Home  About us  Contact
 

Venous Hemodynamics (venous + hemodynamic)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

MR-based visualization and quantification of three-dimensional flow characteristics in the portal venous system

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010
Zoran Stankovic MD
Abstract Purpose: To evaluate the feasibility of time-resolved flow-sensitive MRI for the three-dimensional (3D) visualization and quantification of normal and pathological portal venous (PV) hemodynamics. Materials and Methods: Portal venous hemodynamics were evaluated in 18 healthy volunteers and 5 patients with liver cirrhosis. ECG- and adaptive respiratory navigator gated flow-sensitive 4D MRI (time-resolved 3D MRI with three-directional velocity encoding) was performed on a 3 Tesla MR system (TRIO, Siemens, Germany). Qualitative flow analysis was achieved using 3D streamlines and time-resolved particle traces originating from seven emitter planes precisely placed at anatomical landmarks in the PV system. Quantitative analysis included retrospective extraction of regional peak and mean velocities and vessel area. Results were compared with standard 2D flow-sensitive MRI and to the reference standard Doppler ultrasound. Results: Qualitative flow analysis was successfully used in the entire PV system. Venous hemodynamics in all major branches in 17 of 18 volunteers and 3 of 5 patients were reliably depicted with good interobserver agreement (kappa = 0.62). Quantitative analysis revealed no significant differences and moderate agreement for peak velocities between 3D MR and 2D MRI (r = 0.46) and Doppler ultrasound (US) (r = 0.35) and for mean velocities between 3D and 2D MRI (r = 0.41). The PV area was significantly (P < 0.01) higher in 3D and 2D MRI compared with US. Conclusion: We successfully applied 3D MR velocity mapping in the PV system, providing a detailed qualitative and quantitative analysis of normal and pathological hemodynamics. J. Magn. Reson. Imaging 2010;32:466,475. © 2010 Wiley-Liss, Inc. [source]

Venous hemodynamics in living donor right lobe liver transplantation

LIVER TRANSPLANTATION, Issue 9 2002
Gabriel E. Gondolesi MD
We evaluated the influence of portal and hepatic venous hemodynamics on the immediate and 3-month postoperative function of living donor right lobe grafts. Portal velocity was measured prospectively by ultrasound in 14 consecutive donor/recipient pairs. Velocity was converted to flow with the Moriyasu formula. Measurements were taken in donors in the operating room and in recipients at 1 hour after reperfusion and 3 months after transplant. Recipient liver function tests were measured postoperatively. Prereperfusion and postreperfusion liver biopsies were evaluated and correlated with the hemodynamic and biochemical results. There were 11 male (78.6%) and 3 female donors (mean age, 38.9 ± 9.8 years) for 10 male (71.4%) and 4 female recipients (mean age, 49.3 ± 14 years). The mean graft/recipient weight ratio was 1.22 ± 0.3. The mean right portal vein pressure was 8 ± 1.8 mm Hg in donors versus 13 ± 4.7 mm Hg in recipients (P < .05). The mean peak flow velocity (Vmax) in the portal vein in donors was 47.6 ± 12.8 cm/sec (normal, 44 cm/sec). One hour after graft reperfusion in the recipient, the mean portal Vmax was significantly higher at 94.7 ± 28.4 cm/sec (P = .004), but by 3 months follow-up, mean portal Vmax had fallen to 58.8 ± 37.8 (P = .01). Recipient portal vein Vmax highly correlated with portal flow (r = 0.7, P = .01). Increased recipient total bilirubin on postoperative day 2 correlated highly with higher recipient portal flow one hour after transplant (r = 0.6; P = .03). Portal vein velocity/flow dramatically increases after reperfusion, returning to baseline about 3 months after transplant. Evaluation of hepatic and portal venous flow is a relatively easy skill to acquire. Intraoperative ultrasound may enable the surgeon to predict graft dysfunction and possibly, may be used to implement pre-emptive therapies. [source]

MR-based visualization and quantification of three-dimensional flow characteristics in the portal venous system

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010
Zoran Stankovic MD
Abstract Purpose: To evaluate the feasibility of time-resolved flow-sensitive MRI for the three-dimensional (3D) visualization and quantification of normal and pathological portal venous (PV) hemodynamics. Materials and Methods: Portal venous hemodynamics were evaluated in 18 healthy volunteers and 5 patients with liver cirrhosis. ECG- and adaptive respiratory navigator gated flow-sensitive 4D MRI (time-resolved 3D MRI with three-directional velocity encoding) was performed on a 3 Tesla MR system (TRIO, Siemens, Germany). Qualitative flow analysis was achieved using 3D streamlines and time-resolved particle traces originating from seven emitter planes precisely placed at anatomical landmarks in the PV system. Quantitative analysis included retrospective extraction of regional peak and mean velocities and vessel area. Results were compared with standard 2D flow-sensitive MRI and to the reference standard Doppler ultrasound. Results: Qualitative flow analysis was successfully used in the entire PV system. Venous hemodynamics in all major branches in 17 of 18 volunteers and 3 of 5 patients were reliably depicted with good interobserver agreement (kappa = 0.62). Quantitative analysis revealed no significant differences and moderate agreement for peak velocities between 3D MR and 2D MRI (r = 0.46) and Doppler ultrasound (US) (r = 0.35) and for mean velocities between 3D and 2D MRI (r = 0.41). The PV area was significantly (P < 0.01) higher in 3D and 2D MRI compared with US. Conclusion: We successfully applied 3D MR velocity mapping in the PV system, providing a detailed qualitative and quantitative analysis of normal and pathological hemodynamics. J. Magn. Reson. Imaging 2010;32:466,475. © 2010 Wiley-Liss, Inc. [source]

Venous hemodynamics in living donor right lobe liver transplantation

LIVER TRANSPLANTATION, Issue 9 2002
Gabriel E. Gondolesi MD
We evaluated the influence of portal and hepatic venous hemodynamics on the immediate and 3-month postoperative function of living donor right lobe grafts. Portal velocity was measured prospectively by ultrasound in 14 consecutive donor/recipient pairs. Velocity was converted to flow with the Moriyasu formula. Measurements were taken in donors in the operating room and in recipients at 1 hour after reperfusion and 3 months after transplant. Recipient liver function tests were measured postoperatively. Prereperfusion and postreperfusion liver biopsies were evaluated and correlated with the hemodynamic and biochemical results. There were 11 male (78.6%) and 3 female donors (mean age, 38.9 ± 9.8 years) for 10 male (71.4%) and 4 female recipients (mean age, 49.3 ± 14 years). The mean graft/recipient weight ratio was 1.22 ± 0.3. The mean right portal vein pressure was 8 ± 1.8 mm Hg in donors versus 13 ± 4.7 mm Hg in recipients (P < .05). The mean peak flow velocity (Vmax) in the portal vein in donors was 47.6 ± 12.8 cm/sec (normal, 44 cm/sec). One hour after graft reperfusion in the recipient, the mean portal Vmax was significantly higher at 94.7 ± 28.4 cm/sec (P = .004), but by 3 months follow-up, mean portal Vmax had fallen to 58.8 ± 37.8 (P = .01). Recipient portal vein Vmax highly correlated with portal flow (r = 0.7, P = .01). Increased recipient total bilirubin on postoperative day 2 correlated highly with higher recipient portal flow one hour after transplant (r = 0.6; P = .03). Portal vein velocity/flow dramatically increases after reperfusion, returning to baseline about 3 months after transplant. Evaluation of hepatic and portal venous flow is a relatively easy skill to acquire. Intraoperative ultrasound may enable the surgeon to predict graft dysfunction and possibly, may be used to implement pre-emptive therapies. [source]