Comparison of DMSA scintigraphy with intravenous urography for the detection of renal scarring and its correlation with vesicoureteric reflux

Dimercaptosuccinic acid scan or ultrasound in screening for vesicoureteral reflux among children with urinary tract infections

BACKGROUND

There is considerable interest in detecting vesicoureteral reflux (VUR) because its presence, especially when severe, has been linked to an increased risk of urinary tract infections and renal scarring. Voiding cystourethrography (VCUG), also known as micturating cystourethrography, is the gold standard for the diagnosis of VUR, and the grading of its severity. Because VCUG requires bladder catheterisation and exposes children to radiation, there has been a growing interest in other screening strategies that could identify at-risk children without the risks and discomfort associated with VCUG.

OBJECTIVES

The objective of this review is to evaluate the accuracy of two alternative imaging tests - the dimercaptosuccinic acid renal scan (DMSA) and renal-bladder ultrasound (RBUS) - in diagnosing VUR and high-grade VUR (Grade III-V VUR).

SEARCH METHODS

We searched MEDLINE, EMBASE, BIOSIS, and the Cochrane Register of Diagnostic Test Accuracy Studies from 1985 to 31 March 2016. The reference lists of relevant review articles were searched to identify additional studies not found through the electronic search.

SELECTION CRITERIA

We considered published cross-sectional or cohort studies that compared the results of the index tests (DMSA scan or RBUS) with the results of radiographic VCUG in children less than 19 years of age with a culture-confirmed urinary tract infection.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the selection criteria to all citations and independently abstracted data. We used the bivariate model to calculate summary sensitivity and specificity values.

MAIN RESULTS

A total of 42 studies met our inclusion criteria. Twenty studies reported data on the test performance of RBUS in detecting VUR; the summary sensitivity and specificity estimates were 0.44 (95% CI 0.34 to 0.54) and 0.78 (95% CI 0.68 to 0.86), respectively. A total of 11 studies reported data on the test performance of RBUS in detecting high-grade VUR; the summary sensitivity and specificity estimates were 0.59 (95% CI 0.45 to 0.72) and 0.79 (95% CI 0.65 to 0.87), respectively. A total of 19 studies reported data on the test performance of DMSA in detecting VUR; the summary sensitivity and specificity estimates were 0.75 (95% CI 0.67 to 0.81) and 0.48 (95% CI 0.38 to 0.57), respectively. A total of 10 studies reported data on the accuracy of DMSA in detecting high-grade VUR. The summary sensitivity and specificity estimates were 0.93 (95% CI 0.77 to 0.98) and 0.44 (95% CI 0.33 to 0.56), respectively.

AUTHORS' CONCLUSIONS

Neither the renal ultrasound nor the DMSA scan is accurate enough to detect VUR (of all grades). Although a child with a negative DMSA test has an < 1% probability of having high-grade VUR, performing a screening DMSA will result in a large number of children falsely labelled as being at risk for high-grade VUR. Accordingly, the usefulness of the DMSA as a screening test for high-grade VUR should be questioned.

Usefulness of analytical parameters in the management of paediatric patients with suspicion of acute pyelonephritis. Is procalcitonin reliable?

OBJECTIVE

To investigate the usefulness of procalcitonin (PCT) and other analytical parameters (white blood cell count [WBC], C-reactive protein [CRP]) as markers of acute renal damage in children after a first febrile or afebrile urinary tract infection (UTI).

METHODS

A retrospective study was conducted on children with a first episode of UTI admitted between January 2009 to December 2011, and in whom serum PCT, CRP and white blood cell count were measured, as well as assessing the acute renal damage with renal scintigraphy with ^99mTc-DMSA (DMSA) within the first 72h after referral. A descriptive study was performed and ROC curves were plotted, with optimal cut-off points calculated for each parameter.

RESULTS

The 101 enrolled patients were divided into two groups according to DMSA scintigraphy results, with 64 patients being classified with acute pyelonephritis (APN), and 37 with UTI. The mean WBC, CRP and PCT values were significantly higher in patients with APN with respect to normal acute DMSA. The area under the ROC curve was 0.862 for PCR, 0.774 for WBC, and 0.731 for PCT. The optimum statistical cut-off value for PCT was 0.285ng/ml (sensitivity 71.4% and specificity 75%).

CONCLUSION

Although the mean levels of fever, WBC, CRP, and PCT were significantly increased in patients with APN than in those who had UTI, the sensitivity and specificity of these analytical parameters are unable to predict the existence of acute renal damage, making the contribution by renal DMSA scintigraphy essential.

Vesicoureteral Reflux in Pediatric Age: Where are we Today?

Although the diagnosis of vesicoureteral reflux and of reflux nephropathy is a well-established and shared procedure, its treatment nowadays is still very controversial. New developments on the knowledge of pathophysiology of renal damage associated to reflux opened the way towards a different diagnostic work-up and different therapeutic approaches.

Recently, the “top-down” diagnostic approach has gained wider interest, versus the “down-top” protocol. The attention has recently focused on the renal parenchyma damage and less interest has been given to the presence and the radiological degree of vesicoureteral reflux.

The review criteria were based on an in-depth search of references conducted on PubMed, using the terms “vesicoureteral reflux”, “children”, “incidence”, “etiology”, “diagnosis”, “treatment” and “outcomes”. The selection of the papers cited in this review was influenced by the content and the relevance to the points focused in the article.

Conservative approaches include no treatment option with watchful waiting, long-term antibiotic prophylaxis and bladder rehabilitation. The operative treatment consists of endoscopic, open, laparoscopic and robotic procedures to stop the refluxing ureter.

No final consensus has been achieved in literature yet, and further studies are necessary in order to better define the subset of children at risk of developing progression of renal damage.

This review aims to clarify the diagnostic management and the urological-nephrological treatment of reflux in pediatric age, on the basis of a review of the best-published evidence.

Diagnosis and management of vesicoureteral reflux in children

Critical evaluation of previously accepted dogma regarding the evaluation and treatment of vesicoureteral reflux (VUR) has raised significant questions regarding all aspects of VUR management. Whereas the standard of care previously consisted of antibiotic prophylaxis for any child with VUR, it is now unclear which children, if any, truly benefit from antibiotic prophylaxis. Operative intervention for VUR constitutes overtreatment in many children, yet there are limited data available to indicate which children benefit from VUR correction through decreased rates of adverse long-term clinical sequelae. Studies with longer follow-up demonstrate decreased efficacy of endoscopic therapy that was previously hoped to approach the success of ureteroneocystostomy. Prospective studies might identify risk factors for pyelonephritis and renal scarring without antibiotic prophylaxis. Careful retrospective reviews of adults with a history of reflux might allow childhood risk factors for adverse sequelae to be characterized. Through analysis of multiple characteristics, better clinical management of VUR on an individualized basis will become the new standard of care.

Comparative efficacies of procalcitonin and conventional inflammatory markers for prediction of renal parenchymal inflammation in pediatric first urinary tract infection

OBJECTIVES

To compare the reliability of procalcitonin (PCT) with conventional laboratory parameters in predicting for renal parenchymal inflammation (RPI).

METHODS

The study cohort consisted of 57 children who were admitted for a first-episode urinary tract infection. All patients underwent measurement of the leukocyte count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum PCT. RPI was evaluated by technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy within 7 days of admission. If the first DMSA findings were abnormal, another analysis was performed 6 months later. The cutoff points for ESR, CRP, and PCT were established by comparing the areas under their receiver operating characteristic curves. Statistical analysis was performed using 1-way analysis of variance.

RESULTS

Of the 57 children, 27 were diagnosed with RPI on the basis of positive DMSA results. The ESR, CRP, and PCT levels were significantly greater (P < .001) in the patients with RPI than in those without RPI. In contrast, the leukocyte count was the same in both groups (P > .05). PCT was a more sensitive and specific marker for differentiating upper and lower urinary tract infection than ESR and CRP. Persistent lesions at the site of previous RPI were found in 12 patients in the follow-up DMSA analysis, with total regression evident in the remaining 15. The PCT levels were significantly greater in those with persistent renal lesions than in those with total regression (P = .005).

CONCLUSIONS

Serum PCT is a more reliable biologic marker than the ESR, CRP, or leukocyte count for the early prediction of RPI in children with a first episode of urinary tract infection. In addition, the greater the elevation of PCT at admission, the more positive the correlation for subsequent permanent renal damage.

Reflux nephropathy

Vesicoureteral reflux may be associated with abnormalities of the renal parenchyma. The purpose of this review is to define what the parenchymal abnormalities are histologically, what their etiologies may be, how they are identified and what their long-term clinical impact may be. Two categories are recognized, renal dysplasia and post-infection, chronic pyelonephritis. The diagnostic gold standard is microscopic evaluation of biopsy specimens but renal scintigraphy can be used in the diagnosis of renal dysplasia versus chronic pyelonephritis. Potential long-term sequelae of reflux nephropathy include hypertension and renal insufficiency although these may occur infrequently. A review of the current literature is provided.

[Evidence-based medicine and vesicoureteral reflux]

Vesicoureteral reflux (VUR) remains one of the most controversial subjects in paediatric urology. Much literature has been published on VUR, making the understanding of this anomaly and its treatments quite opaque. Evidence-Based Medicine (EBM) should be helpful to clarify the various VUR approaches contained in the 6224 titles found on Medline using the keywords "vesicoureteral reflux" and "vesicoureteric reflux". These articles were critically reviewed and graded according to EBM scorings, with regard to their methodological designs. This review of VUR literature suggests that most of our knowledge is based on publications with a low level of evidence, and that EBM lacks arguments to support recommendations for VUR diagnostic and treatment. It appears yet that antenatal dilatation of the urinary tract and symptomatic urinary tract infections (UTI) justify VUR screening. Surgery should be discussed in recurrent UTIs or deterioration of renal function. There is no consensus in case of persistent asymptomatic VUR regarding indication and duration of antibio-prophylaxis, and selection of radical treatment.

Magnetic resonance voiding cystography in the diagnosis of vesicoureteral reflux: comparative study with voiding cystourethrography

PURPOSE

To evaluate the feasibility of magnetic resonance voiding cystography (MRVC) compared with voiding cystourethrography (VCUG) for detecting and grading vesicoureteral reflux (VUR).

MATERIALS AND METHODS

MRVC was performed upon 20 children referred for investigation of reflux. Either coronal T1-weighted spin-echo (SE) or gradient-echo (GE) (fast multiplanar spoiled gradient-echo (FMPSPGR) or turbo fast low-angle-shot (FLASH)) images were obtained before and after transurethral administration of gadolinium solution, and immediately after voiding. The findings of MRVC were compared with those of VCUG and technetium-99m ((99m)Tc) dimercaptosuccinic acid (DMSA) single-photon emission computed tomography (SPECT) performed within 6 months of MRVC.

RESULTS

VUR was detected in 23 ureterorenal units (16 VURs by both methods, 5 VURs by VCUG, and 2 VURs by MRVC). With VCUG as the standard of reference, the sensitivity of MRVC was 76.2%; the specificity, 90.0%; the positive predictive value, 88.9%; and the negative predictive value, 78.3%. There was concordance between two methods regarding the grade of reflux in all 16 ureterorenal units with VUR detected by both methods. Of 40 kidneys, MRVC detected findings of renal damage or reflux nephropathy in 13 kidneys, and (99m)Tc DMSA renal SPECT detected findings of reflux nephropathy in 17 kidneys.

CONCLUSION

Although MRVC is shown to have less sensitivity for VUR than VCUG, MRVC may represent a method of choice offering a safer nonradiation test that can additionally evaluate the kidneys for changes related to reflux nephropathy.

How does study quality affect the results of a diagnostic meta-analysis?

BACKGROUND

The use of systematic literature review to inform evidence based practice in diagnostics is rapidly expanding. Although the primary diagnostic literature is extensive, studies are often of low methodological quality or poorly reported. There has been no rigorously evaluated, evidence based tool to assess the methodological quality of diagnostic studies. The primary objective of this study was to determine the extent to which variations in the quality of primary studies impact the results of a diagnostic meta-analysis and whether this differs with diagnostic test type. A secondary objective was to contribute to the evaluation of QUADAS, an evidence-based tool for the assessment of quality in diagnostic accuracy studies.

METHODS

This study was conducted as part of large systematic review of tests used in the diagnosis and further investigation of urinary tract infection (UTI) in children. All studies included in this review were assessed using QUADAS, an evidence-based tool for the assessment of quality in systematic reviews of diagnostic accuracy studies. The impact of individual components of QUADAS on a summary measure of diagnostic accuracy was investigated using regression analysis. The review divided the diagnosis and further investigation of UTI into the following three clinical stages: diagnosis of UTI, localisation of infection, and further investigation of the UTI. Each stage used different types of diagnostic test, which were considered to involve different quality concerns.

RESULTS

Many of the studies included in our review were poorly reported. The proportion of QUADAS items fulfilled was similar for studies in different sections of the review. However, as might be expected, the individual items fulfilled differed between the three clinical stages. Regression analysis found that different items showed a strong association with test performance for the different tests evaluated. These differences were observed both within and between the three clinical stages assessed by the review. The results of regression analyses were also affected by whether or not a weighting (by sample size) was applied. Our analysis was severely limited by the completeness of reporting and the differences between the index tests evaluated and the reference standards used to confirm diagnoses in the primary studies. Few tests were evaluated by sufficient studies to allow meaningful use of meta-analytic pooling and investigation of heterogeneity. This meant that further analysis to investigate heterogeneity could only be undertaken using a subset of studies, and that the findings are open to various interpretations.

CONCLUSION

Further work is needed to investigate the influence of methodological quality on the results of diagnostic meta-analyses. Large data sets of well-reported primary studies are needed to address this question. Without significant improvements in the completeness of reporting of primary studies, progress in this area will be limited.

Can MRI replace DMSA in the detection of renal parenchymal defects in children with urinary tract infections?

BACKGROUND

Renal parenchymal defects may be a consequence of urinary tract infections (UTI) in childhood. MRI is a non-radiation imaging modality compared with DMSA scanning.

OBJECTIVE

To compare DMSA with MRI for the detection of renal parenchymal defects in children presenting for radiological investigation after a first UTI.

MATERIALS AND METHODS

Both DMSA and MRI were performed at the same appointment in 37 children (aged 4 months-13 years; mean 4.5 years) with a history of UTI. Both planar and SPECT DMSA were performed. MRI of the kidneys employed axial and coronal T1-, T2- and fat-saturated T1-weighted (T1-W) sequences. Some children had imaging after IV contrast medium.

RESULTS

The coronal fat-saturated T1-W sequence was the best sequence and it detected all the findings on MRI. MRI had a sensitivity of 77% and a specificity of 87% for the detection of a scarred kidney using DMSA as the gold standard. MRI diagnosed pyelonephritis in two children that had been interpreted as scarring on DMSA.

CONCLUSIONS

Renal MRI using a single, coronal, fat-saturated T1-W sequence is a rapid, accurate and minimally invasive technique for the detection of renal scarring that does not employ ionizing radiation.

The conditions for which the geometric mean method revealed a more accurate calculation of relative renal function in 99mTc-DMSA scintigraphy

AIMS

(1) To compare the results of calculating relative renal function (RRF) by using only posterior images (POST) with the geometric mean (GM) through both anterior and posterior imaging on dimercaptosuccinic acid (DMSA) scintigraphy. (2) To determine whether there was an age-related difference between them and whether some renal pathologies or asymmetrical renal function cause an error in the RRF calculation by using posterior images only.

METHODS

Eight hundred and ninety-one DMSA scans were studied retrospectively. The patients were divided into five age groups: group I, < or =2 years; group II, >2 to < or =5 years; group III, >5 to < or =10 years; group IV, >10 to < or =18 years; and group V, >18 years. The RRF of the right kidney (RKF) was calculated from the POST and GM counts. The differences between RKFGM and RKFPOST were calculated in all the patients.

RESULTS

Among the 891 patients, nine had malrotated or malpositioned kidneys, 373 had renal pathologies of pyelonephritis, hydronephrosis, cortical scarring and atrophy, 247 had asymmetrically functioning kidneys and 509 had normal kidneys. When the patients were analysed according to different age groups, significant differences were found between all groups (P<0.05) except groups I-II and IV-V (P>0.05) with the F-test. The clinically meaningful RRF variance (> or =5% difference between two methods) rate differed significantly between groups I, II and III, and groups IV and V (chi-squared test, P<0.05). In patients aged < or =10 years, a clinically meaningful RRF variance (> or =5%) rate was significantly higher in the groups with pathological or asymmetrically low (< or =40% RRF) functioning kidneys than in the groups without pathological or asymmetrically low functioning kidneys, respectively (P<0.05).

CONCLUSIONS

According to our findings, the calculation of RRF using the GM method differs significantly from that using posterior images. Calculation of the GM can effectively correct the RRF measurement not in only adults, but also in the patient population musical #10 years of age. In addition, a significant correction can be made in patients aged musical #10 years who have a renal pathology or an asymmetrically low functioning kidney.

Renal outcome in adults with renal insufficiency and irregular asymmetric kidneys

BACKGROUND

The commonest cause of end-stage renal failure (ESRF) in children and young adults is congenital malformation of the kidney and urinary tract. In this retrospective review, we examine whether progression to ESRF can be predicted and whether treatment with angiotensin converting enzyme inhibitors (ACEI) can delay or prevent this.

METHODS

We reviewed 78 patients with asymmetric irregular kidneys as a consequence of either primary vesico-ureteric reflux or renal dysplasia (Group 1, n = 44), or abnormal bladder function (Group 2, n = 34). Patients (median age 24 years) had an estimated GFR (eGFR) < 60 ml/min/1.73 m2 with at least 5 years of follow up (median 143 months). 48 patients received ACEI. We explored potential prognostic factors that affect the time to ESRF using Cox-regression analyses.

RESULTS

At start, mean (SE) creatinine was 189 (8) mumol/l, mean eGFR 41 (1) ml/min 1.73 m2, mean proteinuria 144 (14) mg/mmol creatinine (1.7 g/24 hrs). Of 78 patients, 36 (46%) developed ESRF, but none of 19 with proteinuria less than 50 mg/mmol and only two of 18 patients with eGFR above 50 ml/min did so. Renal outcome between Groups 1 and 2 appeared similar with no evidence for a difference. A benefit in favour of treatment with ACEI was observed above an eGFR of 40 ml/min (p = 0.024).

CONCLUSION

The similar outcome of the two groups supports the nephrological nature of progressive renal failure in young men born with abnormal bladders. There is a watershed GFR of 40-50 ml/min at which ACEI treatment can be successful at improving renal outcome.

Comparative study between intravenous urography and renal scintigraphy with DMSA for the diagnosis of renal scars in children with vesicoureteral reflux

PURPOSE

To assess the value of intravenous urography (IVU) in detecting and grading the renal scar, comparing its results with those of scintigraphy with dimercaptosuccinic acid (DMSA).

MATERIALS AND METHODS

The study included 43 children investigated by DMSA and IVU, who had vesicoureteral reflux diagnosed and classified through voiding cystourethrography.

RESULTS

Among the kidneys with reflux, there was agreement between the results of DMSA and IVU concerning the presence and the absence of scars in 82.4% of the cases. Based on the results obtained, IVU would have a sensitivity of 66.6%, specificity of 94.4%; accuracy of 82.5%; positive predictive value (PPV) of 90% and negative predictive value (NPV) of 79%, when compared with DMSA results. Our data also confirm the close relation between the reflux grade and the presence of renal scar, since 75% of the kidneys with grade IV and V reflux presented scars. In relation to the grading of nephropathy, in 78% of patients the classification of the scar by both methods was identical. The highest disagreement was verified in the group with segmental scar on DMSA, where 41.6% of the kidneys were classified as normal on IVU.

CONCLUSION

The data obtained confirm that the scintigraphy with DMSA is essential in the investigation of patients with renal scar, and cannot be replaced by IVU, due to its low sensitivity and lower ability of satisfactory grading.

Imaging of renal scarring

Children with urinary tract infection should be investigated and followed up, as those with pyelonephritis may develop renal scarring. In this review, after discussing the advantages and disadvantages of various imaging modalities for diagnosis of renal scarring, it is concluded that DMSA scintigraphy and urography can both be used to detect significant renal scarring. With DMSA scintigraphy, small renal lesions (functional uptake defects) not seen at urography will also be detected. The long-term clinical significance of these lesions is, as yet, unknown. A normal DMSA scintigraphy after infection indicates low risk for clinically significant damage. In order to allow acute, reversible lesions to first disappear, a follow-up DMSA examination should not be performed until at least 6 mo after the acute infection. Ultrasonography in isolation cannot be recommended for the diagnosis of renal scarring.

Urinary tract infections in children. Epidemiology, evaluation, and management

Accurate documentation of UTIs in children is essential for proper evaluation and management. Urine cultures with multiple organisms or colony counts less than 50,000 to 100,000 CFU/ml should be considered suspect and require confirmation, particularly with clean-catch specimens. Children with well-documented UTIs should be evaluated based on their age and presenting symptoms. Infants and young children require imaging, usually with a cystogram and sonogram of the kidneys and bladder. Older girls with febrile UTIs and boys at any age should also be considered for urinary tract imaging. Renal cortical scintigraphy with 99mTc-DMSA has emerged as the imaging study of choice for acute pyelonephritis and renal scarring in children with UTIs. Treatment of UTIs in children ideally commences with culture-specific antimicrobial therapy, although treatment may be started in sick children before culture results are available. Short-course treatment (3-5 days) is sufficient for children with acute uncomplicated lower UTIs. Children with acute pyelonephritis require 10 to 14 days of antibiotics, which can be administered on an outpatient basis in older infants and children who are not toxic, as long as good compliance is expected. Patients with first-time UTIs who require imaging should be maintained on low-dose antibiotic prophylaxis until their workup is completed. Treatment of ABU does not seem necessary if the urinary tract is otherwise normal. Long-term antibiotic prophylaxis is indicated for children with frequent symptomatic recurrences of UTI and for those with known VUR. Diagnosis and treatment of underlying voiding dysfunction and constipation is an essential component of the successful management of UTIs in children.

Transient pyelonephritic changes on 99mTechnetium-dimercaptosuccinic acid scan for at least five months after infection

A prospective study was performed on 185 children with symptomatic urinary tract infection (UTI), 130F and 55M, having a median age of 0.9 y (range 0.1-9.8) at the time of UTI. The aim of the study was to find out how the 99mTechnetium-dimercaptosuccinic acid (DMSA) scan should be used to investigate UTI, and to follow the development of renal changes during pyelonephritis into subsequent permanent renal damage. All children were investigated with a DMSA scan within 5 days after admission and after 3.9-53.3 (median 9.2) weeks, and 159 were studied again after approximately 2 y (range 1.5-3.9 y). They all underwent micturition cystourethrography at the time of the second study. At the time of infection, the DMSA scan was abnormal in 85% of the children, in 58% at the first follow-up and in 36% at the second follow-up. An abnormal DMSA scan performed within 20 weeks from infection became normal in 38% of cases on the third study, while only 1/10 abnormal DMSA scans performed more than 20 weeks after infection became normal after 1.5-3.9 y. Persistent renal changes were more common in children > 4 y of age than in children < or = 1 y of age. Two months after the presenting infection, it was unusual to see a normal DMSA scan in a child with a VUR gr. > or = 3. The study suggests that DMSA changes after an index UTI may be transient for a longer period of time than has been previously considered. Therefore, in order to detect persistent changes, a DMSA scan should be performed more than 5 months after UTI.

Renal damage one year after first urinary tract infection: role of dimercaptosuccinic acid scintigraphy

OBJECTIVE

The aim of this study was to determine whether age, C-reactive protein (CRP), body temperature, or results of voiding cystourethrography at diagnosis of first-time symptomatic urinary tract infection could predict the risk of renal damage as evaluated by dimercaptosuccinic acid (DMSA) scintigraphy performed 1 year after the infection.

DESIGN

The study included 157 children (median age, 0.4 year, range, 5 days to 5.8 years) with first-time symptomatic urinary tract infection. In children 1 year of age or older, a body temperature of 38.5 degrees C or higher was necessary for inclusion. CRP and body temperature were measured at the time of infection, and voiding cystourethrography was performed shortly thereafter. DMSA scintigraphy was performed 1 year later in all children.

RESULTS

After 1 year, 59 (38%) of the 157 children had renal damage as evaluated by DMSA scintigraphy, and of these, 28 (47%) had reflux. There was a positive correlation between renal damage and CRP, body temperature, and reflux. Children with high levels of CRP, high fever, and dilating reflux had a risk of renal damage up to 10 times higher than children with normal or slightly elevated CRP levels, no or mild fever, and no reflux.

CONCLUSION

CRP concentration and body temperature at the index infection, in combination with the results of voiding cystourethrography, are useful in classifying children at high and low risk of scintigraphic renal damage 1 year after urinary tract infection.

Where are we with nuclear medicine in pediatrics?

The practice of nuclear medicine in children is different from that in adults. Technical considerations including immobilization, dosing of radiopharmaceuticals, and instrumentation are of major importance. Image magnification and the capability to perform single-photon emission tomography are essential to performing state of the art pediatric nuclear medicine. New advances in instrumentation with multiple detector imaging, the possibility of clinical positron emission tomography imaging in children, and new radiopharmaceuticals will further enhance pediatric scintigraphic imaging. This review highlights advances in pediatric nuclear medicine and discusses selected clinical problems.

Long-term follow up to determine the prognostic value of imaging after urinary tract infections. Part 2: Scarring

Long term follow up of children with urinary tract infections, in whom imaging investigations were performed at presentation, has been used to identify features that distinguish those at greatest risk of progressive renal damage. No single investigation at presentation was able to predict subsequent deterioration but, by employing a combination of imaging investigations, it was possible to separate groups with high or low probability of progressive damage. In the low risk group the incidence of progressive damage was 0.2% (95% confidence interval (CI) 0 to 1.3%). The combination of both scarring and reflux at presentation, or one only of these but accompanied by subsequent documented urinary tract infection, was associated with a 17-fold (95% CI 2.5 to 118) increase in the relative risk of progressive renal damage compared with children without these features. The recommended combination of investigations at presentation for girls of any age and boys over 1 year is ultrasound and dimercaptosuccinic acid (DMSA) scintigraphy in all, to detect both scarring and significant structural abnormalities, renography in children with dilatation of any part of the urinary tract on ultrasound, to distinguish dilatation from obstruction, and an isotope voiding study in all who have acquired bladder control. This gives the best separation between those at high and those at low risk of progressive damage with least radiation dose and lowest rate of instrumentation. Micturating cystourethrography (MCU) should be restricted to girls who have not acquired bladder control, unless there is reason to suspect a significant structural abnormality such as urethral valves. A single non-febrile urinary tract infection that responds promptly to treatment is not a justification for performing MCU in boys under 1 year or in children of any age with bladder control. No case can be made for any abbreviated schedule of investigation. These risk factors should be taken into account when designing follow up protocols.

A comparative study of evaluating renal scars by 99mTc-DMSA planar and SPECT renal scans, intravenous urography, and ultrasonography

The purpose of this prospective study is to compare 3 types of 99mTc-DMSA renal scan [(a) planar, (b) x-ray type film static SPECT presentation (SPECT-1) and (c) dynamic three-view display of SPECT slices (SPECT-2)], intravenous urography, and ultrasonography in the diagnosis of renal scars. All these studies were performed in 130 pediatric patients, with urinary tract infection (42 patients), vesicoureteral reflux (37), and unilateral or bilateral small kidney(s) (51). The number of renal scars detected was highest with the 99mTc-DMSA renal SPECT-1 scan and next came the 99mTc-DMSA renal SPECT-2 studies. There is a significant difference (p < 0.05) between the ability of planar and SPECT-1 to recognize renal defects. However, SPECT-2 may provide the best stereotactic localization and image quality of all the methods.

Rational use of CT in acute pyelonephritis: findings and relationships with reflux

Enhanced renal CT scanners were performed in 38 children (82% girls) to rule out acute pyelonephritis. Patients were divided in 2 groups on the basis of clinical presentation and bacteriology data. In patients of group A (n = 16, preliminary study), upper urinary tract infection (UTI) was certain. CT confirmed the diagnosis in all but 3 patients (a 2-year-old child and 2 patients with UTI developed on prior obstruction). In subsequently studied patients of group B (n = 22), clinical findings or bacteriology data were negative or questionable. CT made the diagnosis of acute pyelonephritis in 11 patients. As well as DMSA scintigraphy, CT scanner can help to diagnose or to rule out upper UTIs in difficult cases. In all boys of both groups, ipsilateral vesico-ureteric reflux (VUR) was found by subsequent voiding cystourethrography (VCUG) on the side of pyelonephritis. In girls, this correlation was shown in only 7 of the 25 kidneys with pyelonephritis. This result supports the hypothesis of a gender-dependent contamination. We believe that absence of radiologic reflux cannot exclude the possibility of bacterial crossings of ureteric meatus capable to lead to genuine upper UTIs.