% with grade I placenta. Ultrasonic placenta grading is subject to interobserver variation, to minimize this variation and to increase the accuracy of acoustic intensity histograms of placenta of patients with pregnancy of 30 weeks and over have been obtained and analysed. Histogram represent echo distributing intensity of the image. Information obtained from histogram consist of total number of pixels in a specified area [T], gray scale level of shade component that is most common in the specified area [L] and number of pixels of the shade component that is most common in specified area [M]. Relationship of the computer analysis of histogram echo pattern and conventional grading of placenta are shown in this preliminary study. Computer analysis appear superior to conventional impressions obtained by sonologists. Computer analysis can further be improved by methods discussed