13 NovSfN 2016 Poster

Anatomical evaluation of Colin 27 against a database of labeled brain scans

Andrew Worth¹, Jason Tourville²

¹ Neuromorphometrics, Inc., Somerville, MA
² Dept. of Speech, Language, and Hearing Sciences, Boston University, Boston, MA

Abstract (download poster, 7.8MB)

The Colin 27 average brain is a stereotaxic registration model from the Montreal Neurological Institute (see Holmes et al. 1998).  This T1 weighted MRI scan has very high signal-to-noise ratio and as a result shows fine anatomical details.  Because it is of such high quality and is readily available, it is often used in research (e.g. Strangman et al. 2013).  While this is a very valuable resource, it is a representation of the anatomy of a single individual.  It may be tempting to use this model as a template to represent a generic brain, but before doing that it is important to understand how it compares with other brains.  Following Ono et al. 1990, we present a quantitative comparison of both topology and topography of the cortical anatomy of the Colin 27 scan against our database of labeled MRI brain scans.

The famous Colin 27 scan was obtained from a 27 year old individual who was scanned 27 times over a period of 3 months.  Individual MRI brain scans were automatically registered to a common space in which they were subsampled and intensity averaged.  To understand the anatomy in detail, every voxel of the brain was given a neuroanatomical label: 72 regions comprehensively covered the brain including: cerebral and cerebellar gray and white matter, ventricles, brain stem, accumbens, amygdala, caudate, hippocampus, pallidum, putamen, and thalamus according to the “General Segmentation” protocol defined by the MGH Center for Morphometric Analysis, and the cortex was parcellated into 51 units based on 36 sulci according to the BrainColor protocol.  After the initial labeling, an anatomist with years of labeling experience checked all results and the technician made corrections as necessary.

We compared the Colin 27 scan with similarly labeled scans of 113 subjects using methods described in the Ono atlas, which gives common topographic variants of cortical anatomy and reports the incidence rate of each variant.  Quantitative measures include sulcus position, replication, interruptions, side branching, and connections to other sulci.  Position with respect to other sulci is used to identify common patterns of local sulcal topography.

The resulting images, plots, and statistics show which regions in the Colin 27 template are anatomically similar to their counterparts in the larger group and those regions that are not. In particular, we noted atypical sulcal topography in, and around, Broca’s area in Colin 27 relative to the larger population. Our results demonstrate a high degree of local variability in cortical anatomy. We conclude that templates derived from individual subjects are insufficient for accurately identifying and/or localizing a specific brain region.

References

Holmes CJ, Hoge R, Collins DL, Woods R, Toga AW, Evans AC. “Enhancement of MR images using registration for signal averaging.” J Comput Assist Tomogr. 1998 Mar-Apr;22(2):324–33.

Strangman GE, Li Z, Zhang Q. “Depth sensitivity and source-detector separations for near infrared spectroscopy based on the Colin27 brain template.” PLoS One. 2013 Aug 1;8(8)

M. Ono, S. Kubik and C. Abernathey (1990). Atlas of the cerebral sulci. G. Thieme Verlag, Stuttgart, Germany