Practice Patterns in the Use of MRI/MRA and Chronic Transfusion Therapy for Monitoring and Treatment of Stroke in Pediatric Patients with Sickle Cell Anemia
Authors: Schlenz Alyssa M , Mueller Martina , Phillips Shannon , Melvin Cathy , Adams Robert J. , Kanter Julie 
Published: October 2019

Abstract
Introduction: Current stroke prevention guidelines in pediatric sickle cell anemia (SCA) specify the use of transcranial Doppler (TCD) and chronic red cell transfusion therapy (CRCT) for detection and prevention of stroke. Guidance on the use of MRI/MRA in the context of stroke prevention, screening, and monitoring is less clear. While overt stroke is able to be identified clinically, silent stroke can be more difficult to diagnose and screening guidelines have not been developed. The DISPLACE Consortium (Dissemination and Implementation Looking at the Care Environment) is a multi-center study funded to evaluate optimal implementation of stroke prevention guidelines. The purpose of the present study was to provide information on practice patterns across the DISPLACE Consortium as they relate to the use of MRI/MRA and CRCT for monitoring and treating stroke in pediatric patients with SCA.
Methods: DISPLACE is a multi-site study in SCA including 28 centers across the United States. A practice patterns survey was sent to the principal investigator (PI) for each DISPLACE site through RedCap. All PIs are specialty care providers in hematology/oncology who provide care to pediatric patients with SCA. The sites were chosen to represent a range of characteristics, including both urban and rural regions, large and small academic institutions, and community-based institutions. The survey was developed by the study investigators and questions were provided predominantly in a multiple choice format. The following types of questions were asked about MRI/MRA: indication for pediatric patients with SCA in general and for those on CRCT for stroke prevention. The following types of questions were asked about CRCT: indication and frequency of CRCT and target hemoglobin S level.
Results: All 28 providers completed the survey (100%). About half of providers were female (53.5%). Most providers identified as White (77.8%), followed by Asian (11.1%) and Black or African American (7.4%). Two identified as Hispanic or Latino (7.4%). MRI was used for the following indications: abnormal TCD (85.7%), conditional TCD (46.4%), recurrent headaches (78.6%), and behavior issues (53.6%). A few sites also reported obtaining an MRI if a child has had poor school performance (10.7%) or if there was concern for developmental delay (3.7%). Indications for MRA were similar. Notably, many sites reported the use of a screening or baseline MRI in the absence of other indications (25.0%). The most common indications for initiating CRCT were abnormal TCD (96.4%) and overt stroke (92.9%), followed by silent stroke (53.6%) and abnormal MRA (50.0%). The majority of sites reported scheduling CRCT at a frequency of every 4 weeks (63.0%), though many (37.0%) described other more frequent transfusions intended to either more rapidly reduce hemoglobin S levels or maintain a level under 30%. Most sites used a target of 30% hemoglobin S, though a few sites noted alternatives including 40% (3.7%) and 50% (3.7%). The frequency of MRI for patients receiving CRCT for stroke prevention was as follows: annually (44.4%), every 2 years (14.8%), and every 5 years (3.7%). Several sites reported obtaining MRIs only if there were new changes or concerns (14.8%) or reported alternative practices (14.8%) that depended on patient characteristics. Frequency for MRA was similar for patients on CRCT.
Conclusions: The results of the DISPLACE practice patterns survey suggested nearly universal adoption of CRCT for children with abnormal TCD and prior overt stroke across sites. The use of MRI/MRA in detecting potential cerebrovascular abnormalities in the absence of clinical neurologic symptoms and for monitoring patients on CRCT was much more variable, which likely reflects the minimal amount of guidance for the use of MRI/MRA in SCA. Notably, a number of sites were using MRI/MRA to screen pediatric patients for cerebrovascular abnormalities and to monitor patients on CRCT. The variability in responses for MRI/MRA highlights the importance of future studies evaluating best neuroimaging practices for detecting cerebrovascular abnormalities (apart from TCD) and for using MRI/MRA to monitor patients on CRCT.

Disclosures
Schlenz: NHLBI: Research Funding. Mueller:NHLBI: Research Funding. Phillips:NHLBI: Research Funding. Melvin:NHLBI: Research Funding. Adams:NHLBI: Research Funding. Kanter:bluebird bio: Membership on an entity's Board of Directors or advisory committees, Research Funding; NHLBI: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Apopharma: Research Funding; Sancilio: Research Funding; Global Blood Therapeutics: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; ASH: Membership on an entity's Board of Directors or advisory committees.