Automated Quantitative Imaging Measurements of Disease Severity in Patients with Nonthrombotic Iliac Vein Compression

Clinical question
Can an automated segmentation technique (AST) quantify disease severity and treatment response on CT venography for patients with lower extremity venous disease?

Take-away point
Automated segmentation technique (AST) can quantify leg volume, skin thickness, and water content of fat on CT venography of patients with lower extremity venous disease.

Reference
Automated Quantitative Imaging Measurements of Disease Severity in Patients with Nonthrombotic Iliac Vein Compression. Reposar, A.L., Mabud, T.S., Eifler, A.C., Hoogi, A., Arendt, V., Cohn, D.M., Rubin, D.L., Hofmann, L.V. Journal of Journal of Vascular and Interventional Radiology (JVIR), Volume 33, Issue 2, 270-275.

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Study design
Single arm, retrospective, cohort study

Funding source
No reported funding

Setting
Academic hospital, Stanford University School of Medicine, United States.




Figure 1. a) Automated segmentation technique (AST) algorithm depicting segmented skin, muscle, subcutaneous fat, and bone. b-d) Individually segmented tissue layers for muscle, fat, and bone, respectively.

Summary

Nonthrombotic iliac vein compression and its associated myriad clinical manifestations can lead to a significant reduction in quality of life. Early diagnosis is critical to ensure a better prognosis. However, there are no consensus imaging tools or quantitative diagnostic criteria. The authors performed a retrospective study of 21 patients with left-sided nonthrombotic iliac vein compression who underwent venous stent placement with pre- and post-stent CT venography and investigated the technical feasibility of an automated segmentation technique (AST) for quantitative disease severity measurements.

Patients included in this study were diagnosed with left-sided nonthrombotic iliac vein compression without right-sided disease, underwent iliofemoral venous stenting (indicated for at least 70% stenosis or axial diameters of less than 4 mm), and had pre- and post-stent diagnostic lower extremity CT venography. Images were obtained from the institutional picture archiving and communications system (PACS), de-identified, curtailed between the inguinal ligament to the ankle, and packaged using OsiriX. An automated segmentation technique (AST) algorithm developed in MATLAB was used for segmentation according to Hounsfield unit (HU) ranges for bone, fat, muscle, and skin with subsequent calculations of leg volume, skin thickness, and water content of fat.

Significant differences were found in all 3 measures of disease severity between the left diseased and right non-diseased legs on pre-stent CT venography. The differences in skin thickness and leg volume persisted on post-stent placement though to lesser degrees while no significant difference was observed in water content of fat between the diseased and non-diseased lower extremity after stent placement. Same leg comparison pre- and post-stent demonstrated significantly lower water content of fat in both the diseased left and the non-diseased right leg; no difference in skin thickness or leg volume was observed within the same leg pre- and post-stent in both the diseased left and the non-diseased right leg.

Commentary

The authors in the paper developed an automated segmentation technique (AST) algorithm and successfully quantified 3 measures of nonthrombotic iliac vein compression disease severity based on pre- and post-stent CT venography. Results demonstrated significant differences between diseased left and non-diseased right leg on pre-stent imaging which persisted on post-stent imaging except for water content of fat. These results suggested that AST quantification of disease severity is technically feasible and may provide a nonobjective perspective on venous disease treatment response in general. This is an important and encouraging first step. Future efforts should focus on larger patient cohort, longer follow-up period, fine-tuning of existing and development of other quantitative measures. Statistical analyses will need to be more robust with the inclusion of multiple-comparison correction.

Post author
Ningcheng (Peter) Li, MD, MS
Integrated Interventional Radiology Resident, PGY-3
Department of Interventional Radiology
Oregon Health and Science University, Dotter Interventional Institute
@NingchengLi

Final Two-Year Outcomes for the Sentry Bioconvertible Inferior Vena Cava Filter in Patients Requiring Temporary Protection from Pulmonary Embolism

Clinical question
What were the clinical outcomes and conversion rates of the Sentry bioconvertible IVC filter?

Take away point
The Sentry filter had a high conversion rate and high clinical success (97%) and no late IVC thrombosis or obstruction after bioconversion.

Reference
Dake, Michael D. et al. Final Two-Year Outcomes for the Sentry Bioconvertible Inferior Vena Cava Filter in Patients Requiring Temporary Protection from Pulmonary Embolism. Journal of Vascular and Interventional Radiology, Volume 31, Issue 2, 221 - 230.e3

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Study design
Prospective multicenter trial of 129 patients that underwent Sentry filter placement with a 2 year follow up.

Funding Source
BTG vascular

Setting
Multicenter, non-randomized single arm trial in 23 U.S. sites and 3 total countries.





Figure 1.  Clinical and technical outcomes in the 129 patients enrolled in the study that had a 24 month follow up.

Summary

While retrievable IVC filters are proven to provide protection against PE in patients that cannot be anticoagulated, retrieval rates for have rarely surpassed 50%, which may lead to complications such as tilting, fracture, embolization, IVC perforation etc. To this end, the Sentry bioconvertible IVC filter was created. This filter transforms from a filter to a non-filter scaffold after 60 days. This manuscript details the 2 year clinical and technical outcomes.

Patients included in the study had a contraindication to or failure of anticoagulation with a documented PE or DVT (40% had a prophylactic indication). 129 patients were included and followed for 24 months. The filter and its conversion was evaluated with CT and X-rays. At each clinical visit patients were evaluated for signs and symptoms of PE, DVT and adverse events.

There was 96.5% bioconversion of the filter at 24 months. Two patients suffered caval thrombosis within the first month with successful subsequent treatment. There were no instances of IVC thrombosis or obstruction after bioconversion at 24 months. Furthermore, there were no new symptomatic PE’s in the first 24 months. In the 5 patients in which the filter did not bioconvert, there were no instances of new DVT, PE or IVC related complications. While there were new DVTs in the study period, none were considered to be device related.

The authors highlight that the freedom from symptomatic PE was similar to what has been observed with retrievable IVC filter. After conversion, the filter did not cause IVC thrombosis or obstruction, and in patients that had thrombus in the filter prior to conversion did not experience a symptomatic PE after conversion.

The study was limited by the single arm design with its inherent bias. The authors conclude that the Sentry filter has a high rate of clinical and technical success in patients that require temporary PE prevention and are unable to be anticoagulated, with the benefit of not requiring removal to prevent long term complications associated with temporary filters.

Commentary

The study provides data to support the use of the Sentry filter in patients that do not require a permanent filter. In the current atmosphere of negative publicity and litigation against IVC filters, a bioconvertable filter is a viable option that removes the need for a second procedure to remove the filter. The data presented in this manuscript supports the conclusion that this filter provides adequate PE prevention in the first 6 months (before bioconversion) and does not cause mid-term complications related to IVC obstruction/thrombosis (after bioconversion).

Post author
Carlos J. Guevara, MD, FSIR
Assistant Professor of Radiology and Surgery
Department of Radiology, Interventional Radiology Division
Washington University in St. Louis, Mallinckrodt Institute of Radiology,
@CarlosGuevaraIR

Factors Influencing in-Stent Occlusion after Femoropopliteal Artery Stent Placement with Intravascular Ultrasound Evaluation

Clinical question
Can In Stent Re-Stenosis (ISR) or In Stent Occlusion (ISO) be predicted at time of stent placement?

Take-away point
Residual plaque after stent placement (>60% narrowing) was the most significant predictor of ISR or ISO.

Reference
Kurata N, Lida O, Asai M, Masuda M, Okamoto S, Ishihara T, Nanto K, Mano T. Factors Influencing In-Stent Occlusion after Femoropopliteal Artery Stent Placement with Intravascular Ultrasound Evaluation. J Vasc Interv Radiology. 2020. 21:213-220.

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Study design
Retrospective

Funding source
Self-funded or unfunded

Setting
Single center

Summary

Femoropopliteal artery lesions are commonly known to cause symptomatic presentation in patients with Peripheral Arterial Disease (PAD). Over the years, endovascular interventions of this anatomic region have surpassed surgical means as a first line (or often the only approach needed). On angiographic evaluation, patients may demonstrate plaque related stenosis or occlusions, as well as less commonly thrombosis. Plaque burden can be considered calcific or non-calcific. Evaluation of the specific underlying cause of the lesion is best confirmed with Intravascular Ultrasound (IVUS). Use of IVUS in peripheral arterial disease is operator and practice dependent. Common reasons for not using IVUS include concerns for time spent in utilization and added cost. No randomized controlled trial has been performed to date to validate outcomes bases on use of IVUS, thus utilization is again operator dependent. Interventional approached for femoropopliteal lesions include plain-old balloon angioplasty (POBA), Drug Coated Balloon angioplasty (DCB), atherectomy and Stent placement (bare metal (BMS), drug eluting stent (DES) and covered stent grafts).

In this article, the authors set out to determine if there were predictors of patients returning with In Stent Re-Stenosis (ISR) or In Stent Occlusion (ISO). This was a retrospective single center analysis of all of the patients with femoropopliteal lesions, that had utilization of IVUS pre and post stent placement. In total, 191 lesions in 162 patients were used in the analysis. Of the patients, approximately one third were Critical Limb Ischemia (CLI) patients, one third had coronary artery disease, and two thirds also had diabetes mellitus. In regard to the lesions, about 50% presented with chronic occlusions, two-thirds had calcified lesions, and the average lesion length was 17cm (+/- ~10cm). Type of stent type favored DES over BMS and Covered stent-grafts (51%/42%/6% respectively). 86% of patients had at least 1-2 vessel runoffs.

After data analysis, it was found that predictors of patients presenting with ISR or ISO were female gender, TASC II C/D, and residual plaque of >60% after stent placement. During the average total follow-up period (in clinic with duplex studies) of 19 months, there were 31% patients with ISR and 15% with ISO, with ISO patients presenting earlier than ISR patients. Patients that had less than 60% residual plaque after stenting had a 20-fold decrease in ISO.

Commentary

The finding that residual plaque of 60% or greater was the biggest predictor of ISR and ISO in this patient population does not seem surprising. Operators commonly encounter resistant stenosis when performing angioplasty of these lesions, especially calcified plaque, which may result in higher dissections and refractory stenosis necessitating a scaffold placement. This is one of the reasons why some chose to perform atherectomy of these lesions, regardless of whether initially presenting with stenosis or occlusion. This has been evaluated in regard to vessel preparation prior to DES placement and DCB use, however currently there is an element of uncertainty as to the safety of widespread use of Paclitaxel based devices. It is also not surprising that patients with greater severity of TASC II lesions would have increased rates of significant recurrent lesions, intervening on chronic occlusions and long multifocal long segment disease can be troubling. As newer technology continues to be developed, including endovascular tacking systems, absorbable scaffolds, and newer iterations of atherectomy, it will be interesting to evaluate if these will help decrease or prolong the recurrence of the disease.

This study demonstrates use of IVUS in these interventions demonstrates a value that may be underappreciated, which is that optimal vessel debulking/prepping with atherectomy, to result in less residual plaque before stent placement, may improve patency rates. This could be better validated with a randomized trial.

Post author
Kumar Madassery, MD
Assistant Professor, Vascular & Interventional Radiology
Director, Advanced Vascular & Interventional Radiology Fellowship
Rush University Medical Center, Chicago IL
Rush Oak Park Hospital, Oak Park IL
Twitter: @kmadass, @vir_rush

Risk of Death and Amputation with Use of Paclitaxel-Coated Balloons in the Infrapopliteal Arteries for Treatment of Critical Limb Ischemia: A systematic Review and Meta-Analysis of Randomized Controlled Trials

Clinical question
Does the use of drug coated balloons in infrapopliteal peripheral arterial disease during revascularization in patient’s with critical limb ischemia lead to an increased risk of death or amputation

Take-away point
Analysis of 8 randomized control trials demonstrated worse amputation-free survival with use of paclitaxel coated balloons

Reference
Konstantinos Katsanos et al. Risk of Death and Amputation with Use of Paclitaxel-Coated Balloons in the Infrapopliteal Arteries for Treatment of Critical Limb Ischemia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Journal of Vascular and Interventional Radiology. Feb, 2020: 31; 2.

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Study design

Meta-Analysis

Funding source

Self-funded or unfunded

Setting

Multi-study







Figure 3. (a) All-cause death and (b) major amputations. A generalized linear mixed (GLM) effects model was employed for sparse data. The summary effect was expressed as OR.

Summary

Placlitaxel-coated balloons (PCBs) gained quick popularity due to multiple studies demonstrating reduced vessel restenosis and decreased target lesion revascularization compared to plain old balloon angioplasty for femoropopliteal disease in claudicants. Recent publications have demonstrated increased patient all-cause mortality at 2 and 5 years with PCBs. This present study performed a similar systematic review and meta-analysis of PCB use in the infrapopliteal segment for patients with critical limb ischemia. Ultimately, 8 studies were identified and included in their analysis. The studies demonstrated a significant reduction in target lesion revascularization. However, the studies homogeneously demonstrated that amputation free survival was significantly lower following treatment with PCBs (number needed to harm of 22 patients). This was demonstrated by both higher rates of amputations and death. Additionally, amputation free survival was worse with higher dose PCBs.

Commentary

This paper dovetails with the major 2018 publication demonstrating increased all-cause mortality with use of PCBs in claudicants with femoropopliteal disease which has since been confirmed by the FDA. This study similarly demonstrates adverse effects, specifically death and amputation, from use of PCBs, however now within the infrapopliteal critical limb ischemia population. This study has limitations, most notably that the meta-analysis does not allow individual patient level analysis and the relatively short follow up time of 1 year. While we still do not have a cause of these adverse outcomes, this further builds evidence to caution our use of PCBs, a marked change after these devices had quickly ascended to be used as near standard of care.

Post author:
David M Mauro, MD
Assistant Professor
Department of Radiology, Vascular and Interventional Radiology
University of North Carolina

@DavidMauroMD