RESUMO
OBJECTIVE: The purpose of this study was to determine whether unenhanced MRI without sedation is a feasible substitute for dimercaptosuccinic acid (DMSA) scintigraphy in the detection of renal scars in pediatric patients. SUBJECTS AND METHODS: Patients scheduled for 99mTc-labeled DMSA scintigraphy for assessment of possible renal scars were recruited to undergo unenhanced MRI (free-breathing fat-suppressed T2-weighted single-shot turbo spin-echo and T1-weighted gradient-echo imaging, 13 minutes' total imaging time). Scintigraphic and MRI studies were evaluated by two independent blinded specialty-based radiologists. For each imaging examination, readers identified scars in upper, middle, and lower kidney zones and rated their diagnostic confidence and the quality of each study. The scintigraphic readers' consensus score opinion for the presence of scars was considered the reference standard. RESULTS: DMSA scintigraphy showed scarring in 19 of the 78 (24.4%) evaluated zones and MRI in 18 of the 78 (23.1%). The two MRI readers found mean sensitivities of 94.7% and 89.5%, identical specificities of 100%, and diagnostic accuracies of 98.7% and 97.4%. Interobserver agreement was 98.7% for MRI and 92.3% for DMSA scintigraphy. The MRI readers were significantly more confident in determining the absence rather than the presence of scars (p = 0.02). MRI readers were more likely to rate study quality as excellent (84.6%) than were the scintigraphic readers (57.7%) (p = 0.024). CONCLUSION: Unenhanced MRI has excellent sensitivity, specificity, diagnostic accuracy, and interobserver agreement for detecting renal scars in older children who do not need sedation. It may serve as a substitute modality, especially when DMSA is not available.
Assuntos
Cicatriz/diagnóstico por imagem , Nefropatias/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Cintilografia/métodos , Compostos Radiofarmacêuticos/administração & dosagem , Ácido Dimercaptossuccínico Tecnécio Tc 99m/administração & dosagem , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Sensibilidade e EspecificidadeRESUMO
Introducción: entre el 5 y 22 % de los niños que padecen pielonefritis aguda desarrollarán cicatriz renal. Objetivo: describir los aspectos clínico-epidemiológicos del daño renal cortical en niños con la primera infección del tracto urinario alto. Métodos: estudio observacional prospectivo y longitudinal sobre el daño renal cicatricial en niños con la primera infección urinaria alta, ingresados en el servicio de nefrología del Hospital Pediátrico Universitario "William Soler", entre el 1º de enero de 2008 y diciembre 31 de 2009. Se diagnosticaron 50 pacientes, y 38 reunieron criterios para incluirlos en el estudio. Los pacientes tenían una edad media de 18 meses. A los 38 pacientes se les realizó ultrasonido renal durante la fase aguda de la enfermedad, y gammagrafía renal estática entre 6 y 12 meses después del cuadro agudo, para precisar la lesión renal cortical. En los casos con cicatriz renal, ausencia o disminución de captación del radiofármaco (99mTc-DMSA), se les realizó uretrocistografía miccional para precisar la existencia de reflujo vesicoureteral. Resultados: 28 pacientes (73,7 %) son del sexo femenino, 17 (44,7 %) menores de 6 meses, 17 (44,7 %) tienen entre 6 y 36 meses, y 4 (10,6 %) > 3 años. La infección urinaria fue atípica en 23 (60,5 %), y el germen aislado, la Escherichia coli en 33 (86,8 %). El ultrasonido de la fase aguda demostró dilatación pélvica renal en 3 (7,9 %) y asimetría renal en 1 (2,6 %). En 2 pacientes (5,2 %) se demostró cicatriz renal y en 11 (28,4 %) hipofunción de la corteza renal. La uretrocistografía miccional demostró reflujo vesicoureteral grado III en una niña, que además, tenía cicatriz renal. No existió relación entre el inicio de los síntomas, comienzo de la terapeútica y lesión cortical. Conclusiones: los factores de riesgo para desarrollar cicatriz renal pospielonefrítica fueron: sexo femenino, edad menor de 3 años y reflujo vesicoureteral grado III.
Introduction: between the 5 and the 22 % of children suffering acute pyelonephritis will develop a renal scar. Objective: to describe the clinical-epidemiological features of the cortical renal damage in children with a first infection of high urinary tract. Methods: a longitudinal, prospective and observational study was conducted on the cicatricial renal damage admitted in the Nephrology services of the "William Soler" University Children Hospital from January 1, 2008 to December 31, 2009. Fifty patients were diagnosed and 38 fulfilled the inclusion criteria to study. Patients had a mean age of 18 months and underwent renal ultrasound during the acute phase of disease and static renal scintigraphy between 6 and 12 months after the acute picture, to specify exactly the cortical renal injury. In cases of renal scar, lack or decrease of the radioactive drug capture (99mTc-DMSA) authors carried out miction uretrocystography to specify exactly the presence of vesicoureteral reflux. Results: twenty six patients (73.7 %) are females, 17 (44.7 %) aged under 6 months, 17 (44.7 %) have between 6 and 36 months and 4 (10.6 %) > 3 years old. The urinary infection was atypical in 23 (60.5 %) and as a isolated germ the Escherichia coli in 33 (86.8 %). Ultrasound of acute phase demonstrated a renal pelvis dilation in 3 (7.9 %) and renal asymmetry in 1 (2.6 %). In 2 patients (5.2 %) there was renal scar and in 11 (28.4 %) an decreased function of the renal cortex. The miction uretrocystography demonstrated the presence of grade III vesicoureteral reflux in a girl, who also had a renal scar. There was not relation between the onset of symptoms, the onset of therapeutics and the cortical injury. Conclusions: the risk factors to develop a post-pyelonephritis renal scar were: female sex, be aged under 3 and grade III vesicoureteral reflux.