Functional MR imaging evaluation of spinal cord function by use of neurophysiological stimuli.
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Artifacts↗
Biomedical subjects
L M Levy
Publications and source records attributed to L M Levy.
MR of slow CSF flow in the spine.
PURPOSE: To evaluate a slow-flow MR sequence in normal CSF flow and in CSF flow disturbance in cases of spinal stenosis. METHOD: The method was tested for flow sensitivity and applied to 67 sites of spinal canal compromise. RESULTS: Phantom studies show that flow can be depicted at a velocity of 0.5-1 mm/sec. On clinical images, stagnant CSF is black, flowing CSF is bright. Typically, in high-grade (90%-100%) stenosis, CSF above and below the site of spinal canal compromise (SCC) is black. With intermediate stenosis (50%-89%), CSF above the SCC remains white but becomes black distal to the SCC. Low-grade stenosis shows only localized flow disturbances. CONCLUSION: This easy-to-use sequence can solidify the MR diagnosis of high-grade stenosis when a distinct flow pattern is recognized. Flow patterns for intermediate and low-grade stenosis are less reliable.
Cerebrospinal Fluid↗
Diagnosis of acute cerebral infarction: comparison of CT and MR imaging.
The appearance of acute cerebral infarction was evaluated on MR images and CT scans obtained in 31 patients within 24 hr of the ictus; follow-up examinations were performed 7-10 days later in 20 of these patients and were correlated with the initial studies. Acute infarcts were visible more frequently on MR images than on CT scans (82% vs 58%). Proton density- and T2-weighted scans usually demonstrated regions of hyperintensity corresponding to acute infarcts, but proton density-weighted scans often showed better definition of the lesion in terms of regional anatomy. Follow-up MR images and CT scans identified approximately 88% of subacute strokes, 54% of which were better defined and/or larger than on the initial examination. In 20% of lesions, "hemorrhagic" characteristics were seen on at least one examination. CT and MR imaging were comparable in delineating acute hemorrhage, but MR detected more cases with evidence of hemorrhage on follow-up examinations. MR appears to be more sensitive than CT in the imaging of acute stroke.
Acute Disease↗