Abstract 19051: Accuracy and Internal Consistency of Cardiac Magnetic Resonance Imaging in Measuring Branch Pulmonary Arterial Flows in Conotruncal Anomalies Patients with Branch Pulmonary Arterial Stents

Abstract

Introduction Conotruncal Anomalies patients may require branch pulmonary arterial (BPA) stent implantation. These ferromagnetic stents generate localized artifact that may affect phase contrast magnetic resonance (PCMR) imaging. There is little data on PCMR measurements in the presence of a BPA stent.

Hypothesis PCMR acquired measurements away from the BPA stent artifact are accurate and internally consistent.

Methods We retrospectively reviewed 43 consecutive repaired Conotruncal Anomalies PCMR and cine MR studies between 2005 and 2012. All patients underwent either left (30) pulmonary artery (LPA) or right (20) pulmonary artery (RPA) stent placement. Three different methods of measuring flow through the stented artery were compared: 1) main pulmonary artery (MPA) - unstented artery, 2) direct PCMR of the stented artery away from the artifact, and 3) pulmonary venous (PV) flows (see Figure). Where available, pulmonary radionuclide scintigraphy (PRS) was compared to each method. Significance was P < 0.05.

Results For the entire study population, the mean age and body surface area were 12.0 ± 7.0 yrs (range 1.5 - 33.2 yrs) and 1.2 ± 0.5 m2. There was good agreement without significant difference between the mean PRS and MPA derived stented artery flow (method 1) (37 ± 17 and 35 ± 21 %, r=0.731, ICC=0.8403, p=0.627) There was even better agreement between PRS and direct measurement (method 2) (39 ± 20 and 40 ± 22%, r=0.888, ICC = 0.943, p=0.757). The greatest agreement was found between method 2 and PV flows (method 3) (48 ± 17 and 47 ± 14%, , r=0.939, ICC=0.961, p=0.837). As another check for internal consistency, there was excellent correlation between the PCMR and cine MR right ventricular stroke volume 70.2 ± 40.4 and 74.0 ± 41.4 cc, r=0.983, ICC=0.989.

Conclusion In the presence of a ferromagnetic BPA stent, accurate measurement of the net fractional flow ratio is feasible. PCMR adjacent to the stent artifact or pulmonary venous flows provide the most internally consistent data.