Adding patient motion from DCE-MRI to anthropomorphic phantoms for dedicated breast CT
M. Mikerov, K. Michielsen, N. Moriakov and I. Sechopoulos.
Extending dedicated breast CT to dynamic contrast-enhanced breast CT will allow functional data by following contrast distribution over multiple time points. As a result of longer scans, unwanted patient motion becomes more likely and motion correction is necessary to avoid artifacts. A crucial part of the development of a motion compensation method is its validation on data with known ground truth. Thus, anthropomorphic phantoms with realistic motion patterns are needed. We present a method to combine motion vector fields, extracted from dynamic contrast-enhanced breast magnetic resonance imaging (DCE-MRI), with digital breast phantoms. DCE-MRI is an ideal source for these data due to its frequent clinical use and a similar prone patient positioning compared to breast CT. Our algorithm consists of three steps. First, the inter-scan motion vector fields are obtained by registration of consecutive images in the DCE-MRI sequence. In the second stage, the digital breast phantoms are aligned on MRI scans using an affine transformation. Finally, the obtained motion vector fields are transformed and applied to the phantoms after parameterization such that the total motion is distributed smoothly in time. The applied motion is evaluated in reconstructions of the simulated breast CT acquisition by qualitative comparison to clinical cases with intra-scan motion. We show that phantoms with simulated motion exhibit the same artifacts as in clinical data such as smooth transitions at the tissue interfaces and ghosting of fine structures.