clinical topic updates

Advanced and Conventional Imaging in Sickle Cell Disease

by Stella T. Chou, MD

Overview

Patients with sickle cell disease (SCD) are at risk for end-organ damage, including silent cerebral infarcts and associated cognitive deficits. Routine magnetic resonance imaging (MRI) screening for silent cerebral infarcts may help to improve the identification of individuals with SCD who would benefit from neuropsychological testing and tailored intervention.

Expert Commentary

Stella T. Chou, MD

Associate Professor of Pediatrics
Chief, Division of Transfusion Medicine
Children’s Hospital of Philadelphia
Perelman School of Medicine at the University of Pennsylvania
Philadelphia, PA

". . . the American Society of Hematology 2020 guidelines now specifically recommend MRI screening for silent cerebral infarcts in both children and adults with SCD. This is a truly important recommendation because it represents a step toward providing care uniformly to patients with SCD throughout the United States.”

Stella T. Chou, MD

Screening with transcranial Doppler (TCD) ultrasound and treatment with regular blood transfusion or hydroxyurea in children with SCD with abnormal TCD ultrasound velocities is the standard of care in the United States. Additionally, MRI and magnetic resonance angiography (MRA) are used to identify silent cerebral infarcts and cerebral vasculopathy. In fact, the American Society of Hematology 2020 guidelines now specifically recommend MRI screening for silent cerebral infarcts in both children and adults with SCD. This is a truly important recommendation because it represents a step toward providing care uniformly to patients with SCD throughout the United States. 

Children with SCD should have at least 1 MRI screening, typically at an early school age, during a time when they are able to sit still for 30 to 45 minutes to get the MRI without having to be sedated. Adults and children with hemoglobin Sβ0-thalassemia should also receive MRI screening. The objective is to better identify patients with silent cerebral infarcts because those who have them may also have associated learning disabilities and deficits in executive cognitive functioning. The identification of silent cerebral infarcts allows for the referral for neuropsychological testing, which can potentially lead to access to individualized educational plans at school. 

In addition to routine screening, imaging may be indicated in children with SCD when there has been a decline in school performance. Typically, we would use MRI/MRA screening, with both imaging studies being performed during the same appointment. MRA can identify vascular narrowing and moyamoya disease, which involves the formation of tiny collateral vessels to compensate for vascular narrowing. Patients with vascular narrowing are at an increased risk for both overt strokes and silent cerebral infarcts. We do occasionally see patients with normal TCD ultrasounds but abnormal MRIs and/or MRAs. In such cases, chronic transfusion therapy may be indicated. Further, encephaloduroarteriosynangiosis, a neurosurgical revascularization procedure, may be indicated in young patients with severe vasculopathy. 

These are the primary uses of advanced imaging techniques (eg, MRI and MRA) in patients with SCD. Conventional imaging has a role in other scenarios on a case-by-case basis. For instance, in patients with fever and respiratory symptoms, the traditional chest x-ray should be performed to screen for acute chest syndrome. Very young children with SCD who present with fever but no respiratory symptoms should nonetheless have a chest x-ray since they may not exhibit overt respiratory symptoms at initial presentation of acute chest syndrome. 

References

DeBaun MR, Jordan LC, King AA, et al. American Society of Hematology 2020 guidelines for sickle cell disease: prevention, diagnosis, and treatment of cerebrovascular disease in children and adults. Blood Adv. 2020;4(8):1554-1588. doi:10.1182/bloodadvances.2019001142

Jain S, Bakshi N, Krishnamurti L. Acute chest syndrome in children with sickle cell disease. Pediatr Allergy Immunol Pulmonol. 2017;30(4):191-201. doi:10.1089/ped.2017.0814

Winstead M, Sun PP, Martin K, et al. Encephaloduroarteriosynangiosis (EDAS) in young patients with cerebrovascular complications of sickle cell disease: single-institution experience. Pediatr Hematol Oncol. 2017;34(2):100-106. doi:10.1080/08880018.2017.1313917

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