Hi !

As expected in our previous post we have performed some tests to assess the effect of different threshold methods and values on total intracranial volume estimation from segmented and modulated MRI data sets.  

We have used either different thresholds (from 0 = no threshold, to 0.9) applied on each of the brain partition, or differently thresholded wholebrain masks (again using thresholds from 0 to 0.9). We thus calculated the total intracranial volume of 19 healthy controls and 28 slightly atrophied patients in these 9*9 conditions, and assessed their inter-correlations. As expected, all values were significantly correlated. Highest correlations (r>0.97) were observed for thresholds from 0 to 0.5 (where TIV values decrease from 0 to 35%, respectively). Thresholds above this value lead to decreased correlations (0.95 < r < 0.70) and more than 49% decrease of the maximum TIV value.

We thus conclude from this preliminary analysis that the use of <0.5 threshold values would lead to more consistent TIV estimation, and this threshold could be indifferently applied to either each brain partition or the whole brain image.