Lesion Segmentation Methodology

Purpose Currently in a dilemma as Hagen did a substantial amount of work editing the z-score FLAIR masks in MNI space, but realize that it is more standard to do such work in patient space Goal of this presentation is to determine how much of Hagen’s work can be salvaged and how much editing needs to be redone with the new patient space method Secondary goal is to determine if zscore > 2 is a good method for selecting DAWM

3 Methods to Choose From Z-score in MNI -> threshold (4, 2) -> patient space -> threshold (.95,.5, 0) – The original method, Hagen edited these Z-score in MNI -> patient space -> threshold (4, 2) – “z-score in MNI” Mean and std. dev. in MNI -> patient space -> z-score -> threshold (4, 2) – “z-score in patient space”

P015 – Low CIS – FLAIR

P015 – Low CIS – Original Method, Lesion Cores, Threshold.95

P015 – Low CIS – Original Method, Lesion Cores, Threshold.5

P015 – Low CIS – Original Method, Lesion Cores, Threshold 0

P015 – Low CIS – z-score in MNI, Lesion Cores

P015 – Low CIS – z-score in patient space, Lesion Cores

P015 – Low CIS – z-score in MNI, Lesion Penumbra

P015 – Low CIS – z-score in patient space, Lesion Penumbra

P009– Low CIS – FLAIR

P009– Low CIS – Original Method, Lesion Cores, Threshold.95

P009– Low CIS – Original Method, Lesion Cores, Threshold.5

P009– Low CIS – Original Method, Lesion Cores, Threshold 0

P009– Low CIS – z-score in MNI, Lesion Cores

P009– Low CIS – z-score in patient space, Lesion Cores

P009– Low CIS – z-score in MNI, Lesion Penumbra

P009– Low CIS – z-score in patient space, Lesion Penumbra

Observations z-score in MNI and in patient space give very similar results, I would argue for z-score in MNI as the better choice for simplicity The Original Method with threshold 0 is reasonable balance between lesion cores and penumbra, needs a look at by expert eyes Threshold z-score > 2 fills in obvious DAWM around lesion cores nicely – Not so great job with areas that did not contain a core

Proposed Options Lesion cores – Keep Hagen’s masks and threshold at.5 after warping to patient space – Alternatively, carry through z-score in MNI method and apply penumbra selection method to them using Hagen’s masks Lesion penumbra (DAWM) – Z-score in MNI method thresholded at 2 then penumbra selection