Functional MRI allows us to visualize cognitive processes as they occur in the brain by:
A. ) measuring currents in neurons within the brain
B. ) imaging the blood flowing into the brain
C. ) imaging local changes in brain tissue signal as the blood oxygenation level changes with flow
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The Gadolinium contrast agent is used to delineate tumors because it:
A. ) increases the T2 relaxation time of fluid in the tumor
B. ) accumulates in highly vascular tissue and shortens the T1 relaxation time of tissue
C. ) targets and destroys cancer cells
The ventricles appear bright in a T2-weighed brain image due to:
A. ) the high water content and long T2 relaxation time of CSF in the ventricle
B. ) the long T1 relaxation time for CSF in the ventricle
C. ) the longer T2 relaxation time of white matter
When scanning the knee for meniscal tears a T2-weighted image is used because:
A. ) bones appear bright in T2 weighted images
B. ) the meniscus has high water content
C. ) fluid with a longer T2 within the tear space appears bright
If you were a MR technologist/radiographer scanning a patient with a knee replacement, it would be safe to proceed with the scan provided:
A. ) you test whether the metal implant is magnetic using a hand-held bar magnet
B. ) the patient tells you that the implant is non-magnetic
C. ) the referring doctor supplies evidence that the metal implant is non-magnetic and certified as MR safe at the field strength of the scanner
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