Ultrasonic Evaluation of Heterogeneity Levels in Normal and Torsed Testes

Testis torsion in pediatric patients is a surgical emergency that requires immediate operative intervention. Heterogeneity, which has been associated with testis loss, is only grossly detected on grayscale ultrasound. To quantify the extent of heterogeneity associated with torsion, we employed a unique, noninvasive technique to determine Dynamic Range (DR) in ultrasound images, and then compared DR in ultrasound of torsed testes with untorsed testes. We performed a retrospective review over a 2-year period of pediatric patients with a chief complaint of testicular pain. Patients who demonstrated an absence of blood flow on testis ultrasound and who underwent scrotal exploration for testis torsion were included in the study population. Representative ultrasound images of the affected testis and its normal contralateral testis were examined. The program uses a dithering technique based on the Floyd-Steinberg algorithm in which the pixels of an ultrasound image are transformed into a binary map. An algorithm was applied to this binary map to determine DR values. Univariate t-test analysis was performed, comparing DR values in testes with confirmed torsion to those of testes with normal blood flow. Among the 25 patients eligible for inclusion in this study, 18 underwent orchiopexy for a viable torsed testis, while 7 patients underwent orchiectomy for a nonviable testis. The mean DR on scrotal ultrasound was significantly greater in torsed testes compared to normal contralateral testes (3.89 vs. 2.75, p=.004). Additionally, using a cut-off point of 3.2 for DR, a 68% correlation was reached for predicting testis torsion on scrotal exploration. Our results demonstrate that measuring DR of the testis as a reflection of heterogeneity correlates with testis torsion. A cutoff DR of 3.2 accurately predicted torsion in 68% of testes. These results argue that DR may be a potential non-invasive indicator of testis torsion in real-time.