MRI of testicular malignancies

3.0 T diffusion tensor imaging and fiber tractography of the testes in nonobstructive azoospermia

PURPOSE

To assess the role of 3.0 T Diffusion Tensor Imaging (DTI) and Fiber Tractography (FT) of the testes in the work-up of nonobstructive azoospermia (NOA).

METHODS

This prospective study included consecutive NOA men and controls. A 3.0 T scrotal MRI was performed, including DTI. The testicular apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were calculated. FT reconstructions were created. The Kruskal-Wallis test, followed by pairwise comparisons, assessed differences in testicular ADC and FA between NOA histologic phenotypes (group 1: hypospermatogenesis; group 2: maturation arrest; and group 3: Sertoli cell-only syndrome) and normal testes. The Mann-Whitney-U test compared ADC and FA between NOA testes with positive and negative sperm retrieval. Visual assessment of the testicular fiber tracts was performed. Fiber tracts fewer in number, of reduced thickness, disrupted and/or disorganized were considered "abnormal". Chi-square tests and binary logistic regression analysis assessed variations in testicular fiber tracts morphology.

RESULTS

Twenty-nine NOA men (mean age: 39 ± 5.93 years) and 20 controls (mean age: 26 ± 5.83 years) were included for analysis. Higher ADC (p < 0.001) and FA (p < 0.001) was observed in NOA testes compared to controls. Differences in FA were found between groups 1 and 3 (0.07 vs 0.10, p = 0.26) and groups 2 and 3 (0.07 vs 0.10, p = 0.03), but not between groups 1 and 2 (p = 0.66). An increase in FA was observed in NOA testes with Sertoli cell-only syndrome compared to hypospermatogenesis and maturation arrest. FA was higher in NOA testes with negative results for the presence of sperm compared to those with positive results (0.09 vs 0.07, p = 0.006). FT showed "abnormal" fiber tracts in NOA testes (p < 0.001).

CONCLUSION

3.0 T DTI and FT provide an insight into deranged spermatogenesis in NOA testes.

Nomogram for predicting testicular yolk sac tumor in children based on age, alpha-fetoprotein, and ultrasonography

Objective

To establish a predictive model for distinguishing testicular benign or yolk sac tumors in children.

Methods

We retrospectively analyzed data for 119 consecutive patients with unilateral testicular tumors treated at a single institution from June 2014 to July 2020. The patients were divided into the benign (n = 90) and yolk sac (n = 29) tumor groups based on the pathological diagnosis. We recorded patient age, serum markers [serum alpha-fetoprotein (AFP), human chorionic gonadotropin], and tumor ultrasonic findings (maximum diameter, ultrasonic echo, blood flow signal). Predictive factors were identified using descriptive statistical methods. A nomogram was established for preoperative prediction. An additional 46 patients were used as a validation cohort to verify the model.

Results

Patients with testicular yolk sac tumors were younger (median age: 14.0 vs. 34.0 months, P = 0.001) and had a higher incidence of elevated AFP levels (93.1% vs. 2.2%, P < 0.001). Ultrasonography indicated that testicular yolk sac tumors tended to have larger maximum diameters (26.5 ± 11.3 vs. 16.6 ± 9.2 cm, P < 0.001), a higher proportion of hypoechoic masses (44.8% vs. 8.9%, P < 0.001), and a higher incidence of masses with strong blood flow signals (93.1% vs. 5.6%, P < 0.001). A nomogram based on age, AFP levels, and ultrasound blood flow signals effectively predicted the probability of yolk sac tumor in children, with an accuracy of 0.98 (95% confidence interval: 0.984-1.003). The Brier score of the nomogram was 0.0002.

Conclusion

A nomogram based on age, AFP levels, and ultrasound blood flow signals can effectively predict the probability of testicular yolk sac tumor preoperatively, aiding in clinical decision-making and patient counseling.

Diffusion tensor imaging and fiber tractography of the normal epididymis

PURPOSE

To evaluate the feasibility of diffusion tensor imaging (DTI) and fiber tractography (FT) of the normal epididymis and to determine normative apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values.

METHODS

Twenty-eight healthy volunteers underwent MRI of the scrotum, including DTI on a 3.0 T system. For each anatomic part of the epididymis (head, body and tail) free-hand regions of interest were drawn and the mean ADC and FA were measured by two radiologists in consensus. Parametric statistical tests were used to determine intersubject differences in ADC and FA between the anatomic parts of each normal epididymis and between bilateral epididymides. Fiber tracts of the epididymis were reconstructed using the MR Diffusion tool.

RESULTS

The mean ADC and FA of the normal epididymis was 1.31 × 10-3 mm2/s and 0.20, respectively. No differences in ADC (p = 0.736) and FA (p = 0.628) between the anatomic parts of each normal epididymis were found. Differences (p = 0.020) were observed in FA of the body between the right and the left epididymis. FT showed the fiber tracts of the normal epididymis. Main study's limitations include the following: small number of participants with narrow age range, absence of histologic confirmation and lack of quantitative assessment of the FT reconstructions.

CONCLUSION

DTI and FT of the normal epididymis is feasible and allow the noninvasive assessment of the structural and geometric organization of the organ.

Discriminating Malignant from Benign Testicular Masses Using Multiparametric Magnetic Resonance Imaging-A Prospective Single-Center Study

Objective: The objective of this study was to prospectively assess the extent to which magnetic resonance imaging (MRI) can differentiate malignant from benign lesions of the testis. Materials and Methods: All included patients underwent multiparametric testicular MRI, including diffusion-weighted imaging (DWI) and subtraction dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). Subsequently, all patients underwent a histopathological examination via orchiectomy or testicular biopsy/partial resection. The Kolmogorov-Smirnov test, t-test, Mann-Whitney U test, Fisher's exact test, and logistic regression were applied for statistical analysis. Results: We included 48 male patients (median age 37.5 years [range 18-69]) with testicular tumors. The median tumor size on MRI was 2.0 cm for malignant tumors and 1.1 cm for benign tumors (p < 0.05). A statistically significant difference was observed for the type (type 0-III curve, p < 0.05) and pattern of enhancement (homogeneous, heterogeneous, or rim-like, p < 0.01) between malignant and benign tumors. The minimum apparent diffusion coefficient (ADC) value was 0.9 for benign tumors and 0.7 for malignant tumors (each ×103 mm2/s, p < 0.05), while the mean ADC was 0.05. The mean ADC value was significantly lower for malignant tumors; the mean ADC value was 1.1 for benign tumors and 0.9 for malignant tumors (each ×103 mm2/s, p < 0.05). The sensitivity, specificity, positive predictive value, and negative predictive value of multiparametric MRI for differentiating malignant from benign testicular lesions were 94.3%, 76.9%, 91.7%, and 83.3%, respectively. The surgical procedures performed included orchiectomy (n = 33; 71.7%) and partial testicular resection (n = 11; 23.9%). Histopathology (HP) revealed malignancy in 35 patients (72.9%), including 26 with seminomas and 9 with non-seminomatous germ cell tumors (NSGCTs). The HP was benign in 13 (27.1%) patients, including 5 with Leydig cell tumors. Conclusions: Malignant and benign tumors differ in MRI characteristics in terms of the type and pattern of enhancement and the extent of diffusion restriction, indicating that MRI can be an important imaging modality for the accurate diagnosis of testicular lesions.

Imaging of pediatric testicular tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Primary intratesticular tumors are uncommon in children, but incidence and risk of malignancy both sharply increase during adolescence. Ultrasound is the mainstay for imaging the primary lesion, and cross-sectional modalities are often required for evaluation of regional or distant disease. However, variations to this approach are dictated by additional clinical and imaging nuances. This paper offers consensus recommendations for imaging of pediatric patients with a known or suspected primary testicular malignancy at diagnosis and during follow-up.

A first look into radiomics application in testicular imaging: A systematic review

The aim of this systematic review was to evaluate the state of the art of radiomics in testicular imaging by assessing the quality of radiomic workflow using the Radiomics Quality Score (RQS) and the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). A systematic literature search was performed to find potentially relevant articles on the applications of radiomics in testicular imaging, and 6 final articles were extracted. The mean RQS was 11,33 ± 3,88 resulting in a percentage of 31,48% ± 10,78%. Regarding QUADAS-2 criteria, no relevant biases were found in the included papers in the patient selection, index test, reference standard criteria and flow-and-timing domain. In conclusion, despite the publication of promising studies, radiomic research on testicular imaging is in its very beginning and still hindered by methodological limitations, and the potential applications of radiomics for this field are still largely unexplored.

An Overview of the Role of Multiparametric MRI in the Investigation of Testicular Tumors

Simple Summary

Although conventional ultrasonography remains the primary imaging modality for the assessment of testicular tumors, multiparametric MRI of the scrotum, which combines morphologic and functional data, serves as a powerful adjunct. Based on the recommendations issued by the Scrotal and Penile Imaging Working Group of the European Society of Urogenital Radiology, scrotal MRI is strongly recommended after equivocal US findings. In cases of testicular masses, the main clinical indications are as follows: lesion characterization when sonographic findings are non-diagnostic, discrimination between germ-cell and non-germ-cell testicular tumors, local staging of testicular tumors in patients who are candidates for testis-sparing surgery, and preoperative histological characterization of testicular germ-cell tumors in selected cases. This article aims to provide an overview of the role of multiparametric MRI in the investigation of testicular tumors.

Abstract

Conventional ultrasonography represents the mainstay of testis imaging. In cases in which ultrasonography is inconclusive, scrotal MRI using a multiparametric protocol may be used as a useful problem-solving tool. MRI of the scrotum is primarily recommended for differentiating between benign and malignant testicular masses when sonographic findings are ambiguous. This technique is also accurate in the preoperative local staging of testicular tumors and, therefore, is recommended in patients scheduled for testis-sparing surgery. In addition, MRI may provide valuable information regarding the histological characterization of testicular germ-cell tumors, in selected cases. Scrotal MRI may also help in the differentiation between testicular germ-cell neoplasms and non-germ-cell neoplasms. Axial T1-weighted imaging, axial and coronal T2-weighted imaging, axial diffusion-weighted imaging, and coronal subtracted dynamic contrast-enhanced imaging are the minimum requirements for scrotal MRI. A variety of MRI techniques—including diffusion tensor imaging, magnetization transfer imaging, proton MR spectroscopy, volumetric apparent diffusion coefficient histogram analysis, and MRI-based radiomics—are being investigated for testicular mass characterization, providing valuable supplementary diagnostic information. In the present review, we aim to discuss clinical indications for scrotal MRI in cases of testicular tumors, along with MRI findings of common testicular malignancies.

The Diagnostic Value of the Added MR Imaging of the Scrotum in the Preoperative Workup of Sonographically Indeterminate Testicular Lesions—A Retrospective Multicenter Analysis

Background: The purpose of this study was to retrospectively analyze the diagnostic accuracy of magnetic resonance imaging (MRI) examinations of the scrotum in comparison with standard ultrasound (US) and histopathology. Methods: A retrospective multi-center analysis of MRI examinations of the scrotum performed between 06/2008 and 04/2021 was conducted. Results: A total of n = 113 patients were included. A total of 53 histopathologies were available, with 52.8% malignant and 50.9% benign findings. Related to histopathology, imaging was true negative, false negative, false positive, and true positive in 4.1%, 2.1%, 25.0% and 37.5% for standard ultrasound (US) and 9.1%, 1.8%, 25.5% and 43.6% for MRI. Sensitivity, specificity, positive predictive value and negative predictive value were 94.7%, 20.0%, 36.0% and 88.9% for US and 85.7%, 72.8%, 52.1% and 93.7% for MRI, respectively. Benign lesions were significantly smaller than malignant ones in standard US (p = 0.001), histopathology (p = 0.001) and MRI (p = 0.004). The size of malignant tumors did not differ significantly between histopathology and standard US (0.72) and between histopathology and MRI (p = 0.88). Conclusions: MRI shows good sensitivity and specificity for the estimation of testicular tumors in this collective. Benign lesions are significantly smaller than malignant ones. Both MRI and US can estimate the size of malignant tumors adequately.

Diffusion-Weighted MRI in the Genitourinary System

Diffusion weighted imaging (DWI) constitutes a major functional parameter performed in Magnetic Resonance Imaging (MRI). The DW sequence is performed by acquiring a set of native images described by their b-values, each b-value representing the strength of the diffusion MR gradients specific to that sequence. By fitting the data with models describing the motion of water in tissue, an apparent diffusion coefficient (ADC) map is built and allows the assessment of water mobility inside the tissue. The high cellularity of tumors restricts the water diffusion and decreases the value of ADC within tumors, which makes them appear hypointense on ADC maps. The role of this sequence now largely exceeds its first clinical apparitions in neuroimaging, whereby the method helped diagnose the early phases of cerebral ischemic stroke. The applications extend to whole-body imaging for both neoplastic and non-neoplastic diseases. This review emphasizes the integration of DWI in the genitourinary system imaging by outlining the sequence's usage in female pelvis, prostate, bladder, penis, testis and kidney MRI. In gynecologic imaging, DWI is an essential sequence for the characterization of cervix tumors and endometrial carcinomas, as well as to differentiate between leiomyosarcoma and benign leiomyoma of the uterus. In ovarian epithelial neoplasms, DWI provides key information for the characterization of solid components in heterogeneous complex ovarian masses. In prostate imaging, DWI became an essential part of multi-parametric Magnetic Resonance Imaging (mpMRI) to detect prostate cancer. The Prostate Imaging-Reporting and Data System (PI-RADS) scoring the probability of significant prostate tumors has significantly contributed to this success. Its contribution has established mpMRI as a mandatory examination for the planning of prostate biopsies and radical prostatectomy. Following a similar approach, DWI was included in multiparametric protocols for the bladder and the testis. In renal imaging, DWI is not able to robustly differentiate between malignant and benign renal tumors but may be helpful to characterize tumor subtypes, including clear-cell and non-clear-cell renal carcinomas or low-fat angiomyolipomas. One of the most promising developments of renal DWI is the estimation of renal fibrosis in chronic kidney disease (CKD) patients. In conclusion, DWI constitutes a major advancement in genitourinary imaging with a central role in decision algorithms in the female pelvis and prostate cancer, now allowing promising applications in renal imaging or in the bladder and testicular mpMRI.

[Magnetic resonance imaging accuracy and utility for testicular cancer diagnosis]

PURPOSE

The purpose of our study is to analyze the imaging findings described in MRI and the histopathologic type of testicular lesions to determine which findings are the best predictors of malignancy.

MATERIALS AND METHODS

Forty six (46) patients with testicular lesions were initially studied with ultrasound (US) and with testicular MRI (tMRI) on a 1.5-T magnet. MRIs were reviewed by a radiologist with 8 years of experience and imaging findings such as the size of the lesion, the signal intensity in T1, T2 weighted sequences, and the enhancement after endovenous contrast administration, were correlated with the histopathologic diagnosis. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were analyzed.

RESULTS

The enhancement after administration of contrast was the finding of better performance with a sensitivity, specificity, PPV and NPV of 90 (71-97), 47 (24-71), 74 (56-87) and 73 (40-92), respectively. Meanwhile, the results for hypointense/heterogeneous lesions in T2 weighted sequences and with enhancement with intravenous contrast were 87 (49-84), 47 (44-89), 74 (55-86) y 67 (35-89), respectively.

CONCLUSION

The finding of a testicular lesion of low signal intensity and heterogeneous in T2 weighted sequences, with IV contrast enhancement represents a valuable predictor of malignancy. The latter being the most sensitive as a predictor of malignancy.

Magnetic Fields and Cancer: Epidemiology, Cellular Biology, and Theranostics

Humans are exposed to a complex mix of man-made electric and magnetic fields (MFs) at many different frequencies, at home and at work. Epidemiological studies indicate that there is a positive relationship between residential/domestic and occupational exposure to extremely low frequency electromagnetic fields and some types of cancer, although some other studies indicate no relationship. In this review, after an introduction on the MF definition and a description of natural/anthropogenic sources, the epidemiology of residential/domestic and occupational exposure to MFs and cancer is reviewed, with reference to leukemia, brain, and breast cancer. The in vivo and in vitro effects of MFs on cancer are reviewed considering both human and animal cells, with particular reference to the involvement of reactive oxygen species (ROS). MF application on cancer diagnostic and therapy (theranostic) are also reviewed by describing the use of different magnetic resonance imaging (MRI) applications for the detection of several cancers. Finally, the use of magnetic nanoparticles is described in terms of treatment of cancer by nanomedical applications for the precise delivery of anticancer drugs, nanosurgery by magnetomechanic methods, and selective killing of cancer cells by magnetic hyperthermia. The supplementary tables provide quantitative data and methodologies in epidemiological and cell biology studies. Although scientists do not generally agree that there is a cause-effect relationship between exposure to MF and cancer, MFs might not be the direct cause of cancer but may contribute to produce ROS and generate oxidative stress, which could trigger or enhance the expression of oncogenes.

Testicular tumors: discriminative value of conventional MRI and diffusion weighted imaging

To explore the feasibility of using conventional MRI features combined with apparent diffusion coefficient (ADC) values for the differential diagnosis of testicular tumors.A total of 63 patients with pathologically confirmed testicular tumors were enrolled in this study. In particular, there were 46 cases of malignant lesions and 17 cases of benign lesions. All patients underwent conventional magnetic resonance imaging (MRI) and diffusion weighted imaging. Multivariate logistic regression models and receiver operating characteristic curves were constructed to assess diagnostic accuracies.T2-homogeneity, intratumoral septa, and peritumoral infiltration were more common in the malignant group, and capsule sign was more common in the benign group (P < .05 for all). The mean ADC value of the malignant group was lower than that of the benign group (P < .05). When the ADC value ≤ 0.90 × 10-3 mm2/s, the diagnosis tended to be malignancy. The conventional MRI model could achieve better diagnostic accuracy than ADC values alone (P < .05). Compared with the conventional MRI model, the specificity and accuracy of the full model (ADC and conventional MRI model) increased by 9.8% and 3.2%, respectively. T2-homogeneity and T2-hypointensity were more common in seminoma and lymphoma, cystic changes were more common in nonseminomatous germ cell tumor (NSGCT), and intratumoral septa was more common in seminoma (P < .05 for all). The ADC value of NSGCT was larger than seminoma, and lymphoma was the smallest (P < .05 for all). Cystic changes, T2-hypointensity, intratumoral septa, and ADC value were independent factors for differentiating the seminoma, NSGCT, and lymphoma subgroups.A combination of conventional MRI features and ADC values can improve the diagnostic efficiency for differentiating benign and malignant testicular tumors, and can additionally distinguish different subtypes of malignant testicular tumors.

Ultrasonography of the scrotum: Revisiting a classic technique

Conventional US is the primary imaging modality for the evaluation of the scrotum, due to its high resolution, availability, cost-effectiveness and absence of ionizing radiation. Grayscale and color Doppler US provide a comprehensive assessment of scrotal diseases. The technique represents the mainstay for imaging of acute scrotum. US is highly accurate in the detection, localization and characterization of scrotal masses. Multiparametric US, including conventional US, contrast-enhanced US and tissue elastography has improved the diagnostic performance of the technique in the assessment of testicular diseases. MRI represents a valuable supplemental imaging tool for the investigation of scrotal pathology, mainly recommended in cases of indeterminate US findings. Recommendations recently issued by the European Society of Urogenital Radiology Scrotal and Penile Imaging Working Group (ESUR-SPIWG) refer to the use of scrotal sonography for the evaluation of pathologic entities, including testicular microlithiasis, small, non-palpable incidentally detected testicular masses, varicocele and scrotal trauma. In this review, the technical specifications for scrotal US and the normal sonographic findings are presented. Grayscale and color Doppler US findings of common acute scrotal diseases and scrotal masses are discussed. The complimentary role of multiparametric US and scrotal MRI is addressed. ESUR-SPIWG's guidelines are also reviewed.

Testicular Germ Cell Tumors: Classification, Pathologic Features, Imaging Findings, and Management

Testicular germ cell tumors (TGCTs) demonstrate a wide variety of histopathologic, genetic, pathogenetic, and immunocytochemical characteristics and various clinical-biologic profiles and prognoses. Most TGCTs arise from an intratubular precursor cell referred to as germ cell neoplasia in situ (GCNIS), which is an embryonic germ cell with the potential to differentiate into a plethora of embryonic and extraembryonic lineages. Advances in pathologic examination and genetics paved the way for the 2016 World Health Organization (WHO) classification system, which recognizes two pathogenetically distinct groups of TGCTs. Although postpubertal tumors originate from GCNIS, almost all prepubertal tumors belong to the non-GCNIS category. Molecular testing for chromosome 12p amplification helps to distinguish the two tumor categories. Imaging techniques such as US, CT, MRI, and fluorine 18 (18F)-fluorodeoxyglucose PET/CT are pivotal to the diagnosis and staging, evaluation of complications and treatment response, and long-term surveillance of TGCTs. In addition, select MRI findings may help to differentiate a seminoma from a nonseminomatous mixed TGCT. Accurate diagnosis of TGCTs has therapeutic and prognostic implications. Although seminomas show exquisite response to chemotherapy and radiation therapy, postpubertal teratomas are highly resistant to both. The 2016 WHO classification system introduced changes in the diagnosis and management of TGCTs, including the development of new treatment and follow-up guidelines. Radiologists play an essential role in the optimal treatment of patients with TGCTs. Online supplemental material is available for this article. ©RSNA, 2021.

Synchronous bilateral testicular cancer with discordant histopathology occurring in a 20-year-old patient: A case report and review of the literature

INTRODUCTION

Bilateral testicular tumors are very rare, accounting for 1%-5% of all testicular germ-cell tumors (TGCTs). The vast majority of primary bilateral TGCTs are metachronous, with synchronous tumors comprising approximately 0.5%-1% of all cases. Those occurring synchronously share mostly the same histological pattern, predominantly seminoma, with synchronous bilateral TGCTs (SBTGCTs) with discordant subtypes being extremely rare.

CASE PRESENTATION

We present the case of a 20-year-old male complaining of a palpable painless right testicular mass incidentally noticed during sexual intercourse. Ultrasonography (US) and magnetic resonance imaging (MRI) of the scrotum demonstrated bilateral testicular lesions, while staging with contrast-enhanced computed tomography (CT) exhibited normal findings. Right radical orchiectomy and left testis-sparing surgery (TSS) with concomitant onco-testicular sperm extraction (onco-TESE) were initially performed. Histology of the right testis revealed a mixed germ-cell tumor, consisting of seminoma and embryonal carcinoma, while that from the left testis disclosed embryonal carcinoma and intratubular germ-cell neoplasia unclassified (IGCNU) infiltrating the surgical margins. Hence, left orchiectomy was subsequently scheduled with histology unveiling IGCNU in the greatest part of the remaining testicular parenchyma. Following adjuvant chemotherapy, with bleomycin, etoposide, and cisplatin (BEP), the patient received testosterone replacement therapy and remained free of recurrence at an 18-month follow-up.

CONCLUSION

This case highlights both the rarity of a bilateral testicular tumor's synchronous appearance and its extremely infrequent discordant histopathology. A comprehensive review of the major series of SBTGCTs with discordant histology cited in the literature is additionally presented.

When to ask for an MRI of the scrotum

Background

Multiparametric MRI (mpMRI) 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 non‐diagnostic US findings) and detection and localization of undescended testes (in cases of inconlusive 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 on the nature of scrotal pathology and the process of spermatogenesis. The technique may improve patient care and reduce the number of unnecessary surgical procedures.

RNA-Binding Proteins Play an Important Role in the Prognosis of Patients With Testicular Germ Cell Tumor

Testicular germ cell tumors (TGCTs) are common urological neoplasms in young adult males. The outcome of TGCT depends on pathologic type and tumor stage. RNA-binding proteins (RBPs) influence numerous cancers via post-transcriptional regulation. The prognostic importance of RBPs in TGCT has not been fully investigated. In this study, we set up a prognostic risk model of TGCT using six significantly differentially expressed RBPs, namely, TRMT61A, POLR2J, DIS3L2, IFIH1, IGHMBP2, and NPM2. The expression profiles were downloaded from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression datasets. We observed by performing least absolute shrinkage and selection operator (LASSO) regression analyses that in the training cohort, the expression of six RBPs was correlated with disease-free survival in patients with TGCT. We assessed the specificity and sensitivity of 1-, 3-, 5-, and 10-year survival status prediction using receiver operating characteristic curve analysis and successfully validated using the test cohorts, the entire TCGA cohort, and Gene Expression Omnibus (GEO) datasets. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and gene set enrichment analyses were carried out to seek the possible signaling pathways related with risk score. We also examined the association between the model based on six RBPs and different clinical characteristics. A nomogram was established for TGCT recurrence prediction. Consensus clustering analysis was carried out to identify the clusters of TGCT with different clinical outcomes. Ultimately, external validations of the six-gene risk score were performed by using the GSE3218 and GSE10783 datasets downloaded from the GEO database. In general, our study constructed a prognostic model based on six RBPs, which could serve as independent risk factor in TGCT, especially in seminoma, and might have brilliant clinical application value.

Diffusion tensor imaging in evaluating testicular injury after unilateral testicular torsion and detorsion in rat model: A preliminary study

Diffusion tensor imaging (DTI) is a functional magnetic resonance sequence based on the movement of water molecules. This study attempted to investigate the feasibility of DTI in evaluating testicular injury after testicular torsion and detorsion. Seventy-two rats were randomly divided into the sham group, torsion group and detorsion group. The left testis in the sham group was brought out through a scrotal incision for 1 hr, and that of the torsion group was twisted 720^o clockwise for 1 hr and fixed to the scrotum, while the detorsion group was restored after being twisted 720° for 1 hr. Rats were further divided into four subgroups according to the set time, then performed DTI and histology analysis. The mean diffusion of the torsion and detorsion groups increased within 24 hr (p <.01), while it in the detorsion-1-week-group was lower than that in the detorsion-24-hr-group (p <.05). The fraction anisotropy of both experimental groups decreased in the acute phase (p <.01), while that of the detorsion-1-week-group increased (p <.01). Cosentino score in both experimental groups showed an increasing trend (p <.05). Besides, the spermatogenic ability of the detorsion-1-week-group decreased (p <.05). In conclusion, DTI was able to evaluate the injury after testicular torsion and detorsion.

Value of Intra-Perinodular Textural Transition Features from MRI in Distinguishing Between Benign and Malignant Testicular Lesions

Purpose

To compare the performance of histogram analysis and intra-perinodular textural transition (Ipris) for distinguishing between benign and malignant testicular lesions.

Patients and Methods

This retrospective study included 76 patients with 80 pathologically confirmed testicular lesions (55 malignant, 25 benign). All patients underwent preoperative T2-weighted imaging (T2WI) on a 3.0T MR scanner. All testicular lesions were manually segmented on axial T2WI, and histogram and Ipris features were extracted. Thirty enrolled patients were randomly selected to estimate the robustness of the features. We used intraclass correlation coefficients (ICCs) to evaluate intra- and interobserver agreement of features, independent t-test or Mann–Whitney U-test to compare features between benign and malignant lesions, and receiver operating characteristic curve analysis to evaluate the diagnostic performance of features.

Results

Eighteen histogram features and forty-eight Ipris features were extracted from T2WI of each lesion. Most (60/66) histogram and Ipris features had good robustness (ICC of both intra- and interobserver variabilities >0.6). Three histogram and nine Ipris features were significantly different between the benign and malignant groups. The area under the curve values for Energy, TotalEnergy, and Ipris_shell1_id_std were 0.807, 0.808, and 0.708, respectively, which were relatively higher than those of other features.

Conclusion

Ipris features may be useful for identifying benign and malignant testicular tumors but have no significant advantage over conventional histogram features.

Should We Use Contrast-Enhanced Ultrasound (CEUS) for the Characterization of Nonpalpable Testicular Lesions? An Analysis from a Cost-Effectiveness Perspective

PURPOSE

 Accurate characterization of testicular lesions is crucial to allow for correct treatment of malignant tumors and to avoid unnecessary procedures in benign ones. In recent years, contrast-enhanced ultrasound (CEUS) proved to be superior in specifying the dignity of small, nonpalpable testicular lesions (< 1.5 cm) compared to native B-mode and color Doppler ultrasound which were previously regarded as the primary imaging method. However, the cost-effectiveness of CEUS has not been evaluated yet. The aim of this study was to analyze the cost-effectiveness of CEUS as compared to unenhanced ultrasound for the characterization of nonpalpable testicular lesions.

METHODS

 A decision model based on Markov simulations estimated lifetime costs and quality-adjusted life years (QALYs) associated with unenhanced ultrasound and CEUS. Model input parameters were obtained from recent literature. Deterministic sensitivity analysis of diagnostic parameters and costs was performed. Also, probabilistic sensitivity analysis using Monte-Carlo Modelling was applied. The willingness-to-pay (WTP) was set to $100 000/QALY.

RESULTS

 In the base-case scenario, unenhanced ultrasound resulted in total costs of $5113.14 and an expected effectiveness of 8.29 QALYs, whereas CEUS resulted in total costs of $4397.77 with 8.35 QALYs. Therefore, the unenhanced ultrasound strategy was dominated by CEUS in the base-case scenario. Sensitivity analysis showed CEUS to be the cost-effective alternative along a broad range of costs.

CONCLUSION

 Contrast-enhanced ultrasound is a cost-effective imaging method for the characterization of nonpalpable testicular lesions.

Proton MR Spectroscopy in Assessing the Biochemical Milieu of Human Testes

Proton magnetic resonance spectroscopy (MRS), considered a connection between metabolism and anatomic and functional information provided by standard MRI, gives information on various tissue metabolites and their pathologic changes. Recently, proton MRS has been added as an adjunct tool to the multiparametric protocol of scrotal MRI, providing a new insight into the extremely complex biochemical milieu of normal and abnormal testes. This article reviews proton MR spectra of normal testes, showing age and bilateralism dependence. Disturbances of various metabolic pathways in testes of infertile men resulting in alterations of metabolite peaks are discussed. Preliminary data on proton MR spectra of testicular mass lesions are presented. LEVEL OF EVIDENCE: 5. TECHNICAL EFFICACY STAGE: 5.

T2-Weighted Image-Based Radiomics Signature for Discriminating Between Seminomas and Nonseminoma

Objective: To evaluate the performance of a T2-weighted image (T2WI)-based radiomics signature for differentiating between seminomas and nonseminomas.

Materials and Methods: In this retrospective study, 39 patients with testicular germ-cell tumors (TGCTs) confirmed by radical orchiectomy were enrolled, including 19 cases of seminomas and 20 cases of nonseminomas. All patients underwent 3T magnetic resonance imaging (MRI) before radical orchiectomy. Eight hundred fifty-one radiomics features were extracted from the T2WI of each patient. Intra- and interclass correlation coefficients were used to select the features with excellent stability and repeatability. Then, we used the minimum-redundancy maximum-relevance (mRMR) and the least absolute shrinkage and selection operator (LASSO) algorithms for feature selection and radiomics signature development. Receiver operating characteristic curve analysis was used to evaluate the diagnostic performance of the radiomics signature.

Results: Five features were selected to build the radiomics signature. The radiomics signature was significantly different between the seminomas and nonseminomas (p < 0.01). The area under the curve (AUC), sensitivity, and specificity of the radiomics signature for discriminating between seminomas and nonseminomas were 0.979 (95% CI: 0.873–1.000), 90.00 (95% CI: 68.3–98.8), and 100.00 (95% CI: 82.4–100.0), respectively.

Conclusion: The T2WI-based radiomics signature has the potential to non-invasively discriminate between seminomas and nonseminomas.

Infantile synchronous primary bilateral testicular germ cell tumor: a case report and review of the literature

Testicular tumors are uncommon in adults, accounting for <1% of all cancers, with testicular germ cell tumors (TGCTs) representing the majority (>95%) of reported cases. Adult and prepubertal TGCTs are fundamentally distinct and the latter is extremely rare, representing 1% of all pediatric solid tumors and having an annual incidence rate of 0.5-2/100,000 boys. Bilateral TGCTs (BTGCTs) account for 0.5-5% of all testicular tumors; the majority are metachronous, while the synchronous account for approximately 0.5-1%. A 16-month-old boy was admitted to our Urology Department with a 2-week history of a painless scrotal mass. Ultrasonography revealed a homogeneous hyperechoic solid mass with rich blood supply in the right testis, and no discernable testicular tissue. A well-delineated heterogeneous echo mass was found within the left testis. Contrast-enhanced computed tomography (CT) scan showed a significantly enhanced mass in the right testis and a mildly enhanced mass in the left testis. Serum alpha-fetoprotein (AFP) was 12,567 ng/mL, while β-human chorionic gonadotrophin (HCG) and total testosterone levels were normal. Accordingly, bilateral testicular tumors were the primary consideration. The patient underwent right radical inguinal orchiectomy with high ligation of the spermatic cord and left testicle-sparing surgery. Final pathology confirmed a pure yolk sac tumor (YST) from the right testis and a cystic mature teratoma from the left. The follow-up ultrasonography showed no recurrence, with serum AFP returned to normal by postoperative day 44. Synchronous primary BTGCT with teratoma and YST respectively can occur coincidently and successfully treated by testicle-sparing surgery.

Testis-sparing surgery for testicular masses: current perspectives

INTRODUCTION

Males who present with a palpable testis nodule are likely to have malignant germ cell tumor in >90% of cases. Therefore radical orchiectomy remains the standard of care for intratesticular tumors. However, due to the recent developments of high-frequency probes in ultrasonography, the incidence of detecting a small non-palpable testis tumor is higher and higher. These lesions are thought to be benign in more than 60-80% of cases, thus a radical orchiectomy should be considered an overtreatment. In addition to that, radical orchiectomy might cause infertility, psychological issues and endocrine disorders, hence an organ-sparing procedure in such cases should be pursued.

EVIDENCE ACQUISITION

Only fourteen reliable retrospective studies met the inclusion criteria. No prospective randomized trials have appeared in Medline database.

EVIDENCE SYNTHESIS

This review of the current literature has confirmed the safety and efficacy of testicular-sparing surgery in selected patients: 1) monorchid patients; 2) bilateral testis masses; 3) normal patients with a small, non-palpable masses detected with US, as long as the dimension of the lesion is up to 3 cm and not greater that 30% of the total volume of the organ.

CONCLUSIONS

According to the literature, testis sparing surgery is a safe and feasible procedure for patients presenting a benign small testis mass. The enthusiasm found in the literature should however be tempered as the small number of patients reported in the studies coupled with the absence of a prospective trial represent important limits that need to be overtaken. Therefore more robust and well-designed studies are needed.