Evaluation of 4D-CT Lung Registration

Non-rigid registration accuracy assessment is typically performed by evaluating the target registration error at manually placed landmarks. For 4D-CT lung data, we compare two sets of landmark distributions: a smaller set primarily defined on vessel bifurcations as commonly, described in the literature and a larger set being well-distributed throughout the lung volume. For six different, registration schemes (three in-house schemes and three schemes frequently used by the community) the landmark error is evaluated and found to depend significantly oil the distribution of the landmarks. In particular, lung regions near to the pleura, show a target registration error three times larger lung near-mediastinal regions. While the inter-method variability oil the landmark positions is rather small, the methods show discriminating differences with respect to consistency and local volume Change. In conclusion, both a. well-distributed set of landmarks and a deformation vector field analysis are necessary For reliable non-rigid registration accuracy assessment.