MICRO-CT-BASED PERFUSION IMAGING IN SMALL ANIMALS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. In vivo measurements of perfusion presents a challenge to existing small animal imaging techniques such as magnetic resonance microscopy (MRM), microCT, microPET, and microSPECT, due to combined requirements for high spatial and temporal resolution. In Micro-CT perfusion to these requirements are added the radiation dose restrictions. In sampling, we have addressed these issues by using a dual source/detector Micro-CT system, and the novel paradigm that the same time density curves can be reproduced in a number of consecutive injections of ¿L volumes of contrast at a series of different angles of rotation. The high temporal resolution requirements and total volume of contrast agent used imposes undersampling which complicates the reconstruction process, since it causes significant streaking artifacts. We demonstrate an approach using a combined static micro-CT set with dynamic but angularly undersampled acquisitions. We provide an iterative reconstruction solution that uses the well sampled static micro-CT set as a prior. A sparseness prior regularized weighted l2 norm optimization is proposed to mitigate streaking artifacts based on the fact that most medical images are compressible. A prior Total Variation (TV) is implemented in this work as the regularizer for its simplicity.