Biomedical subjects

D R Enzmann

Publications and source records attributed to D R Enzmann.

166 records · Page 10Linked to original sources

PubMedDate not supplied

Cerebrospinal fluid flow measured by phase-contrast cine MR.

PURPOSE: This prospective study was designed to establish the temporal and quantitative relationship between blood flow and cerebrospinal fluid (CSF) flow using a phase-contrast cine MR pulse sequence. METHODS: A cine phase-contrast MR pulse sequence using peripheral gating was used to measure CSF flow direction and velocity. Data were acquired continuously and interpolated into 16 images throughout the cardiac cycle. RESULTS: The timing of systolic CSF flow in the cervical subarachnoid space (SAS) correlated very closely to the brain arteriovenous blood flow difference during the cardiac cycle. This arteriovenous difference was a measure of brain expansion. Aqueduct CSF flow during the cardiac cycle differed from SAS flow in that systolic flow was delayed in comparison with systolic cervical SAS flow. The normal aqueductal oscillatory flow volume was 1.7 +/- .4 mL/min or 0.03 +/- 0.01 mL per cardiac cycle. This represented 14.5% +/- 3.1% of the total CSF flow and tissue displacement through the incisura which was 14.5 +/- 2.2 mL/min or 0.22 +/- 0.03 mL per cycle. CSF oscillatory flow volume in the cervical SAS was 39.0 +/- 4.0 mL/min or 0.65 +/- 0.08 mL per cycle. CONCLUSION: CSF flow can be measured. Results in healthy subjects show relatively low oscillatory flow through the aqueduct which is slightly out of phase (delayed) compared with SAS CSF flow.

Blood Flow Velocity↗

PubMedDate not supplied

Qualitative phase contrast MRA in the normal and abnormal circle of Willis.

PURPOSE: To determine the direction of blood flow in the circle of Willis using a 3-D phase contrast MR angiographic (MRA) technique with high spatial resolution. SUBJECTS: Fifty healthy subjects and 15 patients with occlusive disease were studied using 3-D phase contrast MRA. RESULTS: In the 50 normal subjects, 39 (78%) had detectable flow in one or both posterior communicating arteries. In 24 (48%) of these subjects, flow was detected in both posterior communicating arteries, whereas unilateral flow was detected in 15 (30%). In 36 (92%) of the 39 normal subjects, flow in the posterior communicating artery was from anterior to posterior with only 3 (8%) showing reverse flow from posterior to anterior. The A1 segment of both anterior cerebral arteries was identified in 100% of normal subjects with flow in the expected direction from carotid to the A2 segment. In patients with carotid occlusion, the pattern of flow in the circle of Willis was altered with reversed flow in the ipsilateral posterior communicating artery and sometimes in the ipsilateral A1 segment. An ipsilateral posterior communicating artery was present in 10 of 17 occluded carotid arteries, all showing reversed flow. CONCLUSION: 3-D phase contrast MRA provides useful information about the hemodynamics of normal and abnormal blood flow in the circle of Willis.

Aged↗

PubMedDate not supplied

Magnetization transfer MR of the normal adult brain.

PURPOSE: To establish a normal baseline of the percent magnetization transfer of gray (cortical and deep) and white matter structures in the brain in healthy adults and to determine whether there are adult age-related differences in these measurements. METHODS: Axial T1-weighted scans (800/20 [repetition time/echo time]) with and without magnetization transfer were prospectively performed on a 1.5-T MR imaging unit on 68 healthy patients (aged 20 to 76 years). Presaturation and postsaturation magnetization transfer images were obtained using an on-resonance binomial pulse. All patients had normal MR scans on all pulse sequences. A calculated "difference" image was used to calculate the percent magnetization transfer in multiple specific regions of the brain. In each hemisphere, 9 discrete areas of cortical and deep gray matter and 29 areas of white matter were measured in 68 patients to generate age-related changes in percent magnetization transfer in these anatomic regions. Ranges of normal percent magnetization transfer in each of the 38 measures were established. RESULTS: The percent magnetization transfer of the gray matter (28% +/- 2%) was lower than that of the white matter (36% +/- 2%). There was no statistically significant difference in the percent magnetization transfer in different areas of gray matter. Deep white matter in the different lobes (percent magnetization transfer, 31% to 38%) also showed no differences by age. Percent magnetization transfer was the highest in the genu of the corpus callosum (42%), and this was statistically significant compared with other white matter measurements. CONCLUSION: There were no statistically significant age-related variations in the percent magnetization transfer in healthy adults in gray or white matter. These percent magnetization transfer measurements provide baseline normative data, which can be used to measure the extent and severity of white matter changes in disease states.

Adult↗

PubMedDate not supplied

Measure of magnetization transfer in multiple sclerosis demyelinating plaques, white matter ischemic lesions, and edema.

PURPOSE: To define the percentage of magnetization transfer of multiple sclerosis (MS) plaques, ischemic white matter lesions, and vasogenic edema to determine whether this measurement can help differentiate these entities. METHODS: Findings were compared in 25 patients with proved MS, 20 patients with white matter ischemic lesions, and 72 patients with white matter edema (caused by tumors, infections, or acute/subacute infarctions) in the periventricular system, centrum semiovale, and subcortical white matter. Magnetization transfer was performed using an on-resonance binomial pulse. The percentage of magnetization transfer of the normal white matter was also calculated. RESULTS: Magnetization transfer was significantly higher in white matter ischemic lesions (range, 31% to 38%; mean, 34% +/- 0.6%) than in demyelinating plaques of MS (range, 19% to 28%; mean, 22.5% +/- 1%) and in edema (range, 29% to 37%; mean, 30.2% +/- 0.4%). No statistical difference in percentage of magnetization transfer was found among lesions in the periventricular system (34% +/- 0.6%), centrum semiovale (35% +/- 0.5%), or subcortical white matter (33% +/- 0.6%), or in vasogenic edema associated with tumors, infections, or infarction. CONCLUSION: Differences in magnetization transfer suggest less change of demyelination in white matter ischemic lesions than in MS plaques and are significantly different in this respect from similar MS plaques. Magnetization transfer of edema was less than that of normal white matter or fell between ischemic abnormalities and MS plaques. Percentages of magnetization transfer below the mid-20% range is highly suggestive of demyelination. Vasogenic edema, our surrogate for increased water content of white matter, caused a decrease in the percentage of magnetization transfer.

Adult↗