Cecilie Benedicte Anker MSc, Abstract Co-Author: Nothing to Disclose

Lauge Sorensen, Abstract Co-Author: Research funded, Biomediq A/S

Akshay Pai, Abstract Co-Author: Nothing to Disclose

Mark Lyksborg PhD, MSc, Abstract Co-Author: Nothing to Disclose

Martin Lillholm PhD, Abstract Co-Author: Employee, Biomediq A/S Shareholder, Biomediq A/S

Mads Nielsen PhD, Presenter: Stockholder, Biomediq A/S Research Grant, Nordic Bioscience A/S Research Grant, SYNARC Inc Research Grant, AstraZeneca PLC

Knut Conradsen, Abstract Co-Author: Nothing to Disclose

Rasmus Larsen, Abstract Co-Author: Nothing to Disclose

Hippocampal volumetry is the most widely used structural MRI biomarker of Alzheimer’s disease (AD), and state-of-the-art, automatic hippocampal segmentation can be obtained using longitudinal FreeSurfer. In this study, we compare the diagnostic AD performance of a single time point, multi-atlas method using the Harmonized Hippocampal Protocol (HHP) to FreeSurfer (FS).

Baseline and month 12 MRI scans from the “complete annual year 2 visits” 1.5-T standardized ADNI dataset were used [169 normal controls (NC), 234 mild cognitive impaired (MCI), 101 AD]. A multi-atlas, affine registration, patch-based segmentation method (MRP) using 40 HHP segmentations in the atlas (12 NC, 11 MCI, 17 AD) was applied to segment the hippocampi. Static- and longitudinal FS (v5.1.0, default parameters) were also applied to segment the hippocampi. Atrophy rate calculated as percent volume change from baseline to month 12 was estimated for the three methods, and diagnostic performance was evaluated using the area under the receiver operating characteristic curve (AUC) of pairwise diagnostic group comparisons.

Mean (SD) atrophy rates were as follows (MRP / static FS / longitudinal FS): NC -0.86 (2.46) / -1.39 (5.41) / -1.63 (2.54), MCI -2.38 (3.28) / -3.69 (5.48) / -3.25 (3.53), AD -4.23 (3.07) / -4.29 (5.32) / -4.83 (3.74). Diagnostic performances were as follows (AUC; MRP / static FS / longitudinal FS): NC vs. MCI 0.65 / 0.67 / 0.64, NC vs. AD 0.80 / 0.69 / 0.76, MCI vs. AD 0.66 / 0.53 / 0.62. The MRP AUC was significantly larger (DeLong) than the static FS AUC for NC vs. AD and MCI vs. AD. In the remaining pairwise group comparisons, MRP AUCs did not differ significantly from FS AUCs.    

The MRP method discriminated AD from either NC or MCI significantly better than static FS, and it was as good as longitudinal FS, which exploits information from both time points simultaneously. Moreover, the standard deviation of the atrophy rate was comparable to that of longitudinal FS, emphasizing longitudinal robustness of segmentations of the proposed method. The combination of MRP and HHP is a robust and fast alternative to FreeSurfer, especially in a setting with many time points. 

Unlike longitudinal FS, the MRP method calculates final atrophy estimates after each visit. Adding the comparable performance, the proposed method is a robust alternative for clinical trials. 

Anker, C, Sorensen, L, Pai, A, Lyksborg, M, Lillholm, M, Nielsen, M, Conradsen, K, Larsen, R, Alzheimer’s Disease Diagnostic Performance of a Multi-Atlas Hippocampal Segmentation Method Using the Harmonized Hippocampal Protocol .  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14012721.html