(a) A typical image slice from a 3D MR data set of the left ankle joint of a healthy volunteer at one position. Boundary of the talus delineated by using the live-wire is illustrated on the image. (b) An image slice of the same ankle joint scanned at another position. The 3D data set of (a) was registered with the 3D data set of (b) by using Mutual Information, and the intersection of the talus, delineated from the 3D data set of (a), with the current image slice of (b), is depicted after registration. The mismatch in identifying the talus is clear. (c) Location of the talus bone in the 3D data set of (b) by using the proposed rigid-model based approach.
Slice of an MRI scene of the ankle joint and the live wire segment displayed between two pairs of points (b) to , and (c) to . The four bones that come close together and their boundaries are shown in (a) for reference.
(a) One slice of an MRI scene of an ankle in Position 2 with the corresponding slice of a segmented binary scene , obtained from of the same ankle in Position 1 per Step S2, and overlaid on . (b) The same slice of as in (a) with the corresponding slice of , obtained after registration as per Step S3, and overlaid on . The bone of interest is the talus.
A 3D rendition of a cervical (and part of thoracic) spine in (a) Position 1 (neutral) and (b) Position 2 (45° of head-neck flexion) obtained from CT scenes and . The insets show closeup views with landmarks indicated on the first cervical vertebra. (c) and (d) are identical to those in Figs. 3(a) and 3(b) but correspond to the CT example of (a) and (b).
(a) Talus in Position 1, segmented by using the live wire method, overlaid on the corresponding slice of an input scene . (b) Segmented talus from Position 1 overlaid on the same numbered slice of the scene in Position 2. (c) Talus in Position 2, segmented by using the model-based method, overlaid on the corresponding slice of . (d)–(f) Similar to (a)–(c) but for a CT scene and for the first cervical vertebra.
(a) Three-dimensional display of talus, calcaneus, tibia, and fibula which were segmented by using live wire from a scene corresponding to Position 1. (b) The same bones segmented by using the model-based method from a scene corresponding to Position 2 of the same foot. (c), (d) Cervical vertebrae C1–C7 segmented from scene in Position 1 by manual interaction (c) and in Position 2 by model-based method (d).
(a) Talus surface segmented by using the live wire method with its principal axes in Position 1 overlaid on the talus surface in Position 2, both segmented by using the live wire method. (b) Talus surface segmented by using the model-based method with its principal axes for Position 2 and the principal axes for the surface in the same position obtained by using the live wire method. (c), (d) Similar to (a) and (b) but for the first cervical vertebra of a cadaveric body. Note that in (b) and (d) only the segmented surface is displayed.
The mean and standard deviation of precision measures estimated from 20 scenes for two bones of the foot, and for two vertebrae of the spine.
Mean and standard deviation of , , distance between geometric centroids, and the angle between the major principal axes for talus, calcaneus, C1 and C3 achieved by the model-based method.
Mean operator time and computational time (in minutes) for the talus, calcaneus, C1, and C3 in the two application areas.
Article metrics loading...
Full text loading...