[Imaging of the diaphragm: A multimodal approach, and the role of MRI]

As the primary muscle of ventilation, the diaphragm is potentially involved in a wide range of acute and chronic respiratory conditions. However, diaphragmatic dysfunction often remains underrecognized because of its non-specific clinical presentation, which may include exertional dyspnea, orthopnea, functional limitation, and/or respiratory failure. Exploration relies on a multimodal approach combining clinical assessment, pulmonary function testing, and imaging. Chest radiography is often the first imaging study to raise suspicion of diaphragmatic abnormalities. Given its accessibility and ease of use, ultrasound has evolved into the main first-line dynamic imaging modality. Computed tomography remains essential to morphological and etiological assessment, particularly when phrenic nerve involvement is suspected. Dynamic magnetic resonance imaging ensures a comprehensive, non-ionizing, three-dimensional evaluation of diaphragmatic morphology and kinetics. The following review presents a practical approach to diaphragm imaging, from the clinical situations that should raise suspicion of diaphragmatic disease to the appropriate selection of functional and morphological imaging modalities. Recent developments in dynamic and quantitative imaging are highlighted.