“…Recently, several imaging modalities, including magnetic resonance imaging (MRI) [ 1 – 3 ], radiography, computed tomography (CT) [ 4 – 9 ], positron emission tomography (PET) [ 10 , 11 ], single-photon emission computed tomography (SPECT) [ 12 , 13 ], electron microscopy, autoradiography, optical imaging, and ultrasound (US) [ 14 – 17 ], have been applied in biomedical, genetic, toxicologic, cancer, cardiology, and pharmacological research worldwide. These are all noninvasive imaging modalities with proven clinical applications that have been extended to in vivo and ex vivo research specimens as small as mice, rats, and marmosets [ 9 , 18 , 19 ].…”