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Session: Poster session II
Session starts: Thursday 24 January, 16:00

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Astrid Moerman ()
Suze-Anne Korteland ()
Stefan Klein ()
Kim van Gaalen ()
Kristina Dilba ()
Dirk Poot ()
Aad van de Lugt ()
Ellen Rouwet ()
Jolanda Wentzel ()
Anton van der Steen ()
Frank Gijsen ()
Kim van der Heiden ()

Abstract:
Wall shear stress (WSS), the frictional force exerted on endothelial cells by blood flow, is hypothesized to influence atherosclerotic plaque growth and composition. We developed a pipeline for image registration of MR and histology images of advanced human carotid plaques and corresponding WSS data. The pipeline required four types of input images, in vivo MRI, ex vivo MRI, photographs of transversal sectioned plaque tissue (en face images) and histology images. These images are transformed to a shared 3D space by applying a combination of rigid and non-rigid registration algorithms. Transformation matrices obtained from registration of these images were used to transform subject-specific WSS data to the shared 3D space as well (see figure). WSS values originating from the 3D WSS map were projected in 2D on the corresponding lumen locations in the histological sections and divided into eight radial segments. In each radial segment, the correlation between WSS values and histological parameter could be assessed. The pipeline was successfully applied to two carotid endarterectomy specimen. The resulting matched contours from the histology and WSS data were well aligned with a Hounsfield distance between 0.55 and 0.75 mm, which is below the in vivo MRI resolution. We investigated the robustness of the image registration pipeline by relocating the WSS data with respect to the stack of histology images, simulating the effect of a mismatch in the rigid registration of imaging modalities on WSS results for 184 segments. This relocation altered the mean WSS values projected on radial bins by 0.2 Pa, compared to the output of optimal registration. Moreover, a mismatch of one image slices changed correlation coefficient between WSS and plaque thickness by l0%, and never lead to a change in sign of the correlation. We conclude that the created pipeline offers the unique opportunity to robustly and quantitatively determine whether correlations between WSS and plaque composition exist.