Published in:
01-04-2015 | Original Article
Diagnostic efficacy of parametric clearance images in detection of renal scars in children with recurrent urinary tract infections
Published in: Annals of Nuclear Medicine | Issue 3/2015
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Objective
Static renal scintigraphy with Tc-99m dimercaptosuccinic acid (DMSA) is considered a scintigraphic gold standard in detection of post-inflammatory renal scars. Reports on usefulness of conventional summed (SUM) Tc-99 m mercaptoacetyltriglycine (MAG3) or Tc-99m ethylene dicysteine (EC) dynamic scintigraphic images in detection of renal scarring are ambiguous and some authors emphasize low sensitivity of this method. The work aimed at assessment of a diagnostic efficacy of parametric clearance images (PAR) generated from a dynamic renal scintigraphy in detection of renal scars.
Methods
A study group consisting of 80 children (56 girls, 24 boys, age 5–18 years) with recurrent urinary tract infections (UTI) and documented one to five incidents of APN—28 children, and with recurrent UTI of the lower part of the urinary tract only—52 children. Altogether 160 kidneys were evaluated. Static renal Tc-99m DMSA SPECT scintigraphy and after 2–4 days Tc-99m EC dynamic renal scintigraphy were performed in every patient not earlier than 6 months after the last documented incident of UTI. PAR images generated from a dynamic renal scintigraphy acquired between 40 and 140 s. generated by in-house developed software and SUM images obtained in the same time period were compared with a reference Tc-99m DMSA SPECT study.
Results
For all kinds of images (SPECT, PAR and SUM), high indices of reproducibility were obtained—89 % (κ = 0.80), 88 % (κ = 0.78) and 89 % (κ = 0.73). Agreement in a Howard scale of a reference method (SPECT) with PAR and SUM methods amounted to 83 and 64 %, respectively (p = 0.004). Sensitivity and accuracy of PAR method as compared with SUM method were significantly higher: 89 vs. 49 % (p < 0.0001) and 88 vs. 73 % (p = 0.002), and specificity was slightly lower: 88 vs. 93 % (p = 0.043). SPECT and PAR methods revealed higher incidence of renal scars than a SUM method in patients with documented incident(s) of APN—64, 68 and 39 %, p = 0.009 and 0.008, respectively.
Conclusion
PAR images generated from a dynamic renal scintigraphy improved sensitivity of detection of renal scars as compared with SUM images, providing a high reproducibility and diagnostic efficacy, similar to that of Tc-99m DMSA, in detection of post-inflammatory renal scarring.