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Efficiency of combined diffusion weighted imaging and conventional MRI in detection of clinically nonpalpable undescended testes
The Egyptian Journal of Radiology and Nuclear Medicine xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
The Egyptian Journal of Radiology and Nuclear Medicine journal homepage: www.sciencedirect.com/locate/ejrnm
Efficiency of combined diffusion weighted imaging and conventional MRI in detection of clinically nonpalpable undescended testes Susan A. Ali MD ⇑, Mohamed G. Mansour MD Radiodiagnosis Department, Ain Shams University Cairo, Egypt
a r t i c l e
i n f o
Article history: Received 1 August 2016 Accepted 27 September 2016 Available online xxxx Keywords: DWI Conventional MRI Combined MRI Undescended testes
a b s t r a c t Purpose: The goal of the study was to highlight the added value of combined DWI and conventional MRI in detecting clinically nonpalpable undescended testes. Patients and methods: Prospective study included 60 males referred for MRI evaluation of clinically diagnosed 66 nonpalpable undescended testes. MRI studies were performed using 1.5-T MRI machine and included axial and coronal spin-echo T1WIs, axial T2WIs, axial and coronal fat suppressed spin-echo T2WIs, and axial DWIs using three sets of b value (50, 400, and 800 s/mm2). All images were transferred to an independent workstation and evaluated by two radiologists for the presence or absence and location of the undescended testes. The findings were compared to laparoscopy results, and then, sensitivity, specificity, and accuracy were calculated for both conventional and combined (DWI and conventional) MRI. Results: According to laparoscopic findings, sensitivity, specificity and accuracy of conventional MRI were 73.91%, 100%, and 80% and 69.57%, 100%, and 76.67% for radiologists 1 and 2 respectively, and of combined MRI were 86.9%, 100%, and 90% and 82.61%, 100%, and 86.67% for radiologists 1 and 2 respectively. Conclusion: Adding DWIs to conventional MRI improves the sensitivity and accuracy of detecting clinically nonpalpable undescended testes. Ó 2016 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
1. Introduction Cryptorchidism or undescended testis (UDT) is the most common genital disorder identified at birth. The main reasons for treatment of cryptorchidism include increased risks of impairment of fertility potential, testicular malignancy, torsion and/or associated inguinal hernia [1].
Peer review under responsibility of The Egyptian Society of Radiology and Nuclear Medicine. ⇑ Corresponding author. E-mail addresses: [email protected] (S.A. Ali), [email protected] (M.G. Mansour).
Approximately 1% of males have undescended testes, 80% of them are clinically palpable and 20% are non-palpable. The term ‘nonpalpable testes’ implies that they cannot be detected on physical examination; they are intraabdominal, absent, vanishing or atrophic [2]. Preoperative detection and localization of testes can determine the optimal type of procedure and allow for appropriate future planning. In the case of vanishing or absent testes, imaging findings could obviate the need for surgical exploration [3]. Different imaging tools have been suggested for identifying and locating non-palpable testes preoperatively with some limitations. Imaging modalities include US (Ultrasonography), CT (computed tomography), routine MRI, MRA
http://dx.doi.org/10.1016/j.ejrnm.2016.09.017 0378-603X/Ó 2016 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article in press as: Ali SA, Mansour MG. . Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.09.017
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(magnetic resonance angiography) and MRV (magnetic resonance venography) [4]. Ultrasound is the least expensive and commonly used tool of all imaging techniques. However it showed low sensitivity in detecting non-palpable testes preoperatively [5]. Conventional MRI shows moderate specificity in diagnosing absent testes but poor sensitivity in detecting non-palpable testes. It appeared to be less efficient in localizing intra-abdominal functioning testes and showed limited sensitivity in localizing inguino-scrotal testes, but it fails to locate most of the atrophied testes, which makes conventional MRI less reliable in differentiating those children needing surgery from those who do not [6]. Additional fat-suppressed T2WI and DWI are useful sequences to improve the accuracy of diagnosing nonpalpable testes and preventing needless surgery [7]. DWI depicts abnormalities on the basis of tumor vascularity and cellularity [8]. Therefore, DWI facilitates characterization of tissue at the microscopic level in a mechanism different from T1 and T2 relaxation [9]. Intraabdominal testes are considerably more cellular than the adjacent tissues and organs, and thus, can be easily detected on DWIs owing to their increased signal intensity. Therefore, adding DWI to routine MRI improves identification of non-palpable undescended testes [10]. The goal of this study was to assess the added value of combined Diffusion-weighted imaging and conventional MRI sequences in proper localization of non-palpable testes before unneeded laparoscopy.
2. Patients and methods 2.1. Patients The study is prospective over the period from May 2014 to March 2016, and included 60 males (ranging in age from 15 months to 15 years with mean age 6.4 ± 3.9) referred for MRI evaluation of clinically diagnosed 66 nonpalpable undescended testes with non-conclusive ultrasonography findings. 54 cases were diagnosed of unilateral UDT (24 on the right side and 30 on the left side) with 6 cases clinically diagnosed of bilateral UDT. Patients with ambiguous genitalia or disorders of sexual development were excluded.
Conventional MRI examination included axial and coronal spin-echo T1-weighted sequence, axial T2-weighted sequence, axial and coronal fat suppressed spin-echo T2-weighted sequence, and axial DWI, slice thickness, 4 mm; interslice gap, 1 mm; field of view, 50 cm2. DWIs were performed using three sets of b value (50, 400, and 800 s/mm2). All MRI images including diffusion-weighted image sequences were transferred to an independent workstation.
2.3. Image analysis Two radiologists with different experiences (9 and 14 years respectively) in MR abdominal imaging independently reviewed the MR images and were aware of the patient’s clinical data. They recorded the presence or absence and the location of UDT. First, the DWIs (with b values of 50, 400, and 800 s/mm2) were reviewed alone, then the conventional MR images, and finally the combined (DWI and conventional) MR images. At DWIs, the abdomen was imaged for focal elliptic areas of hyperintensity, that did not represent T2 shine through from fluid-containing structures, recorded as testes, and their anatomic location was classified into intracanalicular, low intraabdominal, and high intraabdominal. On conventional MR images, testes appeared as elliptic areas hypointense on T1WIs and iso- or hyperintense on T2WIs, in the aforementioned locations. On the combined (DW and conventional) MR images, conventional MRI was used for anatomic localization of elliptic hyperintense areas on the DWIs.
2.4. Laparoscopy and histopathologic examination All the patients underwent laparoscopic exploration under general anesthesia within 2 weeks of the MR imaging to determine the location of all nonpalpable testes. Intraabdominal atrophic testes were treated with laparoscopic orchiectomy. Orchiectomy samples were taken for histopathologic examination.
2.5. Statistical analysis 2.2. MR imaging All MRI studies were performed with a 1.5-T MRI system (Achieva; Philips Medical Systems, Best, the Netherlands) using body coil (a phased-array coil). T1WIs, T2WIs and fat suppressed T2WIs as well as DWIs were performed during the same MRI examination for all patients. Images will be acquired with the patient is in supine position with head pointing to the magnet (head first supine; HFS). The body coil was securely tightened using straps to prevent respiratory artifacts. At the center the laser beam localizer will be placed over symphysis pubis. Chloral hydrate syrup at a dose of 1 ml/kg body weight was needed for children less than 5 years for sedation during MRI examination.
DWIs, conventional MRI, and combined (DWIs and conventional) MRI findings were compared with laparoscopy results. For each observer, sensitivity, specificity, and accuracy of location of the testes were calculated for DWIs, conventional MRI, and combined (DWIs and conventional) MRI. Data were statistically described in terms of mean ± standard deviation (±SD), and range, or frequencies (number of cases) and percentages when appropriate. Comparison of sensitivity and overall accuracy between the different techniques was done using Chi squared test (McNemar test). Accuracy was represented using the terms such as sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy. All statistical calculations were done using computer program.
Please cite this article in press as: Ali SA, Mansour MG. . Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.09.017
S.A. Ali, M.G. Mansour / The Egyptian Journal of Radiology and Nuclear Medicine xxx (2016) xxx–xxx
3. Results According to the laparoscopic findings, 48 undescended testes were diagnosed in 60 patients, and located as follows: 4 high intraabdominal, 24 low intraabdominal (Fig. 1), and 20 intracanalicular (Figs. 2–4), whereas, 18 testes were absent (testicular agenesis) as shown in Table 1. The combination of DWI and conventional MRI was the most accurate and sensitive technique, facilitating the localization of 40 testes by radiologist 1 and 38 testes by radiologist 2, with accuracy of 90% and 86.67%, compared to 80% and 76.67% for conventional MRI, respectively. Sensitivity of 86.96% and 82.61% by combined MRI compared to 73.91% and 69.57% by conventional MRI, was found for radiologists 1 and 2, respectively. However, both combined and conventional MR imaging had a specificity of 100% (Table 2). In 14 patients (23.33%), laparoscopy revealed testicular agenesis, compared to 20 patients (33.33%) reported using MRI combined imaging. By conventional MRI, UDTs were detected in 34 (56.66%) and 32 (53.33%) patients by radiologists 1 and 2, respectively, while by combined MRI, they detected UDTs in 40 (66.66%) and 38 (63.33%) patients, respectively, compared to 46 patients (76.66%) diagnosed with UDTs on laparoscopy. Radiologist 2 could not identify two cases of left high intraabdominal testes identified by radiologist 1 and confirmed by laparoscopy. Both radiolo-
3
gists could not identify two left UDTs on conventional and combined MRI that was left lower abdominal UDT by laparoscopy. Two right UDTs were not identified on both conventional and combined MRI by both radiologists and reported by laparoscopy as right low intraabdominal UDT. On two laparoscopic examinations, bilateral low intraabdominal atrophic UDT was detected and was overlooked on both conventional and combined MRI by both radiologists (Table 3). 4. Discussion The incidence of UDTs varies from 21% in preterm infants to 1.8–4.0% in term boys [11]. 80% of UDTs are clinically palpable and 20% of them are nonpalpable [12]. Nonpalpable testis implies that the testis cannot be detected on clinical examination [13]. Accurate diagnosis and appropriate surgical treatment are important for proper testicular function and can facilitate early detection of malignancy [14,15]. Preoperative localization of the testes aids in planning surgical approach, reducing extent of exploration and anesthesia time [16]. Laparoscopy is the most reliable diagnostic technique for the detection of nonpalpable UDTs; however, it is invasive [17–19]. Thus, different diagnostic imaging modalities have been used for detection and localization of nonpalpable UDTs including ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI) [20].
Fig. 1. 3 years old boy presented with right sided clinically nonpalpable testis. MRI imaging revealed a right low intraabdominal testis close to internal ring, showing intermediate signal intensity on axial T2WI (a), and marked hyperintensity on axial DWI (b) obtained with b value of 800 s/mm2.
Fig. 2. 15 months old boy presented with right sided clinically nonpalpable testis. MRI imaging revealed a right intracanalicular testis (arrowed), showing intermediate signal intensity (surrounded by mild vaginal hydrocele) on axial fat suppressed T2WI (a), and marked hyperintensity on axial DWI (b) obtained with b value of 800 s/mm2.
Please cite this article in press as: Ali SA, Mansour MG. . Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.09.017
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Fig. 3. 5 years old boy presented with right sided clinically nonpalpable testis. MRI imaging revealed a right intracanalicular testis (arrowed), surrounded by mild vaginal hydrocele and showing intermediate signal intensity on axial T1WI (a), axial and coronal T2WIs (b and c), and marked hyperintensity on axial DWI (d) obtained with b value of 800 s/mm2.
Fig. 4. 17 months old boy presented with left sided clinically nonpalpable testis. Conventional MRI imaging failed to detect the undescended testis on axial T2WIs (a), while on axial DWI obtained with b value of 800 s/mm2 (b), a markedly hyperintense small left intracanalicular testis (arrowed), was detected and confirmed by subsequent laparoscopy.
Table 1 Location based distribution of 66 clinically nonpalpable UDTs in 60 patients according to laparoscopy findings. Location
Absent
Intra-canalicular
Low intra-abdominal
High intra-abdominal
Total
Right testis Left testis Total
6 12 18
14 6 20
10 14 24
0 4 4
30 36 66
MRI is a noninvasive diagnostic imaging technique and does not entail ionizing radiation. A study done by Kanemoto et al. found that MRI has an accuracy, sensitivity and specificity of 85%, 86% and 79%, respectively, for the diagnosis of nonpalpable UDTs [21]. Another study conducted by Sarihan et al. found that MRI had sensitivity and specificity of 78.6% and 100%, respectively, in the detection of nonpalpable UDTs [22]. Both studies used conventional MRI techniques. In the current study, the performance of two radiologists with different levels of experience in interpreting the MRI findings of 60 patients, referred with clinically nonpalpable UDTs, was compared. Using MRI alone, the
sensitivity was 73.91% and 69.57%, while accuracy was 80% and 76.67% for radiologists 1 and 2, respectively. However, when DWI was added to conventional MRI, both sensitivity and accuracy were increased for radiologists 1 and 2 (sensitivity 86.96% and 82.61%; accuracy 90% and 86.67%). So, with combined DWI and conventional MRI, both radiologists performed better in detection and localization of UDTs and our results confirm that DWI findings complement that obtained with conventional MRI on identifying and locating undescended testes. Kato et al. reported that sensitivity, specificity, positive and negative predictive values for combined DWI and conventional MRI versus the operative findings were 100%,
Please cite this article in press as: Ali SA, Mansour MG. . Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.09.017
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Table 2 Comparison of performance indices of conventional MRI and combined (DWI and conventional) MRI in 60 patients by two radiologists according to laparoscopy findings. R Radiologist, TP True positive, FN False negative, TN True negative, FP False positive, PPV Positive predictive value, NPV Negative predictive value, DWI Diffusion Weighted Imaging, Con. MRI Conventional magnetic resonance imaging, Com. MRI Combined imaging using conventional MRI and DWI. Imaging tool
R.
TP (No.)
FN (No.)
TN (No.)
FP (No.)
PPV (%)
NPV (%)
Sensitivity (%)
Specificity (%)
Accuracy (%)
Con. MRI
R1 R2
34 32
12 14
14 14
0 0
100 100
53.85 50
73.91 69.57
100 100
80 76.67
Com. MRI
R1 R2
40 38
6 8
14 14
0 0
100 100
70 63.64
86.96 82.61
100 100
90 86.67
Table 3 Comparison between the localization of nonpalpable UDT by combined DWI and conventional MRI in 60 patients by two radiologists and laparoscopy. R Radiologist, Com. MRI Combined imaging using conventional MRI and DWI. Location
R.
Com. MRI
Laparoscopy
No
%
No
%
Absent (agenesis)
R1 R2
20 20
33.33 33.33
14
23.33
Intracanalicular
R1 R2
20 20
33.33 33.33
20
33.33
Low intraabdominal
R1 R2
16 16
26.66 26.66
22
36.66
High intraabdominal
R1 R2
4 2
6.66 3.33
4
6.66
97.3%, 96.3% and 100%. The overall prediction accuracy was 98.4% [7]. Our results also agreed with those of a study conducted by Kantarci et al. who investigated the diagnostic performance of DWI and MRI in localizing nonpalpable UDTs, reported higher sensitivity and accuracy of combined MRI. It also compared the performance of two radiologists of different experiences in MRI interpretation. With MRI alone, the sensitivity was 85% for both radiologists, while accuracy was 86% for radiologist 1 and 84% for radiologist 2. However, when DWI was added to conventional MRI, both the sensitivity and accuracy were improved for both radiologists (sensitivity 91% and 88%; accuracy 92% and 86%) [10]. Another recent study by Emad-Eldin et al. revealed that conventional MRI alone had an accuracy of 91.5% in detecting nonpalpable undescended testes, while the combination of DWI and MRI increased accuracy to 95.7%, with a sensitivity of 93.5% and 100% specificity [23]. 5. Conclusion Adding DWIs to conventional MRI increased its sensitivity and accuracy of preoperative detection and localization of clinically nonpalpable testes. Conflict of interest The authors declare that there are no conflict of interests. References [1] Elder JS. Cryptorchidism and testicular cancer: separating fact from fiction. J Urol 2009;181(2):452–61. [2] Kavoussi LR, Wein AJ, Novick AC, et al. Campbell-walsh urology, 9th ed., vol. IV. Philadelphia: Saunders Company; 2007. p. 3761–98. chapter 127.
[3] Shah A, Shah A. Impalpable testes–is imaging really helpful? Indian Pediatr 2006;43:720–3. [4] Miller DC, Saigal CS, Litwin MS. The demographic burden of urologic diseases in America. Urol Clin North Am 2009;36(1):11–27. [5] Tasian GE, Copp HL. Diagnostic performance of ultrasound in nonpalpable cryptorchidism: a systematic review and metaanalysis. Pediatrics 2011;127:119–28. [6] Krishnaswami S et al. Magnetic resonance imaging for locating nonpalpable undescended testicles: a meta-analysis. Pediatrics 2013;131(6):1908–16. [7] Kato T, Kojima Y, Kamisawa H, et al. Findings of fat-suppressed T2weighted and diffusion-weighted magnetic resonance imaging in the diagnosis of non-palpable testes. BJU Int 2011;107(2):290–4. [8] Koh DM, Collins DJ. Diffusion-weighted MRI in the body: applications and challenges in oncology. AJR 2007;188:1622–35. [9] Kato H, Kanematsu M, Tanaka O, et al. Head and neck squamous cell carcinoma: usefulness of diffusion-weighted MR imaging in the prediction of a neoadjuvant therapeutic effect. Eur Radiol 2009;19:103–9. [10] Kantarci M, Doganay S, Yalcin A, Aksoy Y, Yilmaz-Cankaya B, Salman B. Diagnostic performance of diffusion-weighted MRI in the detection of non-palpable undescended testes: comparison with conventional MRI and surgical findings. AJR Am J Roentgenol 2010;195:268–73. [11] Poenaru D, Homsy YL, Peloquin F, Andze GO. Laparoscopic management of the impalpable abdominal testis. Urology 1993;42:574–8. [12] Elder JS. The undescended testis:hormonal and surgical management. Surg Clin North Am 1988;68:983–1006. [13] Schneck FX, Bellinger MF. Abnormalities of the testes and scrotum and their surgical management. In: Wein AJ, Kavoussi LR, Novick AC, Partin AW, Peters CA, editors. Campbell-Walsh Urology. 9th ed.. Philadelphia: Saunderes Company; 2007. p. 3761–98. Chapt127. [14] Kucheria R, Sahai A, Sami TA, et al. Laparoscopic management of cryptorchidism in adults. Eur Urol 2005;48:453–7. [15] Chew G, Hutson JM. Incidence of cryptorchidism and ascending testes in trisomy 21: a 10 year retrospective review. Pediatr Surg Int 2004;20:744–7. [16] Williams EV, Appanna T, Foster ME, et al. Management of the impalpable testis: a six year review together with a national experience. Postgrad Med J 2001;77:320–2. [17] Patil KK, Green JS, Duffy PG. Laparoscopy for impalpable testes. BJU Int 2005;95:704–8. [18] Argos Rodriguez MD, Unda Freire A, Ruiz Orpez A, Garcia LorenzoC. Diagnostic and therapeutic laparoscopy for nonpalpable testis. Surg Endosc 2003;17:1756–8.
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[19] Mathers MJ, Sperling H, Rübben H, et al. The undescended testis: diagnosis, treatment and longterm consequences. Dtsch Arztebl Int 2009;106:527–32. [20] Ho KM, Nicholson ML, Wastie ML, Wenham PW. Localization of intra-abdominal testis by magnetic resonance imaging. Br J Urol 1992;70(2):215. [21] Kanemoto K, Hayashi Y, Kojima Y, et al. Accuracy of ultrasonography and magnetic resonance imaging in the diagnosis of nonpalpable testis. Int J Urol 2005;12:668–72.
[22] Sarihan H, Sari A, Abes M, Dinc H. Nonpalpable undescending testis: value of magnetic resonance imaging. Minerva Urol Nefrol 1998;50:233–6. [23] Emad-Eldin S, Abo-Elnagaa NA, Hanna SAZ, et al. The diagnostic utility of combined diffusion-weighted imaging and conventional magnetic resonance imaging for detection and localization of non palpable undescended testes. J Med Imaging Radiat Oncol 2016;60 (3):344–51.
Please cite this article in press as: Ali SA, Mansour MG. . Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.09.017
Contents lists available at ScienceDirect
The Egyptian Journal of Radiology and Nuclear Medicine journal homepage: www.sciencedirect.com/locate/ejrnm
Efficiency of combined diffusion weighted imaging and conventional MRI in detection of clinically nonpalpable undescended testes Susan A. Ali MD ⇑, Mohamed G. Mansour MD Radiodiagnosis Department, Ain Shams University Cairo, Egypt
a r t i c l e
i n f o
Article history: Received 1 August 2016 Accepted 27 September 2016 Available online xxxx Keywords: DWI Conventional MRI Combined MRI Undescended testes
a b s t r a c t Purpose: The goal of the study was to highlight the added value of combined DWI and conventional MRI in detecting clinically nonpalpable undescended testes. Patients and methods: Prospective study included 60 males referred for MRI evaluation of clinically diagnosed 66 nonpalpable undescended testes. MRI studies were performed using 1.5-T MRI machine and included axial and coronal spin-echo T1WIs, axial T2WIs, axial and coronal fat suppressed spin-echo T2WIs, and axial DWIs using three sets of b value (50, 400, and 800 s/mm2). All images were transferred to an independent workstation and evaluated by two radiologists for the presence or absence and location of the undescended testes. The findings were compared to laparoscopy results, and then, sensitivity, specificity, and accuracy were calculated for both conventional and combined (DWI and conventional) MRI. Results: According to laparoscopic findings, sensitivity, specificity and accuracy of conventional MRI were 73.91%, 100%, and 80% and 69.57%, 100%, and 76.67% for radiologists 1 and 2 respectively, and of combined MRI were 86.9%, 100%, and 90% and 82.61%, 100%, and 86.67% for radiologists 1 and 2 respectively. Conclusion: Adding DWIs to conventional MRI improves the sensitivity and accuracy of detecting clinically nonpalpable undescended testes. Ó 2016 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
1. Introduction Cryptorchidism or undescended testis (UDT) is the most common genital disorder identified at birth. The main reasons for treatment of cryptorchidism include increased risks of impairment of fertility potential, testicular malignancy, torsion and/or associated inguinal hernia [1].
Peer review under responsibility of The Egyptian Society of Radiology and Nuclear Medicine. ⇑ Corresponding author. E-mail addresses: [email protected] (S.A. Ali), [email protected] (M.G. Mansour).
Approximately 1% of males have undescended testes, 80% of them are clinically palpable and 20% are non-palpable. The term ‘nonpalpable testes’ implies that they cannot be detected on physical examination; they are intraabdominal, absent, vanishing or atrophic [2]. Preoperative detection and localization of testes can determine the optimal type of procedure and allow for appropriate future planning. In the case of vanishing or absent testes, imaging findings could obviate the need for surgical exploration [3]. Different imaging tools have been suggested for identifying and locating non-palpable testes preoperatively with some limitations. Imaging modalities include US (Ultrasonography), CT (computed tomography), routine MRI, MRA
http://dx.doi.org/10.1016/j.ejrnm.2016.09.017 0378-603X/Ó 2016 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Please cite this article in press as: Ali SA, Mansour MG. . Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.09.017
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(magnetic resonance angiography) and MRV (magnetic resonance venography) [4]. Ultrasound is the least expensive and commonly used tool of all imaging techniques. However it showed low sensitivity in detecting non-palpable testes preoperatively [5]. Conventional MRI shows moderate specificity in diagnosing absent testes but poor sensitivity in detecting non-palpable testes. It appeared to be less efficient in localizing intra-abdominal functioning testes and showed limited sensitivity in localizing inguino-scrotal testes, but it fails to locate most of the atrophied testes, which makes conventional MRI less reliable in differentiating those children needing surgery from those who do not [6]. Additional fat-suppressed T2WI and DWI are useful sequences to improve the accuracy of diagnosing nonpalpable testes and preventing needless surgery [7]. DWI depicts abnormalities on the basis of tumor vascularity and cellularity [8]. Therefore, DWI facilitates characterization of tissue at the microscopic level in a mechanism different from T1 and T2 relaxation [9]. Intraabdominal testes are considerably more cellular than the adjacent tissues and organs, and thus, can be easily detected on DWIs owing to their increased signal intensity. Therefore, adding DWI to routine MRI improves identification of non-palpable undescended testes [10]. The goal of this study was to assess the added value of combined Diffusion-weighted imaging and conventional MRI sequences in proper localization of non-palpable testes before unneeded laparoscopy.
2. Patients and methods 2.1. Patients The study is prospective over the period from May 2014 to March 2016, and included 60 males (ranging in age from 15 months to 15 years with mean age 6.4 ± 3.9) referred for MRI evaluation of clinically diagnosed 66 nonpalpable undescended testes with non-conclusive ultrasonography findings. 54 cases were diagnosed of unilateral UDT (24 on the right side and 30 on the left side) with 6 cases clinically diagnosed of bilateral UDT. Patients with ambiguous genitalia or disorders of sexual development were excluded.
Conventional MRI examination included axial and coronal spin-echo T1-weighted sequence, axial T2-weighted sequence, axial and coronal fat suppressed spin-echo T2-weighted sequence, and axial DWI, slice thickness, 4 mm; interslice gap, 1 mm; field of view, 50 cm2. DWIs were performed using three sets of b value (50, 400, and 800 s/mm2). All MRI images including diffusion-weighted image sequences were transferred to an independent workstation.
2.3. Image analysis Two radiologists with different experiences (9 and 14 years respectively) in MR abdominal imaging independently reviewed the MR images and were aware of the patient’s clinical data. They recorded the presence or absence and the location of UDT. First, the DWIs (with b values of 50, 400, and 800 s/mm2) were reviewed alone, then the conventional MR images, and finally the combined (DWI and conventional) MR images. At DWIs, the abdomen was imaged for focal elliptic areas of hyperintensity, that did not represent T2 shine through from fluid-containing structures, recorded as testes, and their anatomic location was classified into intracanalicular, low intraabdominal, and high intraabdominal. On conventional MR images, testes appeared as elliptic areas hypointense on T1WIs and iso- or hyperintense on T2WIs, in the aforementioned locations. On the combined (DW and conventional) MR images, conventional MRI was used for anatomic localization of elliptic hyperintense areas on the DWIs.
2.4. Laparoscopy and histopathologic examination All the patients underwent laparoscopic exploration under general anesthesia within 2 weeks of the MR imaging to determine the location of all nonpalpable testes. Intraabdominal atrophic testes were treated with laparoscopic orchiectomy. Orchiectomy samples were taken for histopathologic examination.
2.5. Statistical analysis 2.2. MR imaging All MRI studies were performed with a 1.5-T MRI system (Achieva; Philips Medical Systems, Best, the Netherlands) using body coil (a phased-array coil). T1WIs, T2WIs and fat suppressed T2WIs as well as DWIs were performed during the same MRI examination for all patients. Images will be acquired with the patient is in supine position with head pointing to the magnet (head first supine; HFS). The body coil was securely tightened using straps to prevent respiratory artifacts. At the center the laser beam localizer will be placed over symphysis pubis. Chloral hydrate syrup at a dose of 1 ml/kg body weight was needed for children less than 5 years for sedation during MRI examination.
DWIs, conventional MRI, and combined (DWIs and conventional) MRI findings were compared with laparoscopy results. For each observer, sensitivity, specificity, and accuracy of location of the testes were calculated for DWIs, conventional MRI, and combined (DWIs and conventional) MRI. Data were statistically described in terms of mean ± standard deviation (±SD), and range, or frequencies (number of cases) and percentages when appropriate. Comparison of sensitivity and overall accuracy between the different techniques was done using Chi squared test (McNemar test). Accuracy was represented using the terms such as sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy. All statistical calculations were done using computer program.
Please cite this article in press as: Ali SA, Mansour MG. . Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.09.017
S.A. Ali, M.G. Mansour / The Egyptian Journal of Radiology and Nuclear Medicine xxx (2016) xxx–xxx
3. Results According to the laparoscopic findings, 48 undescended testes were diagnosed in 60 patients, and located as follows: 4 high intraabdominal, 24 low intraabdominal (Fig. 1), and 20 intracanalicular (Figs. 2–4), whereas, 18 testes were absent (testicular agenesis) as shown in Table 1. The combination of DWI and conventional MRI was the most accurate and sensitive technique, facilitating the localization of 40 testes by radiologist 1 and 38 testes by radiologist 2, with accuracy of 90% and 86.67%, compared to 80% and 76.67% for conventional MRI, respectively. Sensitivity of 86.96% and 82.61% by combined MRI compared to 73.91% and 69.57% by conventional MRI, was found for radiologists 1 and 2, respectively. However, both combined and conventional MR imaging had a specificity of 100% (Table 2). In 14 patients (23.33%), laparoscopy revealed testicular agenesis, compared to 20 patients (33.33%) reported using MRI combined imaging. By conventional MRI, UDTs were detected in 34 (56.66%) and 32 (53.33%) patients by radiologists 1 and 2, respectively, while by combined MRI, they detected UDTs in 40 (66.66%) and 38 (63.33%) patients, respectively, compared to 46 patients (76.66%) diagnosed with UDTs on laparoscopy. Radiologist 2 could not identify two cases of left high intraabdominal testes identified by radiologist 1 and confirmed by laparoscopy. Both radiolo-
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gists could not identify two left UDTs on conventional and combined MRI that was left lower abdominal UDT by laparoscopy. Two right UDTs were not identified on both conventional and combined MRI by both radiologists and reported by laparoscopy as right low intraabdominal UDT. On two laparoscopic examinations, bilateral low intraabdominal atrophic UDT was detected and was overlooked on both conventional and combined MRI by both radiologists (Table 3). 4. Discussion The incidence of UDTs varies from 21% in preterm infants to 1.8–4.0% in term boys [11]. 80% of UDTs are clinically palpable and 20% of them are nonpalpable [12]. Nonpalpable testis implies that the testis cannot be detected on clinical examination [13]. Accurate diagnosis and appropriate surgical treatment are important for proper testicular function and can facilitate early detection of malignancy [14,15]. Preoperative localization of the testes aids in planning surgical approach, reducing extent of exploration and anesthesia time [16]. Laparoscopy is the most reliable diagnostic technique for the detection of nonpalpable UDTs; however, it is invasive [17–19]. Thus, different diagnostic imaging modalities have been used for detection and localization of nonpalpable UDTs including ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI) [20].
Fig. 1. 3 years old boy presented with right sided clinically nonpalpable testis. MRI imaging revealed a right low intraabdominal testis close to internal ring, showing intermediate signal intensity on axial T2WI (a), and marked hyperintensity on axial DWI (b) obtained with b value of 800 s/mm2.
Fig. 2. 15 months old boy presented with right sided clinically nonpalpable testis. MRI imaging revealed a right intracanalicular testis (arrowed), showing intermediate signal intensity (surrounded by mild vaginal hydrocele) on axial fat suppressed T2WI (a), and marked hyperintensity on axial DWI (b) obtained with b value of 800 s/mm2.
Please cite this article in press as: Ali SA, Mansour MG. . Egypt J Radiol Nucl Med (2016), http://dx.doi.org/10.1016/j.ejrnm.2016.09.017
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Fig. 3. 5 years old boy presented with right sided clinically nonpalpable testis. MRI imaging revealed a right intracanalicular testis (arrowed), surrounded by mild vaginal hydrocele and showing intermediate signal intensity on axial T1WI (a), axial and coronal T2WIs (b and c), and marked hyperintensity on axial DWI (d) obtained with b value of 800 s/mm2.
Fig. 4. 17 months old boy presented with left sided clinically nonpalpable testis. Conventional MRI imaging failed to detect the undescended testis on axial T2WIs (a), while on axial DWI obtained with b value of 800 s/mm2 (b), a markedly hyperintense small left intracanalicular testis (arrowed), was detected and confirmed by subsequent laparoscopy.
Table 1 Location based distribution of 66 clinically nonpalpable UDTs in 60 patients according to laparoscopy findings. Location
Absent
Intra-canalicular
Low intra-abdominal
High intra-abdominal
Total
Right testis Left testis Total
6 12 18
14 6 20
10 14 24
0 4 4
30 36 66
MRI is a noninvasive diagnostic imaging technique and does not entail ionizing radiation. A study done by Kanemoto et al. found that MRI has an accuracy, sensitivity and specificity of 85%, 86% and 79%, respectively, for the diagnosis of nonpalpable UDTs [21]. Another study conducted by Sarihan et al. found that MRI had sensitivity and specificity of 78.6% and 100%, respectively, in the detection of nonpalpable UDTs [22]. Both studies used conventional MRI techniques. In the current study, the performance of two radiologists with different levels of experience in interpreting the MRI findings of 60 patients, referred with clinically nonpalpable UDTs, was compared. Using MRI alone, the
sensitivity was 73.91% and 69.57%, while accuracy was 80% and 76.67% for radiologists 1 and 2, respectively. However, when DWI was added to conventional MRI, both sensitivity and accuracy were increased for radiologists 1 and 2 (sensitivity 86.96% and 82.61%; accuracy 90% and 86.67%). So, with combined DWI and conventional MRI, both radiologists performed better in detection and localization of UDTs and our results confirm that DWI findings complement that obtained with conventional MRI on identifying and locating undescended testes. Kato et al. reported that sensitivity, specificity, positive and negative predictive values for combined DWI and conventional MRI versus the operative findings were 100%,
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Table 2 Comparison of performance indices of conventional MRI and combined (DWI and conventional) MRI in 60 patients by two radiologists according to laparoscopy findings. R Radiologist, TP True positive, FN False negative, TN True negative, FP False positive, PPV Positive predictive value, NPV Negative predictive value, DWI Diffusion Weighted Imaging, Con. MRI Conventional magnetic resonance imaging, Com. MRI Combined imaging using conventional MRI and DWI. Imaging tool
R.
TP (No.)
FN (No.)
TN (No.)
FP (No.)
PPV (%)
NPV (%)
Sensitivity (%)
Specificity (%)
Accuracy (%)
Con. MRI
R1 R2
34 32
12 14
14 14
0 0
100 100
53.85 50
73.91 69.57
100 100
80 76.67
Com. MRI
R1 R2
40 38
6 8
14 14
0 0
100 100
70 63.64
86.96 82.61
100 100
90 86.67
Table 3 Comparison between the localization of nonpalpable UDT by combined DWI and conventional MRI in 60 patients by two radiologists and laparoscopy. R Radiologist, Com. MRI Combined imaging using conventional MRI and DWI. Location
R.
Com. MRI
Laparoscopy
No
%
No
%
Absent (agenesis)
R1 R2
20 20
33.33 33.33
14
23.33
Intracanalicular
R1 R2
20 20
33.33 33.33
20
33.33
Low intraabdominal
R1 R2
16 16
26.66 26.66
22
36.66
High intraabdominal
R1 R2
4 2
6.66 3.33
4
6.66
97.3%, 96.3% and 100%. The overall prediction accuracy was 98.4% [7]. Our results also agreed with those of a study conducted by Kantarci et al. who investigated the diagnostic performance of DWI and MRI in localizing nonpalpable UDTs, reported higher sensitivity and accuracy of combined MRI. It also compared the performance of two radiologists of different experiences in MRI interpretation. With MRI alone, the sensitivity was 85% for both radiologists, while accuracy was 86% for radiologist 1 and 84% for radiologist 2. However, when DWI was added to conventional MRI, both the sensitivity and accuracy were improved for both radiologists (sensitivity 91% and 88%; accuracy 92% and 86%) [10]. Another recent study by Emad-Eldin et al. revealed that conventional MRI alone had an accuracy of 91.5% in detecting nonpalpable undescended testes, while the combination of DWI and MRI increased accuracy to 95.7%, with a sensitivity of 93.5% and 100% specificity [23]. 5. Conclusion Adding DWIs to conventional MRI increased its sensitivity and accuracy of preoperative detection and localization of clinically nonpalpable testes. Conflict of interest The authors declare that there are no conflict of interests. References [1] Elder JS. Cryptorchidism and testicular cancer: separating fact from fiction. J Urol 2009;181(2):452–61. [2] Kavoussi LR, Wein AJ, Novick AC, et al. Campbell-walsh urology, 9th ed., vol. IV. Philadelphia: Saunders Company; 2007. p. 3761–98. chapter 127.
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