The role of shear wave elastography in predicting tissue viability and spermatogenesis in rats with induced testicular torsion

Introduction and Objective: The aim is to evaluate the effectiveness of Shear Wave Elastography in the early diagnosis of testicular torsion, as well as predicting spermatogenesis and testicular viability, which are among scrotal emergencies. Methods: Between June 2022 and June 2023, 60 Wistar albino male rats aged 10- 12 weeks were used in the Experimental Animal Unit of the Adnan Menderes University Faculty of Medicine in Aydın. The rats were divided into 4 groups: Group 1: Control (sham) group (n:6), Group 2 (n=18): 180 0 testicular torsion (TT) group, Group 3 (n=18): 360 0 testicular torsion group, and Group 4 (n=18): 720 0 testicular torsion group. Two rats were excluded from the study due to mortality during the study Before performing any surgical intervention, basal Shear Wave Elastography (SWE) measurements were taken from both the right and left testes in the Control (Sham) group rats. The rats were administered ketamine (100mg/ml vial) / xylazine (20mg/ml vial) intraperitoneally. Under anesthesia (Ketamine at a dose of 1mg/kg (10%) and Xylazine at a dose of 2mg/kg (2%)), a scrotal incision was made to explore the left testis. After waiting for about 1 minute without causing damage to vascular structures, the spermatic cord was closed without torsion. Basal SWE measurements were taken from both the right and left testes after the procedure. Before performing left testicular torsion on the surgical group rats (Groups 2, 3, and 4), SWE measurements were taken. Similarly, after making a left scrotal incision, the left testis was exteriorized. Then, the left testis was rotated medially to induce torsion at 180 0 for Group 2 rats, 360 0 for Group 3 rats, and 720 0 for Group 4 rats. The spermatic cord was twisted to induce torsion, and the testis was fixed to the scrotum at the lower and upper poles. The scrotum was closed to prevent the testis from returning. The surgical group rats (each containing 18 rats in Groups 2, 3, and 4) were further divided into 3 separate subgroups, with each subgroup containing 6 rats. Subgroup A rats underwent detorsion surgery at the 4th hour, Subgroup B rats at the 12th hour, and 12 Subgroup C rats at the 24th hour. Prior to the detorsion procedure, SWE measurements were taken from the torsioned left testes in these subgroups at the same time points (4, 12, and 24 hours) according to their respective groups. After the SWE measurements were taken, the rats were anesthetized again and underwent surgery to release the torsioned testes and return them to their original state. They were then fixed to the scrotum after being detorsioned. Due to mortality of one rat each in the 4 hour 180 degree and 24 hour 180 degree groups, they were excluded from the study. At the 72nd hour, orchiectomy was performed on all rats in the entire group, and tissue samples were taken for histopathological examination. Samples were taken from the testes to evaluate spermatogenesis. These samples were placed in Bouin's solution, while the remaining tissues were stored in formalin solution. After the tissue collection, euthanasia was performed on the rats using a high dose of anesthetic drugs Results: The 58 Wistar albino rats aged 10-12 weeks, included in the study, were divided into 10 subgroups. The p-values for the Torsion-Pre SWE (TOSWE) measurement values within the groups and subgroups were found to be 0.021, for the Detorsion-Pre SWE (DTSWE) p-value was 0.018, for the proportional increase between the two SWE measurements was 0.067, for the Johnsen score was <0.001, for the degree of edema was <0.001, for the degree of inflammation was 0.118, and for the degree of necrosis was <0.001 As the time and degree increase in SWE, the difference in DTSWE and TOSWE values was found to be significant at 4 hours 720 degrees (n:6, p: 0.05), 12 hours 180 degrees (n:6, p<0.001), 12 hours 360 degrees (n:6, p:0.02), 12 hours 720 degrees (n:6, p:0.01), 24 hours 360 degrees (n:6, p: 0.05), and 24 hours 720 degrees (n:6, p: 0.01). A weak negative significant correlation (r:-0.342, p:0.009) was found between the proportional difference between TOSWE and DTSWE and the Johnsen score. A strong negative significant correlation (r:-0.764, p<0.001) was observed between the Johnsen score and the degree of necrosis. A positive weak significant correlation (r: 0.350, p: 0.007) was found between the proportional increase between DTSWE and TOSWE measurements and the levels of necrosis. 13 A highly significant difference (p<0.001) was found between the Johnsen scores and the degrees of necrosis in the testes sent for pathology after the torsion and detorsion procedures. Conclusions: In our study, we demonstrated that the Shear Wave Elastography method can provide preliminary information about the proportional difference between DTSWE and TOSWE measurements and spermatogenesis and testicular viability. Our SWE results showed that tissue stiffness changed with the hours and degrees after torsion. Upon reviewing the literature, our study is the first to compare SWE measurements with spermatogenesis and necrosis degrees in different degree and hour groups. We believe that preoperative evaluation of the testis using SWE and comparing it with the SWE values of the contralateral testis can provide preliminary information about testicular viability and spermatogenesis in patients diagnosed with testicular torsion. This approach may guide the decision regarding the surgical procedure to be performed on the patient It is recommended that SWE measurements in testicular torsion be supported by more comprehensive studies. Due to the large number of subgroups in our study, our sample size is inadequate, and it is recommended to be supported by larger sample and clinical studies.