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AAN –Toronto, April 11, 2010. Development of a harmonized protocol for hippocampal tracing An EADC-ADNI joint effort METHODS. METHODS. Operationalization of protocols’ differences and extraction of tracing units Quantification of tracing units’ features Harmonized protocol.

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slide1

AAN –Toronto, April 11, 2010

Development of a harmonized protocol for hippocampal tracing An EADC-ADNI joint effortMETHODS

slide2

METHODS

Operationalization of protocols’ differences and extraction of tracing units

Quantification of tracing units’ features

Harmonized protocol

slide3

OPERATIONALIZATION

Selection of segmentation protocols

  • Selection criteria
  • Being based on 3D T1 MRI with field strength greater than 1 Tesla
  • Providing explicit description of landmarks for tracing of hippocampal borders
  • Being validated on AD/MCI samples, or being widely adopted in the literature about AD.
slide4

OPERATIONALIZATION

Protocols’ features extraction

Plane of tracing: AC-PC line; Normalization to the Talairach space

Tracing start from the tail of hippocampus to the hippocampal head

In the following slices, you can find the hippocampal tracing on consecutive coronal slices (1.5T) of the control

subject and AD patient according to Pruessner's criteria

slide5

OPERATIONALIZATION

Prototypical tracings

Tracings carried out on a control and an

AD subject from the ADNI dataset

Tracings sent to the Authors for correction or approval

slide6

CTRL

Most posterior slice : slice where an ovoid mass of gray matter (1) started to appear inferomedially of the atrium of lateral ventricle (2)

2= Atrium of lateral ventricle

4= Parahippocampal gyrus

5= Gyrus dentatus

6= Cornu Ammonis

7= Gyrus fasciolaris

8= Gyrus of Andreas-Retzius

9= Isthmus

The fornix can be excluded by a horizontal line (in fuchsia) from the superior border of the quadrigeminal cistern (3) to the lateral ventricle (2).

Part of gyrus fasciolaris (7) and of Andreas-Retzius gyrus (8) can be excluded by a vertical line (in red) from the medial end of the lateral ventricle (2) down to the parahippocampal gyrus (4).

Sagittal

view

slide7

AD

Most posterior slice : slice where an ovoid mass of gray matter (1) started to appear inferomedially of the atrium of lateral ventricle (2)

2= Atrium of lateral ventricle

4= Parahippocampal gyrus

5= Gyrus dentatus

6= Cornu Ammonis

7= Gyrus fasciolaris

8= Gyrus of Andreas Retzius

9= Isthmus

In AD subjects the cerebral structures are atrophic, lateral

ventricle (2) and ambient cistern (3) result enlarged. Therefore,

the lines used to exclude the gyrus fasciolaris, the Andreas-

Retzius gyrus and the fornix do not intersect the hippocampal

tail. That being so, is there another way to exclude the gyrus

fasciolaris, the Andreas-Retzius gyrus and the fornix in these

subjects?

Sagittal

view

slide8

OPERATIONALIZATION

Authors’ check

For each protocol:

features extraction, tracing and author’s certification

CTRL

X 10

AD

slide9

OPERATIONALIZATION

Extraction of similarities and differences

Harmonized language

Reduction of redundancy

Tracing units and subunits

slide10

OPERATIONALIZATION

Extraction of similarities and differences

slide14

METHODS

Operationalization of protocols’ differences

Quantification of tracing units’ features

Harmonized protocol

slide15

QUANTIFICATION OF TRACING UNITS’ FEATURES

Contribution to hippo volume in control and AD

Effect on re-test variability

Contribution to differences between AD and controls

slide16

METHODS

Operationalization of protocols’ differences

Quantification of tracing units’ features

Harmonized protocol

slide17

HARMONIZED PROTOCOL

Participants to a Delphi panel based on:

expertise in hippocampal anatomy

manual tracing scientific production

Assisted decisions based on:

Low variability, highly informative.. ..included in harmonized protocol

High variability, little informative.. ..excluded from harmonized prot

slide18

HARMONIZED PROTOCOL

Validation & implementation

Validation with neuropathological data

Comparison with currently used protocols

Public tracings and probability maps

Standard environment for tracing, learning, and certification