Anatomy, MR, Imaging sequences, Dementia
E. Tuzzi, G. E. Hagberg, D. Balla, J. Loureiro, M. Neumann, C. Laske, R. Pohmann, K. Scheffler; Tübingen/DE
A variation of 70ms-1ca.
in the effective transverse relaxation rate was observed between grey and white matter in AD patient compared to healthy subject (Figure 1).
A pattern between grey and white matter,
corresponding to paramagnetic effects,
was also detected in the susceptibility map (0-0.04 ppm) of the AD patient with respect to the healthy subject (Figure 1).
the spatial resolution reached in-vivo was not sufficient to reveal microstructure of the cortical layers at higher level of detail.
Ex-vivo R2* maps showed the same pattern observed in-vivo,
with increased values of R2* (0-130ms-1) in Alzheimer’s patient compared to healthy subject (Figure 2).
Also a different layering was found in the cortex of the patient,
with an apparent broadening of the central layer,
with respect to the healthy subject.
As for the susceptibility maps,
variations of susceptibility (-0.03 - 0.03 ppm),
consistent with paramagnetic effects,
were detectedin AD in the layer between grey and white matter at the spatial resolution of 37 µm3 (Figure 2) Significantly,
paramagnetic effects were also observed in the cortex in AD patient compared to control,
corresponding to the apparent central layer broadening observed in R2* maps.
The histological exam of the AD sample revealed Beta-Amyloid plaques corresponding to the paramagnetic effects detected in the cortex by QSM.
a significative difference between AD and HS in Beta-Amyloid load detection was found ex-vivo at three different ersolutions (Figure 3).
Figure 3 shows the fraction of paramagnetic effects in QSM within the cortex at different cutoff,
for each resolution.
A slight better performance at both 37 and 50 micron compared to 100micron was found.
The fraction of plaques in the histological slice is also shown (black line).