Figure 2.

Properties of Various Whole-Body Imaging Modalities

Imaging modalities are ordered according to their molecular detection sensitivities with achievable imaging depth shown in gray alongside. Achievable spatial resolution (left end) and fields of view (right end) are shown in cyan/green. Where bars are green, they overlay purple bars and indicate the same parameters but achievable with instruments available for clinical imaging. Instrument cost estimations are classified as follows: $, <$130,000; $$, $130,000–$300,000; $$$, >$300,000. ^†Contrast agents sometimes used to obtain different anatomical/functional information. ^‡Sensitivity is highly dependent on contrast-forming features/contrast agent. A new mammalian reporter gene for US imaging was recently reported to detect a minimum of 135 gas vesicles per voxel with dimensions of 100 μm.^112&Dual-isotope PET is feasible but not routinely in use; it requires two tracers, one with a positron emitter (e.g., ¹⁸F, ⁸⁹Zr) and the other with a positron-gamma emitter (e.g., ¹²⁴I, ⁷⁶Br, ⁸⁶Y), and is based on recent reconstruction algorithms to differentiate the two isotopes based on the prompt-gamma emission.121, 122, 123^%Multichannel MRI imaging has been shown to be feasible¹²⁴ but is not routinely available. ^#Generated by positron annihilation (511 keV). BLI, bioluminescence imaging; PET, positron emission tomography; SPECT, single-photon emission computed tomography; FMT, fluorescence molecular tomography; PAT/MSOT, photoacoustic tomography/multispectral optoacoustic tomography; MRI, magnetic resonance imaging; NIR, near-infrared; VIS, visible; HF, high-frequency; CT, computed tomography.