Magnetic resonance imaging of experimental testicular torsion

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. P 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.

Role of Strain Elastography in the Evaluation of Testicular Torsion: An Experimental Study

OBJECTIVES

To evaluate the utility of real-time strain elastography in experimentally induced testicular torsion at different degrees and torsion hours.

METHODS

Thirty-one Wistar albino rats were divided into 4 torsion groups by twisting left testes (group I, sham operated; group II, 360°; group III, 720°; and group IV, 1080°). Elastography was applied at the 8th and 24th hours of torsion. Elasticity patterns (pattern 1, soft testis; pattern 2, moderately soft testis; pattern 3, predominantly hard testis; and pattern 4, almost entirely hard testis) and strain ratios were recorded. Histopathologic evaluation was done at the 24th hour. Interobserver agreement was analyzed.

RESULTS

Changes in elastographic patterns and strain ratios among groups II, III, and IV were statistically significant at both hours as determined by both radiologists (P < .01). Elastographic patterns changed from 2 to 3 in groups II and III to 4 in group III between the 8th and 24th hours (P < .05), but in group IV, patterns were reversed, and pattern 1 was observed at both hours. Pathologically severe necrosis (grade 4) was seen in left testes in group IV. In the other groups, pathologic grading in the left testes was as follows: mostly grade 1 in groups I and II and mostly grade 2 in group III. Elastography showed that right testes were affected in group IV, with significant differences in elastographic patterns and strain ratios (P < .01). Interobserver agreement for elastographic patterns in right testes was substantial at the 8th hour (κ = 0.72) and otherwise excellent (κ = 0.81-0.85). Concordance of strain ratios between observers was excellent for right and left testes at the 8th and 24th hours (intraclass correlation coefficients, 0.990 at the 8th hour and 0.987 at the 24th hour).

CONCLUSIONS

Our results show that real-time strain elastography can be a complementary method in the evaluation of testicular tissue in testicular torsion and can guide surgeons in their surgical approach.

Magnetic Resonance Imaging of Acute Scrotum

Background and Aims:

The aim of the pilot study was to evaluate the feasibility of dynamic contrast enhanced (CE)-magnetic resonance imaging (MRI) in the detection of testicular ischemia and its ability to differentiate testicle torsion from other causes of acute scrotum.

Material and Methods:

Seventeen boys or young men with an acute scrotum were included in the prospective study during the time period from October 2001 to December 2005. The median age of the patients was 16,4 (7–44) years. The duration of the symptoms preceding the MRI study varied from six hours to 30 days. The study protocol included physical examination by a surgeon, laboratory tests and Doppler ultrasound (DUS) and finally testicles were imaged by using a 1,5 T MRI scanner; T1-weighted and diffusion weighted images were produced. The gadolinium uptake, reported as the region of interest (ROI) perfusion values and presented as curves, was compared between the affected and contralateral testicle. In testicles with normal blood circulation the ROI values increased during the imaging time. Nine patients were operated on, because the spermatic cord torsion could not be excluded by clinical or DUS findings.

Results and Conclusions:

All the normal testicles gave increasing ROI values meanwhile all three testicles with torsion gave constantly low values referring to no perfusion. Other causes of acute scrotum, such as epididymitis and torsion of testicular appendage seemed to be related with normal perfusion. Dynamic CE-MRI seems to show reliably ischemia of testicle and thus it may be helpful in selecting patients with acute scrotum for urgent operation.

Visualization of seminiferous tubules in rat testes in normal and diseased conditions by high-resolution MRI

Rat seminiferous tubules were visualized for the first time using high-spatial-resolution MRI and their MRI features were investigated under normal and various kinds of pathological conditions. All testes images were obtained at 4.7 T with a dedicated quadrature surface coil. T2- and T2 *-weighted images with in-plane resolution of 66 x 66 microm(2) demonstrated numerous tubular structures with low-signal-intensity walls and high-signal-intensity lumens tightly packed throughout the entire testicle. The tubular structures were attributed to the seminiferous tubules in the histological specimens. In testicular ischemia, T2*-weighted images demonstrated prominent low-signal-intensity bands along the radiate veins and normal-appearing seminiferous tubules. As the ischemic condition persisted, the contour of the seminiferous tubules became less visible on both T2- and T2*-weighted images, reflecting the disorganization of the seminiferous epithelia and severe interstitial edema. Changes in the images of testes treated with glycerol or diethylstilbestrol, a synthetic estrogen hormone, were also investigated. In the chronic spermatogenic impairment caused by these substances, extensive shrinkage of the seminiferous tubules was demonstrated. High-resolution MRI aids in noninvasive evaluation of seminiferous tubules, and therefore has potential as a diagnostic test for human testes.

Diffusion-weighted imaging of adnexal torsion

We report the diffusion-weighted imaging findings (DWI) of a case with ovarian torsion. Magnetic resonance imaging revealed a large cyst within a non-enhancing ovary. DWI depicted restricted diffusion which in turn was found to be related with the infarction of the ovary in the laparoscopic salpingo-oophorectomy performed.

Testicular torsion: a race against time

Torsion of the testis is a medical emergency that is most commonly encountered in adolescents. Patients usually present with sudden onset scrotal pain associated with nausea and vomiting. On physical examination the involved testis is tender, high riding and usually horizontal. The cremasteric reflex is usually absent. If left untreated irreversible ischaemia starts appearing in 6 h. Doppler ultrasound is the diagnostic imaging of choice. The ideal treatment is surgical exploration and orchidectomy with contralateral orchidopexy or bilateral orchidopexy depending on the condition of the affected testis. If surgical options are delayed then manual detorsion should be attempted.