Co-Registration of Optoacoustic Tomography and Magnetic Resonance Imaging Data from Murine Tumour Models

As optoacoustic tomography emerges as a mainstream preclinical imaging modality, understanding the relationship between optoacoustic and other imaging biomarkers in the context of the underlying tissue biology becomes vitally important. For example, assessment of blood haemoglobin concentration and oxygenation can be achieved using OT, and also by several magnetic resonance imaging (MRI)-based techniques. To evaluate the relationship between these metrics and the relative performance of the two modalities in assessment of haemoglobin physiology, co-registration of their output imaging data is required. Unfortunately, this poses a significant challenge due to differences in the data acquisition geometries. Here, we present an integrated framework for registration of OT and MR image data in small animals. Our framework combines a novel MR animal holder, to improve animal positioning for deformable tissues, and a landmark-based software co-registration algorithm. We demonstrate that our protocol significantly improves registration of both body and tumour contours between these modalities.