Published in:
01-03-2012 | Computer Applications
A grid overlay framework for analysis of medical images and its application to the measurement of stroke lesions
Published in: European Radiology | Issue 3/2012
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Objectives
To create and evaluate an interactive software tool for measuring imaging data in situations where hand-drawn region-of-interest measurements are unfeasible, for example, when the structure of interest is patchy with ill-defined boundaries.
Methods
An interactive grid overlay software tool was implemented that enabled coding of voxels dependent on their imaging appearance with a series of user-defined classes. The Grid Analysis Tool (GAT) was designed to automatically extract quantitative imaging data, grouping the results by tissue class. Inter- and intra-observer reproducibility was evaluated by six observers of various backgrounds in a study of acute stroke patients.
Results
The software tool enabled a more detailed classification of the stroke lesion than would be possible with a region-of-interest approach. However, inter-observer coefficients of variation (CVs) were relatively high, reaching 70% in “possibly abnormal” tissue and around 15–20% in normal appearing tissues, while intra-observer CVs were no more than 13% in “possibly abnormal” tissue and generally less than 1% in normal-appearing tissues.
Conclusions
The grid-overlay method overcomes some of the limitations of conventional Region Of Interest (ROI) approaches, providing a viable alternative for segmenting patchy lesions with ill-defined boundaries, but care is required to ensure acceptable reproducibility if the method is applied by multiple observers.
Key Points
• Computer software developed to overcome limitations of conventional regions of interest measurements
• This software is suitable for patchy lesions with ill-defined borders
• Allows a more detailed assessment of imaging data