A volumetric index for the quantification of deep venous thrombosis

Femoral to abdomen tunneling at the bedside for medium/long term venous access

BACKGROUND

Femoral to abdomen tunneling of small-bore central venous catheters is a bedside technique for patients with contraindications to a thoracic approach, or as an alternative to a lower extremity catheter exit site.

METHOD

A femoral to abdomen tunneling technique was implemented for patients receiving medium and long-term intravenous treatments with contraindications to the thoracic venous approach or as an alternative to a lower extremity catheter exit site. All venous access devices were inserted with ultrasound guidance under local anesthesia, and catheter tip placement assessed by post procedural radiography.

RESULTS

In this case series, from January 2020 to January 2023, a total of eight FTA-tunneled venous access devices were inserted. There were seven ambulatory patients and one bedbound patient. The median length of the subcutaneous tunnel was 20 cm, ranging from 15 to 27 cm. The median length of the intravenous catheter to the terminal tip was 31 cm, ranging from 23 to 40 cm. Tip location was confirmed by post-procedural abdominal radiograph. The catheter tip locations were interpreted to be at the level of T8-T9 (2), T12 (1), L4 (2), L2 (2), L1(1).No insertion or post insertion related complication was reported. Six patients completed the scheduled intravenous treatment. One patient was unable to be tracked due to transfer to an outside facility. One catheter initially demonstrated to be coiled over the left common iliac vessel was repositioned using a high flow flush technique. There was one reported catheter dislodgment by the nurse providing care and maintenance. The overall implant days were 961, with a median dwell time of 125 days ranging from 20 to 399 days.

CONCLUSION

Femoral to abdomen tunneling provides an alternative exit site useful in select patients with complex intravenous access. The data of this small retrospective review suggests this a safe and minimally invasive bedside procedure.

Assessment of flow mechanics in the lower extremity venous system

BACKGROUND

The Reynolds number (R_e) is a dimensionless parameter that describes fluid flow mechanics. Veins are compliant and collapsible vascular conduits that can accommodate large volume changes in response to small pressure changes. However, only sparse information is available about flow parameters such as the R_e in the venous system.

METHODS

Bilateral duplex ultrasound examination of 15 healthy volunteers (30 limbs) was performed before and after exercise (four flights of stairs) of the veins of the lower extremity (left and right sides) and inferior vena cava. These volunteers had been confirmed to not have any signs or symptoms of lower extremity venous disease via focused history and physical examination findings.

RESULTS

Most of the volunteers were women (73%). Their mean age was 37 ± 12.8 years. The R_e was highest in the inferior vena cava among all the veins examined (470 ± 144 before exercise and 589 ± 205 after exercise; P = .04). The association between the change in R_e before and after exercise and the specific vein examined was also significant for the right and left external iliac veins, right and left common femoral veins, right and left profunda femoris veins, right and left femoral veins, and right common iliac vein. Resistance and velocity maps for the lower extremity venous system were also created. The velocity increased and the resistance decreased as one moved up the venous tree toward the right atrium.

CONCLUSIONS

The R_e increased for most of the lower extremity veins after exercise in our healthy volunteers. However, the critical value for turbulent flow was not reached despite the exercise.

Deep Learning for Accurate Segmentation of Venous Thrombus from Black-Blood Magnetic Resonance Images: A Multicenter Study

Objective

Deep vein thrombosis (DVT) is the third-largest cardiovascular disease, and accurate segmentation of venous thrombus from the black-blood magnetic resonance (MR) images can provide additional information for personalized DVT treatment planning. Therefore, a deep learning network is proposed to automatically segment venous thrombus with high accuracy and reliability.

Methods

In order to train, test, and external test the developed network, total images of 110 subjects are obtained from three different centers with two different black-blood MR techniques (i.e., DANTE-SPACE and DANTE-FLASH). Two experienced radiologists manually contoured each venous thrombus, followed by reediting, to create the ground truth. 5-fold cross-validation strategy is applied for training and testing. The segmentation performance is measured on pixel and vessel segment levels. For the pixel level, the dice similarity coefficient (DSC), average Hausdorff distance (AHD), and absolute volume difference (AVD) of segmented thrombus are calculated. For the vessel segment level, the sensitivity (SE), specificity (SP), accuracy (ACC), and positive and negative predictive values (PPV and NPV) are used.

Results

The proposed network generates segmentation results in good agreement with the ground truth. Based on the pixel level, the proposed network achieves excellent results on testing and the other two external testing sets, DSC are 0.76, 0.76, and 0.73, AHD (mm) are 4.11, 6.45, and 6.49, and AVD are 0.16, 0.18, and 0.22. On the vessel segment level, SE are 0.95, 0.93, and 0.81, SP are 0.97, 0.92, and 0.97, ACC are 0.96, 0.94, and 0.95, PPV are 0.97, 0.82, and 0.96, and NPV are 0.97, 0.96, and 0.94.

Conclusions

The proposed deep learning network is effective and stable for fully automatic segmentation of venous thrombus on black blood MR images.

Pediatric May-Thurner Syndrome-Systematic review and individual patient data meta-analysis

BACKGROUND

The outcomes of deep vein thrombosis (DVT) in children with May-Thurner Syndrome (MTS) remain unclear.

OBJECTIVES

This systematic review and patient-level meta-analysis aims to describe the outcomes of children with MTS presenting with DVT.

METHODS

A systematic review of the published literature was performed. Data related to patients <18 years diagnosed with MTS and DVT was extracted. Risk of bias was assessed using the Murad criteria. Outcomes included vessel patency post-treatment, DVT recurrence, and post-thrombotic syndrome (PTS). Predictive and explanatory models were developed for these outcomes.

RESULTS

In total, 109 cases were identified (age range 4-17 years; 77 females) in 28 studies; 75% of patients had ≥1 additional risk factor for DVT. PTS was seen in 61% of patients, DVT recurrence in 38%, and complete vessel patency post-treatment in 65%. The models developed to predict and explain PTS performed poorly overall. Recurrent thrombosis (adjusted for age and patency) predicted PTS (odds ratio [OR] 3.36, 95% confidence interval [CI] 1.28-8.82). DVT management strategies (adjusted for age and DVT characteristics) predicted vessel patency (OR 2.10, 95% CI 1.43-3.08). Lack of complete vessel patency (adjusted for age and thrombophilia) predicted recurrent DVT (OR 2.70, 95% CI 1.09-6.67). Sensitivity analyses showed the same direction of effects for all outcomes.

CONCLUSIONS

PTS and DVT recurrence occur frequently in pediatric MTS. PTS prediction is complex and it was not possible to identify early predictors to guide clinical practice. Use of imaging-guided therapy and thrombus burden predicted venous patency, and lack of patency predicted DVT recurrence.

Comparison of Pharmacomechanical Catheter-Directed Thrombolysis versus Catheter-Directed Thrombolysis for the Treatment of Acute Iliofemoral Deep Vein Thrombosis: Measures of Long-Term Clinical Outcome and Quality of Life

BACKGROUND

We studied the occurrence of post-thrombotic syndrome (PTS) in patients with either Pharmacomechanical Catheter-Directed Thrombolysis (hereafter "pharmacomechanical thrombolysis"; PT) or Catheter-Directed Thrombolysis (CDT) for the treatment of acute iliofemoral deep vein thrombosis (DVT).

METHODS

This retrospective study of data archived between September 2013 and September 2015 was surveyed. Two separate patient populations were identified and analyzed: patients were separated into PT group or CDT group. For up to 5 years post-treatment, the incidence, severity of PTS, and chronic venous insufficiency questionnaire (CIVIQ) score difference were compared.

RESULTS

The study identified 131 patients divided into PT group (65) and CDT group (66). Within the 5-year follow-up period, there was no significant difference in the incidence of PTS (45.0% PT vs. 57.6% CDT; odds ratio (OR) = 0.602; 95% confidence interval (CI), 0.291-1.242; P = 0.201), but there was reduced severe PTS in the PT group (Villalta scale ≥15 or ulcer:11.7% PT vs. 27.1% CDT; OR 0.355; 95%CI 0.134-0.941, P = 0.039; and Venous Clinical Severity Score (VCSS) ≥8: 13.3%PT vs. 28.8% CDT; OR 0.380; 95% CI 0.149-0.967, P = 0.045). There was also a larger improvement of venous disease-specific quality of life (QOL) in the PT group at 5 years [(62.89 ± 14.19) vs (56.39 ±15.62), P = 0.036] compared to the CDT group.

CONCLUSION

In patients with acute iliofemoral DVT treated with PT, PT significantly reduced PTS severity scores, and resulted in greater improvement in venous disease-specific QOL. However, the incidence of was not significantly different from that measured in the CDT.

Lower-extremity Arterial Thrombosis Associated with COVID-19 Is Characterized by Greater Thrombus Burden and Increased Rate of Amputation and Death

Background During the peak of the coronavirus disease 2019 (COVID-19) pandemic, the authors noted an increase in positive lower-extremity CT angiography examinations in patients who presented with leg ischemia. The goal of this study was to determine whether lower-extremity arterial thrombosis was associated with COVID-19 and whether it was characterized by greater severity in these patients. Materials and Methods In this retrospective propensity score-matched study approved by the institutional review board, 16 patients who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and who underwent CT angiography of the lower extremities and 32 patients who tested negative for SARS-CoV-2 observed from January to April 2018, January to April 2019, and January to April 2020 were compared using three scoring systems: two systems including all vessels, with weighting in one system given to more proximal vessels and with weighting in the other system given to more distal vessels, and a third system in which only the common iliac through popliteal arteries were considered. Correlation with presenting symptoms and outcomes was computed. Fisher exact tests were used to compare patients who tested positive for COVID-19 with patients who tested negative for COVID-19 regarding the presence of clots and presenting symptoms. A Mantel-Haenszel test was used to associate outcome of death and/or amputation with COVID-19 adjusted according to history of peripheral vascular disease (PVD). Results Sixteen patients with confirmed COVID-19 (70 years ± 14 [standard deviation]; seven women) who underwent CT angiography and 32 propensity score-matched control patients (71 years ± 15; 16 women) were included. All patients with COVID-19 (100%, 95% confidence interval [CI]: 79%, 100%) had at least one thrombus, and only 69% of control patients (95% CI: 50%, 84%) had thrombi (P = .02). Ninety-four percent of patients with COVID-19 (95% CI: 70%, 99.8%) had proximal thrombi compared with 47% of control patients (95% CI: 29%, 65%) (P < .001). The mean thrombus score using any of the three scoring systems yielded greater scores in patients with COVID-19 (P < .001). Adjusted for history of PVD, death or limb amputation was more common in patients with COVID-19 (odds ratio = 25; 95% CI: 4.3, 147; P < .001). Patients with COVID-19 who presented with symptoms of leg ischemia only were more likely to avoid amputation or death than patients who also presented with pulmonary or systemic symptoms (P = .001). Conclusion Coronavirus disease 2019 is associated with lower-extremity arterial thrombosis characterized by a greater clot burden and a more dire prognosis. © RSNA, 2020.

Review of imaging and endovascular intervention of iliocaval venous compression syndrome

Iliocaval venous compression syndrome (ICS) is the extrinsic compression of the common iliac vein by the overlying iliac artery against the vertebra. Chronic compression can lead to venous stenosis and stasis, which manifests as chronic venous disease and treatment resistance. Therefore, early recognition of ICS and prompt treatment are essential. Clinical presentations of ICS can be ambiguous and diagnosis requires a high index of suspicion with the relevant imaging studies. The initial imaging test is typically a Duplex ultrasound for vessel assessment and pelvic ultrasound to exclude a compressive mass, which is followed by computed tomography (CT) or magnetic resonance (MR) venography. CT and MRI can identify the anatomical causes for venous compression. In patients with high clinical suspicion for ICS, negative findings on CT and MR venography would still warrant further investigations. Definitive diagnosis can be established using catheter-based venography complemented with intravascular ultrasonography but the nature of their invasiveness limits its utility as a routine imaging modality. In this review paper, we will discuss the evidence, utility and limitations of the existing imaging modalities and endovascular intervention used in the management of ICS.

Effect of Model Thrombus Volume and Elastic Modulus on Magnetomotive Ultrasound Signal Under Pulsatile Flow

Direct ultrasonic imaging of arterial and venous thrombi could aid in diagnosis and treatment planning by providing rapid and cost-effective measurements of thrombus volume and elastic modulus. Toward this end, it was demonstrated that open-air magnetomotive ultrasound (MMUS) provides specific contrast to superparamagnetic iron oxide-labeled model thrombi embedded in gelatin-based blood vessel-mimicking flow phantoms. MMUS was performed on model thrombi in the presence of pulsatile flow that mimics cardiac-induced motion found in real vasculature. The MMUS signal and contrast-to-noise ratio (CNR) were measured across a range of physiologically relevant thrombus volumes and elastic moduli. Model thrombus volumes as small as 0.5 ml were shown to be detectable (CNR > 1) over the entire range of elastic moduli tested (3.5-40 kPa). It was also found that MMUS signal and CNR are increased with increasing thrombus volume ( ) and decreasing elastic modulus ( ), while variations in pulsatile flow rate had little effect. These findings demonstrate that MMUS has promise as a direct in vivo thrombosis imaging modality for quantifying thrombus volume and stiffness.

Analysis of threshold stenosis by multiplanar venogram and intravascular ultrasound examination for predicting clinical improvement after iliofemoral vein stenting in the VIDIO trial

BACKGROUND

Selecting patients for iliofemoral vein stenting has traditionally relied on the identification and quantification of stenotic lesions with imaging such as multiplanar venography. Recently, intravascular ultrasound (IVUS) imaging has become more available. However, to date, the usefulness of these imaging modalities using the customary >50% treatment threshold for diameter (multiplanar venography) and area (IVUS) stenosis of iliofemoral veins has not been validated prospectively within the context of clinical improvement.

METHODS

The multicenter Venogram Versus Intravascular Ultrasound for Diagnosing and Treating Iliofemoral Vein Obstruction (VIDIO) trial prospectively enrolled 100 symptomatic patients (Clinical Etiologic Anatomic Pathophysiologic [CEAP] classification of 4-6) with suspected iliofemoral venous outflow disease. Venous stenting for presumed significant iliofemoral vein stenosis, based on imaging and clinical findings, was performed on 68 patients. Based on imaging, stenosis was characterized as nonthrombotic in 48 patients and post-thrombotic in 20 patients. Each underwent baseline and poststenting venography and IVUS to compare the diagnostic and clinical usefulness of the tests. The revised Venous Clinical Severity Score was used to assess clinical patient outcome. A >4-point reduction in the revised Venous Clinical Severity Score between baseline and 6 months was used as an indicator of clinically meaningful improvement. Receiver operating characteristic curve analysis was used to determine the optimal diameter and area thresholds for prediction of clinical improvement.

RESULTS

Clinical improvement after stenting was best predicted by IVUS baseline measurement of area stenosis (area under the curve, 0.64; P = .04), with >54% estimated as the optimal threshold of stenosis indicating interventional treatment. With measurement of lumen gain from baseline to after the procedure, the optimal reduction in vein stenosis correlative of later clinical improvement was >41%; IVUS measurement of area stenosis was most predictive (area under the curve, 0.70; P = .004). Venographic measurements of baseline stenosis and stenotic change were not predictive of later improvement. In a 48-patient nonthrombotic subset analysis, IVUS diameter rather than area measurements of baseline stenosis were significantly predictive of clinical success, but indicated a higher optimal threshold of stenosis (>61%) may be necessary.

CONCLUSIONS

This study suggests that IVUS shows significant usefulness at predicting when stenting iliofemoral vein stenosis in patients clinical-etiologic-anatomic-pathophysiologic classification of 4-6 will result in significant symptom improvement. Our findings corroborate the conventional >50% cross-sectional area threshold by IVUS as defining a clinically significant iliofemoral stenosis that, when stented, has significant predictive value for symptom improvement. In nonthrombotic patients, however, a threshold of >61% diameter stenosis by IVUS may better predict clinical improvement.

What is the definition of successful lysis: reporting standard?

Deep vein thrombosis, and the resultant development of post-thrombotic syndrome, is a significant health issue. Recent evidence demonstrates that the severity of post-thrombotic syndrome symptoms is directly related to the level of venous thrombosis and following treatment these subsequent symptoms are inversely related to the degree of thrombus removal. If we can improve, and preferably standardise the terminology associated with pre-treatment assessment of thrombus load and post-treatment success of thrombus removal techniques, we should then be able to choose more tailor-made techniques to greater benefit our patients. A number of scoring systems have been devised for the assessment of venous thrombus burden, with a majority impractical for everyday usage. In order to provide a more practical solution, the lower extremity thrombosis classification has been developed, using information on anatomical location for venous thrombus combined with a clinical indicator as to the likely sequelae. Anatomical success following venous thrombolysis can be defined by assessing restoration of anterograde flow in the treated vein or the percentage degree of thrombolysis, using venography. The second option is the method most frequently utilised, with the Venous Registry grading system applied. Data from recent trials have given us conflicting and confusing data mainly because we are not using standardised terminology. We urgently need to agree on a standard method of description of thrombus removal before stent placement which also incorporates the likely clinical impact of the area involved in the thrombosis.

A Multicenter MRI Protocol for the Evaluation and Quantification of Deep Vein Thrombosis

We evaluated a magnetic resonance venography (MRV) approach with gadofosveset to quantify total thrombus volume changes as the principal criterion for treatment efficacy in a multicenter randomized study comparing edoxaban monotherapy with a heparin/warfarin regimen for acute, symptomatic lower extremities deep vein thrombosis (DVT) treatment. We also used a direct thrombus imaging approach (DTHI, without the use of a contrast agent) to quantify fresh thrombus. We then sought to evaluate the reproducibility of the analysis methodology and applicability of using 3D magnetic resonance venography and direct thrombus imaging for the quantification of DVT in a multicenter trial setting. From 10 randomly selected subjects participating in the edoxaban Thrombus Reduction Imaging Study (eTRIS), total thrombus volume in the entire lower extremity deep venous system was quantified bilaterally. Subjects were imaged using 3D-T1W gradient echo sequences before (direct thrombus imaging, DTHI) and 5 min after injection of 0.03 mmol/kg of gadofosveset trisodium (magnetic resonance venography, MRV). The margins of the DVT on corresponding axial, curved multi-planar reformatted images were manually delineated by two observers to obtain volumetric measurements of the venous thrombi. MRV was used to compute total DVT volume, whereas DTHI was used to compute volume of fresh thrombus. Intra-class correlation (ICC) and Bland Altman analysis were performed to compare inter and intra-observer variability of the analysis. The ICC for inter and intra-observer variability was excellent (0.99 and 0.98, p <0.001, respectively) with no bias on Bland-Altman analysis for MRV images. For DTHI images, the results were slightly lower (ICC = 0.88 and 0.95 respectively, p <0.001), with bias for inter-observer results on Bland-Altman plots. This study showed feasibility of thrombus volume estimation in DVT using MRV with gadofosveset trisodium, with good intra- and inter-observer reproducibility in a multicenter setting.

Relationship between the extent of deep venous thrombosis and the extent of acute pulmonary embolism as assessed by CT angiography

The aim of our study is to investigate prospectively the quantitative relationship between deep venous thrombosis (DVT) and acute pulmonary embolism (PE). 110 patients clinically suspected of having venous thromboembolic disease underwent combined CT pulmonary angiography (CTPA) and venography of lower limb veins. 44 patients presented with clinical signs of DVT and positive ultrasonography or ascending venography, but no clinical sign of PE (Group 1). 66 patients presented with clinical signs of PE and positive CTPA (Group 2). Clot load in lower limb veins and pulmonary arteries were scored by two independent readers, each using two separate systems for DVT and two for PE. 27 (61%) patients in Group 1 also had PE, and 55 (83%) patients in Group 2 also had DVT. Correlations between PE and DVT scores were weak but statistically significant in Group 2 (r(s) ranging from 0.470-0.520; p< or =0.001), but only some were significant in Group 1 (r(s) ranging from 0.253-0.318; p-values ranging from 0.035-0.097). In conclusion, although PE occurs in a majority of patients with DVT, and vice versa, the amount/burden of clot load in one condition does not necessarily indicate - or indicates only weakly - the degree of burden in the other condition.

Can CT pulmonary angiography allow assessment of severity and prognosis in patients presenting with pulmonary embolism? What the radiologist needs to know

Computed tomographic (CT) pulmonary angiography has been established as a first-line diagnostic technique in patients suspected of having pulmonary embolism. Risk stratification is important in patients with pulmonary embolism because optimal management, monitoring, and therapeutic strategies depend on the prognosis. Acute right-sided heart failure is known to be responsible for circulatory collapse and death in patients with severe pulmonary embolism. Acute right-sided heart failure can be assessed at CT pulmonary angiography by measuring the dimensions of right-sided heart cavities or upstream venous structures, such as the superior vena cava or azygos vein. The magnitude of pulmonary embolism can be calculated at CT pulmonary angiography by applying angiographic scores adapted for CT (Miller and Walsh scores) or dedicated CT scores (Qanadli and Mastora scores). The advent of CT pulmonary angiography performed with electrocardiographic gating permits new advances in assessment of acute right-sided heart failure, such as measurement of the ventricular ejection fraction. Although such findings may be useful for assessment of treatment effectiveness, their effect on prognosis in patients with severe pulmonary embolism is debated in the literature.