Table 1.

A summary of the features and advantages and disadvantages of the neuroimaging methods discussed in this review

Neuroimaging method	Nature of signal	Spatial resolution	Temporal resolution	Advantages	Disadvantages
fMRI – BOLD	Stimulus evoked hemodynamic activity in the brain as determined by oxyhemoglobin and deoxyhemoglobin	mm	Seconds	Good spatial resolution Can measure cognitive processes	Indirect measure of neuronal activity Use of artificial stimulus may not reflect clinical pain
fMRI – ASL	Cerebral blood flow using magnetically labeled endogenous water in the blood acting as a diffusible tracer	mm	Minutes	Task or pain stimulus is not needed Representative of ongoing clinical pain	Indirect measure of neuronal activity Few studies in pain to test feasibility
MRI–DTI	Diffusion of water through white matter	mm	Weeks–years	Increase understanding of brain networks	Suffers from data artifacts
MRI – structural	Structural information about the gray matter and white matter using VBM	mm	Weeks–years	Provides excellent structural information Allows assessment of disease over time	MRI scanners are expensive
NIRS	Stimulus-evoked hemodynamic response determined by differences in NIR light absorption spectra	mm	Seconds	More portable than fMRI Can measure cognitive processes	Can only scan cortex Use of artificial stimulus may not reflect clinical pain
PET	Cerebral blood flow, oxygen uptake, and glucose metabolism using specific radionucleotides	mm	Minutes	Measures cerebral metabolism Ligand and drug binding	Expensive Uses radioactive tracer limiting repeat application
EEG	ERPs detected by voltage changes resulting from neuronal information transfer	mm–cm	Milliseconds	Lower cost Portable Widely available Signals generated directly from neural activity	Use of artificial stimulus may not reflect clinical pain Source localization is difficult
MEG	ERPs detected by magnetic field disturbances resulting from neuronal information transfer	mm	Milliseconds	Signals generated directly from neural activity Good spatial resolution	Needs a magnetically shielded room

Note: Data from various studies.¹⁶–¹⁹,²²,²³,²⁶–²⁸,⁴³,⁴⁴,¹²²

Abbreviations: fMRI, functional magnetic resonance imaging; BOLD, blood oxygen level dependent; ASL, arterial spin labeling; MRI–DTI, magnetic resonance imaging–diffusion tensor imaging; VBM, voxel-based morphometry; NIRS, near-infrared spectroscopy; PET, positron emission tomography; EEG, electroencephalography; ERP, event-related potential; MEG, magnetoencephalography.