Landmark‐Based Shape Analysis of the Brain: An Error Study

Abstract

Neuroanatomic phenotypes are often assessed using volumetric analysis. Although powerful and versatile, this approach is unable to 1) determine whether changes in size are global or local, 2) quantify changes in shape, or 3) describe how regions are interrelated. Statistical shape analysis is the preferred method for testing these aspects of phenotype. Coordinate data from biologically relevant landmarks are one commonly used way to quantify “shape” of an object. To date, approximately fifty landmarks have been used to study brain shape. Of the studies that used landmark‐based statistical shape analysis on the brain, most have not published the protocols they used for landmark identification or the results of reliability studies on these landmarks. The primary aims of this study were two‐fold: (1) to collaboratively develop detailed protocols for a set of brain landmarks, and (2) to complete an inter‐observer (n = 4) validation study of the set of landmarks on 10 MR scans of three trials each. Detailed protocols were developed for 29 cortical and subcortical landmarks. MANOVA revealed that this set of landmarks was able to accurately distinguish between individuals (p < 0.01). Precision varied between 0.71 – 6.50 mm. This was the first study to quantitatively assess landmarks for use in statistical shape analysis of the brain and documents the utility of landmark data for studies of neuroanatomic phenotypes.Grant Funding Source: NIDCR 1F31DE021302‐01