Perfusion Paths: Inference of Voxelwise Blood Flow Trajectories in CT Perfusion
In CT perfusion imaging (CTP) multiple, consecutive 3D CT scans of an organ are made during the administration of contrast agent. This results in a 3D movie of the contrast agent entering and subsequently leaving the organ. Currently, this modality is mai
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iMinds - Medical Image Computing (ESAT/PSI), KU Leuven, Belgium Department of Radiology, University Hospitals Leuven, KU Leuven, Belgium Department of Neurology, University Hospitals Leuven, KU Leuven, Belgium
Abstract. In CT perfusion imaging (CTP) multiple, consecutive 3D CT scans of an organ are made during the administration of contrast agent. This results in a 3D movie of the contrast agent entering and subsequently leaving the organ. Currently, this modality is mainly used for voxelwise analysis of perfusion parameters such as blood flow, blood volume, transit time etc. In this work, we propose to analyze these images in a more global fashion and introduce a method to infer the connectivity of the vascular structure underlying the perfusion – even if the vasculature itself is on a subvoxel scale. This novel approach enables several new applications for CTP. The feasibility of the method is illustrated on clinical data.
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Introduction
The vascular system plays a crucial function in our body, permitting blood to circulate from the heart, through arteries and arterioles to the capillary bed, and through venules and veins back to the heart. In the capillary bed, perfusion takes places: the process of exchanging nutrients, oxygen, waste, etc. with the surrounding cells. Perfusion is essential for the function and survival of living tissue and hence there is vasculature virtually everywhere in the body. Traditional vascular imaging modalities, such as CT angiography (CTA) and MR angiography (MRA), have a limited imaging resolution. In the resulting image, the vascular structure is sparse and most voxels will be considered non-vessel, while in reality they do contain (micro)vasculature. In CT perfusion imaging (CTP) multiple, consecutive 3D CT scans of an organ are made during the intravenous administration of a iodine contrast agent bolus. Each scan is a volumetric image, showing for every voxel the X-ray attenuation coefficient in Hounsfield units (HU). The result is a 3D movie of the contrast agent entering and subsequently leaving the organ. Alternatively, it can be considered as a 3D image with in every voxel a time series of the HU variation due to the local contrast passage. Subtracting the first image, which is made
David Robben is supported by a Ph.D. fellowship of the Research Foundation Flanders (FWO).
c Springer International Publishing Switzerland 2015 N. Navab et al. (Eds.): MICCAI 2015, Part II, LNCS 9350, pp. 407–414, 2015. DOI: 10.1007/978-3-319-24571-3_49
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Fig. 1. Illustration of a cerebral CT perfusion. Left: axial slice of a cerebral CTP during the late arterial phase. The red, blue and green markers are located in respectively an artery, a vein and the grey matter. Right: time series in the markers.
before the contrast agent enters the organ, from the subsequent ones results in difference images that show the increase in HU due to the contrast agent. An illustration of a cerebral CTP image is given in Fig. 1. This modality is very information rich and useful in
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