Magnetic Resonance Angiography to Assess Anomalous Coronary Arteries in Children at 3-Tesla: Diagnosis, Risk Stratification, and Interobserver Reliability.

Background: Anomalous aortic origin of the coronary arteries (AAOCA) is the second most common cause of sudden cardiac death (SCD) in young athletes. The prevalence, pathophysiology, and optimal method of evaluating AAOCA are unknown. The reliability of coronary magnetic resonance angiography (MRA) in assessing AAOCA, and the use of contrast enhanced coronary MRA in children at 3-Tesla has not been well described. We present our institutional experience using a 3-dimensional (3D) IR-FLASH sequence with slow gadolinium infusion and respiratory navigation at 3-Tesla to diagnose and risk stratify AAOCA in children. Methods: A retrospective review was conducted of all MRA patients referred for possible AAOCA between January 1, 2011 and May 9, 2016. Patients with complex congenital heart disease were excluded. Coronary anomalies with an intramural or interarterial course were classified as high risk, and a high aortic origin or intraseptal course were classified as low risk. Completed studies were anonymized and evaluated by two blinded independent observers for image quality, diagnosis of AAOCA, intramural course, and interarterial course. Reliability analyses, utilizing kappa, assessed diagnostic agreement between raters. MRA and surgical findings were compared in patients with AAOCA repair. Results: Fifty-nine patients were referred for suspected AAOCA (median age 13.79 years, range 5.19 – 19.84, 73% male). For 58 successfully acquired angiograms, 31 were high risk, 11 were low risk, and 16 were normal. Overall image quality was rated good to excellent. The two raters showed excellent agreement on image quality, κ = .85 (93%), diagnosis of AAOCA, κ = .81 (91%), and diagnosis of proximal interarterial course, κ = .81 (88%). There was moderate agreement about diagnosis of intramural course, κ = .63 (74%). For all 11 cases with surgical repair, the combined MRA ratings correctly diagnosed the presence of AAOCA and interarterial course. The presence of an intramural course was correctly rated in all 9 cases, while the absence of an intramural course was correctly rated in 1 of 2 cases. Conclusions: Coronary MRA using 3D IR-FLASH with slow contrast infusion at 3-Tesla showed high inter-rater reliability for diagnosing and characterizing AAOCA in pediatrics. Furthermore, findings were validated at time of surgical repair. This protocol is an effective means to examine AAOCA in pediatric patients and help stratify those who may be at high risk of SCD.