scholarly journals MRI- and CT-venography in the diagnosis of hemodynamic disorders in patients suffering from lower extremities chronic venous disorders. Part II. Possibilities of MRI in diagnostics of the deep vein thrombosis

2021 ◽  
Vol 25 (1) ◽  
pp. 117-139
Author(s):  
E. V. Shajdakov ◽  
A. B. Sannikov ◽  
V. M. Emelyanenko ◽  
L. N. Kryukova ◽  
A. E. Baranova ◽  
...  
Keyword(s):  
Blood Flow ◽  
Magnetic Resonance ◽  
Contrast Agents ◽  
Lower Limb ◽  
Pulse Sequences ◽  
Vena Cava ◽  
Venous Blood Flow ◽  
Vein Thrombosis ◽  
Thrombus Imaging ◽  
Specificity And Sensitivity

In this literature review, the analysis of the studies of venous blood flow pathology in the inferior Vena cava system using magnetic resonance imaging (MRI) is carried out. Special attention is paid to the attempts made to use this method in the diagnosis of chronic lower limb vein disorders (CVD) through magnetic resonance venography (MRV). Historically and methodically, the gradual introduction of MRV methods in the diagnosis of lower limb vein thrombosis (LEDVT) and venous thromboembolism (VTE) has been shown.Methods of non-contrast MRV based on the effect of blood flow, as in the case of MR-Angiography, are divided into two principal groups: methods based on the amplitude effects of Time-of-Flight (TOF) and methods based on Phase Contrast effects (PC). Techniques for conducting contrast-free MRV are described in detail. Attention is paid to pulse sequences used in the world for visualization of veins in contrast-free MRV in TOF and PC mode (FR-FBI, SPADE, SSFP) and post-processing methods: 2D-TOF MRV FLASH, 2D-TOF MRV CRASS, FIPS, VED, VENS.Contrast-enhanced MRV (CE MRV) is based on the use of “blood pool” contrast agents, which feature the ability to form stable compounds with blood plasma proteins. Worldwidesubstances with magnetic and supermagnetic properties based on gadolinium or iron oxide are used as contrast agents for CE MRV. The result of using these contrast agents is an increase in the quality of visualization due to a better signal to noise ratio (SNR) using 3D image processing (3D CE MRV) using fast sequences: GRE, TFLAS, VESPA, CAT, in conditions of direct and indirect CE MRV.It is noted that in recent years, certain restrictions have been imposed on certain linear contrast agents containing gadolinium in their further use. Therefore, for the purpose of CE MRV, it is efficientl to use only cyclic contrast agents to avoid unnecessary risks.Contrast-free MRV has again received intensive development in recent years, due to the restrictions imposed, one of these methods is direct thrombus imaging (Direct Thrombus Imaging – DTI or Magnetic Resonance Direct Thrombus Imaging - MRDTI) using fast pulse sequences: bSSFP, BBTI, DANTE. The latest research on this LEDVT diagnostic method was published in 2019 and has shown high diagnostic value.For all the most commonly used methods of MRV, specificity and sensitivity are shown.Further MRV in patients with CVD and DVT is a promising diagnostic task in modern phlebology. MRV should be introduced into clinical practice more actively than it is today.

Effect of sitting in ergonomic chairs on lower limb venous blood flow

2009 ◽  
Vol 8 (2,3) ◽  
pp. 125-132 ◽  
Author(s):  
Erik Levin ◽  
Deborah Macintosh ◽  
Tanya Baker ◽  
Mark Weatherall ◽  
Richard Beasley
Keyword(s):  
Blood Flow ◽  
Lower Limb ◽  
Venous Blood ◽  
Venous Blood Flow

scholarly journals Magnetic Resonance Thrombus Imaging to Differentiate Acute from Chronic Portal Vein Thrombosis

TH Open ◽  
2020 ◽  
Vol 04 (03) ◽  
pp. e224-e230
Author(s):  
Lisette F. van Dam ◽  
Frederikus A. Klok ◽  
Maarten E. Tushuizen ◽  
Walter Ageno ◽  
Sarwa Darwish Murad ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Portal Vein ◽  
Portal Vein Thrombosis ◽  
Test Performance ◽  
Expert Panel ◽  
Three Dimensional ◽  
Acute Thrombosis ◽  
Vein Thrombosis ◽  
Thrombus Imaging ◽  
Enhanced Computed Tomography

Abstract Introduction Timely diagnosis and treatment of portal vein thrombosis (PVT) is crucial to prevent morbidity and mortality. However, current imaging tests cannot always accurately differentiate acute from chronic (nonocclusive) PVT. Magnetic resonance noncontrast thrombus imaging (MR-NCTI) has been shown to accurately differentiate acute from chronic venous thrombosis at other locations and may also be of value in the diagnostic management of PVT. This study describes the first phase of the Rhea study (NTR 7061). Our aim was to select and optimize MR-NCTI sequences that would be accurate for differentiation of acute from chronic PVT. Study Design The literature was searched for different MRI sequences for portal vein and acute thrombosis imaging. The most promising sequences were tested in a healthy volunteer followed by one patient with acute PVT and two patients with chronic PVT, all diagnosed on (repetitive) contrast-enhanced computed tomography (CT) venography to optimize the MR-NCTI sequences. All images were evaluated by an expert panel. Results Several MR-NCTI sequences were identified and tested. Differentiation of acute from chronic PVT was achieved with 3D T1 TFE (three-dimensional T1 turbo field echo) and 3D T1 Dixon FFE (three-dimensional T1 fast field echo) sequences with best image quality. The expert panel was able to confirm the diagnosis of acute PVT on the combined two MR-NCTI sequences and to exclude acute PVT in the two patients with chronic PVT. Conclusion Using 3D T1 TFE and 3D T1 Dixon FFE sequences, we were able to distinguish acute from chronic PVT. This clinical relevant finding will be elucidated in clinical studies to establish their test performance.

Magnetic resonance direct thrombus imaging: a novel technique for imaging venous thromboemboli

2003 ◽  
Vol 89 (05) ◽  
pp. 773-782 ◽  
Author(s):  
Beverley Hunt ◽  
Alan Moody ◽  
James Kelly
Keyword(s):  
Magnetic Resonance ◽  
Noninvasive Imaging ◽  
Diagnostic Errors ◽  
Filling Defect ◽  
Intravenous Contrast ◽  
Vein Thrombosis ◽  
Novel Technique ◽  
Thrombus Imaging ◽  
Noninvasive Imaging Technique ◽  
Initial Imaging

SummaryInvasive testing is now seldom required in patients with suspected venous thromboembolism (VTE). However, a corollary of noninvasive imaging is increased complexity as results are often yielded as probabilities rather than definitive answers and additional testing is frequently required following initial imaging. This creates a milieu in which misunderstandings and protocol violations are common, potentially leading to diagnostic errors. A highly accurate noninvasive imaging technique which allows immediate treatment decisions to be made is needed. Magnetic resonance direct thrombus imaging (MRDTI) is a novel technique which detects methaemoglobin in clot, allowing visualisation of thrombus without using intravenous contrast. It has two major advantages over conventional modalities which identify it as having the potential to fill this role. Firstly, direct visualisation of thrombus overcomes many of the pitfalls of conventional techniques, which have either identified thrombus as a filling defect or in terms of surrogates. Secondly, simultaneous imaging of the legs and chest allows a comprehensive assessment of thrombus load, minimising the importance of overlooked subsegmental pulmonary embolism (PE) and potentially facilitating more titrated treatment.Early data suggest MRDTI is highly accurate for the detection of both deep vein thrombosis (DVT) and PE, and ongoing outcome studies are evaluating the safety of withholding treatment in suspected DVT and PE on the basis of negative MRDTI alone. If favorable, a multi-centre outcome study evaluating cost-effectiveness as well as safety would be justified. Subject to further evaluation, this technique has the potential greatly to simplify and standardise the investigation of suspected VTE.

scholarly journals Effect of spontaneous breathing on umbilical venous blood flow and placental transfusion during delayed cord clamping in preterm lambs

2019 ◽  
Vol 105 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Emma Brouwer ◽  
Arjan B te Pas ◽  
Graeme R Polglase ◽  
Erin V McGillick ◽  
Stefan Böhringer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Body Weight ◽  
Spontaneous Breathing ◽  
Venous Blood ◽  
Vena Cava ◽  
Venous Blood Flow ◽  
Delayed Cord Clamping ◽  
Venous Flow ◽  
Cord Clamping ◽  
Pregnant Sheep

IntroductionDuring delayed umbilical cord clamping, the factors underpinning placental transfusion remain unknown. We hypothesised that reductions in thoracic pressure during inspiration would enhance placental transfusion in spontaneously breathing preterm lambs.ObjectiveInvestigate the effect of spontaneous breathing on umbilical venous flow and body weight in preterm lambs.MethodsPregnant sheep were instrumented at 132–133 days gestational age to measure fetal common umbilical venous, pulmonary and cerebral blood flows as well as arterial and intrapleural (IP) pressures. At delivery, doxapram and caffeine were administered to promote breathing. Lamb body weights were measured continuously and breathing was assessed by IP pressure changes.ResultsIn 6 lambs, 491 out of 1117 breaths were analysed for change in body weight. Weight increased in 46.6% and decreased in 47.5% of breaths. An overall mean increase of 0.02±2.5 g per breath was calculated, and no net placental transfusion was observed prior to cord clamping (median difference in body weight 52.3 [−54.9–166.1] g, p=0.418). Umbilical venous (UV) flow transiently decreased with each inspiration, and in some cases ceased, before UV flow normalised during expiration. The reduction in UV flow was positively correlated with the standardised reduction in (IP) pressure, increasing by 109 mL/min for every SD reduction in IP pressure. Thus, the reduction in UV flow was closely related to inspiratory depth.ConclusionsSpontaneous breathing had no net effect on body weight in preterm lambs at birth. UV blood flow decreased as inspiratory effort increased, possibly due to constriction of the inferior vena cava caused by diaphragmatic contraction, as previously observed in human fetuses.

VWF-Mediated Platelet Adhesion is Required for Deep Vein Thrombosis in a Flow Restriction Model.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 473-473
Author(s):  
Alexander Brill ◽  
Tobias Fuchs ◽  
Janie Yang ◽  
Maria Köllnberger ◽  
Anil K. Chauhan ◽  
...  
Keyword(s):  
Blood Flow ◽  
Deep Vein Thrombosis ◽  
Vessel Wall ◽  
Conflicts Of Interest ◽  
Blood Stasis ◽  
Vena Cava ◽  
Oxygen Mixture ◽  
Vein Thrombosis ◽  
Flow Restriction ◽  
Deep Vein

Abstract Abstract 473 Deep vein thrombosis (DVT) and its life-threatening complication, pulmonary embolism, are wide-spread in the Western world. Disturbance of blood flow without substantial endothelial denudation is a leading pathogenic factor for non-cancer related DVT. Von Willebrand Factor (VWF), a large multimeric protein, facilitates hemostasis via two separate pathways by stabilizing coagulation Factor VIII (FVIII) and by recruiting platelets to injured vessel wall or thrombi through the interaction with GPIb-alpha. Whereas the role of FVIII in DVT has been suggested by clinical studies (Koster T et al., Lancet, 345(8943):152-5,1995), whether VWF-platelet interaction is implicated in venous thrombosis remains unclear. We utilized murine models of partial and complete flow restriction in the inferior vena cava (IVC) in mice to mimic clinical conditions in which thrombus develops in deep veins. In 8-10 week old C57BL/6 male mice anesthetized by isoflurane-oxygen mixture, IVC and two side branches were ligated by a polypropylene suture immediately below the renal veins to obtain complete blood stasis. For partial flow restriction (stenosis), IVC ligation was performed over a 30G needle and then the needle was removed. Mice were euthanized after 48 h and thrombi from the IVC were taken for analysis. Results were evaluated using the chi-square test. The VWF-/- mice were completely protected from thrombosis in the stenosis model: none of the 14 VWF-/- mice developed a thrombus compared to 6/6 wild-type (WT) mice (p<0.001). In the stasis model, a similar albeit less pronounced phenotype was observed (33% of VWF-/- mice with thrombus, n=9, versus 82% in WT mice, n=11; p<0.03). Stenosis-induced thrombi in WT mice contained abundant amounts of VWF, as was shown by immunostaining. To delineate the involvement of VWF-platelet interactions, we infused WT mice with GPG-290, a recombinant GPIb-alpha N-terminal domain conjugated with human IgG1 Fc fragment. This compound has been shown to inhibit VWF-GPIb-alpha interaction (Hennan JK et al., Thromb Haemost, 95(3):469-75, 2006), but does not interfere with FVIII binding and turnover. Infusion of GPG-290 markedly reduced thrombus development in the stenosis model (3/9 GPG-290-treated WT mice developed DVT versus 9/9 vehicle-treated control mice; p=0.003). Notably, in the absence of blood flow (stasis model), GPG-290 was less effective (83% thrombosis development in vehicle-treated WT, n=6, versus 55.6% thrombosis in GPG-290-treated WT group, n=9; p=0.26). We next addressed the events preceding thrombus formation in the DVT stenosis model using intravital microscopy on living mice. We observed accumulation of fluorescently labeled platelets and leukocytes in the IVC in the area below the suture 6 h after stenosis induction. The amount of both adhering platelets and leukocytes was substantially reduced in VWF-/- mice compared to WT (approx. 20-fold, p<0.005 and 11-fold, p<0.001, respectively). In conclusion, VWF mediates platelet and leukocyte recruitment to the vessel wall. This initiates thrombus development in the absence of major endothelial injury. Interference with the VWF-GPIb-alpha axis may be a potential target for prophylaxis of deep vein thrombosis. Disclosures: No relevant conflicts of interest to declare.

Azygos venous blood flow while fasting, postprandially, and after endoscopic variceal ligation, measured by magnetic resonance imaging

1999 ◽  
Vol 34 (3) ◽  
pp. 310-314 ◽  
Author(s):  
Shigeo Sugano ◽  
Kunihiro Yamamoto ◽  
Naoko Takamura ◽  
Kouich Momiyama ◽  
Manabu Watanabe ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Venous Blood ◽  
Endoscopic Variceal Ligation ◽  
Venous Blood Flow ◽  
Resonance Imaging
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