AAN –Toronto, April 11, 2010 Development of a harmonized protocol for hippocampal tracing An EADC-ADNI joint effort METHODS

Operationalization of protocols’ differences and extraction of tracing units Quantification of tracing units’ features Harmonized protocol METHODS

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

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 OPERATIONALIZATION Protocols’ features extraction

Tracings carried out on a control and an AD subject from the ADNI dataset Tracings sent to the Authors for correction or approval OPERATIONALIZATION Prototypical tracings

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

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 Sagittal view 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?

For each protocol: features extraction, tracing and author’s certification AD CTRL X 10 OPERATIONALIZATION Authors’ check

OPERATIONALIZATION Extraction of similarities and differences Harmonized language Reduction of redundancy Tracing units and subunits

OPERATIONALIZATION Extraction of similarities and differences

Plane of tracing Axis of hippocampus [B,C,J,L,S] AC-PC line [H,K,M,Pa,Pr] Most posterior slice Where inferior and superior colliculi are jointly visualized [B] Where crus of fornix is visible in full profile [C,K,L] Where the crura of the fornices are seen in full profile on both sides [J,S] Where gray matter is visible inferomedially to the trigone of the lateral ventricle [H,M,Pa,Pr] Superior border Lower border of alveus/fimbria [B,H,K,Pa,S] Upper border of alveus/fimbria [C,J,L,M,Pr] Horizontal line from the superior border of the quadrigeminal cistern to the lateral ventricle (tail) [Pr] Separation subiculum/enthorinal cortex vertical line from the CA to the WM of the parahippocampal gyrus [C] 45° line connecting the most inferior part of the subiculum medially to the cistern (head and body) [Pr] Oblique line with same inclination of parahippocampal WM, connecting the inferior part of the subiculum to the quadrigeminal cistern [K,L,M ¥ ] Orizontal line from the highest medial point of the parahippocampal WM to the cistern [B,H,J ¥ ] Line outlining the contour of white matter of parahippocampal gyrus [Pa,S]

Operationalization of protocols’ differences Quantification of tracing units’ features Harmonized protocol METHODS

Contribution to hippo volume in control and AD Effect on re-test variability Contribution to differences between AD and controls QUANTIFICATION OF TRACING UNITS’ FEATURES

Operationalization of protocols’ differences Quantification of tracing units’ features Harmonized protocol METHODS

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 HARMONIZED PROTOCOL

Validation with neuropathological data Comparison with currently used protocols Public tracings and probability maps Standard environment for tracing, learning, and certification HARMONIZED PROTOCOL Validation & implementation