Table 1.

Imaging Technologies used in Preclinical Brain Studies

Imaging Technology	Imaging Measures	Biological Measures	Advantages	Disadvantages	References
Functional MRI	BOLD, CBV, CBF	Brain Activation following stimulation Brain networks in resting state	Non-invasive, repeatable, spatial, temporal resolution	Indirect brain activation measure.	(Borsook et al., 2006)
Pharmacological MRI (phMRI)	BOLD, CBV, CBF	De-novo effects in brain induced by drug	Non-invasive, repeatable, spatial, temporal resolution	Indirect brain activation measure.	(Wise and Tracey, 2006; Pohlmann et al., 2007; Martin and Sibson, 2008)
Structural MRI	Volumetric, fiber integrity, fiber connectivity	Atrophy, fiber degeneration	Non-invasive, repeatable, high spatial resolution	Time consuming, may require very high magnetic field scanners	(Strome and Doudet, 2007)
Near Infrared Spectroscopy (NIRS)	Hemoglobin changes	Brain activation following stimulation	Non-invasive, repeatable, spatial, temporal resolution	Indirect measure, could be invasive	(Crespi, 2007)
Magnetic Resonance Spectroscopy (MRS)	Metabolic concentrations	Alterations in brain chemistry	Can perform absolute measures, repeatable	Low spatial, temporal resolution, might be limited in certain brain structures	(Schaeffter and Dahnke, 2008)
Positron Emission Tomography (PET)	Radioligand concentration, displacement, blood volume changes	Brain activation following or not stimulation,	Absolute changes in blood volume, receptor displacement	Requires development of specific ligand for receptor studies	(Wang and Maurer, 2005; Cherry, 2006)
PET/MR	Combination of fMRI, phMRI, MRS, Structural MRI and PET	As described above	Simultaneous detection of PET and MRI measures in the same subject	Under development	(Wehrl et al., 2009)
Transcription MRI	Gene Activity in living brains using tMRI probes	Measures of endogenous gene transcription	Tracking, targeting and binding to intracellular mRNA	Use of contrast agents (e.g., SPION) as coupling agents may alter neuronal effects	(Liu et al., 2008)