Breath-hold MRI in evaluating patients with pectus excavatum

Pectus excavatum (PE) is a congenital condition in which the sternum is dis placed posteriorly with associated changes in the adjacent costal cartilage s. The aetiology of PE is uncertain although various underlying abnormaliti es of the diaphragm have been implicated. There is sparse information regar ding the use of fast MRI in evaluating the deformity. Our aims were to use fast MRI to evaluate static and respiratory-related dynamic chest wall char acteristics, the extent of cardiac displacement and diaphragmatic excursion in patients. FLASH and TurboFLASH MR sequences in axial and coronal planes were performed on the thoraces of six young patients with PE and six indiv idually matched healthy controls during full inspiratory and full expirator y breath-holds. The Pectus Index was derived from chest wall measurements u sing axial images. The distances of the left and right cardiac borders from the midline were measured using axial images, and excursion of the dome of each hemidiaphragm was measured using coronal images. The degree of sterna l depression worsened substantially in expiration. Anterior chest wall move ment was similar in the two groups. Patients had significantly flatter ches ts than the controls. There was a trend towards leftward cardiac displaceme nt in the patients (maximum distance between left heart border and midline during full expiration 99.5 mm in patients and 91.8 min in controls). The r ight diaphragmatic dome excursion was greater than the left in the controls (53.6 min and 47.4 mm, respectively), but this was not seen in the patient s (50.2 mm and 50.4 turn, respectively). It is concluded that fast MRI is v ery informative in evaluating skeletal abnormalities, chest wail motion, an d cardiac and diaphragmatic changes seen in PE.