Renal SPECT with Tc-99m DMSA in children with upper urinary tract infections using a triple-headed gamma camera

Interrater Reliability of 99mTc-DMSA Scintigraphy Performed as Planar Scan vs. SPECT/Low Dose CT for Diagnosing Renal Scarring in Children

99mTc-dimercaptosuccinic acid (DMSA) scintigraphy is currently the method of choice for assessing renal scarring in children, but it is not established whether conducting the scan as a single photon emission tomography combined with low-dose CT (SPECT/ldCT) scan provides additional diagnostic benefits when compared to conventional planar scintigraphy. In the present study, we evaluated the interrater reliability of DMSA SPECT/ldCT vs. planar DMSA scintigraphy for diagnosing renal scarring.

METHODS

Two nuclear medicine physicians blinded to patient data retrospectively analysed all paediatric 99mTc-DMSA scintigraphes that were conducted in our department for the assessment of post pyelonephritis renal scarring between 2011 and 2016. All scintigraphies included both a planar scan and SPECT/ldCT, and were performed on either a Phillips Precedence 16 slice CT or a Siemens Symbia 16 slice CT. The readers were blinded to each other's readings and to patient data, and assessed all scans dichotomously for evidence of renal scarring. For each scan, the readers further noted if they were confident in their interpretation.

RESULTS

A total of 46 pairs of planar SPECT/ldCT DMSA scans were included. The readers were unconfident about their interpretation of 40% of the planar scans and 5% of the SPECT/ldCT scans. The interrater agreement rate was 72% for planar scans and 91% for SPECT/ldCT, and the corresponding Cohen's kappa values were 0.38 and 0.79.

CONCLUSION

DMSA SPECT/ldCT is associated with higher reader confidence and interrater reliability than conventional planar DMSA scintigraphy for the assessment of post pyelonephritis renal scarring in children.

Vesicoureteral reflux and urinary tract infection: evolving practices and current controversies in pediatric imaging

OBJECTIVE

Pediatric patients with urinary tract infection (UTI) undergo imaging tests to detect vesicoureteral reflux (VUR) in the belief that VUR correlates to risk of renal scarring. This article describes recent evolution and controversies in the management of UTI and VUR.

CONCLUSION

Multitechnique imaging of UTI and VUR is complex and controversial. Evolution in practice patterns is motivated by the desire to rationally minimize unnecessary interventions and radiation exposure. Ongoing evidence-based research is needed to further improve practice guidelines.

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.

SPECT imaging with [123I]-beta-CIT in Parkinsonism: comparison of SPECT images obtained by a single-headed and a three-headed gamma camera

Single photon emission computed tomography (SPECT) imaging of dopamine transporters by using the cocaine derivative [123I]-(1R)-2-beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane ([123I]-beta-CIT) has been shown to be useful in patients with Parkinsonism. The aim of this study was to compare beta-CIT imaging with single-headed (SHS) and three-headed gamma camera systems (THS). In 17 patients with Parkinsonism, SPECT imaging with an SHS and a THS was performed 24 h after injection of 180 MBq of [123I]-beta-CIT. The SPECT studies were evaluated by visual assessment of the caudate nucleus (CN) and the putamen (PT) and the calculation of the striatal/cerebellar (S/C) ratios (with additional comparison to clinical symptoms measured by the Unified Parkinson's Disease Rating Scale (UPDRS)). The S/C ratios measured by the SHS and THS showed highly significant correlation (two-tailed P < 0.01) with Spearman correlation coefficients (SCCs) of 0.864 for the right side, 0.676 for the left side, and 0.761 for both sides. By the SHS, a sufficient visual differentiation between the CN and the PT could not be achieved. A significantly better distinction could be achieved by using the THS (Wilcoxon P<0.05). The S/C ratios of the THS only showed a significant (P < 0.05) SCC of -0.514 comparing to the UPDRS. Pathological alterations in the beta-CIT uptake pattern could be identified by using the SHS, but a significantly better differentiation of CN and the PT was possible by using the THS. The significant correlation of the S/C ratios measured by THS only emphasizes the value of THS in beta-CIT imaging.

Consensus on renal cortical scintigraphy in children with urinary tract infection. Scientific Committee of Radionuclides in Nephrourology

A questionnaire related to cortical scintigraphy in children with urinary tract infection was submitted to 30 experts. A wide consensus was reached on several issues related to planar images: 99mTc dimercapto succinic acid (DMSA) appears as the most appropriate tracer for renal imaging; dynamic tracers are considered to be inferior, in particular 99mTc diethylenetriaminepentaacetate, which is not recommended. The general opinion is that DMSA scintigraphy is not feasible with a minimal dose below 15 MBq, whereas the maximum dose should not be higher than 110 MBq. The dose schedule generally is based on body surface area, and sedation is only exceptionally given to children. Images are obtained 2 to 3 hours after injection, preferably with high resolution collimators; pinhole images are used by only half of the experts. Posterior and posterior oblique views are used by most of the experts, and the posterior view is acquired in supine positions. At least 200.000 kcounts or 5 minute acquisition is required for nonzoomed images. As a quality control, experts check the presence of blurred or double outlines on the DMSA images. Color images are not used and experts report on film or directly on the computer screen. As far as normal DMSA images are concerned, most experts agree on several normal variants. Hydronephrosis is not a contraindication for DMSA scintigraphy but constitutes a pitfall. Differential renal function generally is measured, but no consensus is reached whether or not background should be subtracted. Most of the experts consider 45% as the lowest normal value. A consensus is reached on some scintigraphic aspects that are likely to improve and on some others that probably represent persistent sequelae. There is a wide consensus for the systematic use of DMSA scintigraphy for detection of renal sequelae, whereas only 58% of the experts are systematically performing this examination during the acute phase of infection.