A Method to Construct Flat Maps of the Brain's Surface and its Application.
ABSTRACT This paper describes a surface flattening technique, which has been developed in particular to obtain a complete view of the cortical surface of the brain. However, the method is able to produce an overall planar view of any anatomical or real-life object, provided it is topologically compatible with the sphere (i.e. genus 0). It computes the shading of the original surface for rays casted from a nearby surrounding surface and unfolds this surface in a 2D plane, without introducing major distortions. The flat image consisting of the mapped shading results has the advantage that the sulci (i.e. the grooves characterizing the superficial brain geometry) of the cortical surface of the brain can be followed in their entirety, which facilitates the study and the recognition of their patterns. The new visualization method is integrated into a versatile medical image analysis environment. A first study to assess its usefulness has been accomplished and is also reported in this paper.
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ABSTRACT: Since dual energy X-ray absorptiometry (DXA) cannot distinguish between different adipose tissue (AT) deposits, it remains unclear how DXA-derived body composition variables relate to anatomical tissue (sub)compartments. The aim of the present study was to compare and relate regional DXA variables with absolute tissue masses obtained by computer tomography (CT) scanning of the lower limbs in elderly persons. Eleven well-preserved white Caucasian adults (seven male and four female cadavers) with a median age of 79.0 years (ranging from 68 to 96 years) were fully scanned with DXA and CT. Separate densities of skin tissue, AT, muscle tissue and bone were obtained by hydrostatic weighing. The leg DXA-variables were significantly related (rho-values between 0.60 and 0.98, P<0.01) to CT-derived tissue counterparts, but showed significant systematic differences except for subcutaneous AT mass (P=0.773). After controlling for other AT depots, fat as measured by DXA (fatDXA) related only to intermuscular AT (rho=0.82, P<0.01) in males and to subcutaneous AT (rho=0.84, P<0.05) in females. Although significantly interrelated, DXA and CT variables should not be used interchangeably since they have different quantitative and physiological significance. Our results suggest that fatDXA represents different parts of AT depots in elderly men and women. Since DXA is not appropriate for assessing tissue variability cautious clinical interpretation is warranted.Experimental gerontology 07/2013; 48(9). DOI:10.1016/j.exger.2013.07.005 · 3.34 Impact Factor