The relationship between digital ultrasonographic image echotexture parameters of the uterus and preovulatory follicle development and ovulation in purebred Arabian mares

Abstract

Objective assessment of ultrasonographic images is only possible using computer-assisted echotexture analysis. This study investigated the relationship between cyclic digital echotexture analysis of ultrasonographic uterine images, and preovulatory follicle development and ovulation in 48 cyclic purebred Arabian mares during the breeding season. When the mares’ ovarian follicle diameters exceeded 30 mm, ultrasonographic examinations were performed and ultrasonographic images recorded with uterine endometrial edema degrees following follicle development until ovulation day. Echotexture measurements, including mean grayness value (MGV), heterogeneity (HET) and contrast (CON) parameters, were performed on the days when ovarian follicle diameters reached 30 mm (Group 1, n = 12), 35 mm (Group 2, n = 12), 40 mm (Group 3, n = 12) and 45 mm (Group 4, n = 12) in images recorded the day before ovulation and on the day of ovulation. MGV was the lowest in Group 2 and the difference from the other groups was statistically significant (P<0.001). CON was significantly higher in Group 2 than Groups 3 and 4 (P<0.01). However, there was no significant difference compared to Group 1 (P>0.05). Variations in HOM (P<0.05), contrast (P<0.05) and MGV (P<0.01) were statistically significant on the day before ovulation and ovulation day. Thus, uterine ultrasonographic echotexture parameters are associated with preovulatory follicle development in mares, which suggests that these parameters can indicate the day of ovulation in purebred Arabian mares.