LOW RESOLUTION SUSCEPTIBILITY MAPPING IN THE ESTIMATION OF IRON CONTENT IN DEEP GREY MATTER OF BRAIN AT 3 TESLA

Objective: The objective of this study is to determine the effect of low resolution in the estimation of iron content in deep grey matter of brain using quantitative susceptibility mapping. Methodology: Six females with mean age 43.16, S.D= 20, age range (23- 66) and 13 males with mean age 28.92 + 8.14 were scanned with 3D SWI sequence at 3 Tesla (Trio-Seimens, Erlangen, Germany). The caudate nucleus, red nucleus, globus pallidus, putamen, white matter, thalamus and substantia nigra of brain were drawn manually based on their anatomical locations in Signal Processing in Nuclear Magnetic Resonance (SPIN). Magnitude and phase images of high resolution (HR) (0.5x0.5x2 mm^3) were processed in SPIN using collapsing parameter to generate the low resolution (LR) (1x1x2 mm^3) susceptibility mapping. Data was analyzed using paired t-test. Results: A strong linear correlation (R^2=0.99, p ≤ 0.05) was found between the susceptibilities of Deep Grey Matter (DGM) at low resolution versus high resolution which showed the consistency of susceptibility at both resolution. When the susceptibilities in ppb of DGM were correlated with iron content (mgFe/100g), a positive correlation was found with R-saqure (R^2=0.67, p ≥ 0.05 at HR, R^2=0.66, p ≥ 0.05 at LR). The slope of the above linear correlation was consistent with the equivalent susceptibility trend at low and high resolution QSM. Conclusion: Linear correlation between susceptibility and iron content at HR and LR has demonstrated that low resolution QSM holds the consistency of susceptibility and does not affect the estimation of iron content in deep grey matter of brain.