NONINVASIVE ASSESSMENT OF COARCTATION OF THE AORTA - COMPARATIVE MEASUREMENTS BY 2-DIMENSIONAL ECHOCARDIOGRAPHY, MAGNETIC-RESONANCE, AND ANGIOGRAPHY

Fifteen patients, aged between 9 and 21 years (mean, 15.1), with native coarctation of the aorta (CoA) or suspected recoarctation after surgical repair, underwent three different diagnostic procedures. Two-dimensional echocardiography (2D echo) and magnetic resonance imaging (MRI) of the thoracic aorta were performed in all patients; 14 patients underwent aortography, and digital subtraction angiography of the aorta was performed in one (after injection via a central venous catheter). Conventional electrocardiographic (ECG) gated MRI was performed, using the sagittal plane, a 256 x 256 acquisition matrix, multi-slice technique and a slice thickness of 10 mm. Diameters at the coarctation site were determined by all methods. Additional diameters of the descending aorta and the aortic arch were measured by MRI and echocardiography, respectively. All noninvasively obtained diameters were compared with angiographic data. Ultrasound imaging of the aortic isthmus was achieved in seven of 15 patients and of the aortic arch in nine of 15. The mean difference compared with angiographically determined diameters was 1.7 (0-7) mm, being greater for the coarctation site [mean, 2.2 (0-4)]. MRI images of the aortic isthmus were obtained in all patients, but the difference to angiographically determined diameters was slightly higher [mean, 3.2 mm (0-8)] than the ultrasound results. This deviation was presumably due to technical conditions, such as slice thickness and orthogonal imaging planes. Including all diameters, the correlation to invasive measurements was r = 0.82 (SEM = 3.1) for MRI and r = 0.89 (SEM = 2.3) for echo recordings. It is concluded that MRI gives a reliable estimate of the severity of coarctation in a higher percentage of investigated patients. However, in patients in whom ultrasound imaging is successful, results are as reliable as those obtained by MRI.