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Delphi Panel Questionnaire

Fifth Round

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daniele

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About the questionnaire ABOUT THE QUESTIONNAIRE

LAST ISSUE

The four Delphi rounds that have been run succeeded in achieving a consensus on the definition of landmarks, and

segmentation modalities.

Here you can find the results of the previous Delphi rounds, represented in the Tables and Figures selected for the

next paper, that you will co-author (consistently with the policy of the journal to which the work will be submitted).

Only one issue remains open: image orientation*.

In the following pages we provide you new evidence, and ask again your opinion.

* Please note that “orientation” does not relate to the position of the head in the gantry during

MRI acquisition, but to the post-processing procedure of re-orienting image stacks.

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Image Orientation: results of the Delphi rounds so far ABOUT THE QUESTIONNAIRE

Image Orientation: results of the Delphi rounds

so farIn Round II, significant agreement was achieved on the fact that images should be aligned along the long axis of the

hippocampus, to properly visualize the coronal slices that will be used for the manual segmentation of the

hippocampus (agreement 62.5%, p=0.012).

As you may remember, we did not provide quantitative data to base your decision on, and your choice was driven

by personal experience, which you supported with a number of satisfactory reasons.

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Image orientation: methodological problem ABOUT THE QUESTIONNAIRE


so far

Image orientation: methodological problem

All of the quantitative information used to support decisions for landmark definition in the previous rounds was

collected on images oriented along the AC-PC line.

Therefore, the methodological problem arises that the shift of the whole protocol on the hippocampal axis might

invalidate all previous decisions.

This is a major methodological problem. The solution would consist in re-running the whole process, including the

collection of quantitative info on Segmentation Units on images orthogonal to the long axis of the hippocampus,

and all Delphi rounds. Unfortunately, this is not feasible.

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Image orientation: NEW DATA ABOUT THE QUESTIONNAIRE


so far


Image orientation: NEW DATA

In order to address this problem, three expert tracers have performed whole hippocampal segmentations on 10

ADNI images oriented in both ways (hippo long axes and AC-PC). Segmentations were based in both cases on the

harmonized landmark definition.

ICC values for intra- and inter-rater agreement on global volumes show that both orientations lead to very good

results (table).

Nonetheless, the examination of spatial overlapping showed an advantage of AC-PC oriented images. Here you can

see the results of the Dice analyses on spatial agreement, and below the movies showing the tracings made by the

three tracers that produced these findings.

"Movie 1"

Minimum Dice for Hippocampal Axis (0.7835) computed between Tracer 1 and Tracer 3, and corresponding to

Subject 9, Right hippo.

"Movie 2"

Maximum Dice for Hippocampal Axis (0.8889) computed between Tracer 2 and Tracer 3, and corresponding to

Subject 4, Left hippo.

"Movie 3"

Minimum Dice for AC-PC (0.7987) computed between Tracer 2 and Tracer 3, and corresponding to Subject 9, Left

hippo.

"Movie 4"

Maximum Dice for AC-PC (0.8908) computed between Tracer 2 and Tracer 3, and corresponding to Subject 3, Right

hippo.

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Image orientation: NEW DATA (II) ABOUT THE QUESTIONNAIRE


so far



Image orientation: NEW DATA (II)

Why does the AC-PC orientation lead to better agreement than the hippo axis, despite theoretically greater partial

volume effect?

We propose that this may be due to the better visualization on the AC-PC line of the CSF separating the posterior

amygdala from the head of the hippocampus. This can be appreciated on axial slices with the 3D navigation tool

(MultiTracer) that we used for segmentation, as illustrated in this Figure

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Summary ABOUT THE QUESTIONNAIRE


so far




Summary

the decision of the Delphi panel to use the Hippocampal axis orientation for Harmonized Protocol

may invalidate the whole process

new data collected on hippocampal segmentations carried out on both AC-PC and hippocampal axis show

better spatial agreement in AC-PC orientation

a greater amount of information regarding the separation of the caudal amygdala from the

hippocampal head on the axial plane might be the source for better spatial agreement in the AC-PC

orientation

an advantage of AC-PC may also consist in greater availability of algorithms for automatic alignment.

The proposed solution in the light of these new considerations is that the AC-PC orientation

should be maintained for the Harmonized Protocol.

We ask your level of agreement with this solution.

If you do not agree with the above solution (Lickert values <5), please provide an alternative that will support the

hippo axis orientation choice in the reviewing process of the paper, without re-running the whole process.

Proposed alternatives will be submitted to the Steering Committee of the project (GB Frisoni, CR Jack, S

Duchesne), who will take a final decision.

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Agree on maintaining AC-PC

After reviewing the newly presented evidence, please

indicate your level of agreement with maintaining the

AC-PC orientation (1=minimum agreement, 9=maximum

agreement).

1 2 3 4 5 6 7 8 9

If your level of agreement is below 5, please provide

alternative solutions. These will be submitted to the

Steering Committee, that will take the final decision.

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ABOUT THE QUESTIONNAIRE


so far




Summary

QUESTION: Agree on maintaining AC-PC

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so far




Summary


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Any further comments?

Please feel free to write any other comments here.You can skip this step by clicking "Final Submission".

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so far




Summary


Further comments

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daniele


Image orientation

Question: After reviewing the newly presented evidence, please indicate your level of agreement with

maintaining the AC-PC orientation (1=minimum agreement, 9=maximum agreement).

Agreement: 9

Eventual alternative

solution:

None

If you click SUBMIT, you will not be able to change your answers anymore. Please click only if you are sure.

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Delphi Panel Questionnaire

welcome to the delphi panel questionnaire fifth round · welcome to the delphi panel questionnaire...

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