Development and evaluation of a high performance T1‐weighted brain template for use in studies on older adults

Abstract

Τhe accuracy of template‐based neuroimaging investigations depends on the template's image quality and representativeness of the individuals under study. Yet a thorough, quantitative investigation of how available standardized and study‐specific T1‐weighted templates perform in studies on older adults has not been conducted. The purpose of this work was to construct a high‐quality standardized T1‐weighted template specifically designed for the older adult brain, and systematically compare the new template to several other standardized and study‐specific templates in terms of image quality, performance in spatial normalization of older adult data and detection of small inter‐group morphometric differences, and representativeness of the older adult brain. The new template was constructed with state‐of‐the‐art spatial normalization of high‐quality data from 222 older adults. It was shown that the new template (a) exhibited high image sharpness, (b) provided higher inter‐subject spatial normalization accuracy and (c) allowed detection of smaller inter‐group morphometric differences compared to other standardized templates, (d) had similar performance to that of study‐specific templates constructed with the same methodology, and (e) was highly representative of the older adult brain.

Development and evaluation of a high resolution 0.5mm isotropic T1-weighted template of the older adult brain

“…The approach used in this work for high resolution template construction combined a widely used iterative image registration process ( Fonov et al, 2011 ; Guimond et al, 2000 ; Joshi et al, 2004 ; Ridwan et al, 2021 ) and concepts of multiple image super resolution. The entire process can be divided into 6 steps.…”

“…The entire process can be divided into 6 steps. Steps 1-3 generally followed the method described in Ridwan et al with modifications ( Ridwan et al, 2021 ), and steps 4-6 included the super resolution portion of template construction.…”

“…The preprocessed images from Dataset 1 were rigidly registered to the previously constructed T1w template of the MIITRA atlas ( Ridwan et al, 2021 ) referred to as MIITRA_1mm in this work ( Fig. 1 ) (the MIITRA_1mm template space was up-sampled to 0.5×0.5×0.5mm 3 voxels using linear interpolation prior to performing the rigid registrations).…”

“…The Gaussian weighted averaging approach of Step 1 was applied to the warped images to generate a new initial template. Using this new initial template as reference, Step 2 was repeated iteratively until the Pearson cross correlation (PCC) between two templates of consecutive iterations was greater than 0.9995 ( Ridwan et al, 2021 ). Convergence was reached after 9 iterations.…”

“…Template-based studies in older adults require templates that are representative of the features of the aging brain (Dickie et al, 2016a, 2016b; Lemaître et al, 2005 ; Matsumae et al, 1996 ; Sullivan et al, 1995 ; Ridwan et al, 2021 ) and use of templates constructed from younger or middle-aged adult data can negatively impact the accuracy of investigations in older adults ( Ridwan et al, 2021 ; Van Hecke et al, 2011 ; Zhang and Arfanakis, 2018 ). To date, the publicly available library of standardized T1w brain templates includes only few that were constructed exclusively from older adult data, and several that combined data from young adults, middle-aged individuals and older adults ( Ridwan et al, 2021 ). The dedicated older adult templates as well as most other templates have a voxel size of 1×1×1mm 3 or larger.…”