3D measurement of brain arteries What can we learn?

2022 ◽  
Keyword(s):  
3D Measurement ◽  
Brain Arteries

Microvascular features that suggest effectors of blood-flow regulation in the brain: Evidence by SEM of corrosion casts of intracerebral vessels

1990 ◽  
Vol 48 (3) ◽  
pp. 274-275
Author(s):  
Enrico D.F. Motti ◽  
Hans-Georg Imhof ◽  
Gazi M. Yasargil
Keyword(s):  
Blood Flow ◽  
Perfusion Pressure ◽  
Corrosion Casts ◽  
Cerebral Microcirculation ◽  
Pial Arteries ◽  
Random Occurrence ◽  
Brain Arteries ◽  
Homogeneous Network ◽  
The Brain

Physiologists have devoted most attention in the cerebrovascular tree to the arterial side of the circulation which has been subdivided in three levels: 1) major brain arteries which keep microcirculation constant despite changes in perfusion pressure; 2) pial arteries supposed to be effectors regulating microcirculation; 3) intracerebral arteries supposed to be deprived of active cerebral blood flow regulating devices.The morphological search for microvascular effectors in the cerebrovascular bed has been elusive. The opaque substance of the brain confines in vivo investigation to the superficial pial arteries. Most morphologists had to limit their observation to the random occurrence of a favorable site in the practically two-dimensional thickness of diaphanized histological sections. It is then not surprising most investigators of the cerebral microcirculation refer to an homogeneous network of microvessels interposed between arterioles and venules.We have taken advantage of the excellent depth of focus afforded by the scanning electron microscope (SEM) to investigate corrosion casts obtained injecting a range of experimental animals with a modified Batson's acrylic mixture.

Bestimmung des zerebralen Blutflusses mittels des 81 Rb/81 mKr-Generatorsystems

1990 ◽  
Vol 29 (01) ◽  
pp. 7-12 ◽  
Author(s):  
J. Bialy ◽  
F.-J. Hans ◽  
E. Oberhausen ◽  
W.J. Peters ◽  
M. Schmitt ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Blood Circulation ◽  
Semiconductor Device ◽  
Animal Experiments ◽  
Initial Value ◽  
Brain Arteries ◽  
Sufficient Concentration ◽  
Static Quantity

A method is being developed which not only measures cerebral blood flow as a static quantity but also its changes with time. For that purpose a semiconductor device ascertains the proportion of intracerebral81 Rb and 81mKr activities. By opening the haemato-encephalic barrier in animal experiments a sufficient concentration of intracerebral81 Rb could be attained and the modified blood circulation after step-wise ligature of all brain arteries brought into relation to the corresponding Rb/Kr quotient. Over the range from undisturbed to completely interrupted cerebral blood flow this quotient varied up to 25% of its initial value.

Counterfeit Parts Recognition and Detection for Failure Analysts

2010 ◽  
Author(s):  
Katherine V. Whittington
Keyword(s):  
Thermal Cycle ◽  
Visual Inspection ◽  
Acoustic Microscopy ◽  
Scanning Acoustic Microscopy ◽  
3D Measurement ◽  
X Ray ◽  
Wide Range ◽  
Electronic Parts ◽  
Testing Awareness

Abstract The electronics supply chain is being increasingly infiltrated by non-authentic, counterfeit electronic parts, whose use poses a great risk to the integrity and quality of critical hardware. There is a wide range of counterfeit parts such as leads and body molds. The failure analyst has many tools that can be used to investigate counterfeit parts. The key is to follow an investigative path that makes sense for each scenario. External visual inspection is called for whenever the source of supply is questionable. Other methods include use of solvents, 3D measurement, X-ray fluorescence, C-mode scanning acoustic microscopy, thermal cycle testing, burn-in technique, and electrical testing. Awareness, vigilance, and effective investigations are the best defense against the threat of counterfeit parts.

Automated 3D measurement of fiber cross section morphology in handsheets

2012 ◽  
Vol 27 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Christian Lorbach ◽  
Ulrich Hirn ◽  
Johannes Kritzinger ◽  
Wolfgang Bauer
Keyword(s):  
Image Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Image Plane ◽  
3D Measurement ◽  
Cross Sectional ◽  
Fiber Cross Section ◽  
Fiber Wall ◽  
Sectional Shape ◽  
Cross Section Geometry

Abstract We present a method for 3D measurement of fiber cross sectional morphology from handsheets. An automated procedure is used to acquire 3D datasets of fiber cross sectional images using an automated microtome and light microscopy. The fiber cross section geometry is extracted using digital image analysis. Simple sample preparation and highly automated image acquisition and image analysis are providing an efficient tool to analyze large samples. It is demonstrated that if fibers are tilted towards the image plane the images of fiber cross sections are always larger than the true fiber cross section geometry. In our analysis the tilting angles of the fibers to the image plane are measured. The resulting fiber cross sectional images are distorted to compensate the error due to fiber tilt, restoring the true fiber cross sectional shape. We use an approximated correction, the paper provides error estimates of the approximation. Measurement results for fiber wall thickness, fiber coarseness and fiber collapse are presented for one hardwood and one softwood pulp.

3D measurement of large-scale object using independent sensors

2017 ◽  
Author(s):  
Liu Yong ◽  
Jia Yuan ◽  
Jiang Yong ◽  
Xia Luo
Keyword(s):  
Large Scale ◽  
3D Measurement

THE EFFECT OF AGE ON THE ELASTICITY OF THE MAJOR BRAIN ARTERIES

1965 ◽  
Vol 43 (2) ◽  
pp. 185-202 ◽  
Author(s):  
Douglas E. Busby ◽  
Alan C. Burton
Keyword(s):  
High Pressures ◽  
Mean Value ◽  
Collagen Fibers ◽  
Peripheral Arteries ◽  
Volume Data ◽  
Maximum Slope ◽  
Brain Arteries ◽  
Autopsy Specimens ◽  
Collagenous Fibers ◽  
The Brain

In previous work on peripheral arteries the law of Laplace has been applied to the pressure–volume data to yield the elastic constants and interrelation of function of elastin and collagenous fibers in the wall, and the changes with age. Similar analysis of major brain arteries has been made on autopsy specimens, aged 2 to 90. Volume (micrometer syringe) and pressure (electromanometer) in arterial segments were accurately measured. Absolute volumes were obtained by collapsing the artery with negative pressure, and the "unstretched circumferences" of the vessel were deduced from the curves. Tension–circumference curves were constructed. These showed the characteristic increasing slope (increased "elastance" or "stiffness") with increasing degree of stretch, interpreted as successive "recruitment" of collagen fibers as they reach their unstretched length.Increases in arterial length with distension were very small and negligible in vessels older than 30 years. Maximum slope (stiffness) was reached at pressures in the physiological range. The maximal stretch was 26 to 38% for vessels aged 30 to 90 years. This is less than for peripheral arteries, except those over 80 years old.Ageing showed itself mainly in reduction of the stretch required to bring 50% of the collagen fibers to their unstretched length, i.e. in the "degree of slackness". This was 30% stretch for younger vessels, 20% for the older. Unlike the peripheral arteries, the brain arteries show no significant increase with age in the maximal stiffness (related to their total collagen content). The mean value of the Young's modulus of the wall at high pressures was 1.93 ± 0.67 × 107 dynes/sq.cm. No significant change in thickness of the wall or lumen diameter with age was found.It is concluded that the major brain arteries are less distensible than peripheral arteries of comparable diameter, particularly in youth. Distensibility decreases with age, mainly because the "degree of slackness" of the collagen fibers is reduced. At physiological pressures the major resistance to distension is due to the collagen fibers rather than to the elastin fibers, which appear histologically to be less abundant, except in the elastica interna, than in peripheral arteries.

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