In: Anatomy and Physiology
Hi. This is a question for my summer neuroscience class.
Q: What is fMRI? What does fMRI measure? What are some of the criteria used to evaluate the appropriateness of any imaging technique? What are some of the limitations of fMRI and PET? What are the controversies about interpreting levels of activation in fMRI tasks?
fMRI stands for Functional Magnetic Resonance Imaging.
fMRI measures brain activity by detecting changes in blood flow in the area of brain. There is increase in blood flow of the area of brain being used.
Criteria used to evaluate the appropriateness of any imaging technique are ACR appropriateness criteria which is guidelines based on evidence to help and assist the physicians to take proper and precise decisions in treatment for clinical conditions by taking proper imaging.
Limitations of fMRI: It has got low temporal resolution, expensive, there is limitations of motion, supine position is must, noisy
Limitations of PET: It is invasive, expensive, and has low temporal and spatial resolution.
Some of the controversies about interpreting levels of activation in fMRI tasks are: BOLD response remains elevated means there is long stimulation effects, draining vein effect is there which cause distortion in fMRI signal, BOLD response is complex as it is both linear and non-linear, fMRI response is slow, difficulty in interpreting negative signal changes, etc.