Table 1.

Functional and molecular imaging methods

Modality	Advantages	Disadvantages
Magnetic resonance
Magnetic resonance imaging (MRI)	High spatial resolution and image detail	Confined space
	Increasing range of contrast agents under development	Contrast design limited by need for magnetic atom
Magnetic resonance spectroscopy (MRS)	Can measure wide range of molecules	Limited spatial resolution
	No contrast needed	Challenging to get high quality spectra in routine imaging
Radionuclide imaging
Positron emission tomography (PET)	Wide range of molecular imaging probes	Limited spatial resolution
	Tracer imaging without perturbing biological system	Some radiation exposure
Single photon emission tomography (SPECT)	Similar to PET	Less quantitatively accurate than PET
	Probes more widely available
Ultrasound, especially with contrast enhancement	Highly portable, inexpensive	Operator dependence
	Molecular microbubble contrast agents possible	Contrast agents confined to vascular space thus far
Optical imaging	Highly portable, inexpensive	Limited penetration from surface, limited to relatively superficial sites
	High spatial resolution possible