Image Registration for Multimodality Small-Animal Imaging

Abstract

Since the discovery of X-rays, imaging has been a vital component of clinical medicine. Increasingly, in vivo imaging of small laboratory animals, i.e. mice and rats, has emerged as an important component of basic biomedical research as well. Historically, clinical and laboratory imaging modalities have often been divided into two general categories, structural (or anatomical) and functional (or physiological). Anatomical modalities, i.e. depicting primarily morphology, include X-rays (plain radiography), CT (computed tomography), MRI (magnetic resonance imaging), and US (ultrasound). Functional modalities, i.e. depicting primarily information related to underlying genetics and metabolism, include (planar) scintigraphy, SPECT (single-photon emission computed tomography), PET (positron emission tomography), MRS/MRSI (magnetic resonance spectroscopy and spectroscopic imaging), fMRI (functional magnetic resonance imaging), and, in small animals, optical (i.e. bioluminescence and fluorescence) imaging modalities. The functional modalities form the basis of the rapidly advancing field of “molecular imaging,” defined as the direct or indirect non-invasive monitoring and recording of the spatial and temporal distribution of in vivo molecular, genetic, and/or cellular processes for biochemical, biological, diagnostic, or therapeutic applications [1].