Magnetic resonance urography: initial experience of a low-dose Gd-DTPA-enhanced technique

Contrast-enhanced magnetic resonance urography (MRU) is a promising tool in the evaluation of the renal collecting system, but it can be limited by T2^* effects resulting from hyperconcentrated gadolinium chelates. The aim of this study was to evaluate a low-dose dimeglumine gadopentetate (Gd-DTPA) MRU technique consisting of a dynamic fast low-angle-shot (FLASH) 2D sequence and a static fast imaging in steady state precession (FISP) 3D sequence for depicting the kidneys and urinary tract. The Gd-DTPA dose (0.01 mmol/kg) was established experimentally in a healthy volunteer study. Ninety-one patients presenting with various renal disorders were examined with a low-dose Gd-DTPA MRU and a T2-weighted turbo spin echo (TSE) MRU technique on a 1.5-T system. Image quality and diagnostic value were considered at least satisfactory in 98.9 % of the FLASH 2D studies, 83.5 % of the FISP 3D studies and 78.5 % of the TSE T2-weighted studies. Typical enhancement patterns were established for the renal cell carcinoma and transitional cell carcinoma. The major limitations were motion artefacts and insufficient hydration of the patients. Low-dose Gd-DTPA MRU appears to be a useful technique in the evaluation of the kidneys and urinary tract, especially in cases of renal tumours. Received: 26 February 1998; Revised: 25 January 1999; Accepted: 14 June 1999     

Magnetic resonance imaging in the assessment of urologic disease: an all-in-one approach

The aim of this study was to evaluate an “all-in-one” MR procedure to examine the kidneys, the renal vascular supply and renal perfusion, and the urinary tract. In 64 patients (58 with urologic disease and 6 healthy volunteers), MR was performed including: (a) T1- and T2-weighted imaging; (b) 3D contrast-enhanced MR angiography (MRA), including the renal arteries, renal veins, as well as renal perfusion; and (c) 3D contrast-enhanced MR urography (MRU) in the coronal and sagittal plane. For the latter, low- and high-resolution images were compared. Prior to gadolinium injection, 0.1 mg/kg body weight of furosemide was administered intravenously. The results were compared with correlative imaging modalities (ultrasonography, intravenous urography, CT), ureterorenoscopy and/or surgical–pathologic findings. Visualization of the renal parenchyma, the vascular supply, and the collecting system was adequate in all cases, both in nondilated and in dilated systems and irrespective of the renal function. One infiltrating urothelial cancer was missed; there was one false-positive urothelial malignancy. Different MR techniques can be combined to establish an all-in-one imaging modality in the assessment of diseases which affect the kidneys and urinary tracts. Continuous refinement of the applied MR techniques and further improvements in spatial resolution is needed to expand the actual imaging possibilities and to create new tracts and challenges in the MR evaluation of urologic disease. Received: 27 September 1999; Revised: 20 January 2000; Accepted: 22 May 2000     

磁共振泌尿造影在肾移植病人术后监测的应用

目的：评价磁共振泌尿造影（MRU）对监测肾移植并发症的临床应用价值。方法：采用快速自旋回波（FSE）重T2加权序列对15例患移植肾进行冠状位扫描，将图像按最大强度投影（MIP）法重建出MRU图像。经手术病理证实为尿路梗阻2例，尿漏2例，吻合口动脉瘤1例，经临床及化验室检查证实为排异反应4例，环孢素A毒性反应2例。移植肾正常4例。结果：各例的MRU均清晰显示移植肾在盆腔内的位置及形态，对梗阻的尿路、肾盂积水及尿路梗阻部位显示良好，解剖结构清晰，结合MR与其它影像资料，可对梗阻作出定性诊断，对肾周积液存在的位置及积液量显示清楚。结论：MRU是无创伤的检查方法，可判断移植肾的大小、肾周积液是否存在及移植肾集合系统是否扩张，对尿路梗阻定位、定性准确，是一种新的安全的术后并发症影像监测手段，最适合于肾移植后输尿管并发症的监测。     

A prospective comparative study of non-contrast helical computed tomography and intravenous urogram for the assessment of renal colic

Objective: To compare noncontrast helical computed tomography (NCHCT) and intravenous urography (IVU) for diagnosis of urinary calculi in evaluation of renal colic. Materials and methods: A 4-month prospective paired study compared NCHCT and IVU in patients being evaluated for renal colic. Each patient was studied with NCHCT followed by an IVU. An IVU was regarded as positive if any of the following were identified: delayed filling, hydronephrosis, hydroureter, ureteral calculus, or extravasation of contrast. A NCHCT was regarded as positive if any of the following were identified: hydronephrosis, hydroureter, ureteral calculus, or perinephric or ureteral inflammatory change. The sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) were reported using the clinical outcome as the gold standard, by either observation of passage or retrieval of calculus. Bladder distention was noted on NCHCT relative to the level of the acetabulum. The charts were also reviewed retrospectively for the results of urinalysis. Results: One hundred sixty-eight patients had both examinations interpreted. Nineteen positive NCHCT and IVU studies were eliminated due to lack of observation or retrieval of calculus, leaving 149 studies for interpretation. NCHCT had Se 0.98, Sp 0.95, PPV 0.98, and NPV 0.95. IVU had Se 0.83, Sp 0.95, PPV 0.97, and NPV 0.67. In 13/168 (8 %) cases, and in 9/37 (24 %) negative cases, NCHCT offered an alternative diagnosis. Ureterovesical junction (UVJ) calculus was identified on 84 NCHCT scans, with near-even distribution between well, partially, and poorly distended bladder. No UVJ calculus was identified on IVU that was not present on NCHCT. Absence of hematuria was found in 26 % of patients with proven urolithiasis. Conclusion: NCHCT is superior to IVU for the evaluation of renal colic. NCHCT identifies significant pathology in 24 % of cases negative for ureteral obstruction/calculus. Bladder distention does not play an important role in detection of UVJ calculus. Hematuria is not universally present in patients with painful urolithiasis.     

Dilatation of the collecting system during pregnancy: physiologic vs obstructive dilatation

Dilatation of the collecting system is a classical phenomenon during pregnancy, due to hormonal and extrinsic compressive factors. Imaging has to differentiate a physiological dilatation and a pathological obstruction due to urolithiasis. Presently, sonography, using both, B-mode and color Doppler, has the potential to demonstrate the physiological compression of ureters at the level of the pelvic brim. A pathological obstruction is considered either when a stone is detected above the usual site of compression or when the ureter appears dilated beyond. Color Doppler helps in localizing the site of ureteral compression against the vessels and in differentiating ureters from veins. Magnetic resonance urography, with strongly T2-weighted sequences, also may show the site and type of obstruction without contrast agent administration. These two non-radiating techniques make it possible to avoid the use of X-rays in most cases for management of these patients. The type of treatment is based mostly on the level of pain and the presence or absence of stone. Received: 2 July 1999; Revised: 3 September 1999; Accepted: 6 September 1999     

Functional significance of air trapping detected in moderate asthma

The aim of this study was to evaluate bronchial and lung abnormalities in patients suffering from moderate asthma as defined by international guidelines, with special attention to air trapping on CT in comparison with that detected in smoking and non-smoking normal subjects. Twenty-two patients classified as moderate asthma and control subjects including healthy volunteers, smokers (n = 10) or non-smokers (n = 12) were prospectively explored by high-resolution CT (HRCT) performed at suspended full inspiration and expiration. The same expiratory protocol was performed 15 min after inhalation of 200 μg of salbutamol. Patients underwent pulmonary function tests within the same week and bronchodilator response was assessed following inhalation of salbutamol. Abnormalities of bronchi and lung parenchyma on inspiratory CT and air trapping on expiratory CT, in dependent and non-dependent areas, were assessed and scored semi-quantitatively by two independent observers. Comparison of score mean values between the different groups was performed using Mann-Whitney test and Spearman correlation between CT findings and pulmonary function tests were calculated. Mosaic perfusion was observed in 23 % of asthmatics. Air-trapping scores were significantly higher in asthmatic patients than in non-smoking control subjects (p = 0.003), but not than in smokers. This difference was ascribed to non-dependent zones of the lung for which air-trapping scores were also higher in asthmatic patients (p = 0.003) and in smoking subjects (p = 0.004) than in normal controls. In the asthmatic group, a significant positive correlation was found between airways resistance and bronchial dilatation score (p = 0.01), and between small airways obstruction index and mosaic perfusion score (p = 0.05). In addition, both FEV1 and reversibility of small airways obstruction values correlated with air-trapping score (p = 0.03 and p = 0.007, respectively). No change could be detected in air-trapping score following salbutamol inhalation. Patients suffering from moderate asthma present mosaic perfusion and larger areas of air trapping than normal subjects, particularly in non-dependent areas of the lung. These lung abnormalities are related to small airways obstruction. Received: 28 December 1999; Revised: 27 April 2000; Accepted: 2 May 2000     

Feasibility of MR urography in neonates and infants with anomalies of the upper urinary tract

The aim of this study was to evaluate the feasibility and diagnostic potential of dynamic MR urography (MRU) in neonates and infants with sonographically detected abnormalities of the upper urinary tract. Thirty infants (age range 5 days to 3 years, mean age 7.9 months; male:female: 22:8) underwent MRU using T2 and contrast-enhanced dynamic T1-weighted sequences. The results were compared with the findings of ultrasound ( n=30), intravenous urography (IVU, n=19) and/or scintigraphy ( n=25) based on the criteria suggestive of obstructive uropathy. Oral sedation was sufficient to perform MRU with diagnostic quality in 20 of 21 patients younger than 1 year; 9 older patients needed intravenous sedation. Diagnosis of the 66 renal units (58 kidneys, 29 successful examinations) included normal systems (contralateral units), duplex systems, vesico-ureteral reflux, obstructive megaureter, ureteropelvic junction obstruction and accompanying renal parenchymal disease, with complex pathology in 10 patients. Magnetic resonance urography demonstrated anatomy better than IVU, particularly the renal parenchyma, (ectopic) ureters, and poorly functioning dilated systems. Magnetic resonance urography was superior to US in showing ureteral pathology. Tiny cysts in dysplastic kidneys were better seen by US. Gadolinium-enhanced dynamic MRU allowed accurate assessment of obstruction applying IVU criteria. Here MRU matched IVU results, and most of the scintigraphic findings. Magnetic resonance urography can be performed in young infants with diagnostic quality using oral sedation. Magnetic resonance urography correctly depicts anatomy and allows assessment of the urinary tract better than US and IVU, with additional functional information. Magnetic resonance urography thus has the potential to replace IVU for many indications.     

Urinary obstruction in renal transplants: diagnosis by antegrade pyelography and results of percutaneous treatment

We reviewed our experience with 51 renal transplants to evaluate the accuracy of antegrade pyelography as compared with that of sonography and nuclear renography in the diagnosis of transplant obstruction. Also, the results of percutaneous treatment were analyzed in 44 of these patients. Obstruction was clinically suspected in all of the patients (increased serum creatinine levels and decreased urine output). Antegrade pyelography showed obstruction in 44 (86%) of the 51 patients, and nephrostomy drainage catheters were inserted. Sonography showed pyelocaliectasis in all 49 cases in which it was performed; in 42, the pyelocaliectasis was due to obstruction (14% false-positive rate). Nuclear renography showed obstruction in only six (18%) of 33 cases in which it was performed; all six cases proved to be obstructed (0% false-positive rate and 82% false-negative rate). Twenty-two (50%) of the 44 patients treated with nephrostomy drainage were managed successfully without surgical intervention; seven of these 22 required balloon dilation of ureteric strictures in addition to catheter decompression of the collecting system. The average duration of catheterization required for successful percutaneous treatment was 35 days. This experience suggests that antegrade pyelography has a definite role in the workup of patients suspected of having renal transplant obstruction. The percutaneous access permits successful catheter drainage. Compared with antegrade pyelography, sonography is reasonably accurate in determining the presence of urinary obstruction, although false-positive diagnoses are found in a substantial number of patients. Nuclear renography is not, however, a useful indicator of obstruction owing to its high false-negative rate. Percutaneous treatment of urinary obstruction in transplantation patients proves successful in approximately 50% of cases.     

磁共振尿路造影在小儿泌尿系梗阻诊断中的价值

目的 探讨磁共振尿路造影(MRU)技术在小儿泌尿系梗阻诊断中的价值. 方法 65例上尿路梗阻患儿行静脉肾盂造影(IVP)、B超及MRU检查,MRU检查应用快速自旋回波重T_2WI序列.对照MRU与手术结果,比较MRU与IVP、BUS在上尿路梗阻诊断中的价值. 结果 MRU诊断肾盂输尿管连接部狭窄36例,重复肾3例(其中误诊1例),原发性巨输尿管症9例,输尿管膀胱入口狭窄4例,输尿管末端囊肿3例,孤立肾2例,肾结石5例,神经性膀胱2例,先天性肾发育不良1例.MRU对上尿路梗阻的诊断正确率为98.5%(64/65),优于IVP及B超(P＜0.05). 结论 MRU是诊断小儿上尿路梗阻的可靠方法.     

MR urography in children: current status and future development

The normal anatomy and many pathologies of the pediatric genitourinary system can be assessed with different imaging modalities. Most of them are based on the use of ionizing radiation and/or invasive techniques. The contribution of magnetic resonance imaging in this regard has opened new ways of approaching pathological conditions in this patient group. The addition of the newly developed rapid techniques has enhanced the superiority of MRI, and both morphological and functional evaluation of the genitourinary system can be achieved. There are different factors on which rely the optimization and the efficiency of magnetic resonance urography (MRU). Of importance is adequate patient immobilization and the use of optimal imaging sequences. The rapid technical development, including the advent of the post-processing respiratory navigator, allows acquisition of high-quality images independent of the patient's respiratory rate. In the future, it is expected that MRU, due to its non-use of ionizing radiation, will become the most important tool in the diagnostic work-up of genitourinary pathologies in infants and small children. Received: 1 June 1999; Revision received: 9 August 1999; Accepted: 11 August 1999     

Postoperative findings following the Whipple procedure: determination of prevalence and morphologic abdominal CT features

This study was conducted to determine characteristic CT findings following the Whipple procedure and to evaluate the usefulness of CT in predicting tumor recurrence. Eighty-four postoperative abdominal CT scans and medical records of 43 patients were retrospectively reviewed. Perioperative histopathologic examinations revealed malignancy in 32 patients (74.4 %). Time interval between surgery and CT varied from 13 days to 6 years and 7 months. Common postoperative findings were unopacified anastomotic bowel loops in the porta hepatis (n = 69 scans), perivascular cuffing (n = 42 scans), pneumobilia (n = 40 scans), dilated intrahepatic bile ducts (n = 22 scans), reactive lymphadenopathy (n = 21 scans), and transient fluid collections (n = 20 scans). Postoperative complications were detected on 17 CT scans (20.2 %): generalized ascites (n = 8 patients), deep abscesses (n = 3 patients), wound abscess (n = 1 patient), pancreatitis (n = 1 patient), and pseudomembranous colitis (n = 1 patient). Tumor recurrence appeared in 15 patients (46.8 %) after a mean postoperative period of 11 months (1 month to 3 years): local (9 of 15), regional lymph nodes (9 of 15), and liver metastasis (8 of 15). Detection of generalized ascites more than 30 days after surgery was associated with tumor recurrence in 6 of 6 patients (100 %). Diffuse ascites (> 30 days after surgery) behaved as an early predictive sign of tumor recurrence. In our series CT accuracy for detecting recurrent tumor with CT was 93.5 %. No predilection site for disease recurrence could be determined. Received: 1 February 1999; Revised: 15 April 1999; Accepted: 19 April 1999     

上尿路梗阻病变的MR尿路成像诊断

目的：探讨磁共振尿路成像（ＭＲＵ）诊断上尿路梗阻病变的价值。材料与方法：上尿路梗阻患者４１例,ＭＲＵ应用ＭＲ水成像技术,三维（３Ｄ）快速自旋回波（ＦＳＥ）和脂肪抑制序列,所有图像经最大信号强度投影（ＭＩＰ）后处理。结果：ＭＲＵ能显示上尿路梗阻部位及积水改变。良性尿路梗阻２６例,恶性尿路梗阻１５例。结合ＭＲＩ,ＭＲＵ显示上尿路梗阻的部位准确性达１００％,ＭＲＵ确定梗阻原因的准确性达８５４％。结论：ＭＲＵ适用于上尿路梗阻病变的诊断,能显示尿路梗阻部位和积水程度,与ＭＲＩ结合有助于上尿路梗阻病变的定性诊断,是一种安全、非侵袭性的泌尿系影像检查新方法。     

Fine-needle antegrade pyelography of transplanted kidneys

Ureteral obstruction or perforation must be considered as a cause of poorly functioning renal transplants. Sonography and radionuclide scanning will demonstrate outflow obstruction and/or pararenal fluid collection, but do not usually provide sufficient information on the site of the lesion. In these cases we have successfully used fine-needle puncture of the renal pelvis under sonographic guidance, and antegrade pyelography. This technique shows excellent anatomical details of the renal pelvis and ureter.     

影像学检查对结石所致上尿路梗阻的诊断价值

目的 评价数字化X线摄影尿路造影[静脉尿路造影(IVU)、逆行尿路造影(RU)和经皮顺行尿路造影(PAu)]、螺旋CT(SCT)、磁共振成像(MRI MRU)对上尿路结石致梗阻的诊断价值方法62例经手术与病理证实的上尿路结石患者均经IVU，其中，26例又经RU，1例经PAU，23例经SCT，以及15例经MRI MRU检查。对不同检查方法的诊断准确率进行了比较。结果 尿路造影对七尿路结石所致梗阻定位、定性及梗阻与扩张程度的诊断准确率分别为98．4％，96．8％，100％；SCT分别为95．7％，100％，95．7％；；MRI MRU分别为86．7％，60％，93．3％。结论 在上尿路结石致梗阻的诊断中，尿路造影和SCT应作为主要检查手段，而MRI MRU可作为一种补充检查。     

MRU对小儿先天性肾积水的临床应用研究

目的:探讨泌尿系统水成像(MRU)技术对小儿先天性肾积水的临床应用价值。方法:回顾性分析52例手术证实为先天性肾积水的小儿MR图像。所有患儿均行冠状位MRU及兴趣区轴位T2WI序列检查。结果:52例患儿中,肾盂输尿管连接部狭窄35例,原发性巨输尿管4例,重复肾盂输尿管畸形7例,输尿管末端囊肿2例,肾发育不全或异位肾4例。手术中所见与MRU图像表现基本一致。结论:MRU能够无放射线、无需对比剂、多角度、直观显示小儿肾脏积水和/或合并其它泌尿系畸形。     

Renal scintigraphy in infants with antenatally diagnosed renal pelvis dilatation

BACKGROUND/AIM: Ureteropelvic junction obstruction and vesicoureteral reflux are the most frequent entities identified on the basis of antenatal hydronephrosis. The aim of this study was to determine the incidence and pattern of abnormal renal scintigraphy findings in postnatal investigation of children with antenatal hydronephrosis. METHODS: Twenty-four infants (19 boys and five girls) presented with antenatal hydronephrosis and mild to moderate hydronephrosis on ultrasound in newborn period were referred for renal scintigraphy. Ten patients with vesicoureteral reflux documented on micturating cystoureterography underwent 99mTc-DMSA renal scintigraphy and 14 patients were subjected to 99mTc-DTPA scintigraphy. RESULTS: Anteroposterior pelvic diameter on ultrasound ranged from 11 to 24 mm. Renal DMSA scans identified congenital scars in two boys with bilateral reflux of grade V and unilateral reflux of grade III. Relative kidney uptake (RKU) less than 40% was found in three, and poor kidney function (RKU less than 10%) in two patients. Significant obstruction was shown on DTPA diuretic renal scintigraphy in 6/14 patients. Some slowing in dranaige (T1/2 greater than 10 minutes) with no reduction in differential renal function was identified in three patients. Differential renal function less than 10% was obtained in one case. CONCLUSION: A high percent of abnormal renal scintigraphy findings was obtained. Renal scintigraphy was useful in determination of underlying cause of antenatally detected hydronephrosis.     

Transitional cell carcinoma of the kidney

Transitional cell carcinoma is an uncommon disease of the renal pelvis, the diagnosis of which depends largely upon radiological investigation. Thirty-eight such tumours in 37 patients have been reviewed to establish the examination of choice. High-dose excretion urography, tailored to the presenting problems, is the primary investigation and the results fall into five main groups. Each presents different differential diagnostic problems. Discrete filling defects within the pyelogram (group I) may be overlooked, but, when seen, can be diagnosed on urography alone. Filling defects with dilated calyces (group II) are easily seen and readily diagnosed. Calyceal obliteration (group III) presents more difficulty in diagnosis and may require retrograde pyelography and selective renal angiography. Hydronephrosis with renal enlargement (group IV) is easily confused with uncomplicated primary pelvic hydronephrosis and will usually require antegrade pyelography for diagnosis. Reduced function without renal enlargement (group V) cannot be diagnosed on excretion urography and requires both retrograde pyeloureterography and selective renal angiography.     

磁共振尿路成像临床应用

目的 探讨磁共振尿路成像(MRU)的临床应用价值。方法 利用PHILIPS T5-NT 0.5T超导型MR扫描机,采用快速自旋回波(TSE)序列重T_2加权技术,对52例患者作MR尿路成像,行最大信号强度投影(MIP)处理,所有患者均先行常规MR扫描。结果 52例中,尿路梗阻扩张26例,其中:肾盂-输尿管交界段狭窄7例,输尿管癌4例,输尿管结石6例,输尿管炎性狭窄4例,输尿管外压1例,膀胱癌2例,神经源性膀胱2例。MRU显示尿路梗阻扩张正确率达100％,对梗阻定性诊断有3例错误。无尿路梗阻17例,其中肾癌3例,肾盂癌2例,肾血管平滑肌脂肪瘤1例,肾囊肿9例,马蹄肾1例,一侧肾缺如1例,均由MRI和MRU相结合确诊。另有9例患者呈现不同程度肾盂积水,未见尿路梗阻征象,其中:6例结合临床诊断为肾盂肾炎。52例中,部分病例与B超、IVU、CT扫描结果进行了比较。结论 MRU为一有效安全无创的影像检查技术,特别适用于肾功能不良和有IVU禁忌症者,对确定尿路梗阻扩张,梗阻的定位、定性有重要的应用价值。MRU和MRI相结合能对泌尿系统疾病的诊断提供更为完整的诊断依据。但在实践中,应依据患者具体情况合理选用MRU检查。     

尿路梗阻性病变的MRU应用

目的 探讨磁共振尿路造影(MRU)技术对尿路梗阻性病变的诊断价值。资料与方法 对46例经B超发现尿路扩张患者采用重T2WI单次激发快速自旋回波(SSFSE)序列行MRU检查，其中41例行静脉肾盂造影(IVP)。结果 46例尿路梗阻性病变包括：良性狭窄19例，先天性异常10例，输尿管结核5例，输尿管癌3例，外在性病变4例，输尿管结石4例，膀胱病变1例。MRU均清楚显示尿路影像，能确定有无梗阻，展示梗阻端的形态和特征，对梗阻水平的定位及梗阻原因的定性均有较高的准确性，明显优于IVP检查。结论 MRU是安全、有效的非侵袭性影像检查方法，特别适用于IVP禁忌症和肾功能丧失者。可多方位、多角度成像，结合常规T1WI、T2WI可获得可疑部位的大量信息，以达到明确诊断目的。     

Split-bolus MR urography: synchronous visualization of obstructing vessels and collecting system in children

Several vascular abnormalities related with urinary system such as crossing accessory renal vessels, retroiliac ureters, retrocaval ureters, posterior nutcracker syndrome, and ovarian vein syndrome may be responsible for urinary collecting system obstruction. Split-bolus magnetic resonance urography (MRU) using contrast material as two separate bolus injections provides superior demonstration of the collecting system and obstructing vascular anomalies simultaneously and enables accurate preoperative radiologic diagnosis. In this pictorial review we aimed to outline the split-bolus MRU technique in children, list the coexisting congenital collecting system and vascular abnormalities, and exhibit the split-bolus MRU appearances of concurrent urinary collecting system and vascular abnormalities.Magnetic resonance urography (MRU) is a noninvasive imaging technique that does not involve ionizing radiation or iodinated contrast medium. Therefore, it has a potential to noninvasively illustrate various urinary tract abnormalities and provides both morphologic and functional information. MRU can be obtained by two different techniques: T2-weighted MRU (also known as static-fluid MRU) and T1-weighted MRU (also known as contrast-enhanced excretory MRU) (1–3). Generally used contrast-enhanced MRU protocol with single-bolus contrast material injection consists of dynamic scanning of urinary system at different phases. However, using the single bolus technique, vessels and collecting systems cannot be demonstrated simultaneously. Although split bolus computed tomography (CT) urography is widely used in adults and described in the literature, the major disadvantage in multiphasic scans and follow-up is the radiation exposure, particularly in pediatric patients who are more susceptible to radiation-related effects including cancer and mutations. Compared with adults, children are considerably more sensitive to radiation and have a longer life expectancy resulting in a larger window for expressing radiation damage (4). Moreover, the administration of potentially nephrotoxic iodinated contrast agents in this group that are prone to renal impairment is an important restriction for CT urography (2).In this article, we aimed to summarize the MRU technique with the emphasis on split-bolus MRU and its role in demonstrating vascular anomalies related with urinary collecting system.