Table 1.

Comparison of the imaging modalities

Imaging modality	Resolution (μm)	Sensitivity	Key features
Optical	2,000	pM–fM	Two-dimensional Limited depth of penetration Molecular and functional imaging Mice (nude or non-pigmented) only
PET	1,500–2,000	nM–pM	Three-dimensional Short- and long-lived isotopes Molecular and functional imaging
SPECT	100–200a	nM–pM	Three-dimensional Potential for imaging multiple probes simultaneously Molecular and functional imaging
CT	30+	μM	Three-dimensional Primarily bone and lung imaging Soft tissue imaging requires contrast agents Anatomical imaging
Ultrasound	30+	μM	Two-dimensional Depth of penetration dependent on transducer frequency User dependent due to manual manipulation of transducers Anatomical imaging
MRI	10+	μM	Three-dimensional No ionizing radiation Anatomical imagingb

^aResolution is scanner dependent

^bPotential for functional imaging using contrast agents