Follow-up of adults with coarctation of the aorta -: Comparison of helical CT and MRI, and impact on assessing diameter changes

Objectives: To compare images of the aorta obtained with helical CT (HCT) scanning and MRI for the follow-up of adults with coarctation of the aorta (CoA). Design: Longitudinal study. Setting: Department of adult congenital heart disease in a tertiary university hospital. Patients: A total of 37 adults (age range, 16 to 68 years; women, 13) with CoA (after surgery, 34 patients; native, 2 patients; after balloon-angioplasty, 1 patient) Measurements and results: All patients underwent both HCT and MRI of the thoracic aorta within a mean (+/- SD) time interval of 1.86 +/- 1.11 years. Aortic diameters measured at six intrathoracic levels showed a high correlation (r = 0.79 to 0.94). On average, slightly lower diameters were measured with MRI (1.2 mm). But there was a substantial variation between the two measurements with differences of up to 9 mm. All other pathomorphologic abnormalities were detected and classified similarly with both methods. Conclusions: HCT and MRI are similarly useful for the noninvasive evaluation of the thoracic aorta in patients with CoA. But there can be a substantial variation in two subsequent measurements without an overall substantial bias toward larger diameter in one of the two methods. In repetitive studies, changes of the diameters should be interpreted with care, especially when assessing the progression of aortic diameters.