RESUMO
OBJECTIVE: The purpose of this study was to assess the repeatability of water-fat MRI and diffusion-tensor imaging (DTI) as quantitative biomarkers of pediatric lower extremity skeletal muscle. SUBJECTS AND METHODS: MRI at 3 T of a randomly selected thigh and lower leg of seven healthy children was studied using water-fat separation and DTI techniques. Muscle-fat fraction, apparent diffusion coefficient (ADC), and fractional anisotropy (FA) values were calculated. Test-retest and interrater repeatability were assessed by calculating the Pearson correlation coefficient, intraclass correlation coefficient, and Bland-Altman analysis. RESULTS: Bland-Altman plots show that the mean difference between test-retest and interrater measurements of muscle-fat fraction, ADC, and FA was near 0. The correlation coefficients and intraclass correlation coefficients were all between 0.88 and 0.99 (p < 0.05), suggesting excellent reliability of the measurements. Muscle-fat fraction measurements from water-fat MRI exhibited the highest intraclass correlation coefficient. Interrater agreement was consistently better than test-retest comparisons. CONCLUSION: Water-fat MRI and DTI measurements in lower extremity skeletal muscles are objective repeatable biomarkers in children. This knowledge should aid in the understanding of the number of participants needed in clinical trials when using these determinations as an outcome measure to noninvasively monitor neuromuscular disease.
Assuntos
Tecido Adiposo/anatomia & histologia , Imagem de Tensor de Difusão/métodos , Interpretação de Imagem Assistida por Computador/métodos , Extremidade Inferior/anatomia & histologia , Músculo Esquelético/anatomia & histologia , Tecido Adiposo/metabolismo , Adolescente , Água Corporal/metabolismo , Criança , Pré-Escolar , Feminino , Humanos , Extremidade Inferior/fisiologia , Masculino , Músculo Esquelético/metabolismo , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
We report a unique case of an infant with testicular torsion in the anterior abdominal wall. In the work-up of acute abdominal pain in a male infant with nonpalpable testes, a careful search for the testes using ultrasound can often identify undescended or ectopic testes. Testicular torsion should remain an important consideration as a potential cause of abdominal pain in this selected group of individuals.