Impact of MRA Echo Time on Stroke Prevention Therapy in Pediatric Patients with Sickle Cell Disease

Background and Purpose: Magnetic Resonance Angiography (MRA) is performed on pediatric patients with sickle cell disease (SCD) to classify degree of cerebrovascular stenosis, informing stroke risk and treatment plan for stroke prevention. Flow artifact intrinsic to MRA and influenced primarily by TE (echo time) can lead to overinterpretation of stenosis. A standardized MRA protocol with shorter TE for patients with sickle cell disease was implemented at our institution. The primary objective of this study was to document any change in stroke prevention therapy that could be attributed to the implementation of this standardized MRA scanning protocol.

Methods: A standardized MRA scanning protocol with an TE of <5msec based on the SWiTCH study protocol for patients with SCD was implemented at Montefiore Medical Center, NY (MMC) May 2016. This project included a retrospective chart review of patients at MMC ≤ 21 years with SCD who had one MRA head pre- AND one MRA post-May 2016. Of the 81 patients that met inclusion criteria, 29 patients were found to have vasculopathy on pre-May 2016 imaging and were included in this analysis. Level of arterial stenosis on MRA, TE, and treatment plans were documented both pre- and post-May 2016. McNemar analysis was used to determine the significance of change in treatment plans before and after implementation of the standardized scanning protocol.

Results: 24/29 (83%) patients were on chronic transfusion therapy for CNS vasculopathy pre-May 2016 whereas 18/29 (62%) were on chronic transfusion therapy post May 2016. Notably, 6 patients had a resolution of vasculopathy on MRA post implementation of the scanning protocol, leading to discontinuation of chronic transfusion therapy. McNemar analysis showed this difference to be statistically significant (p = 0.042).

Conclusion: Implementing a standardized MRA scanning protocol allowed for chronic transfusion therapy to be discontinued in 6 out of 24 patients due to minimizing flow artifact. Screening for arterial stenosis with TE <5msec can improve accurate interpretation of true cerebrovascular disease and ensure appropriate treatment plans are in place for SCD stroke prevention.

Mitchell:Octapharma: Consultancy. Manwani:Pfizer: Consultancy; Novartis: Consultancy; Global Blood Therapeutics: Consultancy.