Magnetic resonance imaging (MRI) is a cross-sectional imaging tool that offers excellent spatial resolution and soft tissue differentiation without the use of ionizing radiation. It is complimentary to other imaging tools when diagnoses have not been established with radiographs, ultrasound, or CT. It is an established non-invasive cross-sectional imaging modality for various organ systems that enables accurate characterization and vascular assessment of tissues and lesions. In addition, it can be used for assessing response to therapy and detecting recurrence and/or metastasis in post-therapeutic follow-up. MRI provides both physiologic and anatomic information with multiplanar imaging capability. Disadvantages of MRA include limited availability, higher cost, long acquisition times, and the need for deep sedation or general anesthesia in young children.
MRI is very helpful for evaluating the thorax, particularly the chest wall and mediastinum. Pulmonary diseases involving alveolar infiltration or exudation patterns such as pneumonia and pulmonary edema are reliably depicted on MRI. Unfortunately, early and subtle interstitial lung diseases are not easily visualized on MRI. This is because the lung has inherent low proton density, high loss of signal due to susceptibility, and substantial motion artifacts.
This lecture presents the clinical indications, preparations and technique in MRI evaluation of thorax in children. MRI appearance of common thoracic abnormalities in children will be discussed in clinic-radiologic approach.