Assessment of Clinical Usefulness of Parametric Clearance Images in Diagnosis of Kidney Cicatrisation in Children with Chronic Infections of the Urinary Tract

BACKGROUND: Cicatrisation of the renal cortex is closely related to chronic infections of the urinary system. Static renal scintigraphy is used as the method enabling detection of local defects of radiopharmaceutical uptake, and is treated as the "gold standard" in the diagnosis of renal scars.The aim of the reported investigation was a comparison of the diagnostic efficacy of parametric clearance images and the conventional summation images -obtained from dynamic scintigraphy -in the detection of local defects of renal function. As the "gold standard" for the above comparison, the static scintigraphy of kidneys was accepted.MATERIAL AND METHODS: Forty-one patients (age 4-19 years), 28 girls and 13 boys, participated in the study. Altogether, 73 kidneys were analyzed (in 9 patients, only one kidney). In each patient dynamic renal scintigraphy was performed after IV administration of 99mTc EC (ethylenedicysteine) and static planar renal scintigraphy using 99mTc-DMSA (dimercaptosuccinic acid) as a reference method. From the dynamic study, summation and parametric clearance images were generated. Each kidney was divided into 3 segments (upper, middle, lower); altogether 219 segments were evaluated by modified Howard's scale. Planar and oblique projection images were compared with corresponding summation and parametric clearance images.RESULTS AND CONCLUSIONS: Parametric clearance imaging has a higher sensitivity and accuracy for detection of regional post-inflammatory changes in the kidneys than conventional summation images (p < 0.05) and shows parenchymal changes similarly to static scintigraphy (high Cohen's kappa index).