madman
Super Moderator
When to ask for an MRI of the scrotum (2021)
Abstract
Background: Multiparametric MRI of the scrotum has been established as a useful second-line diagnostic tool for the investigation of scrotal diseases. Recently, recommendations on clinical indications for scrotal MRI were issued by the Scrotal and Penile Imaging Working Group of the European Society of Urogenital Radiology.
Objective: To update current research on when to ask for an MRI of the scrotum.
Methods: PubMed database was searched for original articles and reviews published during 2010- 2021.
Results: Eighty-three articles fulfilled the search criteria. Scrotal MRI is mainly recommended after inconclusive US findings or inconsistent with the clinical examination and should be asked in the following cases: differentiation between intratesticular and paratesticular lesions (in rare cases of uncertain US findings), characterization of paratesticular and intratesticular lesions (when US findings are indeterminate), discrimination between germ cell and sex cord-stromal testicular tumors, local staging of testicular malignancies (in patients planned for testis-sparing surgery), differentiation between seminomas and non-seminomatous tumors (when immediate chemotherapy is planned and orchiectomy is delayed), assessment of acute scrotum and scrotal trauma (rarely needed, in cases of nondiagnostic US findings). Although preliminary data show promising results in the evaluation of male infertility, no established role for mpMRI still exists.
Conclusion: Multiparametric MRI of the scrotum, by assessing morphologic and functional data represents a valuable problem-solving tool, helping to improve our understanding of the nature of scrotal pathology and the process of spermatogenesis. The technique may improve patient care and reduce the number of unnecessary surgical procedures.
1. INTRODUCTION
Color Doppler ultrasonography (CDUS) represents the imaging modality of choice for the initial assessment of scrotal pathology.1-9 It is a safe, widely available, easily performed, inexpensive technique, and does not use ionizing radiation. CDUS is highly sensitive and accurate in the assessment of scrotal diseases, often guiding proper treatment. Current guidelines, including the National Comprehensive Cancer Network and the European Association of Urology, advocate the use of US for the evaluation of a suspected testicular mass.8,10 However, conventional US has limitations associated with operator-dependence, relatively small field of view, and difficulties in tissue characterization. Accurate differentiation of the nature of scrotal lesions, especially lesions of small size is not always possible, based on sonographic features.11-13 Diagnoses, such as a minor tear in the tunica albuginea in blunt scrotal trauma or chronic epididymoorchitis and partial or delayed torsion may sometimes be missed on sonography.14-18 The introduction of multiparametric US (including CDUS) real-time elastography and contrast-enhanced US into clinical practice has improved the diagnostic performance of standard US in the investigation of scrotal diseases.19-23
Multiparametric MRI (mpMRI) of the scrotum has emerged as a valuable supplemental technique for the investigation of scrotal pathology.7-9,11,12,15,24-46 Scrotal MRI due to the wide field of view and multiplanar capabilities depicts in excellent anatomic detail both testes, epididymides, spermatic cords, and inguinal regions. The technique provides high soft-tissue contrast, high sensitivity for contrast enhancement, and functional information, it is less dependent on the operator compared to US and does not include ionizing radiation. Scrotal MRI allows differentiation between intratesticular and paratesticular lesions and accurate tissue characterization, by showing the presence of fat, hemorrhage, fibrosis, fluid content, and contrast-enhancing tissue. MRI findings may narrow the differential diagnosis, helping in planning more precise treatment strategies and reducing the need for unnecessary surgical explorations. 7-9,11,12,15,24-46
Recently, the Scrotal and Penile Imaging Working Group (SPIWG) appointed by the board of the European Society of Urogenital Radiology (ESUR) has produced recommendations on clinical indications for scrotal MRI, based on literature published before 2016 and combined expertise of the group.24 MRI of the scrotum is primarily recommended for the characterization of paratesticular and intratesticular lesions in questionable cases when US findings are indeterminate, and for the identification and localization of undescended testes. The technique may provide valuable information in the preoperative planning, local staging, and histologic characterization of testicular germ cell neoplasms (TGCNs), in selected cases. It represents a supplemental, problem-solving tool for the investigation of the acute scrotum and scrotal trauma, following equivocal US findings.24 Scrotal MRI may prove reliable in differentiating between TGCNs and sex cord-stromal tumors, specifically in characterizing Leydig cell tumors (LCTs), allowing the adoption of conservative surgery and active surveillance, in compliant patients, as treatment options.24,47 The protocol of scrotal MRI should include axial T1-weighted imaging (T1WI), axial and coronal T2-weighted imaging (T2WI), axial diffusion-weighted imaging (DWI), and coronal subtracted dynamic contrast-enhanced (DCE) imaging.24
*In this review, we summarize current research on when to ask for an MRI of the scrotum
Main Findings (Indication for Pathologies)
3.1 Scrotal lesions
3.1.1 Lesion localization: intratesticular versus paratesticular
3.1.2 Paratesticular lesions
3.1.3 Intratesticular lesions
3.1.3.1 Lesion characterization: benign versus malignant
3.1.3.2 Germ cell versus sex cord-stromal testicular tumors
3.1.4 Local staging and histologic characterization of TGCNs
3.2 Acute scrotal diseases
3.2.1 Acute scrotum
3.2.2 Scrotal trauma
3.3 Undescended testes
3.4 Infertility
4 CONCLUSIONS
Although, CDUS remains the primary modality for the investigation of scrotal pathologies, mpMRI may be used as a valuable diagnostic adjunct. The technique represents a tool of high diagnostic performance, providing morphologic and functional information. The main goal in scrotal imaging is to reduce the number of unnecessary radical surgical explorations. MRI greatly helps by improving scrotal lesion characterization.
Based on recommendations published by the SPIWG and a review of the recent literature, scrotal MRI should be asked for the following: (1) discrimination between intratesticular and paratesticular lesions (rarely needed), (2) characterization of paratesticular and intratesticular lesions, in case of ambiguous US findings, (3) differentiation between germ cell and sex cord-stromal testicular neoplasms, especially in case of small, nonpalpable testicular tumors, incidentally found on US, (4) preoperative local staging of testicular germ cell neoplasms, in candidates for testis-sparing surgery, (5) differentiation between seminomas and nonseminomas, when immediate chemotherapy is needed, (6) assessment of acute scrotum and scrotal trauma (in rare cases of equivocal US findings, as a complimentary examination), and (7) detection and localization of undescended testes, following uncertain US findings. Although, reported preliminary data are promising, the potential role of mpMRI in the assessment of impaired spermatogenesis in infertile men is still under investigation. New and specialized MRI techniques have recently been added to the MRI protocol of the scrotum, helping us to improve our knowledge of the nature of scrotal masses and the extremely complex process of spermatogenesis.
Abstract
Background: Multiparametric MRI of the scrotum has been established as a useful second-line diagnostic tool for the investigation of scrotal diseases. Recently, recommendations on clinical indications for scrotal MRI were issued by the Scrotal and Penile Imaging Working Group of the European Society of Urogenital Radiology.
Objective: To update current research on when to ask for an MRI of the scrotum.
Methods: PubMed database was searched for original articles and reviews published during 2010- 2021.
Results: Eighty-three articles fulfilled the search criteria. Scrotal MRI is mainly recommended after inconclusive US findings or inconsistent with the clinical examination and should be asked in the following cases: differentiation between intratesticular and paratesticular lesions (in rare cases of uncertain US findings), characterization of paratesticular and intratesticular lesions (when US findings are indeterminate), discrimination between germ cell and sex cord-stromal testicular tumors, local staging of testicular malignancies (in patients planned for testis-sparing surgery), differentiation between seminomas and non-seminomatous tumors (when immediate chemotherapy is planned and orchiectomy is delayed), assessment of acute scrotum and scrotal trauma (rarely needed, in cases of nondiagnostic US findings). Although preliminary data show promising results in the evaluation of male infertility, no established role for mpMRI still exists.
Conclusion: Multiparametric MRI of the scrotum, by assessing morphologic and functional data represents a valuable problem-solving tool, helping to improve our understanding of the nature of scrotal pathology and the process of spermatogenesis. The technique may improve patient care and reduce the number of unnecessary surgical procedures.
1. INTRODUCTION
Color Doppler ultrasonography (CDUS) represents the imaging modality of choice for the initial assessment of scrotal pathology.1-9 It is a safe, widely available, easily performed, inexpensive technique, and does not use ionizing radiation. CDUS is highly sensitive and accurate in the assessment of scrotal diseases, often guiding proper treatment. Current guidelines, including the National Comprehensive Cancer Network and the European Association of Urology, advocate the use of US for the evaluation of a suspected testicular mass.8,10 However, conventional US has limitations associated with operator-dependence, relatively small field of view, and difficulties in tissue characterization. Accurate differentiation of the nature of scrotal lesions, especially lesions of small size is not always possible, based on sonographic features.11-13 Diagnoses, such as a minor tear in the tunica albuginea in blunt scrotal trauma or chronic epididymoorchitis and partial or delayed torsion may sometimes be missed on sonography.14-18 The introduction of multiparametric US (including CDUS) real-time elastography and contrast-enhanced US into clinical practice has improved the diagnostic performance of standard US in the investigation of scrotal diseases.19-23
Multiparametric MRI (mpMRI) of the scrotum has emerged as a valuable supplemental technique for the investigation of scrotal pathology.7-9,11,12,15,24-46 Scrotal MRI due to the wide field of view and multiplanar capabilities depicts in excellent anatomic detail both testes, epididymides, spermatic cords, and inguinal regions. The technique provides high soft-tissue contrast, high sensitivity for contrast enhancement, and functional information, it is less dependent on the operator compared to US and does not include ionizing radiation. Scrotal MRI allows differentiation between intratesticular and paratesticular lesions and accurate tissue characterization, by showing the presence of fat, hemorrhage, fibrosis, fluid content, and contrast-enhancing tissue. MRI findings may narrow the differential diagnosis, helping in planning more precise treatment strategies and reducing the need for unnecessary surgical explorations. 7-9,11,12,15,24-46
Recently, the Scrotal and Penile Imaging Working Group (SPIWG) appointed by the board of the European Society of Urogenital Radiology (ESUR) has produced recommendations on clinical indications for scrotal MRI, based on literature published before 2016 and combined expertise of the group.24 MRI of the scrotum is primarily recommended for the characterization of paratesticular and intratesticular lesions in questionable cases when US findings are indeterminate, and for the identification and localization of undescended testes. The technique may provide valuable information in the preoperative planning, local staging, and histologic characterization of testicular germ cell neoplasms (TGCNs), in selected cases. It represents a supplemental, problem-solving tool for the investigation of the acute scrotum and scrotal trauma, following equivocal US findings.24 Scrotal MRI may prove reliable in differentiating between TGCNs and sex cord-stromal tumors, specifically in characterizing Leydig cell tumors (LCTs), allowing the adoption of conservative surgery and active surveillance, in compliant patients, as treatment options.24,47 The protocol of scrotal MRI should include axial T1-weighted imaging (T1WI), axial and coronal T2-weighted imaging (T2WI), axial diffusion-weighted imaging (DWI), and coronal subtracted dynamic contrast-enhanced (DCE) imaging.24
*In this review, we summarize current research on when to ask for an MRI of the scrotum
Main Findings (Indication for Pathologies)
3.1 Scrotal lesions
3.1.1 Lesion localization: intratesticular versus paratesticular
3.1.2 Paratesticular lesions
3.1.3 Intratesticular lesions
3.1.3.1 Lesion characterization: benign versus malignant
3.1.3.2 Germ cell versus sex cord-stromal testicular tumors
3.1.4 Local staging and histologic characterization of TGCNs
3.2 Acute scrotal diseases
3.2.1 Acute scrotum
3.2.2 Scrotal trauma
3.3 Undescended testes
3.4 Infertility
4 CONCLUSIONS
Although, CDUS remains the primary modality for the investigation of scrotal pathologies, mpMRI may be used as a valuable diagnostic adjunct. The technique represents a tool of high diagnostic performance, providing morphologic and functional information. The main goal in scrotal imaging is to reduce the number of unnecessary radical surgical explorations. MRI greatly helps by improving scrotal lesion characterization.
Based on recommendations published by the SPIWG and a review of the recent literature, scrotal MRI should be asked for the following: (1) discrimination between intratesticular and paratesticular lesions (rarely needed), (2) characterization of paratesticular and intratesticular lesions, in case of ambiguous US findings, (3) differentiation between germ cell and sex cord-stromal testicular neoplasms, especially in case of small, nonpalpable testicular tumors, incidentally found on US, (4) preoperative local staging of testicular germ cell neoplasms, in candidates for testis-sparing surgery, (5) differentiation between seminomas and nonseminomas, when immediate chemotherapy is needed, (6) assessment of acute scrotum and scrotal trauma (in rare cases of equivocal US findings, as a complimentary examination), and (7) detection and localization of undescended testes, following uncertain US findings. Although, reported preliminary data are promising, the potential role of mpMRI in the assessment of impaired spermatogenesis in infertile men is still under investigation. New and specialized MRI techniques have recently been added to the MRI protocol of the scrotum, helping us to improve our knowledge of the nature of scrotal masses and the extremely complex process of spermatogenesis.
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