Objective:

To determine whether successful hematopoietic stem cell transplant (HSCT) for adults with sickle cell disease (SCD) is associated with longitudinal brain atrophy or FLAIR white matter hyperintensity (WMH) accumulation.

Background:

Adults with SCD are at risk for silent cerebrovascular disease and cognitive decline. HSCT can be curative, but conditioning regimens risk new complications, particularly for adults with accumulated organ damage.

Design/Methods:

Adults with severe SCD received nonmyeloablative allogeneic HSCT as part of 4 research protocols. Annual brain MRIs were acquired pre- and post-transplant for up to 17 years with a protocol that included 3D T1 and axial FLAIR. Freesurfer was used to segment longitudinal total brain volumes, corrected for intracranial volume (ICV), as the brain parenchymal fraction (BPF). A deep learning algorithm was used to segment total WMH volume from FLAIR, corrected for ICV and log-transformed (WMHv). HSCT success (engraftment vs. graft failure) and change in hemoglobin (Hb post – Hb pre) were used to predict volumetric changes using mixed linear models that adjusted for age, sex, participant intercept and slope, and scanner variance.

Results:

80 participants (mean age 32±9, 43% female) who underwent HSCT were followed for median 4.9 years (IQR=4.7). For 67 participants with successful HSCT (352 person-years), BPF declined -0.07%/year [-0.12 to -0.02, p=0.005]. Thirteen participants with graft failure (61 person-years) had a 6-fold greater BPF decline of -0.42%/year [-0.57 to -0.26, p<0.001; interaction p<0.001]. A smaller hemoglobin change was also associated with steeper BPF decline (-0.03%/year per point Hb, interaction p<0.001). WMHv grew in both groups similarly (0.027%/year; interaction p=0.96) and accumulation was associated with older age but not graft success.

Conclusions: