Nonpalpable testes in young boys: evaluation with MR imaging

A prospective evaluation of magnetic resonance (MR) imaging for localization of a nonpalpable testis was performed in 24 boys aged 11 months to 6 years. Definitive surgical follow-up was obtained for 15 nonpalpable testes in 14 patients who form the basis of this study. MR imaging correctly indicated the unilateral absence of a testis in six of seven patients prospectively and all seven patients retrospectively. Surgically localized undescended testes were identified with MR imaging in five of eight cases prospectively and seven of eight cases retrospectively. Like scrotal testes, undescended testes were hypointense to fat on sequences with a short repetition time (TR) and echo time (TE) in all cases, and hyperintense or isointense to fat on long TR/TE sequences in all but two cases. Inguinal testes were located along the course of a linear low-signal-intensity structure that extended to the scrotum, which may represent the remnant of the gubernaculum testis. A low-signal-intensity band through the testis, presumably the mediastinum testis, was seen in five of the undescended testes. Although MR imaging can often be used to localize a nonpalpable testis, currently MR is not sensitive enough to allow complete exclusion of the diagnosis of an undescended testis; thus failure to localize a testis with MR imaging should not defer laparoscopy or surgical exploration when indicated.     

Selective spermatic arteriography for localization of an impalpable undescended testis

Thirty patients with undescended testes, including 15 children, were studied by selective spermatic angiography. Six patients had both arteriography and venography, and 24 had bilateral arteriography for assessment of testicular size. In 7 patients, arteriography revealed an impalpable testis following unsuccessful surgical exploration. In 17, subsequent surgery confirmed the angiographic findings; testicular agenesis was diagnosed in 7, and catheterization failed in 2. There were no complications. Preoperative testicular arteriography localizes the testis, facilitates surgery, and may aid in tumor detection. Angiographic identification of testicular agenesis precludes exploration. Arteriography is more accurate, simpler, and less complicated than venography.     

MRI in venous thromboembolic disease

We evaluated the ability of magnetic resonance (MR) imaging to detect deep venous thrombosis (DVT) and pulmonary embolism (PE). MR venography was performed on 217 patients suspected of having DVT. Cine-MR imaging of the pulmonary arteries was performed in 14 other patients who were thought to have PE based on other imaging studies. In a third group of 5 patients, MR pulmonary angiograms were performed in the sagittal and coronal planes with a multislice fast gradient recalled echo technique. All but one of the 217 MR venograms were technically adequate. In 72 patients with correlative imaging studies (venography and ultrasound) MR venography was 99% sensitive and 95% specific. On the basis of follow-up (mean 8.3 months), no false-negative MR venograms were detected in an additional 64 patients. In 11 other patients MR revealed a diagnosis other than DVT. Cine-MR showed PE in all 14 patients evaluated. MR pulmonary arteriography demonstrated filling defects consistent with acute PE in 2 of 3 patients with acute PE; in the third patient only a questionable filling defect was seen. Coarctations or webs were found in the pulmonary arteries of both patients with chronic PE. These preliminary data suggest that MR imaging may be able to evaluate both the peripheral venous and the pulmonary arterial component of venous thromboembolic disease. Further technical refinement and more extensive clinical experience will be required to establish the role of this method in diagnosing pulmonary embolism, but MR venography is now used routinely in our hospital for the diagnosis of deep venous thrombosis. Correspondence to: H. D. Sostman     

Intracranial venous system: gadolinium-enhanced three-dimensional MR venography with auto-triggered elliptic centric-ordered sequence--initial experience

PURPOSE: To evaluate gadolinium-enhanced three-dimensional auto-triggered elliptic centric-ordered (ATECO) magnetic resonance (MR) venography for imaging of the intracranial venous system. MATERIALS AND METHODS: ATECO MR venography was performed in 23 patients, eight of whom also underwent two-dimensional time-of-flight (TOF) MR venography for imaging of the intracranial venous system. Seventeen predefined venous structures were evaluated on all venograms by two neuroradiologists. Visualization of venous structures was defined as completely visible (including clearly pathologic), partially visible, or not visible. Readers were also asked to compare the visibility of these predefined structures on ATECO and TOF MR venograms, where available. RESULTS: Of the 23 patients, six had dural venous sinus disease. Of the remaining 17 healthy patients, five underwent both ATECO and TOF MR venography and 12 underwent ATECO MR venography alone. On ATECO MR venograms obtained in the healthy patients, visibility of the 17 predefined venous structures was complete in 92% (531 of 578) of evaluations. For the five normal TOF MR venograms, the rate of complete visibility of the same venous structures was 61% (104 of 170). The rate of complete visibility of the large dural venous sinuses was 99% for ATECO MR venograms and 75% for TOF MR venograms. CONCLUSION: ATECO MR venography provides high-quality images of the intracranial venous anatomy and was superior to TOF MR venography for consistent complete visibility of venous structures.     

MRI of the scrotum

Surface coil magnetic resonance (MR) imaging of the scrotum allows differentiation of the testis, epididymis, and spermatic cord. Intratesticular and extratesticular lesions are demarcated by the tunica albuginea. The sensitivity of MR is very high for detection of scrotal abnormalities but is non-specific since it is unable to distinguish primary testicular tumors from benign lesions. Undescended testes which lie proximal and distal to the internal inguinal ring are well visualized by MR imaging. The advantages of MR imaging in locating undescended testes is that it is noninvasive, without ionizing radiation, and capable of multiplanar images.     

Society of Uroradiology Award paper. The pars infravaginalis gubernaculi: importance in the identification of the undescended testis

The gubernaculum, a cordlike structure that extends from the testis to the scrotum and guides the testis in its descent, has a bulbous termination, the pars infravaginalis gubernaculi. We reviewed seven surgically proved cases in which the pars infravaginalis gubernaculi was mistaken for an undescended testis on imaging studies. The studies included sonography (five cases), CT (two cases), and MR imaging (two cases). Identification of the mediastinum testis on sonograms or MR images confirms that a structure is testis and not the pars infravaginalis gubernaculi. In two of these patients, testicular venography was used to further identify the undescended testis. In these two patients, the pampiniform plexus, which is used to identify the presence and position of testis, was located adjacent to the pars infravaginalis gubernaculi. Our experience indicates that the pars infravaginalis gubernaculi can be similar in appearance to the undescended testis on any imaging study. The finding of an apparent cord leading to a testislike structure on caudad sectional imaging does not obviate searching for the testis as far as the renal hila.     

Isolated pelvic deep venous thrombosis: relative frequency as detected with MR imaging

PURPOSE: To determine the relative frequency of deep venous thrombosis (DVT) isolated to the pelvic veins, as demonstrated with magnetic resonance (MR) imaging. MATERIALS AND METHODS: The reports of 769 MR examinations performed from June 1993 through December 1999 in patients with suspected DVT were reviewed retrospectively. MR venography was performed by using a two-dimensional gradient-recalled-echo sequence (typically repetition time, 34 msec; echo time, 13 msec; flip angle, 60 degrees ). The presence of DVT was categorized by location in the pelvis, thigh, or calf. RESULTS: DVT was identified in 167 (21.7%) of the 769 MR examinations. Thirty-four (20.4%) of the 167 studies demonstrated DVT isolated to the pelvic veins. CONCLUSION: The relative frequency of isolated pelvic DVT detected with MR venography was higher than that reported in prior studies with ultrasonography (US) or ascending venography. MR venography should be performed in patients with suspected pelvic DVT or when clinical suspicion persists despite a negative US study.     

Testes and scrotum: MR imaging at 1.5 T

Magnetic resonance (MR) images of the scrotum were obtained at 1.5 T in 20 subjects, 13 patients with intrascrotal pathologic conditions and seven healthy subjects. Characteristic MR imaging signals obtained on T1- and T2-weighted images allowed differentiation of testis from epididymis and spermatic cord. Masses were differentiated from normal testicular parenchyma in all cases. Atrophic or ischemic testes had lower signal intensity than normal testes on T2-weighted images. Hematoma displayed a characteristic high intensity on both T1- and T2-weighted images. Intratesticular and extratesticular pathologic conditions were readily differentiated. These results suggest that MR imaging is useful in the diagnosis of scrotal and testicular abnormalities.     

Magnetic resonance venography in consecutive patients with suspected deep vein thrombosis of the upper extremity: initial experience

Purpose: To assess the feasibility and accuracy of two magnetic resonance (MR) venography methods in a consecutive series of patients with suspected deep vein thrombosis of the upper extremity (DVTUE).

Material and Methods: Consecutive in- and outpatients who were referred for imaging of suspected DVTUE in a large teaching hospital during the period April 2001 to October 2002 were eligible for inclusion. All patients were scheduled to undergo contrast venography with the intention to perform additional MR venography. Both time-of-flight and gadolinium-enhanced 3D MR venography were scheduled. All MR imaging were interpreted independently by consensus of two experienced radiologists, who were blinded for contrast venography outcome. Patients were managed based on contrast venography only.

Results: A total of 44 patients were eligible for inclusion. Thirteen patients were excluded (5 refused consent, 2 inability to gain venous access, 2 renal failure, 4 logistic reasons). Contrast venography was performed in 31 patients, and demonstrated DVTUE in 11 patients. MR imaging was not feasible in 10 patients (4 unable to lie flat, 3 claustrophobia, 1 too large for MR scanner, 1 osteosynthesis of shoulder, 1 pacemaker). The sensitivity and specificity of TOF MRV versus Gadolinium 3D MRV was 71% and 89% versus 50% and 80%, respectively.

Conclusion: A high number of patients were unable to undergo MR venography in this setting. Contrast-enhanced MRV did not improve diagnostic accuracy. The clinical utility of MR venography in the setting of suspected DVTUE seems disappointing.     

MR portal venography: preliminary results of fast acquisition without contrast material or breath holding

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate the feasibility of using the steady-state free precession (SSFP) sequence to perform magnetic resonance (MR) venography of the portal venous system without the use of contrast material or breath holding. MATERIALS AND METHODS: Eleven patients underwent MR venography with the SSFP technique. Coronal three-dimensional images were obtained with respiratory triggering. Contrast material and respiratory suspension were not used. All patients had recently undergone at least one other imaging study (conventional angiography, transhepatic portal venography, ultrasound, or contrast-enhanced computed tomography), and these findings were correlated with those from MR venography. The structures evaluated were the main portal vein, right portal vein, left portal vein, superior mesenteric vein, and splenic vein. RESULTS: MR venography with SSFP accurately depicted the status of these veins in all cases except one. In this patient, MR venography depicted portal vein thrombus but could not indicate that it was tumor thrombus. CONCLUSION: MR venography with SSFP accurately depicted the portal venous system in 10 of 11 patients without the use of respiratory suspension or contrast material.     

Undescended testis: value of MR imaging

Magnetic resonance (MR) imaging was performed in 32 male patients, 20 with no abnormalities and 12 with clinically suspected undescended testes. The results were compared with ultrasonographic, computed tomographic, clinical, and surgical findings. The undescended testes were unilateral in eight patients (one had testicular duplication) and bilateral in four. Of 16 undescended testes, 15 were correctly identified on MR images. One intraabdominal testis was not seen. Testis-fat contrast at 0.35 T was optimal with a short repetition time (TR) and a short echo time (TE). At 1.5 T, good contrast was achieved with short TR/TE sequences, but the contrast was even more pronounced with even longer TR/TE parameters. In seven patients with unilateral undescended testes, the undescended and contralateral testes showed symmetrical tissue signal intensity on both T1- and T2-weighted images. In three, the undescended testis was of lower signal intensity, suggesting atrophy. MR imaging promises to become an important diagnostic tool in the detection of undescended testes.     

Isolated calf vein thrombosis: comparison of MR venography and conventional venography after initial sonography in symptomatic patients.

RATIONALE AND OBJECTIVES: The authors performed this study to compare magnetic resonance (MR) venography and conventional venography in the diagnosis of deep venous thrombosis (DVT) in the calf after sonography. MATERIALS AND METHODS: Sonography was performed in 595 patients who were suspected of having lower-extremity DVT. Patients with positive above-knee duplex sonograms, allergy to iodinated contrast material, renal insufficiency, or cardiac pacemakers and patients who were obese were excluded. The remaining 73 patients were asked to undergo MR venography and conventional venography. All studies were to be performed within 48 hours of the clinical diagnosis and according to standard clinical practice. Images were interpreted by radiologists who were blinded to the results of other modalities. Two separate analyses were performed: one in which conventional venography was used as the standard of reference, and one in which the presence of at least two positive studies for thrombus was considered diagnostic. RESULTS: Although 36 patients agreed to participate in the study, only 14 underwent MR venography and conventional venography within 48 hours of the clinical diagnosis. With use of any two positive studies for confirmation, acute DVT was diagnosed in three patients. Conventional venography depicted two of the three cases, whereas sonography and MR venography each depicted all three. The findings were concordant in only five of the 14 patients. CONCLUSION: Moderate discrepancy among modalities was demonstrated. This suggests radiologists should undertake comparisons among these three modalities for the detection of calf DVT. In patients with a high clinical suspicion, a second modality may be useful if the initial study is negative.     

MR imaging of the scrotum with a high-resolution surface coil

Magnetic resonance (MR) imaging of the scrotum with a high-resolution surface coil was performed in ten healthy volunteers and 20 patients with scrotal abnormalities demonstrated by high-resolution real-time ultrasound (US). Four patients had an abnormal testis (two tumors, one cyst, one testicular atrophy), and 16 patients had extratesticular abnormalities (four hydroceles, five epididymal cysts, one hernia, and six cases of epididymitis). The normal structures of the scrotum were depicted clearly on MR images. In all cases, the tunica albuginea was easily differentiated from the testis and epididymis. MR imaging enabled one to distinguish intratesticular from extratesticular lesions and to determine whether a lesion was solid or cystic. Complicated and simple fluid collections could also be differentiated. In general, MR imaging and US scanning provided similar information. A potential advantage of MR imaging is in the evaluation of patients with painful scrotal lesions that may limit US evaluation.     

动态3D CE-MRV在颅内疾病诊断及治疗中的应用初探

目的：探讨动态3D CE-MRV在颅内静脉系统疾病诊断中的成像优势及其对颅内疾病临床诊断及治疗的指导意义.方法：可疑或确诊为颅内静脉病变者36例应用3T磁共振仪及3D TRICK技术行动态CE-MRV检查,9例无颅内静脉病变者同时行2D TOF序列MRV检查.分析动态3D CE-MRV图像,观察颅内深浅静脉系统主干及其分支的显示情况,比较其相对于2D TOF序列MRV的优势;分析动态3D CE-MRV对颅内疾病如静脉窦及静脉血栓、累及静脉的血管畸形、肿瘤和外伤等的诊断价值及其对临床治疗的指导意义.结果：与2D TOF序列比较,3D CE-MRV对静脉窦属支、上下吻合静脉及海绵窦等显示更清晰（P〈0.05）.动态CE-MRV显示36例受检者大致可分为4种结果：①正常者16例,含静脉发育变异6例;②累及静脉的颅内血管畸形3例;③静脉窦或静脉血栓11例,其中3例为溶栓术后复查显示再通;④肿瘤及外伤6例：脑膜瘤或颈静脉球瘤压迫或侵犯静脉窦者3例;外伤致颅内静脉异常者3例,其中1例为颈内动脉海绵窭瘘.结论：动态3D CEMRV对颅内静脉尤其是细小静脉的观察明显优于2D TOF序列的MRV;多时相显影和多方位重组可对颅内静脉变异、静脉畸形和累及静脉的疾患能清晰显示,为临床诊断、治疗方案的确定及疗效评价提供重要的影像依据.     

Deep venous thrombosis evaluation with limited-flip-angle, gradient- refocused MR imaging: preliminary experience

Sixteen patients (17 lower extremities) were prospectively examined with venography and limited-flip-angle, gradient-refocused magnetic resonance (MR) imaging for the presence or absence of deep venous thrombosis. Thrombosed vessels showed decreased-to-absent signal intensity, while patent vessels had high signal intensity. In 16 of 17 extremities, MR images allowed accurate detection and localization of the thrombi found with venography. In the remaining extremity, MR imaging allowed correct identification of thrombus in the iliac and femoral veins but incorrectly demonstrated clot in the calf and popliteal veins. MR imaging with limited-flip-angle, gradient-refocused pulse sequences appears to be a sensitive, noninvasive means of detecting deep venous thrombosis.     

颅内静脉血栓形成的磁共振诊断

目的:探讨磁共振成像(MRI)及磁共振静脉成像(MRV)对颅内静脉窦血栓形成(CVST)的诊断价值。方法:回顾性分析经临床和影像学方法确诊的14例CVST患者。MR检查技术包括平扫,增强扫描及MRV,14例均行CT平扫,其中1例行DSA检查。结果:14例CVST累及上矢状窦血栓形成4例,横窦血栓形成6例、乙状窦5例,MRI可清晰显示颅内静脉窦血栓形成的直接征象和间接征象,MRV可显示受累静脉窦不显影或者充盈缺损形成。结论:常规MRI结合MRV对颅内静脉窦血栓形成的早期诊断具有重要价值。     

Cerebral MR venography in children: comparison of 2D time-of-flight and gadolinium-enhanced 3D gradient-echo techniques

PURPOSE: To prospectively compare two-dimensional (2D) time-of-flight cerebral magnetic resonance (MR) venography with gadolinium-enhanced three-dimensional (3D) gradient-echo cerebral MR venography in children. MATERIALS AND METHODS: This investigation had investigational review board approval and was Health Insurance Portability and Accountability Act compliant; parental informed consent was obtained. Thirty-seven patients (20 boys, 17 girls) who ranged in age from 4 days to 15 years underwent 2D and 3D MR venography. Two pediatric neuroradiologists compared the visibility of the superior sagittal, straight, transverse, and sigmoid sinuses and the internal jugular veins on images obtained with the two sequences. RESULTS: In 17 (46%) of the 37 patients, the sequences were equivalent in terms of their depiction of venous anatomy. In 19 (51%) of the 37 patients, 3D MR venography was superior to 2D MR venography. Suboptimal enhancement of veins occurred in one (3%) patient at 3D MR venography. Venous anomalies suggested at 2D MR venography but not present at 3D MR venography included flow gaps in the nondominant transverse sinuses of four patients, unilateral transverse sinus atresia in eight, and a narrowed superior sagittal sinus in two. Two-dimensional MR venography results failed to reveal a persistent falcine sinus associated with straight sinus atresia in one patient and suggested transverse sinus thrombosis in two patients in whom 3D MR venography results were normal. Additionally, the extent of dural thrombosis was overestimated at 2D MR venography in one patient. As compared with 3D MR venography, 2D MR venography failed to reveal sigmoid sinus stenosis in one patient and poorly depicted posterior fossa dural sinus anatomy in two patients with dural arteriovenous fistula. CONCLUSION: Three-dimensional MR venography is often superior to 2D MR venography in the delineation of major cerebral venous structures in children. Most of the artifactual loss of vascular signal seen with the use of 2D MR venography occurred in nondominant transverse sinuses.     

磁共振在未降睾丸诊断中的临床价值初探

目的评价ＭＲＩ对未降睾丸的诊断价值。方法对１５例年龄在１～２８岁、临床不可触及的未降睾丸病人行ＭＲＩ检查，均经手术证实。结果所有未降睾丸（１８枚）均由ＭＲＩ正确显示，１５例中，３例为双侧，１２例为单侧。结论ＭＲＩ具有无创性、无辐射性，且能多方位成像的特性。本组病例证实其为未降睾丸定位的一种非常有用的影像手段，ＭＲ影像能揭示未降睾丸的解剖及组织学特征，最佳的成像平面为横断位及冠状位，ＧｄＤＴＰＡ增强有助于未降睾丸的显示     

Testicular venography in the nonpalpable testis.

Localization and identification of a nonpalpable testis can be done accurately by testicular venography. The identification of the pampiniform plexus is essential to the localization of the testis by this method. We evaluated 15 patients 3-39 years of age with 21 nonpalpable testes. Fourteen successful testicular venograms were performed showing four retroperitoneal testes, four testes within the inguinal canal, and two testes located in the superficial inguinal pouch. Three nonpalpable testes were thought to be due to true agenesis, and one venogram was performed after prior surgical removal of the testis. Catheterization of the left testicular vein was accomplished with greater ease and accuracy (79%) to the right side (42%).     

The value of computed tomography in the localization of undescended testes

Eight patients with unilateral and four with bilateral (4) unpalpable testes were evaluated with CT for localization. All patients were later submitted to laparascopy and/or surgery and 13 cryptorchid testes and 3 atrophic or agenesic testes were found. CT detected correctly 11 of the cryptorchid testes - (85%) with one false positive and one false negative finding. In the three atrophic or agenesic testes, CT did not identify any image suspicious of being a testis, so there three were no false positive studies here. It is concluded that CT is an accurate noninvasive method for the preoperative detection of cryptorchid testes.