scholarly journals Comparison of Retinal Microvessel Blood Flow Velocities Acquired with Two Different Fields of View

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Jin Zhou ◽  
Min Li ◽  
Wan Chen ◽  
Ye Yang ◽  
Liang Hu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Conversion Factor ◽  
Retinal Function ◽  
Retinal Blood Flow ◽  
Retinal Function Imager ◽  
Blood Flow Velocities ◽  
Wide Fov ◽  
Retinal Arteriolar ◽  
Flow Velocities

To compare the different retinal blood flow velocities (BFVs) acquired with different fields of view (FOVs) using the retinal function imager (RFI), twenty eyes of twenty healthy subjects were enrolled in the study. Retinal microvessel BFV in the macula was acquired with both a wide FOV (35 degrees, 7.3 × 7.3 mm2) and a commonly used small FOV (20 degrees, 4.3 × 4.3 mm2). The 35-degree FOV was trimmed to be equivalent to the 20-degree FOV to compare the BFVs of the similar FOVs using different settings. With the 35-degree FOV, both retinal arteriolar and venular BFVs were significantly greater than the 20-degree FOV (P<0.001). When the 20-degree FOV was compared to the trimmed equivalent 20-degree FOV acquired using the 35-degree FOV, significant BFV differences were found in both the arterioles (P=0.029) and venules (P<0.001). This is the first study to compare retinal blood flow velocities acquired with different FOVs using RFI. The conversion factor from 35 degrees to 20 degrees is 0.95 for arteriolar BFV and 0.92 for venular BFV, which may be used for comparing BFVs acquired with different FOVs.

Blood Flow Velocities in the Vertebral Veins of Healthy Subjects: A Duplex Sonographic Study

1999 ◽  
Vol 9 (4) ◽  
pp. 198-200 ◽  
Author(s):  
Olaf Hoffmann ◽  
Markus Weih ◽  
Thomas von Münster ◽  
Stephan Schreiber ◽  
Karl Max Einhäupl ◽  
...  
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Blood Flow Velocities ◽  
Flow Velocities

scholarly journals A Comparison of Regional Cerebral Blood Flow and Middle Cerebral Artery Blood Flow Velocities: Simultaneous Measurements in Healthy Subjects

1992 ◽  
Vol 12 (6) ◽  
pp. 1049-1054 ◽  
Author(s):  
Arve Dahl ◽  
David Russell ◽  
Rolf Nyberg-Hansen ◽  
Kjell Rootwelt
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Cerebral Arteries ◽  
Transcranial Doppler Ultrasound ◽  
Velocity Increase ◽  
Mental Activation ◽  
Middle Cerebral Arteries ◽  
Blood Flow Velocities ◽  
Perfusion Territory ◽  
Flow Velocities

Blood flow velocities were measured in both middle cerebral arteries (MCAs) of 36 healthy subjects using transcranial Doppler ultrasound. Measurements were first made using a hand-held probe. Velocities were then studied bilaterally with fixed probes under resting conditions and during simultaneous regional CBF (rCBF) measurements. A significant (p < 0.05) positive correlation was found between MCA flow velocities and rCBF in the estimated perfusion territory of this artery. The correlation coefficient was highest when the measurements were performed simultaneously (p < 0.001) or when velocities recorded with a hand-held probe were adjusted to take into account the significant velocity increase induced by the CBF study situation. The increased velocities during CBF measurements cannot be fully explained by the moderate but significant Pco2 increase. Other possible mechanisms are increased blood flow due to mental activation or MCA vasoconstriction secondary to stimulation of the sympathetic nervous system. The effect of mental activation and Pco2 differences should therefore be considered when comparing the results of repeated velocity and CBF measurements.

scholarly journals Estimating Retinal Blood Flow Velocities by Optical Coherence Tomography

2016 ◽  
Vol 134 (10) ◽  
pp. 1104 ◽  
Author(s):  
Gerald Seidel ◽  
Gerold Aschinger ◽  
Christoph Singer ◽  
Sereina Annik Herzog ◽  
Martin Weger ◽  
...  
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Retinal Blood Flow ◽  
Optical Coherence ◽  
Blood Flow Velocities ◽  
Flow Velocities

scholarly journals Simultaneous Assessment of Vasoreactivity Using Transcranial Doppler Ultrasound and Cerebral Blood Flow in Healthy Subjects

1994 ◽  
Vol 14 (6) ◽  
pp. 974-981 ◽  
Author(s):  
Arve Dahl ◽  
David Russell ◽  
Rolf Nyberg-Hansen ◽  
Kjell Rootwelt ◽  
Petter Mowinckel
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Healthy Subjects ◽  
Regional Cerebral Blood Flow ◽  
Cerebral Arteries ◽  
Repeated Measurements ◽  
Regional Cerebral Blood ◽  
Velocity Increase ◽  
Blood Flow Velocities ◽  
Flow Velocities

Blood flow velocities in both middle cerebral arteries and regional cerebral blood flow in their perfusion territories were measured simultaneously in 36 healthy subjects. In 20 subjects, the measurements were first performed under basal conditions and then repeated 15–20 min after an intravenous injection of 1 g of acetazolamide. Reproducibility of simultaneous blood flow and velocity measurements was tested by examining 16 subjects on two occasions under basal conditions with an interval of 20 min. Relatively good reproducibility was found for repeated measurements of velocity and blood flow, being best when side-to-side asymmetry was assessed. The increase in blood flow velocities after acetazolamide was symmetrical (right side, 34.2%; and left side, 35.5%), and the velocity increase was significantly correlated with basal values. The increase in cerebral blood flow was also symmetrical (right side, 29.8%; left side, 30.1%) but not correlated with basal flow values. No significant relationship was found between velocity increase and increase in regional cerebral blood flow. This finding is probably not only due to methodological inaccuracies but may suggest that acetazolamide has an effect on the diameter of the middle cerebral artery or on the magnitude of this artery's perfusion territory. This study supports the use of acetazolamide for assessing cerebral vasoreactivity following the definition of lower limits for velocity and flow increase and for asymmetry of the response.

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