Imaging and the first urinary infection in children. Respective role of each test during the initial evaluation apropos of 122 cases

122 pediatric patients with a first urinary tract infection underwent renal ultrasonography (US) and voiding cystourethrography (VCUG) to evaluate the usefulness of this association. The US was always the first examination undertaken, its sensitivity seems to be very good in detecting renal abnormalities. The major finding on the VCUG was the vesico-ureteral reflux: 25% of cases. When the sonogram and the VCUG are normal, 60% of cases, excretory urography is not considered necessary.     

Sonography as a substitute for excretory urography in children with urinary tract infection

The possibility was explored of substituting renal sonography for excretory urography in children with urinary tract infection. Seventy-one patients were studied prospectively with voiding cystourethrography, sonography, and excretory urography; each examination was reviewed independently and without knowledge of the results of the others. Compared with urography the sensitivity and specificity of sonography was 100% and 51%, respectively, provided sonograms were of good technical quality. In a few instances, however, focal renal parenchymal scars were clearly seen only on urography. The findings suggest that in the absence of vesicoureteral reflux children with urinary tract infection should be studied with sonography. No further study is needed if a good-quality sonogram is within normal limits. In the presence of vesicoureteral reflux, however, or a suspicious or abnormal sonogram, excretory urography appears to be still necessary, at least at the present level of knowledge and technical expertise.     

Urinary tract infection in children. A reappraisal of its radiologic investigation

In a prospective study, 100 children with either an acute or a previous history of urinary tract infection were investigated by intravenous urography, micturition cystourethrography, and ultrasonography. The results from the three diagnostic modalities were compared: The urinary tracts in 59 patients were normal, and revealed some abnormality in 41. Ultrasonography proved to be superior to intravenous urography in outlining renal contours and in detecting subtle cortical changes secondary to urinary tract infection (such as slight increases in cortical thickness and edema or cortical scarring). The mucosa of the renal pelvis and bladder was more easily assessed by ultrasound than by intravenous urography. Both modalities were "equally" accurate in detecting important congenital malformations of the urinary tract. Ultrasound failed to detect 24 of 28 ureters demonstrating reflux on voiding cystourethrography. We propose that carefully performed abdominal ultrasonography can replace intravenous urography in the initial investigation of urinary tract infection in children. It should be done in association with a radiographic or radionuclide voiding cystogram. Intravenous urography would then become a complementary examination for abnormal or problematic patients.     

Potential impact of pediatric MR urography on the imaging algorithm in patients with a functional single kidney

OBJECTIVE: The purpose of this study was to evaluate the potential of MR urography in the assessment of children with a suspected "functional single kidney." SUBJECTS AND METHODS: Sixty patients (age range, 2.7 weeks to 15.7 years) who had been referred for assessment of a suspected functional single kidney underwent MR urography in addition to detailed sonography of the urinary tract and the currently indicated standard imaging. The results of the conventional imaging ((99m)Tc-dimer captosuccinic acid scintigraphy, voiding cystourethrography, and genitography) were compared with the results of sonography and MR urography; surgical findings served as the gold standard if available. RESULTS: Twenty-six patients had a single kidney. The other diagnoses were six contralateral multicystic dysplastic kidneys, two normal ectopic kidneys, one crossfused double system, and 25 ectopic or dysplastic renal buds. Scintigraphy detected all normal kidneys, two ectopic kidneys, and two dysplastic renal buds. Detailed sonography missed two ectopic kidneys and two orthotopic dysplastic renal buds, but one additional renal bud that could not be confirmed on other imaging techniques (accuracy, 91.7%; sensitivity, 88.2%; specificity, 96.2%) was suspected. MR urography results were correct in all patients and verified in all 13 with surgical correlation. CONCLUSION: MR urography allows a reliable assessment of renal and ureteral anatomy and of dysplastic or ectopic renal buds, even in non- or poorly functioning systems. MR urography therefore has the potential to replace the currently used excretory urography and scintigraphy. In patients with a suspected functional single kidney a detailed sonographic study and MR urography should be considered the diagnostic algorithm of choice.     

Voiding cystourethrography: the initial radiologic study in children with urinary tract infection

The order in which children with urinary tract infection should undergo voiding cystourethrography (VCUG), excretory urography (EU), and/or renal ultrasonography (US) is not standardized. To determine a logical sequence of study, we performed VCUG and then either US or EU on 389 consecutive children with urinary tract infections. Thirty-seven percent (133/358) of the children were found to have reflux; of these, 22.5% (30/133) had an abnormal excretory urogram. No correlation was found between either the age of the child and the degree of reflux or the age of the child and the percentage of children with abnormal excretory urograms. Since normal EU or US results do not exclude significant reflux, VCUG is recommended as the preferred initial screening examination in children with urinary tract infection.     

Renal growth retardation in children: sign suggestive of vesicoureteral reflux?

Of 141 children undergoing surgery for vesicoureteral reflux detected by voiding cystourethrography, preoperative excretory urography demonstrated signs suggestive of vesicoureteral reflux in 154 (67.5%) of 228 refluxing ureter. In 48 refluxing ureters (21%) renal growth retardation was the only sign; the latter was appreciated by applying the index described by Hodson, that is, the ratio of bipolar parenchymal thickness to total renal length. It was concluded that it is important to systematically calculate this simple index from every child's excretory urogram.     

Radiographic manifestations of congenital anomalies of the lower urinary tract

The evaluation of anomalies of the lower urinary tract (ureter, bladder, and urethra) requires high quality ultrasonography, voiding cystourethrography, and, occasionally, intravenous urography and contrast sinography. Infants with these anomalies present because of abnormal intrauterine ultrasonographic examinations, urinary tract infections, or obvious external malformations. With a solid embryologic knowledge of the development of the lower urinary tract the radiologist can tailor the imaging procedures to demonstrate almost all aspects of the anomaly and the presence or absence of frequently associated malformations.     

Ureterektopie mit Harnträufeln im Kindesalter — eine diagnostische Herausforderung

Based on the observations in four girls suffering from constant urinary dribbling we analyzed the special features and difficulties in making the diagnosis of an ectopic ureter. In all patients there was marked diagnostic delay. In one symptomatic case the abnormality was not detected before the age of 18 years. Failure to recognize the characteristic signs and symptoms played a crucial role in delaying the diagnosis. Moreover, imaging of ureteral ectopia represents a diagnostic challenge. The ectopic ureters were associated with dysplastic, poorly functioning renal moieties. Common diagnostic imaging procedures, such as ultrasound, intravenous pyelography, or voiding cystourethrography yielded incomplete diagnostic information and often failed to provide a definitive diagnosis. The latter could only be obtained with MR urography. We assessed the diagnostic value of the different examinations and compared our findings with those reported in the literature.     

Kidneys in infants and children: evaluation with MR

Magnetic resonance (MR) imaging was performed in 58 children aged 1 day to 17 years. In 43 patients with suspected renal abnormalities, the results of MR were compared with those obtained by ultrasonography, computed tomography, or excretory urography. The remaining 15 children with no known renal disease were initially imaged to define the appearance on MR images of the normal kidneys according to the child's age. The signal intensity from hilar adipose tissue increased with age; corticomedullary differentiation was best seen in younger children. Compared with other imaging modalities, MR added useful information in evaluating the complications associated with renal failure and in patients with renal neoplasms. The use of MR in children with possible renal disease is limited, and the modality should be used as an adjunct to renal ultrasonography in a carefully selected group of patients.     

Undiversion of the urinary tract: the pre-and postoperative evaluation

Each uroradiologic procedure performed in the pre- and postoperative evaluation of the child undergoing undiversion contributes unique information. Function and anatomy of both the upper and lower urinary tracts must be carefully assessed. If the immediate postoperative studies show that the undiversion has been successful, the patient should be monitored yearly with excretory urography. If urinary tract symptoms develop, a more extensive radiographic evaluation (voiding cystourethrography, excretory urography, scintigraphy) may be warranted.     

Imaging in ureteral complications of renal transplantation: value of static fluid MR urography

Ureteral obstruction is an infrequent complication after renal transplantation that may cause rapid loss of transplant function. We tested static fluid MR urography for determining the cause of graft hydronephrosis. Magnetic resonance urography was performed in nine transplants with dilated collecting systems on ultrasound. A heavily T2-weighted 3D turbo spin-echo sequence on a 1.5-T scanner was used and maximum intensity projections were obtained. The patients also underwent excretory urography (n = 1), renal scintigraphy (n = 1), antegrade pyelography (n = 3), voiding cystourethrography (n = 4), and non-enhanced CT (n = 2). Six patients had pathologic conditions including ureteral stricture, compression by lymphoceles, implantation stenosis, vesicoureteral reflux, and late-occurring transitional cell carcinoma at the implantation site. Static MRU was able to diagnose or exclude a dilation of the graft collecting system. It visualized the course of the ureters and localized the obstruction site in four of five obstructed transplants. In one case the ureter was obscured by lymphoceles, which were demonstrated by hydrographic MRU as well. The definite cause for obstruction was provided in only 2 of 5 cases. Dilation due to vesicoureteral reflux could not be differentiated. The current multimodality approach to renal transplant imaging already provides comprehensive assessment of graft hydronephrosis. Static MRU may be useful in some cases since complications associated with intravenous iodinated contrast or antegrade pyelography can be avoided. Its main drawback, the lack of functional information, may be overcome by combining it with contrast-enhanced MRU. Received: 18 February 1999; Revised: 23 July 1999; Accepted: 18 November 1999     

Radionuclide imaging in the assessment of primary chronic pyelonephritis.

The diagnostic value of radionuclide imaging as a supplement to excretory urography was assessed in 33 patients with primary chronic pyelonephritis. Both 99mTc-glucoheptonate and 131I-Hippuran were used. Radionuclide imaging did not improve the sensitivity of detection by urography alone (31 of 33 patients). Nevertheless, in one third of cases the radionuclide studies demonstrated certain abnormalities more readily, including focal parenchymal damage, renal functional impairment, and decreased renal perfusion. Radionuclide imaging is useful when minimal or no abnormalities are observed on the excretory urogram or nephrotomogram.     

Imaging of children with urinary tract infection: a tailored approach

We reviewed the initial imaging studies of 283 children with urinary tract infection in order to decide on the most effective approach. A voiding cystogram was performed in all, complemented by either urography (147 patients), ultrasonography (65), or both (71 patients). In the latter group there was good correlation between sonographic and urographic findings, except for a more accurate delineation of renal scars and anomalies on urography, all in children with vesicoureteral reflux and/or abnormal sonograms. From these data we derived two imaging sequences tailored to the clinical circumstances: cystography as the initial study in ambulatory patients after infection has subsided, and sonography followed by cystography in children hospitalised with severe infection. The upper tracts are studied by ultrasonography and/or urography in patients with significant vesicoureteral reflex or an abnormal sonogram. Both these sequences reduce radiation by omitting the urogram in roughly half of the patients.     

CT and ultrasonography of acute renal abnormalities

Computed tomography and ultrasonography are important in the evaluation of patients with acute renal abnormalities, either as adjuncts or, less commonly, as alternatives to excretory urography. Ultrasonography has become the imaging procedure of choice in evaluation of acute renal failure. Detection of obstructive uropathy by ultrasonography is very accurate, although the potential pitfalls of minimal dilatation obstructive uropathy, false absence of caliectasis in dehydrated patients, and peripelvic cysts simulating hydronephrosis should be considered. Both CT and ultrasonography have improved our ability to define specific causes of intrinsic or extrinsic renal or ureteral obstructing lesions, including tumor, inflammatory masses, and calculi. Renal infections and infarctions also have characteristic appearances on CT and ultrasonography, though ultrasonography is somewhat limited by its inability to reliably demonstrate gas-containing or small abscesses, and its inability to provide functional information about the concentrating capacity of regional areas of the kidney.     

Anomalies of the distal ureter, bladder, and urethra in children: embryologic, radiologic, and pathologic features.

Congenital anomalies of the lower urinary tract are a significant cause of morbidity in infancy. Radiologic investigation is an important source of clinical information in lower urinary tract disorders but should not inconvenience the patient, expose the patient to unnecessary radiation, or delay surgical correction. In pediatric patients with suspected underlying urologic structural anomalies, screening ultrasonography is commonly the initial diagnostic study. If dilatation of the urinary tract is confirmed, voiding cystourethrography is performed to determine the presence of vesicoureteral reflux (VUR) and other causes of upper tract dilatation. If VUR is confirmed, follow-up with nuclear cystography or echo-enhanced cystosonography may be performed. If VUR is excluded, nuclear diuresis renography is the primary test for differentiating between obstructed and nonobstructed megaureter. Intravenous urography can be used to specifically identify an area of obstruction and to determine the presence of duplex collecting systems and a ureterocele. Computed tomography and magnetic resonance (MR) imaging are unsuitable for general screening but provide superb anatomic detail and added diagnostic specificity. MR imaging is mandatory in the evaluation of associated spinal anomalies. MR urography can demonstrate ectopic extravesical ureteric insertions, thereby providing a global view of the malformation. Familiarity with anomalies of the lower urinary tract is essential for correct diagnosis and appropriate management.     

The role of ultrasonography in the diagnosis of tumours of the renal pelvis

The authors have evaluated 22 patients with renal pelvis tumour (RPT) by means of excretory urography and ultrasonography. Six patients also underwent arteriography. The value of the three investigations in the diagnosis of the lesion, the nature, the pyelic origin and the extension are presented. It is concluded that urography remains the method of choice for the evaluation of RPT while ultrasonography may be considered complementary to urography in cases of non-functioning kidney, when the urographic filling device defect is uncertain and in the differentiation between the pyelic or parenchymal origin of the tumour.     

Radiologic investigation of renal colic: unenhanced helical CT compared with excretory urography.

OBJECTIVE: Our aim was to compare unenhanced helical CT and excretory urography in the assessment of patients with renal colic. SUBJECTS AND METHODS: Fifty-three of 70 consecutive patients with acute signs of renal colic were prospectively examined with unenhanced helical CT, which was followed immediately by excretory urography. Two radiologists who were unaware of the findings independently interpreted these examinations to determine the presence or absence of ureteral obstruction. On all CT scans that had positive findings for ureteral stones or obstruction, we looked for secondary signs of obstruction (perinephric or periureteral fat stranding, ureteral wall edema, ureteral dilatation, and blurring of renal sinus fat). RESULTS: A stone was recovered in 45 of the 53 patients, nine before and 36 after imaging. The latter 36 patients had their stones identified on CT, whereas only 24 patients had their stones identified on excretory urography. Eight patients without stone disease had normal ureters on both CT and excretory urography. Of the 45 patients who had stone disease, 26 had ureteral dilatation on both CT and excretory urography, and 36 patients who recovered a stone after CT had secondary signs of obstruction. Of the nine patients who recovered a stone before CT, three had secondary signs of obstruction. Two patients had periureteral fat stranding, ureteral wall edema, and renal sinus fat blurring. One patient had only ureteral wall edema. CONCLUSION: Compared with excretory urography, unenhanced helical CT is better for identifying ureteral stones in patients with acute ureterolithiasis. Secondary CT signs of obstruction, including renal sinus fat blurring, were frequently present even when the stone was eliminated before imaging.     

Ultrasound versus excretory urography in evaluating acute flank pain

To determine the role of ultrasound (US) in patients with acute flank pain and suspected acute urinary tract obstruction, a prospective study was performed on 20 patients comparing US with emergency excretory urography. US was not as sensitive as excretory urography for diagnosing hydronephrosis, for detecting ureteral or renal calcification, or for diagnosing forniceal rupture. Although US is an effective screening modality for hydronephrosis in patients with chronic renal obstruction, it is not useful for evaluating patients with acute flank pain in whom acute obstruction may be present. In this group of patients, excretory urography remains the examination of choice.     

Ultrasonography versus excretory urography: value in urological disease

Considerable savings in cost and some reduction in gonad dose and contrast medium allergy can be expected if excretory urography can be replaced by real-time ultrasonography as the first examination in upper urinary tract disease. For one year, all patients referred for excretory urography (UG) are first examined with real-time ultrasonography (US) to establish whether UG can be completely replaced by US, or the indications for which US should be the first examination of choice. The results in 200 consecutive patients indicate that both methods sometimes fail, but not in the same patients. A combination of the two may be unbeatable, but uneconomical. The results obtained over one year may give the answer. Hopefully studies at other centres will be initiated to increase the size of the case material.     

The role of DMSA renal scintigraphy in the first episode of urinary tract infection in childhood

Objective

The role of dimercaptosuccinic acid (DMSA) renal scintigraphy in the first episode of urinary tract infection (UTI) has been the subject of debate for many years. The aim of this study was to evaluate the relationship of voiding cystourethrography (VCUG), renal ultrasonography and DMSA renal scintigraphy and to detect renal parenchymal changes by performing DMSA renal scintigraphy at 6 months after the first episode of UTI.

Methods

A prospective study was conducted in 67 hospitalized children (46 boys, 21 girls). Mean age of the patients was 0.97 ± 1.57 years (0.02–7.26 years). All children received VCUG, renal ultrasonography and DMSA renal scintigraphy. DMSA renal scintigraphy was performed at 1 and 6 months after UTI.

Results

Of 67 children, 17 (25.4 %), 23 (34.3 %) and 20 (29.9 %) had vesicoureteral reflux (VUR), abnormal renal ultrasonography and abnormal DMSA renal scintigraphy, respectively. Unilateral hydronephrosis had a significant correlation with VUR at p value 0.024. In renal units, abnormal renal ultrasonography and hydronephrosis had significant correlations with VUR at p values 0.039 and 0.021, respectively. In patients and renal units, hydronephrosis had no significant correlation with abnormal DMSA renal scintigraphy at 1 month after UTI. However, abnormal renal ultrasonography and VUR had significant correlations with abnormal DMSA renal scintigraphy at p values 0.022 and <0.001 in patients and at p values 0.024 and <0.001 in renal units, respectively. Both in patients and renal units, VUR (Grade I–III) had no significant correlation with abnormal DMSA renal scintigraphy. However, severe VUR (Grade IV–V) had significant correlations with abnormal DMSA renal scintigraphy at p values <0.001 and <0.001, respectively. Seventeen patients underwent DMSA renal scintigraphy at 6 months after UTI. In addition, 15 (88.2 %) developed persistent renal scarring.

Conclusion

Abnormal renal ultrasonography and severe VUR identify renal parenchymal changes. DMSA renal scintigraphy in the first episode of UTI should be carried out in those patients. Abnormal DMSA renal scintigraphy at 1 month after UTI has a tendency to persist.