Preliminary study of hemodynamics of iliac venous compression syndrome using magnetic resonance imaging

Preliminary application of three-dimensional venography and fusion navigation technique in May-Thurner syndrome

OBJECTIVE

The purpose of this study was to report a technique for intraprocedural guidance of endovascular iliac vein stenting procedures using three-dimensional (3D) venography images as an overlay on live biplanar fluoroscopy.

METHODS

Using 3D venography and a fusion navigation technique, percutaneous transluminal angioplasty and stent placement were performed to evaluate the feasibility of using 3D venography images and the fusion navigation technique to treat MTS compared with traditional digital subtraction angiography. The general epidemiologic data (ie, age, gender), clinical manifestations (ie, major symptoms, affected extremity, CEAP [clinical, etiology, anatomy, pathophysiology] classification, comorbidity, stenosis rate), intraoperative findings (ie, stent type, stent count, stent to inferior vena cava distance, procedure time, radiation dose, contrast agent dosage), and postoperative recovery were obtained and analyzed.

RESULTS

A total of 30 consecutive patients with symptomatic MTS from our institution were enrolled in the present study. Of the 30 patients, 12 (group A) were treated using 3D venography images and fusion navigation and 18 (group B) were treated with two-dimensional venography images during endovascular management. Significant differences were observed between the two groups with respect to the procedure time (64.42 ± 4.35 minutes vs 76.61 ± 3.47 minutes; P = .04), radiation dose (2152 ± 124.7 mGy vs 2561 ± 105.6 mGy; P = .02), and contrast agent dosage (71.42 ± 4.87 mL vs 86.17 ± 4.14 mL; P = .03).

CONCLUSIONS

3D venography and its fusion navigation technique can improve prediction of the coverage area of the stent. Its use can also shorten the procedure time and reduce the contrast agent dose and radiation exposure, making it a valuable tool for both the diagnosis and the treatment of symptomatic MTS.

Diagnosis of chronic iliac venous obstruction

Stenting has become the first line of treatment for symptomatic chronic iliofemoral venous obstruction in patients with quality-of-life-impairing clinical manifestations who have failed conservative therapy. Patient selection for such intervention is, however, dependent on clear identification of relevant clinical manifestations and subsequent testing to confirm the diagnosis. In this regard, the physician engaged in management of such patients needs to be well-aware of symptoms and signs of chronic iliofemoral venous obstruction, and instruments used to grade chronic venous insufficiency and determine quality of life, in addition to diagnostic tests available and their individual roles. This review serves to provide an overview of the diagnosis of chronic iliofemoral venous obstruction and patient selection for stenting.

Application of 4D flow MRI for exploring factors affecting haemodynamics of iliac veins in asymptomatic population

BACKGROUND

Haemodynamics plays an important role in the development of vascular disease. There is currently a lack of studies evaluating the characteristics and affecting factors of the iliac vein haemodynamics in clinical practice.

OBJECTIVE

The goal of this study was to use 4D flow MRI to explore the haemodynamic characteristics of iliac veins and its affecting factors in an asymptomatic population.

METHODS

Thirty consecutive volunteers without venous-related symptoms or signs underwent four-dimensional postprocessing of their MRI images. Relevant parameters, the demographic data, common iliac vein-inferior vena cava angle, iliac vein area, tortuosity, iliac vein mean flow, mean velocity was computed and analysed. T tests and Spearman's tests were used for analysing. A P value of 0.05 or less was considered significant.

RESULTS

Height and iliac vein area were positively correlated with flow, while degree of stenosis, and common iliac-inferior vena cava angle were negatively correlated with that. Degree of stenosis was positively correlated with velocity, but the common iliac-inferior vena cava angle and iliac vein tortuosity were negatively correlated with that. The mean flow and velocity of iliac veins in females were lower than males. The mean flow and velocity of the left iliac veins were lower than those of the right.

CONCLUSION

The height, gender, tortuosity, degree of stenosis, common iliac vein-inferior vena cava angle of the iliac vein are important factors that affect flow and velocity of the iliac veins. There were differences in haemodynamic parameters of the bilateral iliac veins.

Evaluation of 3-dimensional rotational venography for the diagnosis of non-thrombotic iliac venous lesion

Background

The purpose of this study was to determine the technical feasibility and safety of 3D rotational venography (3D-RV) in the diagnosis of non-thrombotic iliac vein lesions compared with traditional 2D-digital subtraction angiography (2-DSA).

Methods

The general epidemiological data (including age, gender), clinical manifestations (including major symptom, affected extremity, CEAP classification, comorbidity, stenosis rate), and intra-operative findings (iliac vein indentation position, collateral circulation, procedure time, X-rays dose, contrast agent dosage) of 61 NIVL patients who were assessed by 3D-RV and traditional 2-DSA between October 2018 to October 2022 were obtained and analyzed.

Results

A total of 61 consecutive patients with symptomatic NIVL from our institution were enrolled in this study. With the aggravation of iliac vein stenosis, the proportion of indicators such as contralateral formation and iliac vein compression indentation reflecting the severity of compression under 3D-RV reconstruction increased significantly. Also, significant differences were observed between the 3D-RV and 2-DSA groups concerning procedure time (10.56 ± 0.09 s vs. 12.59 ± 0.37 s; p < 0.01), X-ray dose (41.25 ± 0.21 mGy vs. 81.59 ± 1.69 mGy; p < 0.01) and contrast agent dosage (21.48 ± 0.24 mL vs. 33.69 ± 0.72 mL; p < 0.01). Contralateral iliac vein imaging (p = 0.002), pelvic collateral vein imaging (p = 0.03), and external iliac vein indentation (p = 0.001) were found to influence the severity of iliac vein compression.

Conclusion

3D-RV can display dynamic stereo image information of NIVL, augmenting the information obtained from traditional 2-DSA. Contralateral iliac vein imaging, pelvic collateral vein imaging, and external iliac vein indentation can be used to evaluate the severity of iliac vein compression to some extent.

Predictors of long-term outcomes after catheter-directed thrombolysis combined with stent implantation in acute deep vein thrombosis secondary to iliac vein compression

The purpose of this study is to analyze predictive factors for long-term clinical outcomes after catheter-directed thrombolysis (CDT) combined with stent implantation for acute deep vein thrombosis (DVT) secondary to iliac vein compression (IVC). A retrospective analysis was performed to review clinical data and follow-up information on 52 patients who underwent CDT combined with stent implantation for acute DVT secondary to IVC from June 2015 to March 2020. Clinical outcomes including stent patency and incidence of postthrombotic syndrome (PTS) were investigated using Kaplan-Meier analysis. All included patients were categorized into 2 groups according to the presence of PTS. Potential risk factors, including age, gender, degree of iliac vein stenosis, time from onset to treatment, dosage of thrombolytic agent, stent extending below the inguinal ligament, and duration of anticoagulation for PTS were evaluated using multivariate logistic regression analysis. Over a median follow-up of 24 months, 4 individuals underwent reintervention due to in-stent stenosis or stent compression. Primary stent patency was 98.1% at 1 month, 94.2% at 6 months, 90.4% at 12 months, and 88.5% at 24 months. Freedom from PTS was 98.1% at 6 months, 84.6% at 12 months, and 75% at 24 months. No treatment-related mortality or morbidity was observed. Based on the development of PTS, 13 patients with PTS were classified into group A and 39 patients without PTS were regarded as group B. Upon multivariate logistic regression analysis, key prognostic factors for PTS were degree of iliac vein stenosis and time from onset to treatment. CDT combined with stent implantation is safe and effective for acute DVT secondary to IVC in the long-term perspective. Severe iliac vein stenosis and longer period from onset to treatment may be associated with a higher risk of PTS.

The association between iliac vein compression degree and characteristics of first diagnosed left lower extremity deep vein thrombosis

Objective

This study aimed to investigate the association between the left common iliac vein (CIV) compression degree and characteristics of first diagnosed left lower extremity deep vein thrombosis (DVT).

Patients and methods

This was a single-center retrospective observational study. Between January 2015 and June 2022, first diagnosed left lower extremity DVT patients with enhanced computed tomography of lower extremities were included. Patient demographics, comorbidities, risk factors, DVT characteristics, and CIV compression degree were collected and analyzed. Logistic regressions were performed to evaluate the odds ratio (OR) with a 95% confidence interval (CI) of iliofemoral or mixed DVT vs. compression percentage. The association between compression percentage and iliofemoral or mixed DVT was evaluated on a continuous scale with restricted cubic splines (RCS). The association between compression percentage and thrombus burden was evaluated using the Spearman test.

Results

A total of 196 (mean age, 61.8 ± 16.1 years; 86 males) patients were included. The median CIV compression percentage in iliofemoral or mixed DVT patients was significantly greater than in non-iliofemoral or non-mixed DVT, respectively (64.4 vs. 46.6%, p < 0.001; 67.8 vs. 54.8%, p = 0.004). CIV compression >50% was associated with significantly increased morbidity of iliofemoral DVT (adjusted OR, 2.96; 95% CI, 1.58-5.52; p = 0.001) or mixed DVT (adjusted OR, 2.39; 95% CI, 1.19-4.81; p = 0.014). RCS showed that a greater compression percentage was associated with a continuously increased OR of iliofemoral DVT (overall p = 0.003, non-linear p = 0.577) or mixed DVT (overall p = 0.020, non-linear p = 0.771). CIV compression percentage had a positive correlation with thrombus burden (rs = 0.284, p < 0.001).

Conclusion

A greater left CIV compression percentage may be associated with increasing likelihood of more proximal location and severe clot extent in first diagnosed left lower extremity DVT.

Comparison of intravascular ultrasound and magnetic resonance venography in the diagnosis of chronic iliac venous disease

BACKGROUND

The diagnosis of chronic iliofemoral venous obstruction (CIVO) can be made with several different modalities. Intravascular ultrasound (IVUS) is the gold standard in the diagnosis of CIVO. However, being invasive, it should not be the initial examination to screen patients with CIVO. The aim of this report is to compare the performance of magnetic resonance venography (MRV) to IVUS in the diagnosis of CIVO.

METHODS

From January, 2016 to December, 2020, records of all patients who underwent pre-operative MRV and then IVUS in the evaluation of CIVO were retrospectively analyzed.

RESULTS

505 patients were evaluated by any modality for CIVO. 15% (78) of these patients were evaluated by MRV. Patients who had failed a trial of conservative therapy for at least 3 - 6 months and who had disabling and life-style limiting symptoms of CIVO were selected to undergo further evaluation with MRV at the treating physician's discretion. For inclusion in analysis, technically satisfactory IVUS and MRV data was mandatory. Data was available for 60 common iliac vein (CIV) segments and 61 external iliac vein (EIV) segments for comparative analysis after appropriate exclusions. The mean age of the patients was 56 ± 15 years. Male to female ratio was 1:2. The distribution of patients across different CEAP classes was as follows: CEAP 3: 28%, CEAP 4: 62%, CEAP 5: 2% and CEAP 6: 8%. Bland-Altman plots of mean difference in area between IVUS and MRI were 74.1% for CIV and 56.9% for EIV. The sensitivity of MRV was 93% and 100% while the specificity was 0 and 50% for CIV and EIV respectively. The positive predictive value was 93% and 86% while the negative predictive value was 0 and 50% for CIV and EIV respectively. Improvement was noted in clinical parameters (Venous Clinical Severity score; VCSS, visual analogue pain scale and grade of swelling) after IVUS and stenting following MRV investigation. For VCSS, the score improved from 6 ± 2.7 (pre-procedure) to 4 ± 2.7 (post-procedure), p=0.0001.

CONCLUSION

There is dimensional disparity between MRV and IVUS in the diagnosis of symptomatic CIVO. MRV has a high sensitivity but low specificity when compared to IVUS and overestimates the severity of the stenosis in both the EIV and CIV. MRV is not a reliable diagnostic tool for iliac vein stenosis and should not be used for the definitive disposition of CIVO patients.