Object strength--an accurate measure for small objects that is insensitive to partial volume effects

Tofts, P. S., Silver, N. C., Barker, G. J. and Gass, A. (2005) Object strength--an accurate measure for small objects that is insensitive to partial volume effects. Magnetic Resonance Materials in Physics, Biology and Medicine, 18 (3). pp. 162-9. ISSN 0968-5243

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Abstract

There are currently four problems in characterising small nonuniform lesions or other objects in Magnetic Resonance images where partial volume effects are significant. Object size is over- or under-estimated; boundaries are often not reproducible; mean object value cannot be measured; and fuzzy borders cannot be accommodated. A new measure, Object Strength, is proposed. This is the sum of all abnormal intensities, above a uniform background value. For a uniform object, this is simply the product of the increase in intensity and the size of the object. Biologically, this could be at least as relevant as existing measures of size or mean intensity. We hypothesise that Object Strength will perform better than traditional area measurements in characterising small objects. In a pilot study, the reproducibility of object strength measurements was investigated using MR images of small multiple sclerosis (MS) lesions. In addition, accuracy was investigated using artificial lesions of known volume (0.3-6.2 ml) and realistic appearance. Reproducibility approached that of area measurements (in 33/90 lesion reports the difference between repeats was less than for area measurements). Total lesion volume was accurate to 0.2%. In conclusion, Object Strength has potential for improved characterisation of small lesions and objects in imaging and possibly spectroscopy.

Item Type: Article
Keywords: Algorithms Artifacts Humans Image Enhancement/ methods Image Interpretation, Computer-Assisted/ methods Imaging, Three-Dimensional/ methods Magnetic Resonance Imaging/ methods Multiple Sclerosis/ diagnosis Reproducibility of Results Sensitivity and Specificity
Schools and Departments: Brighton and Sussex Medical School > Brighton and Sussex Medical School
Depositing User: Paul Stephen Tofts
Date Deposited: 28 Feb 2007
Last Modified: 30 Nov 2012 16:50
URI: http://sro.sussex.ac.uk/id/eprint/806
Google Scholar:1 Citations
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