Test-retest precision of functional MR in sensory and motor task activation.
OBJECTIVE
To determine the test-retest precision of functional MR maps of regions in the brain "activated" by sensory, motor, and cognitive tasks.


METHODS
Echo-planar images were acquired at 1.5 T in four subjects during voluntary motor activity involving the thumb and fingers and during tactile stimulation of the palm. Each subject performed the two tasks twice. Functional images of each task were generated at three thresholds. Test-retest precision was calculated in terms of two ratios: 1) the pixels activated in both iterations of the tasks in proportion to the pixels activated by either iteration of the task, and 2) the ratio modified to include first-order neighboring pixels. The first is referred to as pixel precision, and the latter as first-order-neighbor pixel precision.


RESULTS
In each subject, activation from the first and second iteration of each task was located in the same region of the same gyrus. Pixel precision was .57 for the two tasks (at a threshold of 0.50). First-order-neighbor precision was greater than .80 for the two tasks at the same threshold.


CONCLUSIONS
High test-retest precision can be obtained in functional MR.
Yetkin
F Z
FZ
Department of Radiology, Medical College of Wisconsin, Milwaukee 53226, USA.
McAuliffe
T L
TL
Cox
R
R
Haughton
V M
VM
D000328:Adult; D001143:Arousal / Q000502:physiology*; D016477:Artifacts; D001921:Brain / Q000098:blood supply*; D001931:Brain Mapping / Q000295:instrumentation*; D017352:Echo-Planar Imaging / Q000295:instrumentation; D005260:Female; D005385:Fingers / Q000294:innervation; D005625:Frontal Lobe / Q000098:blood supply; D006225:Hand / Q000294:innervation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D010296:Parietal Lobe / Q000098:blood supply; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results; D014110:Touch / Q000502:physiology*