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Feasibility of automated matching of supine and prone CT-colonography examinations

¹ Department of Radiology, Academic Medical Center, Amsterdam, ² Philips Medical Systems, Best, The Netherlands

View larger version (8K): [in a new window]   Figure 1. The performance of the algorithm was calculated by measuring the distance from the actual polyp location in supine position to the calculated(expected) polyp position in prone position after the match was made. (A, match error).

View larger version (124K): [in a new window]   Figure 2. User interface panel shows both the supine and prone dataset in an unfolded three-dimensional rendering, in a two-dimensional axial rendering and in a volume rendered overview of the colon. On the left the supine position was displayed, on the right the prone position. Interactive navigation along the pre-calculated centre-line was possible. This panel shows a calculated match. In this example a match error of 27 mm was measured and the corresponding polyp was immediately visible (category I). This match error must not be confused with the difference in "distance along path". The matching was evaluated with the use of a colonoscopically proven polyp (arrow) (Prototype based on EasyVision; Philips Medical Systems, Best, The Netherlands).

View larger version (5K): [in a new window]   Figure 3. (a) The absolute match error of the method based on the maximal alignment of the centre-line plotted against the relative location of a polyp along the centre-line in supine position. The 0 on the x-axis corresponds to caecum and 1 to rectum. (b) The absolute match error of the NDAC method plotted against the relative location of a polyp along the centre-line in supine position. The 0 on the x-axis corresponds to caecum and 1 to rectum. The three circled arrows indicate polyps from three different patients with a relatively large absolute match error.