The EADC‐ADNI Harmonized Protocol for manual hippocampal segmentation on magnetic resonance: Evidence of validity

Abstract

Background An international Delphi panel has defined a harmonized protocol (HarP) for the manual segmentation of the hippocampus on MR. The aim of this study is to study the concurrent validity of the HarP toward local protocols, and its major sources of variance. Methods Fourteen tracers segmented 10 Alzheimer's Disease Neuroimaging Initiative (ADNI) cases scanned at 1.5 T and 3T following local protocols, qualified for segmentation based on the HarP through a standard web-platform and resegmented following the HarP. The five most accurate tracers followed the HarP to segment 15 ADNI cases acquired at three time points on both 1.5 T and 3T. Results The agreement among tracers was relatively low with the local protocols (absolute left/right ICC 0.44/0.43) and much higher with the HarP (absolute left/right ICC 0.88/0.89). On the larger set of 15 cases, the HarP agreement within (left/right ICC range: 0.94/0.95 to 0.99/0.99) and among tracers (left/right ICC range: 0.89/0.90) was very high. The volume variance due to different tracers was 0.9% of the total, comparing favorably to variance due to scanner manufacturer (1.2), atrophy rates (3.5), hemispheric asymmetry (3.7), field strength (4.4), and significantly smaller than the variance due to atrophy (33.5%, P < .001), and physiological variability (49.2%, P < .001). Conclusions The HarP has high measurement stability compared with local segmentation protocols, and good reproducibility within and among human tracers. Hippocampi segmented with the HarP can be used as a reference for the qualification of human tracers and automated segmentation algorithms.

Relationship Between Hippocampal Volume, Serum BDNF, and Depression Severity Following Electroconvulsive Therapy in Late-Life Depression

“…Manual editing was performed using ITK-SNAP version 2.4 (http://www.itksnap.org/pmwiki/pmwiki.php) in accordance with the HarP guidelines (Frisoni et al, 2015). Hippocampal volumes were normalized using the following equation (Jack Jr. et al, 1989): normalized hippocampal volume = original hippocampal volume (OHV) − linear regression coefficient × (total intracranial volume (TIV) − mean total intracranial volume).…”

Optic Radiations Microstructural Changes in Glaucoma and Association With Severity: A Study Using 3Tesla-Magnetic Resonance Diffusion Tensor Imaging

“…34 Hippocampus was segmented using a patch-based multitemplate approach 35 following the international consortium from the European Alzheimer's Disease Consortium-Alzheimer's Disease Neuroimaging Initiative Harmonized Protocol for anatomical definitions of the hippocampus. 36 To control variations in head size between subjects, total brain volumes and hippocampal volumes were scaled using the volumetric scaling factor determined through the affine registration to the MNI brain template.…”

Hippocampal Subfield Atrophy in Multi-Domain but Not Amnestic Mild Cognitive Impairment

“…Hence, choosing subregions of interest, we only included the larger structures with the best Dice overlap measures with manual delineation [50]. An extensive effort to harmonize a manual protocol for HP segmentation has just been validated by European Alzheimer's Disease Consortium-Alzheimer's Disease Neuroimaging Initiative (EADC-ADNI) [56]; however, further validation studies and developments to improve automated HP segmentation are needed [50,53]. The patients and controls in the present study were considerably younger than in most other MCI HP subfield studies [19,20,21,57]; the effect of age on brain structure integrity may represent a confounder with respect to the direct comparison of results.…”