Quantitative susceptibility mapping (QSM) and R2* of silent cerebral infarcts in sickle cell anemia

The objective of this work was therefore to investigate the composition of segmented SCI lesions using quantitative MRI for R2* and quantitative magnetic susceptibility mapping (QSM). 211 SCI lesions were segmented from 32 participants with SCA and 6 controls. SCI were segmented according to two definitions (FLAIR+/–T1w-based threshold) using a semi-automated pipeline. Magnetic susceptibility (χ) and R2* maps were calculated from a multi-echo gradient echo sequence and mean SCI values were compared to an equivalent region of interest in normal appearing white matter (NAWM). SCI χ and R2* were investigated as a function of SCI definition, patient demographics, anatomical location, and cognition. Compared to NAWM, SCI were significantly less diamagnetic (χ = –0.0067 ppm vs. –0.0153 ppm, p < 0.001) and had significantly lower R2* (16.7 s−1 vs. 19.2 s−1, p < 0.001). SCI definition had a significant effect on the mean SCI χ and R2*, with lesions becoming significantly less diamagnetic and having significantly lower R2* after the application of a more stringent T1w-based threshold. SCI-NAWM R2* decrease was significantly greater in patients with SCA compared with controls (–2.84 s−1 vs. –0.64 s−1, p < 0.0001). No significant association was observed between mean SCI–NAWM χ or R2* differences and subject age, lesion anatomical location, or cognition. The increased χ and decreased R2* in SCI relative to NAWM observed in both patients and controls is...
Source: Frontiers in Neurology - Category: Neurology Source Type: research