Table 1.
Characteristics of molecular imaging modalities.
| Imaging Modality | Type of Signals | Spatial Resolution | Probes/Needed Amount | Sensitivity (1/(Probe), In Vivo Concentration) | Radiation Hazard | Clinical Translation |
|---|---|---|---|---|---|---|
| Ultrasound | High frequency sound waves | 30–500 μm | Microbubbles μg-mg | 10−9–10−12 moles | No | Good |
| MR | Radio waves | 50–250 μm | Gadolinium, iron oxides μg-mg | 10−4–10−7 moles | No | Good |
| Nuclear (SPECT or PET) | γ rays | 0.3–2 mm | Radioisotopes ng | 10−12 moles | Yes | Good |
| Optical (Bioluminescence or Fluorescence) | Visible light or near infrared | 1–5 mm | d-luciferin, coelentrazine, fluorophore ng-μg | ~10−17 moles | No | Limited |
MR: Magnetic resonance, SPECT: Single-photon emission computed tomography, PET: positron emission tomography.