|A study commissioned by Florida Cattleman’s Association in 2007, 2016 and 2017 found ovarian follicular dysplasia (OFD) to be the major abnormal ovarian condition linked to subfertility and infertility in Florida’s beef herd. Ovarian follicular dysplasia is a slowly progressive bilateral abnormal growth and/or development of ovarian follicles that eventually transforms into “Sertoli-form” Granulosa Theca Cell Tumor (GTCT). The objective of this study was to determine the variation in ultrasound examination when compared to histologic findings utilizing 7MHz and 8MHz linear probes. Ante-mortem and post-mortem ultrasound images, magnetic resonance imaging and histology of 35 cows’ ovaries were blindly compared for classification of different stages of OFD. Our hypothesis was that an 8MHz or greater ultrasound probe could be utilized for detection of earlier stages of OFD.
A comparison of all groups found that there was a 77.1% diagnostic agreement for presence of OFD between the ultrasound and histological analysis for OFD. The agreement of post-mortem ultrasonography with histologic examination for detection of OFD in groups 1 and 2 remained the same as the ante-mortem-histologic examination being 66.6% and 93.3%, respectively. The first group (group 1) was composed of 15 heifers, and the second group (group 2) was comprised of 15 cows. All animals from groups 1 and 2 were Bos t. indicus (Brahman) x Bos t. taurus (Angus, Simmental, Charolais). Most of the disagreement was found with calling an ovary OFD grade I that was histologically found to be normal, type I error. If the OFD grade I’s were removed from this analysis, then there would be 100% agreement between ultrasound and histology for diagnosis of OFD. The discrepancy between ultrasound grading and histological grading is based on a number of important factors such as amount of ovary evaluated, microscopic versus macroscopic (gross) analysis, and interpretation of what the hyperechogenicity represents. The ultrasound picture can be misleading because of the various angles and the density of the tissues is compounded throughout the ovary. However, some significant correlations were found when comparing the ultrasound versus the histological analysis.
Statistical analysis was performed and found that the p-value for testing correlation of histological follicle number (HFol) and ante-mortem ultrasound follicle number (AFol) was found to be less than 0.05, therefore the correlation between HFol and AFol was found to be statistically significant in group 1. The p-value for testing correlation of ante-mortem ultrasound hyperechogenicity grade (AHEch) and ante-mortem OFD grade (AOFD) was found to be less than 0.05, therefore the correlation between AHEch and AOFD was found to be statistically significant for group 2. The p-value for the testing correlation of ante-mortem ultrasound OFD grade (AOFD) and histologic OFD grade (HOFD) was found to be less than 0.05. Therefore, the correlation between AOFD and HOFD was statistically significant for group 2. The p-value for testing correlation of post-mortem ultrasound OFD grade (POFD) and histological OFD grade (HOFD) was found to be less than 0.05, therefore the correlation between POFD and HOFD was statistically significant for group 2. The p-value for testing correlation of post-mortem hyperechogenicity score (PHEch) and post-mortem OFD score (POFD) was less than 0.05, therefore the correlation between PHEch and POFD was found to be statistically significant. The p-value for testing correlation of AHEch and post-mortem hyperechogenicity (PHEch) was not less than 0.05, therefore the correlation between AHEch and PHech was not statistically significant for group 2. The p-value for testing correlation of AOFD and POFD was not less than 0.05. Therefore, the correlation between AOFD and POFD was not statistically significant
Also, one ovary from each animal in Groups 1, 2 and 3 was also submitted for MRI. The evaluation of the MRI images was inconclusive for the presence of OFD. After MRI was performed, five ovaries were submitted for CT in an effort to more accurately determine the presence of dystrophic mineralization within the ovary. The CT results showed that 20% of the ovaries contained some areas of mineralized tissue. Additional studies are necessary to determine the tissues that may lead to the hyperechoic areas within the ovary. More comparison studies are needed between histology, ultrasound, MRI and micro-CT to more fully elucidate the connection between histological analysis and ultrasound.
Furthermore, the difference between 7MHz (ante-mortem US) and 8MHz (post-mortem US) probes’ did not affect the results of this study and both correlated with histological detection of OFD. This study also showed a correlation between ante-mortem and post-mortem US AFC and US HEch as well as a correlation between US AFT and MRI AFT. Trans-rectal ultrasound is a reliable tool to diagnose OFD ante-mortem.