Theoretical principles of perfusion imaging. Application to magnetic resonance imaging

Perfusion magnetic resonance imaging (MRI) offers relative safety (no ionizing radiation), high spatial/temporal resolution, multi-orientation imaging capability, and relative low cost when compared with sophisticated techniques, such as positron emission tomography (PET). Several methods have been recently proposed to image perfusion. Some techniques mimic conventional nuclear medicine principles, but use radioactively inert tracers. Other approaches directly use blood as an endogenous natural tracer. Such methods are totally noninvasive, and offer original insights, for instance by monitoring variations in blood oxygenation in human brain cortex during activation tasks. These methods are presented and compared. Emphasis is given on advantages and drawbacks, and potential clinical applications.