Supplementary Material for: Cerebral Lesions on 7 Tesla MRI in Patients with Sickle Cell Anemia

Background: Patients with sickle cell anemia (SCA) are at a high risk to develop cerebral damage. Most common are silent cerebral infarctions (SCIs), visible as white matter hyperintensities (WMHs) on MRI in a patient without neurological deficits. The etiology of SCIs remains largely unclear. In addition, patients are at an increased risk for overt stroke, which is associated with large vessel disease. This classification based on the presence or absence of neurological deficits may not be the most fitting for research purposes, as it does not match the different underlying pathology. A classification based on imaging findings may therefore be a more straightforward approach for research purposes. We explored the feasibility to identify imaging features of SCIs in young, asymptomatic patients with SCA using ultra high-field 7 Tesla (7T) MRI. 7T MRI has a high resolution, which offers a unique chance to investigate small subclinical brain lesions in detail. To explore the superiority of 7T in identifying imaging abnormalities, we compared our results with 3T MRI. Methods: Ten young, neurologically asymptomatic patients with SCA underwent 7T and 3T MRI; 10 healthy, age-matched controls underwent 7T MRI. We used existing neuroimaging standards to classify the brain lesions. We scored 7T and 3T scans separately, blinded for all other results. Results: Using 7T MRI, we identified more patients with intracerebral lesions (9/10 vs. 5/10), a higher total count of WMHs (203 vs. 190, p = 0.016) and more lacunes (5 vs. 4) compared to 3T MRI. Abnormalities seen on 7T, which could not be identified on 3T, were cortical hyperintensities (in 3/10) and a different aspect of irregular WMHs, closely associated with cortical hyperintensities in a patient with large vessel stenosis. In 7 controls, a total of 13 WMHs were present. Conclusion: Using 7T MRI, we identified more intracerebral lesions compared to 3T, and found several abnormalities not visible on 3T. 7T MRI in SCA seems of particular interest to study the cortical involvement and the relation between WMHs and the cortex. We found some imaging features that are thought to be representative for small vessel disease, including WMHs, lacunes and prominent perivascular spaces; to understand whether small vessel disease plays a role in SCA requires further research.