Diffusion-Weighted Imaging and Color Doppler Ultrasound in Evaluation of Partial Testicular Torsion in Rat Model.

Background: To evaluate the utility of histogram analysis of apparent diffusion coefficient (ADC) in the diagnosis of incomplete testicular torsion.

Material/methods: Fourteen Wistar albino rats were randomly allocated into two groups. In group 1 (control), left testicles were kept outside for 45 seconds and then replaced, whereas left testicles were twisted by 360° in group 2. Four hours later, DWI was performed. After that, magnetic resonance imaging (MRI) and testicular color Doppler ultrasound (CDU) were performed by two radiologists who looked for the presence or absence of blood flow. ADC measurements were carried out by two radiologists who were blinded to each other's measurements. After CDU, testes were surgically removed and a pathological examination was performed after four hours of torsion. Comparisons of minimum, mean, and maximum ADC values in testicles were performed with the Wilcoxon test. value of 0.05 or less was considered as statistically significant. Inter-observer agreement was also analyzed.

Results: In the torsion group, minimum ADC values for left testicles were significantly lower than for the control group (p<0.05), regardless of the observer. Inter-observer agreement for measurements of ADCmin and ADCmax values was substantial, with an ICC score of 0.751 and 0.774, respectively (95% CI). Inter-observer agreement for the measurement of ADCmean value was excellent, with an ICC score of 0.844 (95% CI). The pathological examination revealed mild interstitial edema and closely packed seminiferous tubules in the left testes, indicating reversible damage in the torsion group.

Conclusions: On the pathological examination, all left testes in the torsion group were recoverable after four hours of torsion. Minimum ADC values can be used as an auxiliary method in the diagnosis of partial testicular torsion. Comparing minimum ADC values between the affected and non-affected testicles can be a useful tool in the early diagnosis of incomplete testicular torsion.