Introduction Although traditional assessment of diaphragm palsy requires ultrasound or fluoroscopy, ultrasound is dependent on operator experience and may suffer from poor reproducibility, and fluoroscopy may confer a higher radiation dose, requires radiologist oversight, and is not available in all centres.^{1 2} We have therefore explored the utility of dynamic chest radiography (DCR) using a novel dynamic X-ray imaging tool to assess diaphragm palsy, and present our experience.

Methods DCR is a low-dose, large field-of-view X-ray imaging system (Konica Minolta, Inc., Japan) that takes sequential PA images of the thorax at 15fps to provide a moving image. It is performed in the same position as an erect PA CXR, carries an effective dose of <0.125 mSv for a 10s exposure, and can be done rapidly without specialist input. Automated computer identification of the diaphragm allows calculation of diaphragm position and velocity. DCR is also of sufficient quality to interpret as a standard PA CXR.

We undertook DCR in 8 cases of suspected diaphragm palsy (mean age 60 years, 3 female), where images were acquired over 10–19 seconds. Three sharps sniffs were followed by a forced maximal deep inspiration.

Results See table 1. Paradoxical diaphragm motion was demonstrated in cases 1 to 6. In cases 7 and 8, abnormal but non-paradoxical motion was demonstrated, in both cases confirmed by fluoroscopy. DCR was well tolerated by all subjects.

Conclusions DCR is a useful tool to quantify diaphragm kinetics. Its low radiation dose and rapid image acquisition make it an attractive alternative to traditional imaging modalities when assessing diaphragm paralysis.

References

1. Nason LK, Walker CM, McNeeley MF, et al. Imaging of the diaphragm: anatomy and function. Radiographics. 2012;32 (2): E51–70

2. Boussuges A, Gole Y, Blanc P. Diaphragmatic motion studied by m-mode ultrasonography: methods, reproducibility, and normal values. Chest. 2009;135 (2): 391–400.