THREE-DIMENSIONAL ANALYSIS OF COLOUR DOPPLER ULTRASOUND IMAGES: THE RELATIONSHIP OF VASCULAR FLOW TO OVARIAN STRUCTURES AND THEIR FUNCTION IN BUFFALO COWS AND BEEF CALVES

The main objective of this thesis was to develop a three-dimensional method to assess ovarian structures and relate their vascularity to their function (i.e. hormone production, oocyte quality, ovulatory capacity, etc.). This novel method uses video segments recorded after free-hand movement of the routine linear-array transducer, obtained vascularity index values are independent of speed of transducer movement, and the method does not require a-priori operator selection of images, i.e. is an objective method. In Study 1, colour Doppler ultrasonography was used to assess the ovaries of water buffalo (Bubalus bubalis) who were induced to ovulate using a gonadotropin releasing hormone analogue. Ultrasonographic examinations were performed daily to assess ovulation and subsequent corpus luteum (CL) development. Recorded cineloops were exported from the ultrasound machine and analyzed on a personal computer equipped with imaging software from two sources, Fiji (ImageJ) and Imaris. Fiji was used to perform conventional two-dimensional image analysis and Imaris was used to develop a new three-dimensional analysis method that does not require operator selection of images (i.e. objective method). Verification of the three-dimensional method was performed using two-dimensional data. Buffalo that did not ovulate within 24 hours of artificial insemination (40h from time of gonadotrophin releasing hormone analogue treatment) (n=3) tended to have lower change in vascular flow (P=0.06) to their preovulatory follicles when compared to those that ovulated (n=13) using the three-dimensional analysis method. In Study 2, power Doppler ultrasonography was used to assess the ovaries of 4-month-old prepubertal beef heifers (Bos taurus) who were superstimulated using two follicle stimulating hormone (FSH) protocols. Ultrasonographic scans were performed on the day of luteinizing hormone (LH) treatment, the day of oocyte collection, and the third and seventh day following follicular aspiration. The three-dimensional method developed in Study 1 was used to calculate vascularity indices for the four time points. Ovarian vascularity was then related to the expansion of the cumulus-oocyte-complexes that were retrieved, as well as the subsequent luteal tissue that developed following follicle aspiration. Luteal vascularity index measured at three days following follicular aspiration were related to the rise in plasma progesterone concentration over time (from 24 h following LH to day seven after aspiration) (r=0.65, P