M-mode sonography of diaphragmatic motion: description of technique and experience in 278 pediatric patients

Background: The use of M-mode sonography for evaluation of diaphragmatic motion has only been previously reported in small series of children, and its use is not widespread among pediatric radiologists. Objectives: To present our experience with M-mode sonography in the evaluation of diaphragmatic motion in a large number of children with suspected diaphragmatic paralysis, to describe the technique used and to correlate sonographic findings with chest radiographs and clinical outcome. Materials and methods: Retrospective analysis of all M-mode sonograms performed in children from September 1999 to December 2003. The available chest radiographs and the clinical findings were reviewed and correlated with the sonographic findings. Results: A total of 742 hemidiaphragms were evaluated in 278 children. There was no visualization of the left hemidiaphragm in 2 children (0.71%). Movement of the right hemidiaphragm was normal in 238 and abnormal in 131. Movement of the left hemidiaphragm was normal in 232 and abnormal in 135. Abnormal diaphragmatic movement was present in 118 (63%) of 187 children in whom chest radiographs had shown normal position of the hemidiaphragms. Follow-up examinations were obtained in 56 children, revealing improvement in diaphragmatic motion in 26, no change in 23 and deterioration of motion in seven. Summary: M-mode sonography should be the modality of choice to assess diaphragmatic motion, as it can easily depict diaphragmatic dysfunction and allows comparison of changes in follow-up studies. Normal chest radiographs are poor predictors of normal diaphragmatic motion.