|Year : 2019 | Volume
| Issue : 1 | Page : 97-100
The diagnostic value of magnetic resonance imaging in the diagnosis of nonpalpable undescended testis
Adel M Al Wakeel1, Sameh M Azab1, Mohamed M Soliman2
1 Department of Radiodiagnosis, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Radiodiagnosis, Ministry of Health, Cairo, Egypt
|Date of Submission||18-Apr-2017|
|Date of Acceptance||18-Jun-2017|
|Date of Web Publication||17-Apr-2019|
Mohamed M Soliman
Meleeg Village, Shebin El Kom, Al Menoufia
Source of Support: None, Conflict of Interest: None
The aim of this study was to assess the value of MRI to localize undescended nonpalpable testis before laparoscopy operation.
Conventional MRI sequences when combined with diffusion-weighted imaging sequence is a good tool for tissue characterization as they provide functional and structural information about tissues. It could detect the site and viability of nondescended testes.
Patients and methods
During a period of 12-month duration from January 2016 to December 2016, 20 male patients ranging in age from 5 months to 25 years (mean = 9.86 ± 6.91 years) were included in this study. All patients selected were referred to the MRI scanning for assessment of nonpalpable undescended testes that are clinically diagnosed before laparoscopy.
Conventional MRI combined with diffusion-weighted images gives better results as regards the location of undescended testis and also detection of viability of testicular tissue. This technique had the highest sensitivity (100%), specificity (90%), and accuracy (90%).
Conventional MRI with fat-suppression technique when combined with diffusion-weighted imaging gives the highest accuracy for localization and detection of viability of undescended nonpalpable testis.
Keywords: diffusion, magnetic, resonance, testis
|How to cite this article:|
Al Wakeel AM, Azab SM, Soliman MM. The diagnostic value of magnetic resonance imaging in the diagnosis of nonpalpable undescended testis. Menoufia Med J 2019;32:97-100
|How to cite this URL:|
Al Wakeel AM, Azab SM, Soliman MM. The diagnostic value of magnetic resonance imaging in the diagnosis of nonpalpable undescended testis. Menoufia Med J [serial online] 2019 [cited 2020 Jun 6];32:97-100. Available from: http://www.mmj.eg.net/text.asp?2019/32/1/97/256095
| Introduction|| |
Cryptorchidism is synonymous with undescended testis, which is defined as absence of one or both testes in the scrotum. Young patients with undescended testis are commonly seen in pediatric clinics . Nonpalpable testis clinically cannot be detected, and may be intra-abdominal or absent. It may be vanishing or atrophic . Preoperative assessment of nonpalpable testis is of great value for choosing the optimal type of surgical procedure. In case of diagnoses of absent or vanishing testes on MRI, there is no need for surgical exploration . Multiple imaging procedures are indicated for assessment of nonpalpable testes before surgical laparoscopy. Variable limitations as well as contraindications could be detected, such as high cost value, high risky intervention, difficult technique, radiation exposure, need for contrast with its expected complications, and risk for anesthesia. Imaging procedures include ultrasonography with complementary Doppler study, computed tomography, conventional magnetic imaging, magnetic resonance angiography, and magnetic resonance venography . Ultrasonography is the most available and very cheap procedure of assessment of undescended testes. However, it shows low sensitivity as proven statistically . Conventional MRI has moderate sensitivity for assessment of absent testis with very poor specificity as well. Functioning intra-abdominal testes are less efficiently seen using conventional MRI sequences. Atrophied nonpalpable testes could not be assessed using conventional MRI; hence, conventional MRI is less efficient for surgical laparoscopy decision, regardless of whether or not required . Fat-suppressed T2-weighted imaging and diffusion-weighted imaging are excellent procedures for the diagnosis of cryptorchidism, as they prevent unneeded laparoscopy . Fat-suppressed T2-weighted imaging is highly sensitive to inflammation and water content , and hence it is a very good tool for distinction between lymph nodes and testes . Diffusion-weighted imaging sequence is an excellent procedure as tissue characterization is obtained. It provides functional and structural information about testicular tissues .
| Aim|| |
The aim of this study was to assess the value of MRI in proper localization and viability detection of nonpalpable testes before unneeded laparoscopy.
| Patients and Methods|| |
Twenty male patients between 5 months and 25 years of age (mean = 9.86 ± 6.91 years) were included in our study. All patients selected were referred by clinicians to the MRI scanning for assessment of nonpalpable undescended testes. All patients had undergone laparoscopy and the results of MRI compared with laparoscopy findings were obtained.
Patients who were clinically diagnosed with absence of a palpable testis in the scrotum, perineum, or inguinal canal were included in the study. All selected patients underwent laparoscopy for result comparison.
Patients with disorders of sexual development or ambiguous genitalia were excluded from the study.
Before magnetic resonance scan, all included patients were subjected to the following:
- Patient's history, complaint, and any medical-related conditions
- Physical examination, which was carried out by the referring doctor with written documentation
- Viewing any previous ultrasound scans.
MRI sequences include T1-weighted imaging, T2-weighted imaging, and fat-suppressed T2-weighted imaging and diffusion-weighted imaging of b value of 800 s/mm 2 were performed during the same MRI examination in all patients. The imaging parameters are demonstrated in [Table 1]. All patients were placed in supine position with the head pointing toward the magnet (head first supine technique). The laser beam localizer was pointed over the symphysis pubis. Only seven of our scanned young patients needed sedation under the supervision of an anesthesia specialist using chloral hydrate syrup at a dose of 1 ml/kg body weight. There were no postanesthesia problems [Figure 1] and [Figure 2].
|Figure 1: Case 1: (a) Axial T1-weighted imaging (T1WI), (b) axial T2WI, (c) coronal T2WI, and (d) sagittal T2WI showing small sized right intracanalicular undescended testis, which displays low signal intensity in axial T1WI and high signal in axial T2WI, coronal T2WI, and sagittal T2WI. (e) Diffusion axial images of the pelvis at b value of 800 s/mm2, as it showed the best quality, otherwise low spatial resolution with some anatomic distortion is seen with other sequences. It was showing high signal intensity of the suspected right pelvic testis (arrows).|
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|Figure 2: Case 2: (a) Axial T1-weighted imaging (T1WI) MRI showing small sized left intracanalicular undescended testis (UDT), which displays low signal intensity (b) T2WI with fat suppression showing small sized left intracanalicular UDT, which displays low signal intensity. (c) Diffusion WI at b value of 800 s/mm2 showing low signal intensity of left intracanalicular UDT (free diffusion) (arrow), thus denoting testicular atrophy. Note high signal intensity of the inguinal lymph nodes (restricted diffusion) (arrowhead).|
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Data were statistically described in terms of mean ± SD, and range, or frequencies (number of cases) and percentages when appropriate. Comparison of sensitivity and overall accuracy between the different techniques was made using the χ2-test (McNemar test). Accuracy was represented using the terms sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy. All statistical calculations were performed using computer program statistical package for the social science (SPSS Inc., Chicago, Illinois, USA).
| Results|| |
Twenty male patients between 5 months and 25 years of age (mean = 9.86 ± 6.91 years) were included in our study. All patients included were referred by clinicians to the MRI unit for assessment of nonpalpable undescended testes before laparoscopy. All patients had undergone laparoscopy and the results of MRI compared with laparoscopy findings were obtained. According to clinical diagnosis, there were three bilateral and the remaining were unilateral; eight on the right side and nine on the left side.
Abdominal, pelvic, and scrotal ultrasound scans were performed to all patients before MRI examinations. Ultrasound scan detected 9/20 cases of undescended testes, with a diagnostic accuracy of 45% (seven in intracanalicular location, two in the lower abdomen intimately related to iliac vessels, and 11 cases not visualized at all along the pathway of testicular descent in the scrotum, inguinal canal, and pelvis) [Table 2].
|Table 2: Identification of undescended testis using ultrasonography before MRI examination (n=20)|
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MRI sequences, T1-weighted imaging, T2-weighted imaging, fat-suppressed T2-weighted imaging, and diffusion-weighted images, were performed to all patients. The results of MRI were compared with laparoscopic findings [Table 3] & [Table 4]. According to the laparoscopic evaluation, the final diagnoses of the location of undescended testes were as follows: intracanalicular (n = 9, 45%), low intra-abdominal (n = 7, 35%), high intra-abdominal (n = 2, 10%). However, the testes were absent (testicular agenesis) in three (15%) cases [Table 3].
|Table 3: Location-based distribution of nonpalpable undescended testes according to laparoscopic findings (n=20)|
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|Table 4: Detection of viability of nonpalpable undescended testes using combined diffusion-weighted imaging and conventional magnetic resonance imaging in comparison with laparoscopy (n=20)|
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On imaging, testicular anatomic location is hyperintense elliptic area on the diffusion-weighted images, low signal on T1-weighted imaging, and high signal on T2 and T2 with fat suppression. Especially on diffusion-weighted images, testes were recorded for focal areas of hyperintensity that did not represent T2 shine-through from fluid-containing structures.
The combination conventional MRI and diffusion-weighted imaging was the most sensitive and the most accurate technique, facilitating the localization and location of 18 testes with a specificity of 90% and sensitivity of 100% as compared with laparoscopy findings, as shown in [Table 4]. Only two cases were misdiagnosed as atrophied testes by MRI sequences and when compared by laparoscopy, they were diagnosed with absent testes. Moreover, we noted that the undescended testes were small comparative to the normal descended one.
| Discussion|| |
In our study, we used diffusion-weighted imaging sequence with a b value of 800 s/mm 2 for assessment of the testis. Testicular high-cellularity content was best obtained on MRI images with a b value of 800 s/mm 2 without a T2 shine-through effect. However, there was low spatial resolution with some anatomic distortion at such a high b value. Therefore, for anatomic details, T2-weighted imaging, fat-suppression imaging, and T2-weighted imaging were very good for detection of anatomic landmarks.
In our study, there were no significant differences in sensitivity and specificity between diffusion-weighted imaging and conventional imaging (P > 0.05), the conventional and combined MRI (P > 0.05), and between diffusion-weighted imaging and combined imaging (P > 0.05) for the assessment of undescended testis.
In this study, the differentiation between the lymph nodes at the inguinal region and testes using diffusion-weighted imaging was not so easy in some cases as both structures display similar signal. However, this problem was resolved using fat-suppressed T2-weighted imaging, as lymph nodes were seen at a lower signal intensity compared with the testes.
This was augmented by the previous study findings of Kato et al. , who said that, there was a sharp contrast between the testis and surrounding structures obtained by sequence of fat-suppressed T2-weighted imaging. However, it was difficult to detect the testis by that sequence when the large retained fluids are seen in abdomen. In our study, diffusion-weighted imaging was the most accurate sequence .
Krishnaswami  said that the accuracy of conventional MRI was very bad as it is used for assessment of the site of atrophied testicles, which makes conventional MRI a less dependable technique in giving advice for differentiation between those who need surgery from those who do not. In our study, addition of diffusion-weighted imaging sequence to the conventional MRI sequences was excellent for assessment testicular viability or atrophy (sensitivity 100%, specificity 90%, and accuracy 90%) before laparoscopy [Table 4].
Kantarci et al.  hypothesized that, on the T2-weighted imaging, the low signal intensity of the testis was because it was small in size and noted atrophy of the seminiferous tubules. On the diffusion-weighted imaging images, however, the low signal intensity was due to the marked low cellularity of the atrophied testis. According to these details, it is speculated that testis with low signal intensity on diffusion-weighted images are no longer viable .
From the results of Kato et al. , they said that all undescended testis cases in which they could see a testicular nubbin or could not make a radiological diagnosis before laparoscopy were finally diagnosed as a testicular nubbin or blinded ending at the structure of the cord as well; they reported a specificity of 97.3% and a negative predictive value of 100%. Therefore, they recommended that if the radiologist is unable to see intra-abdominal or intracanalicular testes as well using these combined MRI sequences, testicular nubbin or a blinded ending cord structure be written and that finding be confirmed before surgery .
Our study had some limitations. First, the sample of the patients was small as the selected patients were admitted for laparoscopy for comparison with MRI scans. Not all who underwent MRI scan were admitted to surgery. Our results have to be confirmed with a larger prospective study. Second, patients younger than 6 years needed sedation or general anesthesia for an optimal MRI examination. We believe that these disadvantages will be diminished with technical improvement.
| Conclusion|| |
MRI is a noninvasive procedure, on which no ionizing radiation is used; it could be used for assessment of positioning of nonpalpable undescended testis, when compared with ultrasonography, which has minimal benefit in clinical practice (specificity of 45%). In our study, we recommended that a combination of conventional MRI including fat-suppression and diffusion-weighted imaging sequences is the most effective mean of localizing nonpalpable undescended testes. Diffusion-weighted imaging is an excellent tool in the assessment of testicular viability or atrophy (sensitivity of 100%, specificity of 90%, and accuracy of 90%).
Moreover, we noted that the undescended testes were small comparative to the normal descended one.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]