Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Transcranial duplex color-flow sonography provides visualization of intracranial structures, and measures angle-corrected blood flow velocity in the basal cerebral arteries of adults. In 44 patients with central nervous system disease, the oblique diameters of the third and the middle part of the lateral ventricle were measured by transcranial duplex color-flow sonography using a system with a 2.5-MHz transducer, and compared to computed tomography measurements. The correlation coefficients for the third and lateral ventricle measurements were r = 0.83 (p < 0.0001, N = 38) and 0.73 (p < 0.0001, N = 78), respectively. ⋯ The intraobserver reproducibility correlation coefficient was r = 0.93 (p < 0.0001, N = 22) for the lateral ventricle in 12 patients. In 49 healthy volunteers the oblique diameters of the lateral and third ventricles were age dependent, measuring 16.7 +/- 2.3 mm and 4.8 +/- 1.9 mm, respectively, in those younger than 59 years, compared to 19.0 +/- 2.9 mm and 7.6 +/- 2.1 mm in those 60 years or older. Therefore, transcranial duplex color-flow sonography measures noninvasively the third and the lateral ventricle in adults.
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Comparative Study
Peak velocity overestimation and linear-array spectral Doppler.
Ultrasound instruments are used to evaluate blood flow velocities in the human body. Most clinical instruments perform velocity calculations based on the Doppler principle and measure the frequency shift of a reflected ultrasound beam. Doppler-only instruments use single-frequency, single-crystal transducers. ⋯ Angles of insonation were 30, 45, 60, and 70 degrees. The single-frequency, single-crystal transducers (PC Dop 842, 2-MHz pulsed-wave, 4-MHz continuous-wave) provided acceptably accurate velocity estimates at all tested velocities independent of the angle of insonation. All duplex Doppler instruments with linear-array transducers (Philips P700, 5.0-MHz; Hewlett-Packard Sonos 1000, 7.5-MHz; ATL Ultramark 9 HDI, 7.5-MHz) exhibited a consistent overestimation of the true flow velocity due to increasing intrinsic spectral broadening with increasing angle of insonation.(ABSTRACT TRUNCATED AT 250 WORDS)
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The purpose of this study was to compare the effects of critical neck angulation (rotation and hyperextension) on vertebral artery perfusion in symptomatic and control populations and to determine whether this represents a risk factor for ischemic stroke. In a cross-sectional study, 64 symptomatic individuals with well-documented brainstem ischemic events (average age, 70.9 yr) and 37 control subjects (average age, 66.3 yr) were evaluated using a dynamic magnetic resonance angiography technique designed to mimic activities of daily living. Abnormalities of perfusion at the atlantoaxial and atlantooccipital junction and distal vertebral artery were recorded and scored independently by two neuroradiologists. ⋯ Occlusion was noted in all subjects with contralateral neck rotation. Postpositional ischemia was present (68%) and correlated with female gender (p < 0.001), severity of stenosis (p < 0.001), vascular risk factors (p < 0.001), and microinfarction on magnetic resonance images (p < 0.05). Flow analysis showed low basilar artery perfusion (< 25 ml/min) in 63.6%, and unsuspected steal with neck motion in 4 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
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To identify normal variations in the magnetic resonance imaging appearances of the corpus callosum with regard to sex and age, a prospective study was performed in 130 normal subjects. Callosal measurements were calculated by morphometric analysis. ⋯ The absolute area did not decrease significantly with aging in normal males or females. However, age-related changes of callosal configuration were shown by a decrease in the ratio of the rostrum and genu to the splenium.
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Transcranial duplex color-flow imaging is a new diagnostic method that allows visual display of blood flow in the basal cerebral arteries. This method allows determination of and correction for the Doppler angle of insonation. Conventional transcranial Doppler sonography has no imaging component and assumes a 0-degree Doppler angle for the calculation of flow velocities. ⋯ Visually controlled measurements of the Doppler angle of insonation were made by color-flow imaging. The data show that the mean angle of insonation was 33 degrees (+/- 15) in the middle cerebral artery, 35 degrees (+/- 17) in the anterior cerebral artery, 45 degrees (+/- 18) in the posterior cerebral artery, and 15 degrees (+/- 14) in the basilar artery. Angle-corrected peak systolic flow velocities were higher in all vessel segments (middle cerebral = 15%, anterior cerebral = 18%, posterior cerebral = 30%, and basilar = 3%), compared to uncorrected velocity readings by conventional Doppler sonography.(ABSTRACT TRUNCATED AT 250 WORDS)