System to measure blood flow in vessels using the ultrasonic "transit time" technique

2010 ◽  
Author(s):  
A. Jimenez ◽  
E. Carrillo ◽  
E. Moreno ◽  
D. Torres ◽  
A. Ramos ◽  
...  
Keyword(s):  
Blood Flow ◽  
Transit Time ◽  
Measure Blood Flow

Hyperacute Stroke: Simultaneous Measurement of Relative Cerebral Blood Volume, Relative Cerebral Blood Flow, and Mean Tissue Transit Time

Radiology ◽  
1999 ◽  
Vol 210 (2) ◽  
pp. 519-527 ◽  
Author(s):  
A. Gregory Sorensen ◽  
William A. Copen ◽  
Leif Østergaard ◽  
Ferdinando S. Buonanno ◽  
R. Gilberto Gonzalez ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Blood Volume ◽  
Transit Time ◽  
Simultaneous Measurement ◽  
Cerebral Blood Volume ◽  
Hyperacute Stroke ◽  
Relative Cerebral Blood Volume

Measurement of arterial transit time and renal blood flow using pseudocontinuous ASL MRI with multiple post-labeling delays: Feasibility, reproducibility, and variation

2017 ◽  
Vol 46 (3) ◽  
pp. 813-819 ◽  
Author(s):  
Dong Won Kim ◽  
Woo Hyun Shim ◽  
Seong Kuk Yoon ◽  
Jong Yeong Oh ◽  
Jeong Kon Kim ◽  
...  
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Transit Time ◽  
Arterial Transit Time

An anatomic and physiological model of hepatic vascular system

1995 ◽  
Vol 79 (3) ◽  
pp. 1008-1026 ◽  
Author(s):  
D. R. Fine ◽  
D. Glasser ◽  
D. Hildebrandt ◽  
J. Esser ◽  
R. E. Lurie ◽  
...  
Keyword(s):  
Blood Flow ◽  
Transit Time ◽  
Vascular System ◽  
Model Parameters ◽  
Activity Time ◽  
Mathematical Relationship ◽  
Portal Flow ◽  
Splenic Blood Flow ◽  
Liver Activity ◽  
Transit Times

Hepatic function can be characterized by the activity/time curves obtained by imaging the aorta, spleen, and liver. Nonparametric deconvolution of the activity/time curves is clinically useful as a diagnostic tool in determining organ transit times and flow fractions. The use of this technique is limited, however, because of numerical and noise problems in performing deconvolution. Furthermore, the interaction of part of the tracer with the spleen and gastrointestinal tract, before it enters the liver, further obscures physiological information in the deconvolved liver curve. In this paper, a mathematical relationship is derived relating the liver activity/time curve to portal and hepatic behavior. The mathematical relationship is derived by using transit time spectrum/residence time density theory. Based on this theory, it is shown that the deconvolution of liver activity/time curves gives rise to a complex combination of splenic, gastrointestinal, and liver dependencies. An anatomically and physiologically plausible parametric model of the hepatic vascular system has been developed. This model is used in conjunction with experimental data to estimate portal, splenic, and hepatic physiological blood flow parameters for eight normal volunteers. These calculated parameters, which include the portal flow fraction, the splenic blood flow fraction, and blood transit times are shown to adequately correspond to published values. In particular, the model of the hepatic vascular system identifies the portal flow fraction as 0.752 +/- 0.022, the splenic blood flow fraction as 0.180 +/- 0.023, and the liver mean transit time as 13.4 +/- 1.71 s. The model has also been applied to two portal hypertensive patients. The variation in some of the model parameters is beyond normal limits and is consistent with the observed pathology.

scholarly journals Blood Flow to Hindquarters of Steers Measured by Transit Time Ultrasound and Indicator Dilution

1987 ◽  
Vol 70 (7) ◽  
pp. 1385-1390 ◽  
Author(s):  
J.H. Eisemann ◽  
G.B. Huntington ◽  
C.L. Ferrell
Keyword(s):  
Blood Flow ◽  
Transit Time ◽  
Indicator Dilution

Blood flow, volume, and transit time in the pulmonary microvasculature using laser-Doppler

1994 ◽  
Vol 76 (6) ◽  
pp. 2643-2650 ◽  
Author(s):  
T. S. Hakim ◽  
E. Gilbert ◽  
E. M. Camporesi
Keyword(s):  
Blood Flow ◽  
Blood Volume ◽  
Transit Time ◽  
Flow Rate ◽  
Venous Pressure ◽  
Laser Doppler ◽  
Flow Volume ◽  
Doppler Flowmetry ◽  
Blood Flow Volume ◽  
Wide Range

Capillary transit time is determined by the ratio of capillary volume to flow rate. Exercise-induced hypoxemia is thought to occur because of the short transit time of erythrocytes in capillaries. The effect of flow rate on capillary volume (recruitment vs. distension) is controversial. In a perfused left lower lobe preparation in canine lungs, we used laser-Doppler flowmetry (model ALF21R) to monitor changes in blood flow, volume, and transit time in the microvasculature near the subpleural surface. Changes in total flow, blood volume, and total transit time (tt) were also measured. The results showed that microvascular volume approached maximum when flow rate was at resting value (0.4 l/min) and pressure in the pulmonary artery was > 6 mmHg relative to the level of the capillaries. In contrast, the total blood volume increased gradually over a wide range of flow rates. When flow increased 4.2 times (from 155 to 650 ml/min), tt decreased from 7.32 to 3.53 s; meanwhile, microvascular flow increased from 6.0 to 12.7 units and microvascular transit time decreased from 3.14 to 1.81 units. The changes in microvascular volume and transit time were essentially independent of whether the venous pressure was higher or lower than alveolar pressure. At very high flow (6–10 times resting value), tt fell gradually to approximately 1 s. Direct monitoring of transit time with the laser-Doppler also revealed a gradual decline in microvascular transit time as flow rate increased from 2 to 10 times the normal flow. (ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The Effects of Changes in PaCO2Cerebral Blood Volume, Blood Flow, and Vascular Mean Transit Time

Stroke ◽  
1974 ◽  
Vol 5 (5) ◽  
pp. 630-639 ◽  
Author(s):  
ROBERT L. GRUBB ◽  
MARCUS E. RAICHLE ◽  
JOHN O. EICHLING ◽  
MICHEL M. TER-POGOSSIAN
Keyword(s):  
Blood Flow ◽  
Blood Volume ◽  
Transit Time ◽  
Mean Transit Time ◽  
Volume Blood ◽  
Volume Blood Flow

Intraoperative use of transit time flow measurement improves patency of newly created radiocephalic arteriovenous fistulas in patients requiring hemodialysis

2020 ◽  
Vol 21 (6) ◽  
pp. 990-996
Author(s):  
Anna E Cyrek ◽  
Johannes Bernheim ◽  
Benjamin Juntermanns ◽  
Peri Husen ◽  
Arkadius Pacha ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arteriovenous Fistula ◽  
Transit Time ◽  
Intraoperative Ultrasound ◽  
Low Flow ◽  
Flow Measurements ◽  
Technical Problems ◽  
Arteriovenous Fistulas ◽  
Time Flow ◽  
Observation Period

Background: The autologous arteriovenous fistula is the primary choice to establish hemodialysis access without high failure rates. Intraoperative ultrasound flow measurements of newly created autologous arteriovenous fistulas represent a possibility of quality control and may therefore be a tool to assess their functionality. The aim of our study was to correlate intraoperative blood flow with access patency. Methods: Between March 2012 and March 2015, intraoperative transit time flow measurements were collected on 89 patients. Measurements were performed 5–10 min after the creation of a standardized anastomosis using 3–6 mm flow probes. To examine the correlation between intraoperative blood flow and access patency, groups of patients with high (> 200 mL/min) versus low flow (< 200 mL/min) were enrolled. Patients were assessed clinically and with ultrasound every 3 months. Data were analyzed retrospectively. Results: In the current short-term follow-up, including 89 patients (age 62 ± 3 years), 61 (68.5%) of the autologous arteriovenous fistulas were currently being used in an observation period ranging from 3 months to 3 years (mean observation period 546 ± 95 days) postoperatively. The intraoperative blood flow in patients with functioning autologous arteriovenous fistula (78) was significantly higher than that of patients without functioning autologous arteriovenous fistulas (407 ± 25 vs 252 ± 42 mL/min, respectively; p < 0.005) (11). Conclusion: The intraoperative measurement of blood flow is a useful tool to predict the outcome of maturation in autologous arteriovenous fistula. With this method, technical problems can be detected and corrected intraoperatively. Routine implementation of intraoperative flow measurements has to be examined by prospective controlled trials.

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