scholarly journals Increased Intravascular Flow Rate Triggers Cerebral Arteriogenesis

2009 ◽  
Vol 29 (4) ◽  
pp. 726-737 ◽  
Author(s):  
Wilma Schierling ◽  
Kerstin Troidl ◽  
Clemens Mueller ◽  
Christian Troidl ◽  
Hanna Wustrack ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Shear Stress ◽  
Magnetic Resonance ◽  
Fluid Shear Stress ◽  
Mononuclear Cells ◽  
Resonance Imaging ◽  
Fluid Shear ◽  
Bilateral Carotid ◽  
Venous Fistula

Peripheral arteriogenesis is distinctly enhanced by increased fluid shear stress. Thus, the aim of this study was to investigate in the rat brain whether increased fluid shear stress can also stimulate cerebral arteriogenesis. To increase fluid shear stress in the cerebral circulation, we developed different shear stress models as the ligature of both common carotid arteries ( Double-Ligature model), bilateral carotid ligature followed by creation of a unilateral arterio-venous fistula (two-stage protocol, Ligature-Shunt model), and unilateral arterio-venous fistula-creation alone ( Solo-Shuntmodel). Blood flow changes were monitored in vivo by quantitative magnetic resonance imaging-analysis. Cerebral arteriogenesis was analyzed by magnetic resonance imaging and contrast agent-angiography. For proliferation and accumulation of mononuclear cells, immunohistochemistry was performed. During the 14 days-observation period, blood flow increased maximal by 5.5-fold in the A. basilaris and 10.3-fold in the fistula-sided A. cerebri posterior of the Ligature-Shunt model. Considerable vessel growth was found in all shear stress-stimulated arteries. Comparative analysis of vessel length and diameter versus blood flow indicated a correlation between the growth of cerebral collaterals and rising intravascular flow rates ( R2 = 0.90/0.96). Immunohistochemistry showed the typical phases of arteriogenesis and accumulation of mononuclear cells. In conclusion, we provide evidence that fluid shear stress is not only the pivotal trigger of peripheral but also of cerebral arteriogenesis.

Inferior vena caval hemodynamics quantified in vivo at rest and during cycling exercise using magnetic resonance imaging

2003 ◽  
Vol 284 (4) ◽  
pp. H1161-H1167 ◽  
Author(s):  
Christopher P. Cheng ◽  
Robert J. Herfkens ◽  
Charles A. Taylor
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Shear Stress ◽  
Magnetic Resonance ◽  
Wall Shear Stress ◽  
Flow Rate ◽  
Inferior Vena ◽  
Resonance Imaging ◽  
Cycling Exercise ◽  
Wall Shear

Compared with the abdominal aorta, the hemodynamic environment in the inferior vena cava (IVC) is not well described. With the use of cine phase-contrast magnetic resonance imaging (MRI) and a custom MRI-compatible cycle in an open magnet, we quantified mean blood flow rate, wall shear stress, and cross-sectional lumen area in 11 young normal subjects at the supraceliac and infrarenal levels of the aorta and IVC at rest and during dynamic cycling exercise. Similar to the aorta, the IVC experienced significant increases in blood flow and wall shear stress as a result of exercise, with greater increases in the infrarenal level compared with the supraceliac level. At the infrarenal level during resting conditions, the IVC experienced higher mean flow rate than the aorta (1.2 ± 0.5 vs. 0.9 ± 0.4 l/min, P < 0.01) and higher mean wall shear stress than the aorta (2.0 ± 0.6 vs. 1.3 ± 0.6 dyn/cm2, P < 0.005). During exercise, wall shear stress remained higher in the IVC compared with the aorta, although not significantly. It was also observed that, whereas the aorta tapers inferiorly, the IVC tapers superiorly from the infrarenal to the supraceliac location. The hemodynamic and anatomic data of the IVC acquired in this study add to our understanding of the venous circulation and may be useful in a clinical setting.

Functional Magnetic Resonance Imaging Measures of Blood Flow Patterns in the Human Auditory Cortex in Response to Sound

1998 ◽  
Vol 41 (3) ◽  
pp. 538-548 ◽  
Author(s):  
Sean C. Huckins ◽  
Christopher W. Turner ◽  
Karen A. Doherty ◽  
Michael M. Fonte ◽  
Nikolaus M. Szeverenyi
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Speech Stimuli ◽  
Complex Stimuli ◽  
Scanning Session ◽  
Auditory Research

Functional Magnetic Resonance Imaging (fMRI) holds exciting potential as a research and clinical tool for exploring the human auditory system. This noninvasive technique allows the measurement of discrete changes in cerebral cortical blood flow in response to sensory stimuli, allowing determination of precise neuroanatomical locations of the underlying brain parenchymal activity. Application of fMRI in auditory research, however, has been limited. One problem is that fMRI utilizing echo-planar imaging technology (EPI) generates intense noise that could potentially affect the results of auditory experiments. Also, issues relating to the reliability of fMRI for listeners with normal hearing need to be resolved before this technique can be used to study listeners with hearing loss. This preliminary study examines the feasibility of using fMRI in auditory research by performing a simple set of experiments to test the reliability of scanning parameters that use a high resolution and high signal-to-noise ratio unlike that presently reported in the literature. We used consonant-vowel (CV) speech stimuli to investigate whether or not we could observe reproducible and consistent changes in cortical blood flow in listeners during a single scanning session, across more than one scanning session, and in more than one listener. In addition, we wanted to determine if there were differences between CV speech and nonspeech complex stimuli across listeners. Our study shows reproducibility within and across listeners for CV speech stimuli. Results were reproducible for CV speech stimuli within fMRI scanning sessions for 5 out of 9 listeners and were reproducible for 6 out of 8 listeners across fMRI scanning sessions. Results of nonspeech complex stimuli across listeners showed activity in 4 out of 9 individuals tested.

A case of prenatal diagnosis of corpus callosum lipoma

2020 ◽  
Author(s):  
A.I. Zamiatina, M.V. Medvedev
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Prenatal Diagnosis ◽  
Magnetic Resonance ◽  
Corpus Callosum ◽  
Color Doppler ◽  
Septum Pellucidum ◽  
Resonance Imaging

A case of prenatal diagnosis of the corpus callosum lipoma at 32–33 weeks of gestation is presented. In a consultative examination, a hyperechoic formation with clear contours was found in the projection of the septum pellucidum, occupying the rostrum, genu, and truncus of corpus callosum, without signs of intratumorally blood flow in the color Doppler mapping mode. The prenatal diagnosis of "callosum lipoma" was established, confirmed after the birth of a child during magnetic resonance imaging.

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