We introduce a framework for the detection of the brain boundary (arachnoid
) within sparse MRI. We use the term sparse to describe volumetric images i
n which the sampling resolution within the imaging plane is far higher than
that of the perpendicular direction. Generic boundary detection schemes do
not provide good results for such data. In the scheme we propose, the boun
dary is extracted using a constrained mesh surface which iteratively approx
imates a 3D point set consisting of detected boundary points. Boundary dete
ction is based on a database of piecewise constant models, which represent
the idealised MR intensity profile of the underlying boundary anatomy. A no
n-linear matching scheme is introduced to estimate the location of the boun
dary points using only the intensity data within each image plane. Results
are shown for a number of images and are discussed in detail. (C) 2000 Else
vier Science B.V. All rights reserved.