Chi-Separation Detects Focal Changes in Cortical Paramagnetism Associated with Behavioral Variant Frontotemporal Dementia

Motivation: Syndrome-specific patterns of iron-rich cortical gliosis have been demonstrated postmortem in Frontotemporal Lobal Degeneration (FTLD) but have not been reliably detected in vivo. Goal(s): Evaluate whether Chi-separation and/or Quantitative Susceptibility Mapping (QSM) can reliably detect regional changes in cortical paramagnetism in behavioral variant frontotemporal dementia (bvFTD) patients. Approach: Patients with bvFTD, Alzheimer's disease, and one age-matched control were imaged at 3T using a multi-gradient echo sequence. Both QSM and Chi-separation maps were analyzed within DKT cortical regions associated with expected pathology. Results: Chi-separation paramagnetic maps showed statistically significant increases in anterior cingulate, a region of expected pathology. Impact: We show that chi-separations maps can be used to detect syndrome-specific paramagnetic cortical changes, demonstrating its ability to quantify the distribution of iron-rich gliosis in vivo in FTLD, which has previously only been reliably visualized postmortem.