Using Gadolinium-Infusion MR Venography to Show the Impalpable Testis in Pediatric Patients

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1 Downloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Wendy W. M. Lam 1 Paul K. H. Tam 2 Victor H. G. i 1 K. L. han 2 F. L. han 1 L. Leong 1 Received May 25, 2000; accepted after revision October 25, Department of Radiology, Queen Mary Hospital, 102 Pokfulam Rd., Hong Kong. ddress correspondence to W. W. M. Lam. 2 Department of Surgery, Division of Pediatric Surgery, the University of Hong Kong, Hong Kong. JR 2001;176: X/01/ merican Roentgen Ray Society Using Gadolinium-Infusion MR Venography to Show the Impalpable Testis in Pediatric Patients OJETIVE. This study evaluated the adjunctive value of gadolinium-infusion MR venography to locate the impalpable testis. SUJETS ND METHODS. Routine MR imaging and MR venography were performed in 34 patients presenting with impalpable testis. MR venography was performed by dynamic injection of gadopentetate dimeglumine bismethylamide with images taken at delayed venous phases. The site of the testis was determined by detection of the contrast-enhanced pampiniform venous plexus. RESULTS. total of 44 impalpable testes were examined. Twenty-six hypoplastic canalicular testes, two testes at pelvic skinfold, four atrophic testes in the scrotum, and five intraabdominal testes were detected on both routine MR imaging and MR venography. Five vanishing testes in the scrotum and two at the groin region were detected by MR venography but not on MR imaging. ONLUSION. Gadolinium-infusion MR venography is superior to MR imaging in the detection of atrophic testes. The method is a useful adjunct in patients with negative MR imaging findings. L ocalization of impalpable testes is a significant treatment problem in pediatric urology and surgery. The incidence of undescended testes at 1 year old has been reported to be eight per 1000 by Scorer [1]. Impalpable testes account for 9 54% of all cases of cryptorchidism [2], but the incidence of cryptorchidism is generally accepted to be 20% [3]. The undescended testis is more prone to undergo torsion than a normal testis because of poor fixation. If left in the ectopic position, it has an increased risk of neoplasia, which is even higher if the testis is in the abdomen. Many diagnostic methods such as conventional venography, arteriography, sonography, T, and MR imaging have been used to locate undescended testes. Laparoscopy is preferred by surgeons as the diagnostic method of choice for such localization [4]. The use of gadolinium-infusion MR venography in the detection of impalpable testes has been reported in a small number of patients [5] and by other authors [6]. ecause of our increased experience, we would like to provide a fuller report. Subjects and Methods Patients Thirty-four patients from 1 to 16 years old (mean age, 6.4 years; median, 4.5 years) presenting with impalpable undescended testes were examined by routine MR imaging and then by gadolinium-infusion MR venography. MR Imaging Techniques MR imaging was performed with a 1.5-T superconducting whole-body imager (Signa Horizon Echospeed; General Electric Medical Systems, Milwaukee, WI). head coil was used for neonates and infants (< 1 year old). Older children were imaged with a body coil. sagittal spin-echo localizer (TR/TE, 500/9), coronal and axial T2-weighted fat-saturation fast spinecho sequences (4000/102; excitations, 4; thickness, 4 mm; matrix size, ), and axial T1-weighted spin-echo sequences (600/9; excitations, 2; thickness, 4 mm; matrix size, ) were performed. MR Venogram Techniques Sagittal T1-weighted fast gradient-echo localizer images (12/1.1; flip angle, 40 ) were acquired first. three-dimensional fast spoiled gradient-recalled echopulse sequence (10.2/1.9; flip angle, 60 ; number of partitions, 28; partition thickness, 2 mm; matrix size, ; field of view, cm; receiver bandwidth, 32kHz) was obtained in the coronal plane. The acquisition time was about sec, depending on the number of slices included. Flow compensation and presaturation pulses were not used. Non breath-hold dynamic three-dimensional images were obtained simultaneously after an IV bolus injection of gadolinium chelate. The dose of contrast material was set at 0.4 mmol of gadopentetate JR:176, May

2 Lam et al. Downloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved dimeglumine bismethylamide (Omniscan; Nycomed, Torshov, Norway) per kilogram of body weight if the body weight was less than 10 kg. dose of 0.3 mmol per kilogram of body weight was given for children who were heavier than 10 kg of body weight. The injections were performed by hand via 22-gauge angiographic catheters. If the calculated volume of contrast material was less than 10 ml, a 1:1 dilution of contrast material to saline was used to increase the column of contrast material entering the vessels. The overall injection time was less than 1 min. Dynamic three-dimensional images were obtained at the start of injection of contrast material and then at 1, 2, 3, 4, and 5 min after the start of contrast injection. The overall scanning time of MR venography was about 5 7 min, including the preparation time. Sedation Patients younger than 5 years old received an oral sedative (chloral hydrate, 50 mg/kg of body weight). n IV sedative (midazolam, mg/ kg of body weight) was added if oral sedation was inadequate. Vital signs of patients were carefully monitored during and after the examination. Image nalysis The testis was detected by enhancement of the pampiniform venous plexus at different time intervals on MR venography sequences. oth the source images and reconstructed images were reviewed. The images were reconstructed with the dvantage Windows workstation (General Electric Medical Systems). Multiplanar volume reconstruction postprocessing software was used. Two radiologists reviewed the MR images first, and then they reviewed the MR venograms separately on the workstation without knowing the name of patients. In case of disagreement between the two radiologists, they reviewed the MR venograms and MR images together. decision was reached by consensus. The findings of MR imaging and MR venography were reported separately in each individual patient. The location of the testis was determined on MR imaging by the identification of focus of hyperintense signal on T2-weighted sequences and hypointense signal on T1-weighted sequences. On MR venograms, the location of the testis was determined by the detection of a bright linear enhanced pampiniform venous plexus. The testis was described as hypoplastic if its size was similar or slightly smaller than the normal one. trophic testis was considered if the size of the testis was small or reduced to a remnant. Vanishing testis was defined if blind-ending vas deferens and spermatic vessels were detected in the absence of the testis itself. In our study, vanishing testis was diagnosed if the bright linear enhanced pampiniform venous plexus was identified on the MR venography, but the testis could not be identified on T1- and T2- weighted sequences. If both MR venography and T1- and T2-weighted MR imaging failed to identify the testis and the pampiniform venous plexus, the testis was considered unidentified. The imaging findings were correlated with surgical exploration or laparoscopic findings. The surgeons were aware of the imaging findings, and the surgical approach was planned according to the MR imaging and MR venography findings. Statistical analysis of the diagnostic difference between MR venography and MR imaging was performed by the chi-square test. ny p value less than 0.05 was considered statistically significant. Results ll patients were well sedated without any problem encountered during the procedure. No adverse contrast reactions or other complications were detected during and after examinations. The pampiniform venous plexus could be detected in all patients (100%). Thirty-four patients with a total of 44 impalpable testes were imaged (unilateral undescended testes, n = 24; bilateral undescended testes, n = 10). Twentysix hypoplastic canalicular testes (Fig. 1), two testes at pelvic skinfold (in a patient with cloacal extrophy) (Fig. 2), four atrophic testes in the scrotum (Fig. 3), and five intraabdominal testes (Fig. 4) were detected on both routine MR imaging and MR venography. Five vanishing testes in the scrotum (Fig. 5) and two at the groin (Fig. 6) were detected on MR venography, but not on MR imaging (Table 1). mong the 26 patients with hypoplastic canalicular testes, there was one patient with crossed ectopia (Fig. 7), in which both testes were seen at the right inguinal canal. On MR venography, the testis appears hypointense. The contrast-enhanced pampiniform venous plexus and the testicular vein appear as a bright line near the epididymis and then along the spermatic cord (Fig. 3). nother signal void line adjacent to the bright line could be caused by chemical shift artifact due to the remnant of a gubernaculum testis. rim of contrast enhancement is detected around the testis (Fig. 1), giving rise to a rim or hook sign. This sign may represent vessels surrounding the testicular capsule. In our study, we found that the best timing for maximal enhancement of the pampiniform venous plexus was between 3 and 4 min after the injection of contrast media. There was no discordance between the two radiologists in the interpretation of MR imaging findings. The two radiologists had discor- TLE 1 Location Detection of Impalpable Testis on MR Imaging and MR Venography MR Imaging MR Venography Hypoplastic testis inside Inguinal canal 0 0 Testis at pelvic skinfold 2 2 Intraabdominal testis 5 5 inside pelvis trophic testis 4 4 at scrotum Vanishing testis t scrotum 0 5 t inguinal canal 0 2 Sensitivity 84% (37/44) 100% (44/44) Specificity 100% 100% Note. p value of diagnostic difference between MR imaging and MR venography was less than 0.05 with chi-square test. Fig. 1. ilateral canalicular testes in 13-year-old boy., T2-weighted coronal MR image shows two hyperintense undescended testes at both sides of groin (arrows)., Gadolinium-infusion MR angiographic source image shows findings similar to. oth testes are hypointense. Note rim of contrast enhancement (arrow ) surrounding testis. Dark line leading to testis represents chemical shift artifact adjacent to enhanced pampiniform venous plexus (arrowhead ) JR:176, May 2001

3 MR Venography of the Impalpable Testis Downloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Fig. 2. ilateral undescended testes in 14-year-old boy with cloacal extrophy., T2-weighted coronal MR image shows two hyperintense testes (arrows) at skinfold next to extrophied bowel and mesentery., Source image from gadolinium-infusion MR angiography shows rim of contrast enhancement around two testes at skinfold (arrows). Pampiniform venous plexus appears as bright line draining from testes (arrowheads)., Source image slightly anterior to shows two testes at skinfold (arrows). Fig. 3. Right atrophic testis in 11- year-old boy., T2-weighted coronal MR image shows normal hyperintense testis in left scrotum; small amount of hydrocele (arrow) is present. Small atrophic testis with small amount of hydrocele (arrowhead ) is seen in right scrotum., Source image from gadoliniuminfusion MR angiography shows right (arrowhead) and left (arrow) pampiniform venous plexus draining from scrotum. dant MR venography findings on initial interpretation in five (14.7%) of 34 patients. The eventual results on MR venography of these five patients were decided by consensus. Final diagnosis was determined by surgical exploration or laparoscopy. The sensitivities of MR imaging and MR venography were 84% and 100%, respectively. The specificities of both were 100%. The p value of the diagnostic difference between MR venography and MR imaging was less than 0.05 with the chi-square test; this difference was statistically significant. Discussion bsent or vanishing testes, canalicular testes, and intraabdominal testes can all present as impalpable testes. Preoperative localization of impalpable testes is important for treatment planning. Identification of the location of the testis permits site-specific planning of surgery. Surgeons can decide if satisfactory treatment can be performed locally or if a referral should be made to a tertiary center. Different causes of impalpable testes require different methods of treatment: groin and abdominal exploration for vanishing testes; standard orchidopexy for canalicular testes; transabdominal orchidopexy, staged orchidopexy, orchidopexy with testicular vessel division [7], or microvascular orchidopexy [8] for intraabdominal testes. n imaging method that can identify accurately the vanishing testis must be completely dependable. Error in this determination will risk leaving a testis if no further exploration is undertaken. These undiscovered testes have the most significant risk of malignant degeneration. lthough proper and adequate surgical exploration is likely to differentiate the various kinds of impalpable testes, the accuracy ranges from JR:176, May

4 Lam et al. Downloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Fig. 4. Right intraabdominal testis and left canalicular testis in 1-year-old boy., T2-weighted coronal MR image shows left hyperintense testis at left side of groin (arrow ). trophic right intraabdominal testis (arrowhead) is next to bladder ()., Source image from gadolinium-infusion MR angiography shows linear pampiniform venous plexus and rim enhancement around left testis at left groin region (thin arrows). Note rim enhancement at right intraabdominal testis (arrowhead), which is partially obscured by contrast-enhanced right external iliac vessels (thick arrow)., Using multiplanar volume reconstruction postprocessing software, we could rotate right external iliac vessels away from plane of interest. Right intraabdominal testis (arrow) could be more clearly shown. Fig. 5. Right vanishing testis in 9-year-old boy., T2-weighted coronal MR image shows normal hyperintense testis in left scrotum (arrow). Right testis could not be found., Source image from gadolinium-infusion MR angiography shows right (arrow) and left (arrowhead) pampiniform venous plexus draining from scrotum., Multiplanar volume reconstruction postprocessing image shows findings similar to. lind-ended right pampiniform venous plexus descended from groin region to right scrotum (thin arrow). Note left pampiniform venous plexus and rim enhancement at left testis (arrowheads). No rim enhancement over right side is seen because right testis was absent. External pudendal veins (thick arrows) run horizontally across groin to penis (P), and rim enhancement is seen at skinfolds (asterisks). 88% to 100%, depending on the expertise of the surgeons [9, 10]. In a number of reported instances, patients with absent testes at previous surgeries were subsequently found to have testes present [11]. X-ray arteriography and venography require general anesthesia and are invasive and difficult to perform in infants. Sonography avoids the use of ionizing radiation and permits examination without sedation. Sometimes sonography can be difficult to perform in an uncooperative unsedated patient. Moreover, imaging testis cephalic to the internal inguinal ring is difficult on sonography. Komine et al. [12] reported a sensitivity of 82.6%, a specificity of 100%, and an accuracy of 84.6% on sonography. Wolverson et al. [13] showed 94% sensitivity on T, 88% sensitivity on sonography, and 100% specificity on both modalities, but their subjects were 3 23 years old, with 80% being 5 years or older. ecause the body fat in a neonate or infant is relatively less than that in an older child, the accuracy of T would be reduced. nother disadvantage of T lies in the use of ionizing radiation. Maghnie et al. [14] reported that neither sonography nor MR imaging is currently sensitive enough to stand alone as a screening modality for impalpable testis because the two modalities used separately each give a useful result of 76%. Their combined specificity compared with surgical findings was 95%. Kier et al. [15] reported that MR imaging is not sensitive enough to allow complete exclusion of diagnosis of an undescended testis; thus, failure to localize a testis with MR imaging should not defer laparoscopy or surgical exploration. The sensitivity of MR imaging in our study was 84% and was comparable to that reported in the literature (63 88%) [14, 15]. The ectopic testis is identified by the presence of characteristic 1224 JR:176, May 2001

5 MR Venography of the Impalpable Testis Downloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved Fig. 6. Right vanishing testis at groin region in 12-year-old boy., T2-weighted coronal MR image shows normal hyperintense testis in left scrotum (arrow). Right testis could not be found., Source image shows left pampiniform venous plexus draining from left scrotum (arrow). Right external pudendal vein (arrowhead) runs horizontally across groin to scrotal region., Source image from gadolinium-infusion MR angiography slightly anterior to shows blind-ended right pampiniform venous plexus (arrow) draining from right groin region. D, Multiplanar volume reconstruction postprocessing image shows blind-ended right pampiniform venous plexus draining from right groin (large arrow) and left pampiniform venous plexus draining from scrotum (arrowhead). Right and left external pudendal veins (small arrows) are shown. Fig. 7. rossed ectopia of right testis in 10-year-old boy., T2-weighted coronal MR image shows round hyperintense testis (arrow) at right groin. Elongated hyperintense testis (ectopic left testis, arrowhead) is also seen inside inguinal canal above round testis., Multiplanar volume reconstruction postprocessing image shows two pampiniform venous plexus (arrows) draining from right groin. No pampiniform venous plexus was detected at left side. D JR:176, May

6 Lam et al. Downloaded from by on 02/16/18 from IP address opyright RRS. For personal use only; all rights reserved bright signal on T2-weighted images and by a linear low-signal structure that represents the remnant of the gubernaculum testis. limitation of MR imaging is that it cannot image the testis if a testis is absent or has vanished. In testicular atrophy, the normal testicular bright signal may be changed or lost, and this change would make it difficult to differentiate the atrophied testis from surrounding tissues. In vanishing testis, the testis is absent with only a blind-ended vas deferens and spermatic vessels remaining. Identifying its vascular supply is the most reliable method of locating the testis. Laparoscopy provides direct visualization of the testicular vessels and has been reported to be a sensitive method for locating the testis [4, 16]. Similar to laparoscopy, gadoliniuminfusion MR venography is intended to localize the pampiniform venous plexus instead of imaging the testis itself, but this modality is noninvasive and can be performed preoperatively without general anesthesia. If the testis could not be found on MR imaging, the cause could be vanishing testis or intraabdominal testis that was unidentified or obscured by the bowels. It is essential to differentiate this cause because an error will risk leaving an intraabdominal testis, which has significant risk of malignant degeneration. In our center, if the testis could not be found on any imaging modalities such as sonography, T, or MR imaging, the surgeon proceeded to laparoscopy and then to surgical exploration if the testis could not be identified by laparoscopy at the groin and lower abdomen. In our study, MR venography could accurately identify the spermatic vessels even when the testis was absent. MR venography is therefore superior to routine MR imaging for the localization of vanishing testes and helps to guide the site of entrance of the laparoscope and the choice of operation. Unplanned groin exploration may be detrimental to the outcome of surgery for intraabdominal testis. Groin exploration could jeopardize the effectiveness of the alternate procedure of microvascular orchidopexy by disrupting tissue planes. To obtain quality images, an adequate dose of contrast material is important. esides the dose, the actual volume of contrast material entering the vessels is important. We found that both the source images and multiplanar volume reconstruction postprocessing images could show the spermatic vessels clearly. However, during the interpretation of images, radiologists should be careful to differentiate the spermatic vessels from other vessels present at the groin and scrotal regions. The spermatic vessels should be draining from the groin or scrotal region to the abdomen via the inguinal canal (Fig. 5). The external pudendal vein should not be mistaken for the spermatic vessel because the external pudendal vein runs horizontally across the groin region from the great saphenous vein to the penis (Fig. 5). The external pudendal vein and the spermatic vessel can be better differentiated on source images than on multiplanar volume reconstruction postprocessing images. We also found that the rim enhancement at skinfolds around the scrotum and penis and the enhancement of dorsal veins at the penis might create some problems in the identification of the spermatic vessels. ecause the penis is usually deviated to the side of scrotum in which the testis is absent, it will obscure the spermatic vessels and thus make interpretation difficult. We recommend stabilization of the penis to the midline of the lower pelvis to avoid the confusion created by the enhancement of dorsal veins and the skinfold. In our few patients with intraabdominal testes, the testes were mainly located near the inguinal canal and next to the bladder. We found that it was more difficult to detect the enhanced pampiniform venous plexus in that region because of enhancement of adjacent vessels such as the external iliac vessels. y adjusting different angles of rotation and different slice thicknesses with multiplanar volume reconstruction postprocessing, the adjacent vessels can be avoided (Fig. 4). So far, we have no experience in detecting high intraabdominal testis. ecause of the enhancement of abundant bowel vessels, we suspect that the detection of spermatic vessels would be problematic in the abdomen. The usefulness of MR venography in such cases has yet to be determined. In our study, we had not referred our patients to sonography; thus, we could not compare the findings on MR imaging and MR venography with those on sonography. However, in comparison with the studies of Komine et al. [12] and Wolverson et al. [13], our sensitivity of MR imaging (84%) was comparable to that of sonography (82 88%). In our opinion, if the testicular tissue is present, MR imaging or sonography may provide similar results. ecause sonography is easily available and without irradiation, it may be considered the first line of investigation. However, in cases of vanishing testis, because the testicular tissue is not present, MR venography is clearly better than MR imaging or sonography in identifying the testis. In summary, gadolinium-infusion MR venography is a noninvasive, safe, and accurate method for the localization of impalpable testis. It is recommended as an adjunctive method for localization of impalpable testis when MR imaging or sonographic findings are negative. 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