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Abstract
Objective To determine mechanisms underlying regional vulnerability to infarction in sickle cell disease (SCD) by measuring voxel-wise cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen utilization (CMRO2) in children with SCD.
Methods Participants underwent brain MRIs to measure voxel-based CBF, OEF, and CMRO2. An infarct heat map was created from an independent pediatric SCD cohort with silent infarcts and compared to prospectively obtained OEF maps.
Results Fifty-six participants, 36 children with SCD and 20 controls, completed the study evaluation. Whole-brain CBF (99.2 vs 66.3 mL/100 g/min, p < 0.001), OEF (42.7% vs 28.8%, p < 0.001), and CMRO2 (3.7 vs 2.5 mL/100 g/min, p < 0.001) were higher in the SCD cohort compared to controls. A region of peak OEF was identified in the deep white matter in the SCD cohort, delineated by a ratio map of average SCD to control OEF voxels. CMRO2 in this region, which encompassed the CBF nadir, was low relative to all white matter (p < 0.001). Furthermore, this peak OEF region colocalized with regions of greatest infarct density derived from an independent SCD cohort.
Conclusions Elevated OEF in the deep white matter identifies a signature of metabolically stressed brain tissue at increased stroke risk in pediatric patients with SCD. We propose that border zone physiology, exacerbated by chronic anemic hypoxia, explains the high risk in this region.
GLOSSARY
- CBF=
- cerebral blood flow;
- CMRO2=
- cerebral metabolic rate of oxygen utilization;
- FLAIR=
- fluid-attenuated inversion recovery;
- HbA=
- hemoglobin A;
- HbS=
- hemoglobin S;
- HbSβthal0=
- hemoglobin S-β thalassemia null;
- HbSS=
- hemoglobin SS;
- MCA=
- middle cerebral artery;
- MRA=
- magnetic resonance angiography;
- OEF=
- oxygen extraction fraction;
- SCD=
- sickle cell disease;
- SCI=
- silent cerebral infarct;
- TCD=
- transcranial Doppler
Footnotes
↵* Drs. Fields and Guilliams contributed equally and are designated as co–first authors.
↵† Drs. Ford and Lee contributed equally and are designated as co–senior authors.
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Editorial, page 585
- Received March 23, 2017.
- Accepted in final form December 5, 2017.
- © 2018 American Academy of Neurology
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