RESUMO
BACKGROUND: Portal hypertension, a major complication of hepatic fibrosis, can affect the stiffness of the spleen. OBJECTIVE: To suggest normal values of spleen stiffness determined by acoustic radiation force impulse imaging in healthy children and to compare measurements using two different US probes. MATERIALS AND METHODS: In a prospective study, 60 healthy children between 1 day and 14 years of age were assigned to four age groups with 15 children in each. Measurements were performed using two transducers (convex 4C1 and linear 9L4), and 10 measurements were obtained in each child, 5 with each probe. RESULTS: The mean splenic shear wave velocities were 2.17 m/s (SD 0.35, 95% CI 2.08-2.26) with the 4C1 probe and 2.15 m/s (SD 0.23, 95% CI 2.09-2.21) with the 9L4 probe (not significant). CONCLUSION: We found normal values for spleen stiffness with no difference in the mean values obtained using two types of US transducers, but with higher variability using a convex compared to a linear transducer.
Assuntos
Envelhecimento/fisiologia , Módulo de Elasticidade/fisiologia , Técnicas de Imagem por Elasticidade/instrumentação , Baço/diagnóstico por imagem , Baço/fisiologia , Transdutores , Adolescente , Criança , Pré-Escolar , Técnicas de Imagem por Elasticidade/normas , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Resistência ao Cisalhamento/fisiologia , Espanha , Estresse MecânicoRESUMO
Acoustic radiation force impulse (ARFI) is an image-guided ultrasound elastography method that allows quantification of liver stiffness by measurement of shear wave velocity. One purpose of the work described in this article was to determine the normal liver stiffness values of healthy children using ARFI with two different probes, 4 C1 and 9 L4. Another purpose was to evaluate the effects of site of measurement, age, gender and body mass index on liver stiffness values. This prospective study included 60 healthy children (newborn to 14 y) divided into four age groups. One thousand two hundred ARFI measurements were performed, that is, 20 measurements per patient (5 measurements in each lobe, with each probe). Means, standard deviations (SD) and confidence intervals for velocity were calculated for each hepatic lobe and each probe in each age group and for the whole group. Mean shear wave velocity measured in the right lobe was 1.19 ± 0.04 m/s (SD = 0.13) with the 4 C1 transducer and 1.15 ± 0.04 m/s (SD = 0.15) with the 9 L4 transducer. Age had a small effect on shear wave measurements. Body mass index and sex had no significant effects on ARFI values, whereas site of measurement had a significant effect, with lower ARFI values in the right hepatic lobe. ARFI is a non-invasive technique that is feasible to perform in children with both the 4 C1 and 9 L4 probes. The aforementioned velocity values obtained in the right lobe may be used as reference values for normal liver stiffness in children.