Comparison of 99Tcm dimercaptosuccinic acid scans and intravenous urography in children

Is Imaging Time Between two Tc 99m DMSA Scans Sufficient for Reporting as Renal Parenchymal Scarring? Healed Parenchymal Renal Defect After 6 Years

We aimed to report a healed renal parenchymal defect after 6 years in a 9-year-old girl who was being followed for recurrent urinary tract infection (UTI). The first UTI was at the age of two. She was being followed with ultrasonography, urine analysis and urine culture since the first UTI. Technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy was repeated four times up to the present day. She had a renal parenchymal defect reported as parenchymal scarring, which healed 6 years after the first DMSA scintigraphy.

Conflict of interest:None declared.

Vesicoureteric reflux is not a benign condition

Renal parenchymal defects may be congenital, usually associated with dilated vesicoureteric reflux (VUR), or they may appear in previously normal kidneys and be caused by reflux nephropathy due to VUR combined with urinary tract infection (UTI). A piglet model defined that the 70% of children with VUR and vulnerable pyramids would scar rapidly with their first UTI. Because most defects are present at first imaging after a UTI, and from the lack of benefit from apparently reasonable clinical interventions, many now believe that most defects are congenital, their association with VUR being a shared dysplasia rather than causal. Consequently, guidelines now argue for less assiduous management. These conclusions ignore adult human transplant evidence, adult pig studies, and clinical anecdotes, which indicate that scars may develop in infant kidneys quicker than urine culture can confirm the diagnosis, and that reflux nephropathy has no age limit. Its rarity over 4 years suggests that most vulnerable children develop scars before then, despite all medical efforts. I argue that preventing such scarring will require better diagnosis of infant UTI, quicker treatment, reliable imaging of scars and VUR, and subsequent protection until VUR resolves. To make a difference, we need more assiduous management, not less, and cannot afford to consider VUR to be a benign condition.

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.

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.

Technetium-99m-N,N-ethylenedicysteine and Tc-99m DMSA scintigraphy in the evaluation of renal parenchymal abnormalities in children

Technetium-99m dimercaptosuccinic acid (Tc-99m DMSA) as a static renal agent is currently the most frequently used agent in the detection of renal scarring, and allows accurate calculation of differential renal function (DRF). But this agent has some disadvantages such as relatively higher radiation dose and time consumption.

METHODS

The purpose of this study was to evaluate the potential of summed image that obtained from parenchymal phase of the dynamic technetium-99m-N,N-ethylenedicysteine (Tc-99m EC) scintigraphy in the detection of renal parenchymal defects and in the estimation of DRF, and to compare the results of this method with those of Tc-99m DMSA scintigraphy. The uptake ratios of the kidney to body background were also calculated for these two methods. Twenty-nine children with various renal disorders underwent both static Tc-99m DMSA and dynamic Tc-99m EC scintigraphy. The cortical analysis of Tc-99m EC scintigraphy was performed on the summed image obtained from dynamic images using the time interval between the first 45-120 sec.

RESULTS

There was a very close correlation between these two methods with respect to DRF (r = 0.99). In the detection of renal parenchymal lesions, scintigraphy with Tc-99m DMSA detected more lesions, and the sensitivity and specificity of the summed Tc-99m EC images were calculated as 92.6% and 100%, respectively. In addition, the ratios of mean uptake values for Tc-99m DMSA and Tc-99m EC images were 7.59 +/- 2.17 and 2.95 +/- 0.91, respectively. This ratio of Tc-99m EC seems to be acceptable and allows good delineation of the kidneys. But, the main disadvantages of the summed Tc-99m EC images in comparison with static Tc-99m DMSA images are the use of only posterior projection that may be an important drawback in patients with abnormal kidney positions, lower image counts and higher pixel size because of dynamic acquisition.

CONCLUSION

These results show that summed Tc-99m EC images with an acceptable high image contrast provide an accurate DRF calculation in patients without abnormal kidney positions and allow the detection of most renal parenchymal abnormalities. However, Tc-99m DMSA scintigraphy remains the gold standard method because of its well known advantages.

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.

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.

The true clinical significance of renography in nephro-urology

Isotopic renography is a non-invasive technique used routinely by the clinician to provide information about kidney structure and function. Whilst there is no doubt of its value in the accurate measurement of glomerular filtration rate and in the detection of parenchymal abnormalities, its role in the diagnosis of renovascular disease (especially in patients with renal insufficiency), the exclusion of obstruction and the evaluation of the patient with either acute renal failure or renal transplant dysfunction remains unproven. In part, this reflects a failure to standardise protocols and rigorously evaluate diagnostic techniques. Recent developments in ultrasound, computerised X-ray tomography and nuclear magnetic resonance now present the clinician with rival techniques and emphasise the need for the clinical development of isotopic renography.

Interleukin-1 alpha and interleukin-1 receptor antagonist in the urine of children with acute pyelonephritis and relation to renal scarring

Urinary concentrations of interleukin-1 alpha (IL-1 alpha) and interleukin-1 receptor antagonist (IL-lra) standardized to urinary creatinine concentrations were studied. The median standardized IL-1 alpha creatinine quotient in children with first-time acute pyelonephritis was 3.6 pg/mumol, but was nondetectable in children with recurrent pyelonephritis, children with non-renal febrile conditions and children convalescent after acute pyelonephritis (p < 0.05-0.01). IL-lra levels were also significantly higher in children with acute first-time pyelonephritis (median of 239 pg/mumol) compared to these three groups of children (p < 0.01-0.001). The highest urinary IL-lra levels, however, were found in the healthy controls (median value 1.019; p < 0.001). Both cytokines were higher among children younger than one year compared to older children. The acute IL-1 alpha creatinine quotients were lowest in children with uptake defects on 99mTC-dimercaptosuccinic acid (DMSA) scintigraphy both during the acute infection (reflecting the acute inflammation) (p < 0.001) and 1 year after the acute infection (reflecting permanent kidney scarring) (p < 0.001). In conclusion, persisting high urinary levels of IL-1 alpha were associated with less renal inflammation and scarring.

Functional parameters and 99mtechnetium-dimercaptosuccinic acid scan in acute pyelonephritis

The diagnostic value of 99mtechnetium-dimercaptosuccinic acid (DMSA) scintigraphy, ultrasonography and renal functional parameters [urine N-acetyl-beta-D-glucosaminidase (NAG)/creatinine and urine albumin/creatinine quotients] in acute pyelonephritis (APN) were studied in 39 children (28 girls, 11 boys, median age 9 months, range 2 weeks to 9.4 years, 28 patients < 1 year, 11 patients > 1 year) with first-time urinary tract infection. Ultrasonography of the urinary tract was performed on admission and together with DMSA scintigraphy (< 10 days from admission). Urine NAG/creatinine and urine albumin/creatinine quotients were measured daily and after 6-8 weeks. Ultrasonography revealed abnormalities in 12 of 39 (31%) patients [11/32 patients (34%) with positive DMSA scintigraphy], while DMSA uptake defects were present in 32 of 39 (82%) patients [21/28 < 1 year (75%), 11/11 > 1 year (100%), P = 0.08]. Urine NAG/creatinine and urine albumin/creatinine quotients were significantly higher in children < 1 year with APN, as well as in non-renal fever controls, than in older children. However, in both age groups the urine NAG/creatinine and urine albumin/creatinine quotients were significantly higher in APN than in non-renal fever. The urine NAG and albumin excretion decreased rapidly after the initiation of antimicrobial therapy and had normalized at 6-8 weeks. The size and grade of the DMSA uptake defect (DMSA score) did not correlate with duration of disease at admission, maximum C-reactive protein or maximum fever. The urine NAG/creatinine quotient in the children < 1 year showed, however, a significant correlation with the DMSA score (r = 0.58, P < 0.05), while no correlation was found in the older children. We conclude that DMSA scintigraphy is a sensitive method to confirm the clinical diagnosis of APN, although a substantial number of infants appear to have normal scans. Early determination of the urine NAG/creatinine and albumin/ creatinine quotients may further improve the diagnostics in the infant.

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.

Does routine ultrasound have a role in the investigation of children with urinary tract infection?

The results of investigations in children with urinary tract infection (UTI) were studied in a district general hospital in order to assess the relative value of the two most widely used screening tests, namely ultrasound (US) and 99mTc dimercaptosuccinic acid (DMSA) scintigraphy. A total of 193 children had undergone both US and DMSA scintigraphy as part of an investigation of proven single or multiple urinary tract infections over a 27 month period. DMSA scintigraphy revealed abnormalities in 22 of the children (11%). The abnormalities ranged from cortical defects to congenital anatomical abnormalities. US revealed abnormalities in six children (3%) but did not contribute any additional information in any. In our institution, the DMSA scintigram alone would have been an adequate screening test for children with UTI. Hydronephrosis is a common abnormality detected by US. Although none were seen in the study group, several children were examined during the study period with dilated collecting systems detected at ante-natal US. No cases of hydronephrosis presented as UTI. We question whether the use of routine US is justifiable in the investigation of children with UTI, and discuss whether a more selective investigation protocol should be adopted.

Renal scarring after acute pyelonephritis

Seventy six children, 18 boys and 58 girls, aged 0-15.9 (median 1.0) years, with acute pyelonephritis were prospectively studied with a technetium-99m dimercaptosuccinic acid (DMSA) scan during infection and two months later. Fifty nine of these children were also studied two years after the infection. Seventeen children with a normal DMSA scan during infection or at two months after infection, or both, were not investigated by a DMSA scan at two years after acute pyelonephritis. A micturition cystourethrogram was performed in all the children after two months. Changes on the DMSA scan were found in 65 (86%) children during acute pyelonephritis, in 45 (59%) children at two months, and in 28 (37%) children at two years after infection. Vesicoureteric reflux (VUR) was found in 19 (25%) children at two months. Renal scarring was significantly correlated with the presence of gross VUR and recurrent pyelonephritis, but 62% of the scarred kidneys were drained by non-refluxing ureters. Children with scars were older at the time of acute pyelonephritis than those without scars but no difference was found between the groups with regard to duration of illness, levels of C reactive protein and maximum white cell count, glomerular filtration rate, nor renal concentration capacity at the time of infection. It is concluded that renal scarring after acute pyelonephritis in children is more common than has been previously thought. Although children with gross VUR and recurrent pyelonephritis are at the greatest risk, renal scarring is more often seen without these risk factors.

Urine interleukin-6 and interleukin-8 in children with acute pyelonephritis, in relation to DMSA scintigraphy in the acute phase and at 1-year follow-up

The relationship between urine interleukin-6 (IL-6) and interleukin-8 (IL-8)/creatinine quotients and 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy, performed within 10 days of acute first-time pyelonephritis and after 1 year, was studied in 41 children. The urine IL-6 and IL-8/creatinine quotients were also related to the urine N-acetyl-beta-D-glucosaminidase (NAG) and albumin/creatinine quotients. Presence of DMSA uptake defects, reflecting local inflammation, in children in the acute phase of pyelonephritis, were associated with elevated urine IL-6/creatinine quotients (median 27 pg/mumol); in children without DMSA changes there was no increase in quotients (median non-detectable) (P < 0.05). Persistent DMSA changes at the 1-year follow-up, probably reflecting renal scarring, were only seen in children with increased urine IL-6/creatinine quotients in the acute phase (P < 0.01). No correlation was found between urine IL-8 and DMSA uptake defects. Vesicoureteral reflux (VUR) at 6-8 weeks did not correlate with the urine cytokine levels in the acute phase. The urine excretion of NAG and albumin, reflecting renal dysfunction, was associated with values of both urine IL-6 and IL-8/creatinine quotients, but not with DMSA defects or VUR. Thus, the initial urine IL-6/creatinine quotients might be used as an indicator of risk for persistent renal damage in acute pyelonephritis.

Can ultrasound reliably detect renal scarring in children with urinary tract infection?

One hundred children with a proven urinary tract infection were studied prospectively using both ultrasound (US) and 99mTc dimercaptosuccinic acid (DMSA) scintigraphy to assess the efficacy of US in the detection of renal scarring. Sixty-nine girls and 31 boys with an age range of 0.5-11.8 years were studied. DMSA scintigraphy detected 19 scarred kidneys in 17 children. Scarring was classified as mild, moderate or gross. US detected a total of seven of the scarred kidneys (sensitivity 37%). US detected 0/6 kidneys with mild scarring, 1/7 kidneys with moderate scarring and 6/6 kidneys with gross scarring. Four kidneys with scarring on DMSA showed abnormalities other than scarring on US. 8/19 scarred kidneys were thought to be normal on US. It is important to detect renal scarring in young children and US cannot be relied upon for this purpose. It should therefore be supplemented with DMSA scintigraphy.

99mTechnetium-dimercaptosuccinic acid scan in the diagnosis of acute pyelonephritis in children: relation to clinical and radiological findings

Seventy-two children, 59 girls and 13 boys, 0.1-15.9 (median 1.1) years of age, with acute pyelonephritis (APN) were investigated with the aid of a dimercaptosuccinic acid (DMSA) scan, renal ultrasonography (US) and a desmopressin test within 5 days of admission. Sixty-two children were reinvestigated approximately 2 months later when intravenous urography (IVU) and micturition cysto-urethrography were also performed. During infection, 92% of the children showed changes in the DMSA scan with 69% by US, and the two investigations agreed in 58% of the kidneys. At follow-up, 68% showed changes in the DMSA scan, 47% by US and 48% by IVU. The DMSA scan and IVU agreed in 60% of the kidneys. Twenty-nine percent of the children had vesico-ureteric reflux (VUR). The presence of grade greater than or equal to 3 VUR was associated with greater defects on the DMSA scan during infection, and at follow-up with a higher frequency of persistent changes compared with no VUR (P less than 0.02 and 0.01, respectively). During infection the size of the defect on the DMSA scan correlated with renal volume and C-reactive protein and inversely with the glomerular filtration rate, and at follow-up it correlated inversely with the renal concentration capacity. The DMSA scan is a sensitive method for diagnosing and localizing APN in children, and findings on DMSA scan show a weak but significant correlation with routine clinical and radiological parameters. It is suggested that persistent renal damage after APN in children without VUR may be more common than previously assumed.

Current imaging of childhood urinary infections: prospective survey

OBJECTIVES

To assess whether ultrasonography alone is adequate for routine screening of childhood urinary infection, whether clinical features determine the need for further investigations, and which investigations are most appropriate.

DESIGN

Prospective survey of children with proved urinary infection and a preinvestigation record of clinical features. Ultrasonography and intravenous urography were routine, with choice of further studies determined by ultrasonographic findings.

SETTING

A children's hospital and two district general hospitals in Mersey region.

MAIN OUTCOME MEASURES

Sensitivity and specificity of ultrasonography both generally and in relation to clinical features. Accuracy of intravenous urography compared with radioisotope examinations.

RESULTS

Specificity of ultrasonography was good (99% (95% confidence interval 96% to 100%)) but sensitivity modest (43% (32% to 55%)), principally with respect to detecting vesicoureteric reflux and renal scarring. Among older children (aged 2-10 years) with positive ultrasound results and fever or vomiting the sensitivity in detecting reflux (with and without renal scarring) was 78% (62% to 89%) and the specificity 69% (60% to 78%); in detecting renal scarring (with and without reflux) the sensitivity was 100% (80% to 100%) and specificity 65% (56% to 74%). Renal scarring and obstructive uropathies were better assessed by radioisotope examinations than by intravenous urography.

CONCLUSIONS

Ultrasonography alone is inadequate for routine screening of childhood urinary infection. Though further investigations remain advisable in infants, in older children they can be restricted to a minority who have positive ultrasound examinations or have had fever or vomiting. Radioisotope examinations largely eliminate the need for intravenous urography.

99Tcm-mercapto acetyl triglycine in paediatric renal tract disease

The use of 99Tcm-mercapto acetyl triglycine (99Tcm-MAG3), a new hippuran substitute, has been reported widely in adults but not in children. Our experience of its use in 100 infants and children for renography and indirect micturating cystography (IMC) is reported. The average age was 5.6 years. 65 patients completed IMC studies and nine patients had 99Tcm-dimercaptosuccinic acid (99Tcm-DMSA) scans performed on the same day. The majority of patients were referred for the investigation of urinary tract infection. 32 kidneys were found to be scarred on 99Tcm-MAG3 scans, 17 kidneys and ureters refluxed on IMC and 14 kidneys were obstructed. The results of 99Tcm-MAG3 scans were compared with those of other urinary tract investigations including ultrasound, micturating cystography (MCUG), intravenous urography (IVU) and 99Tcm-DMSA scintigraphy. No kidney which was scarred had a normal 99Tcm-MAG3 scan. All significant degrees of dilatation or obstruction on IVU or ultrasound were also detected by 99Tcm-MAG3. 99Tcm-MAG3 gave more information than any other single imaging modality and we believe it represents an ideal initial screening test in the investigation of urinary tract infection in older toilet-trained children.