Magnetic resonance blood flow measurements in the follow-up of pediatric patients with aortic coarctation – A re-evaluation

Background Previous studies have suggested the feasibility of a non-invasive quantification of vascular trans-stenotic pressure gradients (ΔP) by phase-contrast MR imaging (PC-MRI). Our purpose was to assess the value of MRI estimated pressure gradients as a screening tool for assessing hemodynamically significant (re-)coarctation of the aorta (CoA) in pediatric patients. Methods Forty-three patients (median age (range), 16 (5–25) years) with CoA (38 postoperative and 5 native) and clinically suspected hemodynamically significant stenosis underwent quantitative and semi-quantitative PC-MRI blood flow measurements and 3D MR-angiography, Doppler ultrasound (US) and conventional catheter angiography (CCA, n = 20). Estimated ΔP for each modality was correlated with percent stenosis. Results The percent stenosis correlated only moderately with ΔPMRI (r = 0.55, p < 0.001) and ΔPCCA (r = 0.48, p < 0.001). Only moderate correlations were observed between ΔPMRI vs. ΔPCCA (r = 0.54, p = 0.02) and vs. ΔPUS (r = 0.40, p = 0.01). In contrast, semi-quantitative analysis of PC-MRI flow profiles predicted with good sensitivity (88%) and specificity (88%) who would be operated on. Thirteen patients met hemodynamic and percent stenosis criteria by CCA for surgical intervention. Conclusion Measured pressure gradients using PC-MRI should be used cautiously when assessing patients for recoarctation of the aorta. The analysis of blood flow profiles by PC-MRI might be a promising alternative in assessing the hemodynamic significance of CoA.