Table 1.

Utilization, advantages, and limitations of imaging modalities.

Modality	Contrast Agent (Examples)	Spatial Resolution (mm)	Advantages	Limitations	Clinical Application
CT	Iodine; nanoparticles; barium; krypton	0.5–0.625 mm	Whole-body imaging available; high spatial resolution; short imaging time; unlimited depth penetration, inexpensive	Use of ionizing radiation; limited soft tissue contrast; molecular imaging not available; no real-time imaging	Yes
US	Microbubbles	0.04–0.1 (micro), 0.1–2 (clinical)	High sensitivity; non-ionizing radiation; real-time imaging; inexpensive, short acquisition time	Whole-body imaging not possible; limited depth penetration; limited contrast agents	Yes
Optical	Fluorescent dye; Nanoparticles	1–5 mm	High sensitivity; non-ionizing radiation; real time imaging; inexpensive, short acquisition time	Whole body imaging not possible; limited depth penetration; limited contrast agents	Yes
MRI	Gadolinium; iron oxide nanoparticles; manganese nanoparticles	0.01–0.1 (micro); 0.5–1.5 (clinical)	Non ionizing radiation; high spatial resolution; high soft tissue contrast; whole-body imaging possible; unlimited depth penetration	Expensive imaging; long acquisition time; low sensitivity	Yes
PET	Radioisotopes	1–2 (micro); 5–10 (clinical)	High sensitivity; whole-body imaging possible; unlimited depth penetration; quantitative imaging; can combine with other imaging technologies and therapy	Expensive imaging; low spatial resolution; long acquisition time; ionizing radiation exposure; need cyclotron or nuclear reactor	Yes
SPECT	Radioisotopes	0.5–2 (micro); 6–15 (clinical)	High sensitivity; whole-body imaging possible; unlimited depth penetration; quantitative imaging; can combine with other imaging technologies and therapy	Expensive imaging; low spatial resolution; long acquisition time; ionizing radiation exposure; need cyclotron or nuclear reactor	Yes