A grid overlay framework for analysis of medical images and its application to the measurement of stroke lesions

Paul A. Armitage*, C. S. Rivers, B. Karaszewski, R. G. R. Thomas, G. K. Lymer, Z. Morris, J. M. Wardlaw

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)625-632
Number of pages8
JournalEuropean Radiology
Volume22
Issue number3
DOIs
Publication statusPublished - Mar 2012

Keywords

  • MISMATCH
  • WHITE-MATTER
  • CEREBRAL-BLOOD-FLOW
  • TISSUE
  • ACUTE ISCHEMIC-STROKE
  • SEGMENTATION
  • PERFUSION
  • DIFFUSION TENSOR
  • Tissue segmentation
  • Region-of-interest
  • Volume measurement
  • MRI
  • BRAIN
  • Grid overlay
  • MRI DATA

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