Scrotal disorders: evaluation of testicular enhancement patterns at dynamic contrast-enhanced subtraction MR imaging

Testicular Torsion: Twists and Turns

Testicular torsion is one of the common causes of acute scrotal pain. This review discusses the clinical and sonographic findings of intravaginal and extravaginal testicular torsion, including the normal sonographic and vascular anatomy of the testis. The role of color flow Doppler and spectral Doppler is also emphasized in the patient's complete, incomplete, and intermittent testicular torsion. Sonographic features of testicular torsion mimics, such as vasculitis, venous thrombosis, scrotal edema, and technical parameters, are also presented. A brief description of new developments such as contrast-enhanced ultrasound, dynamic contrast magnetic resonance imaging, and near-infrared imaging is included.

Multicenter assessment of ultrasound of the spermatic cord in children with acute scrotum

PURPOSE

Intravaginal or extravaginal spermatic cord torsion is a diagnostic challenge for the surgeon and radiologist. Color Doppler sonography can be inaccurate, leading to dangerous false-negative results. To date, no single reliable test has been able to provide 100% diagnostic accuracy. The direct visualization of the twisted cord during emergency high resolution ultrasonography has been proposed to avoid systematic and abusive surgical exploration. The aim of this multicenter study was to assess the validity and reproducibility of high resolution ultrasonography based management of acute scrotum in children.

MATERIALS AND METHODS

A total of 919 patients from 11 European university hospitals underwent color Doppler sonography and high resolution ultrasonography for acute scrotum between 1992 and 2005. The spermatic cord was studied along its complete length to detect a spiral twist. The surgical findings were correlated with the preoperative results.

RESULTS

A total of 208 patients had spermatic cord torsion proved at surgery. Intratesticular vascularization was absent in the affected testis in only 158 cases (76%). In contrast, high resolution ultrasonography detected the twist as a snail shell-shaped mass, measuring 7 to 33 mm, in 199 patients (96%). High resolution ultrasonography revealed a linear cord for all other causes of acute scrotum (711 patients) with a specificity of 99%. The radiologist training level was the best predictive factor of high resolution ultrasonography reliability (p <0.05).

CONCLUSIONS

High resolution ultrasonography based management of acute scrotum is reliable and reproducible. Thanks to its high sensitivity and specificity for the diagnosis of spermatic cord torsion, high resolution ultrasonography can significantly improve the management of acute scrotum in children.

Dynamic contrast-enhanced subtraction magnetic resonance imaging in diagnostics of testicular torsion

OBJECTIVES

To retrospectively correlate the magnetic resonance imaging (MRI) diagnosis with the surgical findings and/or clinical outcomes in patients presenting with an acute scrotum.

METHODS

From January 1997 to June 2004, 39 selected patients presenting with an acute scrotum underwent dynamic contrast-enhanced subtraction MRI as a 24-hour stand-by examination. The MRI diagnosis was based solely on the presence or absence of testicular contrast enhancement, without respect to the clinical history or physical examination findings.

RESULTS

Contrast enhancement of the affected and normal testes could be accurately compared in all cases. The MRI diagnosis was testicular torsion (no testicular contrast enhancement, n = 13), nonspecific (reduced to normal enhancement, n = 10), appendiceal torsion (n = 3), and epididymitis (n = 13). The surgical findings and/or subsequent clinical outcomes showed that MRI diagnosis of testicular torsion was accurate in all 13 cases. Furthermore, exploration revealed testicular torsion in 1 case with very little enhancement. The sensitivity and specificity of MRI in the diagnosis of testicular torsion was 93% (13 of 14) and 100% (25 of 25), respectively. Although MRI detected testicular perfusion, 5 of the 6 patients with clinical suspicion of intermittent torsion underwent surgical exploration.

CONCLUSIONS

MRI is a highly accurate imaging modality for the diagnosis of testicular torsion. However, it could not be used to rule out intermittent torsion and the clinical use of negative findings for an MRI torsion test was less than 100% specificity. Because this was a preliminary retrospective study, the true clinical value of MRI should be evaluated by prospective studies.

Hodentorsion: Diagnose, Differenzialdiagnose und Therapie im Kindesalter

Acute scrotum represents an emergency situation although testicular torsion is present in less than 20% of the cases. Sonography has meanwhile become the definitive modality for diagnosis. Its increasing use before surgical intervention has led to technical improvements in ultrasound diagnostics and critical assessment of ultrasound criteria to exclude testicular torsion as well as standardization of examination procedures. Central arterial and venous perfusion shown to be bilaterally equal on Doppler sonography is the most important criterion for excluding torsion. This article discusses other criteria such as the "resistance index," comparison of parenchymal structure of both testes, evidence for spermatic cord torsion, or differences between the sides in perfusion of the testicular parenchyma and highlights the difficulties involved in partial and intermittent testicular torsion. Alternative investigative methods and the significance of sonography in the differential diagnosis of other underlying causes are addressed. In summary, the combination of interpreting B-mode imaging, color Doppler, and power Doppler sonography and analyzing Doppler flow curves after clinical examination results in successful and conclusive evaluation of the testes in cases of acute scrotum in boys.

Magnetic resonance imaging of experimental testicular torsion

We investigated the feasibility of contrast enhanced (CE)-dynamic magnetic resonance imaging (MRI) for the detection of testicular torsion induced hypoperfusion in an experimental rat model. Adult Sprague-Dawley rats were subjected to unilateral testicular torsion of 360 or 720 degrees. After 1 h, the tail veins of the anaesthetized rats were cannulated and T2 -, diffusion-weighted and T1-weighted CE-dynamic MRI were subsequently performed by a 1.5 T MRI scanner. On apparent diffusion coefficient (ADC) images, the region of interest values of the ischaemic and control testes was compared. From CE-dynamic MR images, the maximal slopes of contrast enhancement were calculated and compared. In testicular torsion of 360 degrees, the maximal slope of contrast enhancement was 0.072%/s vs. 0.47%/s in the contralateral control testis (p < 0.001). A torsion of 720 degrees diminished the slope of contrast enhancement to 0.046%/s vs. 0.37%/s in the contralateral testis (p < 0.001). Diminished blood flow during torsion also followed in decreased ADC values in both 360 degrees (12.4% decrease; p < 0.05) and 720 degrees (10.8% decrease; p < 0.001) of torsion. Torsion of the testis causes ipsilateral hypoperfusion and decreased gadolinium uptake in a rat model that can be easily detected and quantified by CE-dynamic MRI. In diffusion-weighted MRI images, acute hypoperfusion results in a slight decrease of ADC values. Our results suggest that CE-dynamic MRI in combination with diffusion-weighted MRI can be used to detect compromised blood flow due to acute testicular torsion.

Gray-Scale and Color Doppler Sonography of Scrotal Disorders in Children: An Update

Ultrasonography (US) is well suited to the study of pathologic conditions of the scrotum in children. US provides excellent anatomic detail; when color Doppler and power Doppler imaging are added, testicular perfusion can be assessed. Gray-scale, color Doppler, and power Doppler US were used to study a spectrum of scrotal disorders in 750 boys aged 1 day to 17 years. The entities studied included processus vaginalis-related disorders (cryptorchidism, inguinal-scrotal hernia, and hydrocele); varicocele; acute scrotum (epididymo-orchitis, torsion of the testicular appendages, and testicular torsion); scrotal tumors; testicular microlithiasis; scrotal trauma; and systemic diseases with scrotal involvement. When combined with the results of clinical and physical examination, the information obtained with US is sufficient to enable diagnosis in most cases of scrotal disease. Moreover, color Doppler imaging is essential for differentiation between processes such as epididymo-orchitis or torsion of the testicular appendages and testicular torsion, which have similar clinical manifestations (pain, swelling, and redness) but are managed differently.

Magnetic resonance imaging and ultrasound evaluation of penile and testicular masses

The purpose of this study is to present the role of ultrasonography and MRI in the investigation of testicular and penile masses, as well as to review the literature. This article is based on our experience with 230 patients who presented with acute or subacute scrotal pain or painless enlargement of the scrotum or penis. Gray scale and color Doppler ultrasonography (CDU) were applied in all cases. In 73 cases, the final diagnosis was established by surgery and in 157 cases by follow-up. MRI was performed in 48 cases. Ultrasonography was the initial imaging modality in all cases. It provided detailed anatomic information with high sensitivity and accuracy in cases of torsion, inflammation, varicocele and trauma. In cases of tumor, US showed the presence of the mass in all cases, while it additionally revealed certain characteristic features of tissue constitution and blood supply. In most cases, differentiation between various types of tumors or differentiation between malignant and benign lesions was impossible. MRI, besides the detailed anatomic imaging, also provided a certain degree of tissue specificity. MRI could help in the detection and staging of penile cancer and in the evaluation of testicular and scrotal masses, especially when a diagnostic dilemma occurred on ultrasonographic examination. Ultrasonography, combining gray scale and color techniques, is irreplaceable in the diagnostic work-up of scrotal and penile masses, while MRI can serve as a problem solving diagnostic modality.

MRI in the diagnosis of testicular Leydig cell tumour

We report the appearance of three cases of Leydig cell tumours on MRI. This imaging method showed well-defined and peripheral intratesticular tumours displaying marked and homogeneous enhancement when contrast medium was used. This latter finding was only observed in Leydig cell tumours when they were compared in a series of 104 patients with different scrotal pathologies.

Continuous arterial spin-labeling perfusion magnetic resonance imaging of the human testis1

RATIONALE AND OBJECTIVES

The purpose of this study was to determine if continuous arterial spin-labeling perfusion magnetic resonance imaging could be used to detect testicular perfusion in human subjects.

MATERIALS AND METHODS

Continuous arterial spin-labeling magnetic resonance perfusion imaging was performed in seven normal male volunteers and in one patient with a painful scrotum following vasectomy.

RESULTS

Normal testicular blood flow was demonstrated in 14 of 14 normal testes in seven volunteers, as well as in two normally perfused testes in the post-vasectomy patient. A change in the steady state magnetization was observed in all of the normally perfused testes of the seven volunteers.

CONCLUSION

It is possible to detect blood flow to the normally perfused testes using noninvasive spin-labeling perfusion magnetic resonance imaging. This modality could potentially, in future investigations, be used to image patients with suspected testicular torsion and resultant testicular ischemia.

Sonography of the scrotum

Ultrasonography (US) with a high-frequency (7.5-10-MHz) transducer has become the imaging modality of choice for examination of the scrotum. US examination can provide information valuable for the differential diagnosis of a variety of disease processes involving the scrotum that have similar clinical manifestations (eg, pain, swelling, or presence of mass). The pathologic condition that may be at the origin of such symptoms can vary from testicular torsion to infection to malignancy. The ability of color and power Doppler US to demonstrate testicular perfusion aids in reaching a specific diagnosis in patients with acute scrotal pain. This review covers the anatomy of the scrotum and the scanning protocol for scrotal US, as well as detailed descriptions of disease processes and their US appearances. Newly described conditions such as intratesticular varicoceles and other benign intratesticular cystic lesions are also discussed.

Scrotal imaging

Color Doppler ultrasound has been the mainstay for the evaluation of the scrotum in a variety of clinical settings. However, ultrasonography results are not always accurate or conclusive. Despite the high cost and limited availability, magnetic resonance imaging with the dynamic contrast-enhanced subtraction technique provides accurate information on morphology as well as blood flow. Infrared scrotal thermography increases accuracy in the diagnosis of varicocele. This article attempts to summarize recent advances in scrotal imaging with regard to testicular and extratesticular disorders.

From the archives of the AFIP: tumors and tumorlike lesions of the testis: radiologic-pathologic correlation

Testicular carcinoma represents only 1% of all neoplasms in men, but it is the most common malignancy in the 15-34-year-old age group. Germ cell tumors constitute 95% of all testicular tumors. Germ cell tumors are a varied group of neoplasms whose imaging features reflect their underlying histologic characteristics. Seminomas are generally well-defined homogeneous lesions, whereas the nonseminomatous tumors (embryonal carcinoma, yolk sac tumor, choriocarcinoma, teratoma, and mixed germ cell tumor) have a much more varied appearance. Germ cell tumors follow a predictable pattern of spread via the lymphatic drainage to the retroperitoneal nodes. Choriocarcinoma, which has a proclivity for early hematogenous spread, is a notable exception. Testicular tumors may also arise from the sex cords (Sertoli cells) and stroma (Leydig cells). Although 90% of these tumors are benign, there are no reliable imaging criteria to differentiate them from malignant masses. Some benign testicular masses can be recognized, obviating an unwarranted orchiectomy. A dilated rete testis is a normal variant and appears as a series of small tubules near the mediastinum testis. Other benign lesions that can be suspected on the basis of imaging findings and history include intratesticular cysts, epidermoid cysts, congenital adrenal hyperplasia, and sarcoidosis.