The Role of High Frequency Ultrasound in Multimodality Small Animal Imaging for Cancer Research

Small-animal models are extensively used in disease research, genomics research, drug development, and developmental biology. The development of noninvasive small-animal imaging techniques with adequate spatial resolution and sensitivity is therefore of prime important. In particular, multimodality small-animal imaging can provide complementary information. This paper presents the role of high frequency ultrasound (microUS) in multimodality small animal imaging for cancer research and some new trends to implement microUS and small-animal positron-emission tomography (microPET) multimodality small animal imaging. The new trends of combining these two imaging systems were extended to perform other imaging systems. Firstly, registration of microUS/microPET is performed using a three-dimensional registration method. In addition, microUS was combined with microPET for tumor progressive assessment. MicroUS provides anatomical information which can be used for tumor volume measurements while microPET is a functional imaging method with positron-emitting radiophamaceuticals, such as F-18-labeled deoxyglucose, [F-18] FDG. To investigate the feasibility of the functional information provided from microUS, the contrast enhanced ultrasound (CEUS) technique is an alternative way to characterize three vascular contrast phases of liver focal lesions in a small animal. Finally, a new technique, ensemble empirical mode decomposition (EEMD), was used for CEUS imaging improvement. Most of primary applications of the proposed methods are applied in cancer research on small-animal models. The multimodality approach represents an effective tool for both drug development and cancer research.