SIR 2023 Abstracts of the Year
The Annual Scientific Meeting Committee has identified three abstracts as the Abstracts of the Year, selected to highlight the best scientific work submitted to the meeting based on their overall quality, timeliness and content. The Abstracts of the Year will be presented Wednesday, March 8, during the plenary session. Find the full details including timing of presentation on sirmeeting.org or the SIR 2023 mobile app. Click the titles below to read each full abstract. Watch for more detailed coverage of these presentations during the annual meeting on sirtoday.org.
Wednesday, March 8
Abstract No. 1, Development and Preclinical Evaluation of an Immunotherapy-Eluting Hydrogel Platform for Stimulating Tumor Immunity
Mandal, K. Davis, B. Koppolu, P. Dorgan, C. Villarreal, M. Williams, C. Dupuis, A. McWatters, R. Sheth
Purpose: To develop and evaluate a versatile hydrogel platform for intratumoral delivery of immunotherapeutics in preclinical models of immune resistant malignancies.
Materials and Methods: A novel Gellan-based hydrogel (ImmunoGel) was developed that allows for incorporation of a broad range of immunotherapeutics. The agent was tested in subcutaneously implanted B16 melanoma and MC38 colorectal cancer mouse models. Two formulations of ImmunoGel, one loaded with the immunostimulatory cytokine IL12 and another with a small molecule CD40 agonist, were then administered into flank tumors (n = 10 per arm). Tumor measurements were performed for both the injected as well as contralateral flank non-injected tumors. The tumors were then harvested at 7 days post-implantation, and immune profiling using IHC, flow cytometry, single cell RNA sequencing, and spatial proteomics were performed. Blank ImmunoGel without loaded immunotherapeutics and saline sham injections were used for negative controls.
Results: ImmunoGel with IL12 resulted in a significant increase in effector (CD8+GZMB+INFg+) T cells compared with sham and blank hydrogel injections for both treated (4.1% total CD45+ cells vs 2.2% and 1.9%, respectively) and non-treated (4.6% vs 2.1% and 3.9%, respectively) tumors in the MC38 tumor model. There was also a decrease in regulatory T cells (CD4+FoxP3+CD25+) in non-treated tumors (0.5% vs 6.1% and 3.5%, respectively). Tumor growth curves in animals survived to 2 weeks post-injection revealed a significant decrease in tumor growth following ImmunoGel with IL12 injection relative to both saline and blank hydrogel controls (P < 0.01). Similar results were seen in the B16 tumor model following ImmunoGel with IL12 injection, with an increase in CD3+CD8+ T cells and a decrease in CD4+FoxP3+ T regulatory T cells, and these results were further corroborated with scRNAseq data. Likewise, ImmunoGel loaded with CD40 agonist increased CD8+ cell populations within the treated and untreated tumor and resulted in suppressed tumor growth compared with blank hydrogel and saline (P < 0.01). Spatial proteomics revealed localization of immunofluorescent staining that corresponds to increased CD8+ T cells in the B16 tumor model treated with ImmunoGel with IL12 injection in comparison to saline.
Conclusion: Intratumoral delivery of immunostimulatory therapeutics with ImmunoGel effects extensive immunostimulatory alterations to the tumor microenvironment and is a promising approach to overcoming immune evasion multiple models of cancer.
Abstract No. 2, Updated Analysis of DOSISPHERE-01 Trial: A Long-Term Analysis of Overall Survival
Garin, L. Tselikas, B. Guiu, J. Chalaye, B. Campillo-Gimenez
Purpose: DOSISPHER-01 study (1) demonstrated at interim analysis a strong improvement of response and overall survival (OS) using 90Y loaded glass microsphere with personalized dosimetry compared with standard dosimetry in non-operable locally advanced hepatocellular carcinoma patients. The aim of this report is to provide long-term analysis of OS.
Materials and Methods: In this phase II study, treatment arm was randomly assigned (1:1) to personalized dosimetry arm (PDA) with the goal to deliver at least 205 Gy (if possible, more than 250-300 Gy) to the index lesion or to the standard dosimetry arm (SDA), with the goal to deliver 120 ± 20 Gy to the treated volume. Response rate was the primary endpoint and OS was one the secondary endpoints. This report is a post hoc long-term analysis of OS.
Results: 60 HCC patients, with a least one lesion >7 cm and at least > 30% of hepatic reserve, were randomized (ITT population, PDA 31, SDA 29), and 56 treated (modified ITT population, 28 in each arm). Portal vein thrombosis (PVT) was present in 68% and of the patients (ITT and modified ITT population). The median follow-up for long-term analysis was 65.8 months (2.1-73.1). Median OS was 22.9 months in the PDA versus 10.8 months in the SDA, HR 0.52 (95% CI: 0.3-0.91), P = 0.023 in the ITT population, and respectively 24.8 months versus 10.7 months, HR 0.51 (95% CI: 0.29-0.9), P = 0.02 in the modified ITT population. According to dosimetry results, median OS was 22.9 months for patients with a Tumor Absorbed Dose (TAD) ≥ 205 Gy versus 10.3 months for those with a TAD < 205 Gy, HR 0.42 (95% CI: 0.22-0.81), P = 0.0095 and median OS was 22.9 months for patients with a Perfused Liver Dose (PLD) ≥ 150 Gy versus 10.3 months for those with a TAD < 205 Gy, HR 0.42 (95% CI: 0.23-0.75), P = 0.0033.Finally, median OS was not reached in the patients secondarily resected (n = 11, 10 in the PDA and 1 in the SDA) versus 10.8 months for the patients without secondary resection (n = 45), HR 0.17 (95% CI: 0.065-0.43), P = 0.0002. OS rates at 1, 2, 3, and 5 years are presented in the table.
Conclusion: After longer follow-up, personalized dosimetry maintained a meaningful improvement of OS. OS was dramatically improved for patients accurately down staged toward resection.
Abstract No. 3, Prostate Artery Embolization—Single-Center Experience of 1,000 Patients with Short-, Mid- and Long-Term Follow-Up
Richardson, A. Maini, K. Richardson, K. Shah, A. Bhatia, R. Reddy, A. Sanan, J. Kumar, H. Jalaeian, S. Bhatia
Purpose: PAE is a minimally invasive treatment of lower urinary tract symptoms (LUTS) and urinary retention secondary to BPH. This study evaluates and expands upon the effectiveness and safety profile of PAE in treating BPH with LUTS or urinary retention.
Materials and Methods: 1,000 patients underwent PAE for either BPH with LUTS or urinary retention from January 2014 to September 2022. Mean patient age was 70.2 ± 9.5 years, mean prostate volume was 107.2 ± 65.1 g, median pre-procedure IPSS and QoL scores were 23 (IQR, 18-28) and 5 (IQR, 4-6), respectively. Transradial access was performed in 820 procedures. Patient evaluation occurred at 6-12, 24, 60 and 72-month (mo) intervals post PAE. Adverse events were recorded using the Clavien-Dindo (CD) classification. Two-tailed P < 0.05 was considered significant.
Results: Median follow-up was 1,027 days (range, 39-3184). 3-12, 24, 60 and 72-mo follow-up data are reported in the table. 6-12 months post PAE median IPSS decreased to 6 (IQR 3-10) (n = 615; P< 0.01), median QoL was 1 (IQR 0-2) (n = 615; P< 0.01) and mean prostate size was 70.9 ± 44.7 g (n = 175; P< 0.01). 24 months post PAE median IPSS was 7 (IQR 3-14) (n = 106; P< 0.01), median QoL was 1 (IQR 0-3) (n = 106 P< 0.01), and mean prostate size was 82.9 ± 47.1 g (n = 59; P< 0.01). 5-years post PAE median IPSS was 3 (IQR 2-14) (n = 35 P< 0.01), median QoL was 1 (IQR 0-2) (n = 35 P< 0.01), and mean prostate size was 69.3 ± 23.3 g (n = 7; P< 0.01). 6-years after PAE median IPSS was 6 (IQR 3-11) (n = 10 P< 0.01) and median QoL was 0.5 (IQR 0-1.8) (n = 10 P< 0.01). 67 patients (6.7%) have required a second procedure for recurrent LUTS; 10 underwent a second PAE. Self-limited frequency, urgency, and dysuria (CD grade I) postoperative symptoms occurred in 33.5% of patients. 3 patients had non-target embolization with penile ulceration (CD grade II) which resolved with local conservative measures. 3 patients (0.3%) developed urosepsis (CD grade IV) and were treated with IV antibiotics. 3 patients had TIAs which resolved without further intervention.
Conclusion: PAE is an established safe and clinically effective procedure for patients LUTS secondary to BPH with great short-term to midterm results. Long-term outcomes including maintained LUTS relief and significant improvement in QoL continue to be promising.
SIR 2023 Featured Abstracts
Featured abstracts were selected through a blinded peer review based on the worthiness of the science, the strength of the methods used, whether the results correspond with those methods and whether the conclusion is based on the results and methods. Find the full details including timing of presentation on sirmeeting.org or the SIR 2023 mobile app. Click the titles below to read each full abstract. Watch for more detailed coverage of these presentations during the annual meeting on sirtoday.org.
Sunday, March 5
Abstract No. 4, Image-Guided Intratumoral Cancer Vaccine to Treat Metastatic Immunotherapy Resistant Cancer with and without Cryoablation
Som,1 E. Wehrenberg-Klee,1 J. Rosenboom,2 A. Chandler,2 G. Ndakwah,2 J. Kim,1 V. Feig,3 A. Marcos-Vidal,1 F. Fintelmann,1 A. Basu,2 R. Langer,2 G. Traverso,3 U. Mahmood1; 1Massachusetts General Hospital; 2Massachusetts Institute of Technology; 3 Brigham and Women’s Hospital
Purpose: Intratumoral immunoadjuvant injections using image-guidance are an area of significant clinical interest, but current therapies suffer because they need frequent injections and are unable to confirm target delivery. Developing controlled release and imageable formulations of injectable immunoadjuvants will greatly improve the clinical translation of these therapies for intratumoral immunotherapy. To address this shortcoming, we have developed and evaluated an injectable hydrogel-based controlled release formulation for the FDA-approved drug imiquimod (“Imigel”) with a drug concentration and release profile that mimics an entire multiday course of therapy with a single injection.
Materials and Methods: All animal studies were approved by the IACUC. Imigel was developed utilizing a combination of previously clinically used PEG based excipients combination with the FDA-approved drug imiquimod. The gel was tested for injectability, shear stress, viscosity, and controlled release ex vivo. Radio-opacity in vivo was evaluated in combination with iopamidol via micro-CT. Using two checkpoint inhibitor (CPI) resistant metastatic tumor murine model mimics, we evaluated for 90-day survival after intratumoral Imigel injection with and without cryoablation. Tumors post injection were subsequently also evaluated by flow cytometry and immunofluorescence for markers of immune activation.
Results: Imigel demonstrated good injectability and depot formation with a temperature sensitive gelation in vivo versus being liquid at room temperature, as well as being radio-opaque when combined with iopamidol. The addition of intratumoral Imigel to systemic CPI significantly increases 90-day survival to 46% (6/13) compared with CPI alone 0% (0/10) (P = .0045 Log Rank Test) and maintains this effect with combination cryoablation. This corresponded to an increase in activated CD8 T-cell activity seen in the non-treated tumor compared with control (P = .03).
Conclusion: Because Imigel uses FDA and clinically approved compounds and excipients, this platform may provide a rapidly translatable adjunct for patients with metastatic disease via image-guided (ultrasound and computed tomography) interventional therapies.
Kimura,1 N. Raghuraman,2 B. Simoes,3 A. Ramesh,3 A. Kulkarni,4 G. Srimathveeravalli2; 1Osaka University Graduate School of Medicine; 2Department of Mechanical and Industrial Engineering, University of Massachusetts; 3Department of Biomedical Engineering, University of Massachusetts; 4Department of Chemical Engineering, University of Massachusetts
Purpose: To investigate the impact of adjuvant macrophage repolarization to inflammatory M1 phenotype on local tumor control and overall survival following irreversible electroporation (IRE) of murine bladder tumors.
Materials and Methods: Mouse bladder cancer cell line (MB49) was used to induce subcutaneous tumors in C57BL/6 (n = 8/group) or NOD-SCID (n = 10/group) mice. Animals were randomized to receive (i) IRE, (ii) supramolecular nanotherapeutic for M1 repolarization (SNT), (iii) IRE+SNT or (iv) sham control. Mice assigned to IRE treatment received electric pulses (875 or 1500V/cm for C57BL/6 mice and 875V/cm for NOD-SCID mice, 90 pulses, 100 us duration) with tweezer electrodes. SNT treatment was administered by intravenous injection (40 mg/kg, 1,3- and 5-days post treatment). Mice were sacrificed at Day 1 or 6 for flow cytometry following IRE or were kept under observation in a survival study. Flow cytometry for macrophage markers (M1: CD80, M2: CD206) and T Cell markers (CD8, CD4 and FoxP3) from tumor samples was performed. Tumor samples underwent immunohistochemistry for cell death, macrophages (F4/80) or T cell markers. Local tumor volume and overall survival were evaluated and compared between cohorts and mouse strains to understand cross-interactions with adaptive immunity.
Results: Ablation of subcutaneous tumor with IRE stimulated robust macrophage infiltration that uniformly exhibited an immunosuppressive M2 phenotype at Day 3 and 5. SNT effectively repolarized macrophages at the site of ablation to M1 phenotype, with corresponding change in gene expression of NOS2 and IL-6. There was significantly higher population of CD80+ cells and reduced CD206+ cells at Day 1. Adjuvant SNT did not alter CD4+ and CD8+ cells but greatly reduced FoxP3+ population in vivo. IRE+SNT treated mice had greater reduction in local tumor growth, reduced lung metastases and high overall survival. These findings were reduced in NOD-SCID mice, indicating contribution of adaptive immunity under conditions of M1 repolarization.
Conclusion: Repolarization of macrophages attracted to the site of ablation to a M1 phenotype promotes local tumor control, reducing the development of metastatic disease and prolonging survival in a mouse model of bladder cancer.
Pastori,1 M. Wagh,1 E. Nafie,1 F. Murad,1 R. Neal1; 1Galvanize Therapeutics
Purpose: Focal tumor ablation may cause secondary immunogenic upregulation that enhances local and distant tumor responses, with profiles that are unique to each modality.,
Pulsed electric fields (PEFs) use short duration-high voltage electrical pulses to destabilize and kill cells through various biochemical processes. Because it does not rely on thermal effects PEF does not damage interstitial proteins, fostering improved antigen integrity and immune signaling which may lead to lesion resolution.
This study compared whether cell death and subsequent interstitial effects caused by PEF and radiofrequency ablation (RFA) result in differentiated primary tumor responses.
Materials and Methods: Thirty female Balb/c mice, divided into sham, PEF, and RFA treatment groups (n = 10/group) were transplanted with EMT6 cells in the left mammary fat pad. Eight days after challenge (d = 0), mice in the PEF and RFA groups received treatment with doses selected to achieve similar subtotal ablation volumes. Three mice from each group were euthanized at day 4 for H&E analysis of ablation zone. The remainder were survived to 10-days post-ablation to monitor tumor growth. Serum was collected on Days -1, +1, +4 and +10 for cytokine analysis.
Results: Four-day histology demonstrated comparable subtotal ablation areas between PEF and RFA treatment. While RFA-treated tumors presented immune cells accumulating at the tumor-treatment zone boundary, PEF-treated tumors showed immune cell infiltration throughout the tumor. Further, PEF treatment slowed tumor growth compared with RFA or sham treatments, with day 10 average tumor volumes of 335, 791, and 857 mm3 for PEF, RFA, and sham group, respectively.
Ingenuity Pathway Analysis (IPA) of 32 serum cytokines revealed most notable differences between groups on day 4 post-ablation. The PEF-treated group had a significant decrease in the levels of CSF1, CSF2, CSF3, CCL2, IL1β, IL6, IL13, and TNF, and an increase in the levels of IL4. These changes suggest that PEF is associated to 1) decreased accumulation of myeloid derived suppressor cells (MDSCs), 2) decreased the proliferation of tumor-associated macrophages (TAMs), 3) decreased proliferation, survival and invasion of tumor cells. Conversely, these changes were all the opposite for the RFA group.
Conclusion: PEF treatment may cause a stronger EMT6 tumor response in mice compared with RFA treatment. These data suggest that PEF may have a greater local and distant tumor response benefit versus RFA thermal ablation. Further studies should explore potential abscopal effects.
Abstract No. 9, Pivotal Study of Magnetic Resonance Imaging-Guided Transurethral Ultrasound Ablation (TULSA) of the Prostate: 4-year Follow-up
Raman,1 S. Arora,2 K. Macura,3 A. Oto,4 J. Futterer,5 R. Staruch,6 T. Tirkes,7 D. Bonekamp,8 M. Haider,9 D. Cool,10 K. Nandalur,11 C. Nicolau,12 D. Costa,13 T. Persigehl,14 G. Clarke,6 J. Chin,15 L. Klotz,16 S. Eggener17; 1David Geffen School of Medicine at UCLA; 2Yale School of Medicine; 3The Russell H. Morgan Department of Radiology and Radiological Science; 4University of Chicago; 5Radboudumc; 6Profound Medical; 7Indiana University; 8German Cancer Research Center; 9University Health Network; 10Schulich School of Medicine; 11Beaumont Hospital; 12Hospital Clinic de Barcelona; 13University of Texas Southwestern Medical Center; 14University Hospital Cologne; 15London Health Sciences Centre; 16Sunnybrook Health Sciences Centre; 17The University of Chicago Medicine & Biological Sciences Division
Purpose: Magnetic resonance imaging-guided transurethral ultrasound ablation (TULSA) of the prostate is a minimally invasive in-bore procedure. The TACT pivotal trial established safety and efficacy at 1 year in patients with low- to intermediate-risk prostate cancer. Here we report 4-year outcomes.
Materials and Methods: 115 men with organ-confined PCa (≤T2b, PSA≤15 ng/mL, GG1/GG2) received a single whole-gland TULSA treatment sparing the urethra and urinary sphincter, across 13 sites in 5 countries. Primary endpoints are frequency and severity of adverse events and PSA reduction at 1 year. Secondary endpoints at 1 year are clinical benefit on 10-core biopsy, and mpMRI prostate volume reduction. Follow-up to five years includes quality-of-life, PSA, and adverse events.
Results: At baseline, median (IQR) age and PSA were 65 (59-69) and 6.3 (4.6-7.9) ng/mL. Proportions of men with GG1/GG2/GG3 disease were 15%/60%/3%. Median (IQR) prostate volume was 40 (31-51) cc ablated in 51 (39-66) min. GG2 disease was eliminated in 54/68 (79%) men and 72/111 (65%) had no evidence of disease. Median prostate volume decreased from 37.3 to 2.8 cc (92%). By 4 years, 18 men (16%) received salvage treatment, which was safe and feasible. Median (IQR) PSA reduction was 86% (75%-95%) to 0.9 (0.4-1.6) ng/mL at 4 years (n = 76), and 96% decrease to nadir. Median IPSS decreased from 7 at baseline to 5 at 4 years (n = 73). Erectile function continued to recover, with 69/92 (75%) preserving erections sufficient for penetration (IIEFQ2≥2) at 1 year and 46/57 (81%) at 4 years. Pad-free urinary continence was preserved at 1 and 4 years by 102/111 (92%) and 68/72 (94%), and social continence by 110/111 (99%) and 71/72 (99%). There was no rectal injury or Grade≥4 adverse event. Grade 3 adverse events occurred in 9 men (8%) and included GU infection, retention, pain, urinoma, stricture, and retention, all resolved before 1 year.
Conclusion: Effective disease control and favorable quality of life and safety profile are durable to 4 years after whole-gland ablation with TULSA.
Abstract No. 22, Safety and Effectiveness of the ClotTriever System for Treating Deep Vein Thrombosis: Six-Month Outcomes of the Fully Enrolled CLOUT Registry
Shaikh1; 1Allegheny Health Network
Purpose: Mechanical thrombectomy is a lytic-free treatment option for deep vein thrombosis (DVT). This study presents 6-month outcomes of the fully enrolled 500-patient CLOUT registry.
Materials and Methods: The CLOUT registry is a prospective, all-comer study for lower extremity DVT patients treated with the ClotTriever System (Inari Medical, Irvine, CA). Primary effectiveness endpoint was complete or near-complete (≥75%) thrombus removal assessed by an independent core laboratory. Serious adverse events (SAE) were adjudicated by an independent medical monitor. Duplex ultrasound for flow and compressibility, revised venous clinical severity (rVCSS), Villalta scores to assess post-thrombotic syndrome (PTS), pain (NPRS), and EuroQoL group 5-D (EQ-5D) scores were assessed through 6 months.
Results: Of the analysis population (499 patients; 521 limbs; 43 US sites), 49.5% were male with mean age of 59.4 ± 15.2. Prior DVT was present in 24.9% of patients and 29.7% were contraindicated to thrombolytics. Most patients (99.4%) were treated in a single session with median thrombectomy time of 26 minutes and blood loss of 40.0 mL. Only 11 (2.2%) patients required post-procedure ICU stay. The primary endpoint of ≥75% thrombus removal was seen in 91.2% of limbs, with complete thrombus removal in 63.8%. The 30-day SAE rate was 8.4% and procedure-related readmission rate was 4.2%. At 6 months, flow was present in 92.0% (vs 27.6% at baseline, P < 0.0001) and normal or partial compressibility improved to 91.5% (vs 28.0% at baseline, P < 0.0001) of limbs. Six-month median Villalta score was reduced to 1 (vs 9 at baseline, P < 0.0001). Median NPRS at 6 months was 0 (vs 5 at baseline, P < 0.001) and EQ-5D quality of life was 1 (vs 0.689 at baseline, P < 0.001). Additional outcomes are shown in Table 1.
Conclusion: The CLOUT registry demonstrates significant thrombus removal post-procedure, strong 30-day safety profile, and excellent 6-month outcomes including reduced pain, PTS severity, and improved quality of life. Study follow-up to 2 years is ongoing.
Abstract No. 24, Bismuth Nanoparticle and Dipyridamole-Loaded Electrospun Polymeric Scaffold as Radiopaque Bioresorbable Drug-Eluting Vascular Graft
Honegger,1 E. San Valentin,2 M. Bernardino,2 J. Damasco,2 K. Court,3 B. Godin,3 S. Huang,2 M. Melancon2; 1University of Notre Dame; 2Department of Interventional Radiology, The University of Texas MD Anderson Cancer Center; 3Houston Methodist Research Institute
Purpose: Failure of arteriovenous graft placement for patients on dialysis can lead to neointimal hyperplasia (NIH). Anti-platelet and vasodilator drugs such as dipyridamole (DPA) mitigate NIH and long-term patency post-graft placement. Nanoparticles allow for visualization and long-term monitoring of these absorbable medical devices. We aim to develop a bioresorbable and radiopaque bismuth nanoparticle (BiNP) and DPA-loaded scaffold made of polycaprolactone (PCL) and polyethylene glycol (PEG).
Materials and Methods: BiNPs (3.44 ± 0.59 nm) were synthesized by thermal decomposition. Solutions of PCL (80,000kDa), PEG (8,000kDa), BiNP, and DPA were electrospun into 3-cm scaffolds. Scaffolds were monitored over 6 weeks in terms of drug and nanoparticle released, tensile strength, and radiopacity. In vitro hemolysis and cytotoxicity assays were done to test biocompatibility of grafts.
Results: Physicochemical properties of grafts are shown in Table 1. DPA-loaded grafts released ~38% of the drug over 7 days, which increased to ~70% release over twelve weeks. BiNP-loaded grafts released between 3-5% of the total BiNP within the first 12 weeks, which correlated with a radiopacity loss of only 16.6% over the 12-week trial period (PCL-PEG-BiNP-DPA: 1001.2 ± 111.8 HU at Week 0 vs. PCL-PEG-BiNP-DPA: 834.7 ± 36.8 HU at Week 12). EC-RF24 and MOVAS remained viable in the presence of BiNP and DPA treated media. The presence of DPA in grafts increased blood lysis by about 2% (PCL-PEG-DPA: 1.8 ± 1.1% vs PCL-PEG-BiNP-DPA: 2.5 ± 0.5%).
Conclusion: Trilayer scaffolds made of PCL and PEG and loaded with both DPA and BiNP demonstrated increased radiopacity with no detrimental effects on epithelial or vascular smooth muscle cells, and an effective release of DPA over time. These results confer its advantage for serial non-invasive imaging over time to assess degree of polymer resorption and potential for in vivo NIH inhibition. Grafts were surgically implanted in rats to begin in vivo imaging and efficacy studies.
Abstract No. 44, Interleaved Angiography for Simultaneous Acquisition of Vessel Morphology and Blood Velocity Quantification
Whitehead,1 S. Periyasamy,2 P. Laeseke,3 M. Wagner,4 M. Speidel5; 1Wisconsin Institutes for Medical Research; 2University of Wisconsin School of Medicine and Public Health; 3University of Wisconsin; 4University of Wisconsin–Madison
Purpose: Quantitative DSA (qDSA) enables blood velocity quantification from high frame rate DSA imaging. To improve clinical translatability, there is a need to reduce qDSA radiation dose. This work evaluates a new interleaved angiography technique that provides high frame rate, lower dose images for blood velocity quantification while simultaneously providing higher dose images at the same frame rate as conventional DSA for visualizing vessel morphology.
Materials and Methods: Interleaved acquisition was implemented on a Siemens Artis zee system with custom software for frame-by-frame modulation of radiation dose. The interleaving protocol consisted of 27 frame/s (fps) imaging, with most frames acquired at low dose except for a high dose image every 10th frame (2.7 fps). Accuracy of qDSA velocity was evaluated in a vessel phantom. Images were acquired with 5 mean flow rates [7.5-14.2 mL/s] and 3 protocols (27 fps DSA and interleaving with 70% and 89% dose rate reduction relative to 27 fps DSA) and 8 repeat acquisitions per state. An ultrasound (US) flow probe provided gold standard velocity measurements. To evaluate angiographic quality, contrast-to-noise ratios (CNRs) of the gastroduodenal artery (chosen for consistent temporal signal) were measured in porcine hepatic angiograms (n = 4) using an interleaved protocol and conventional 3 fps DSA.
Results: In the phantom study, linear regression showed strong agreement between US and qDSA velocity for each interleaving protocol (n = 40, Pearson’s r: [0.98-0.99]). For the lowest dose protocol, the slope was 0.97 (95% CI: [0.9, 1.0]) with a bias of -0.2 cm/s (95% CI: [-2.7, 2.4]). The 27 fps interleaved dose rate was 2.6 mGy/s, which was 9.4 times lower than the 24.3 mGy/s for 27 fps DSA. For reference, the DSA dose rate would have been 2.7 mGy/s for a conventional 3 fps DSA. In vivo, the CNRs in the high dose interleaved images and conventional DSA images were 6.5 ± 0.5 and 7.2 ± 0.5.
Conclusion: The proposed interleaved angiography technique enables simultaneous acquisition of intra-procedural blood velocity and vessel morphology at dose rates comparable to conventional DSA. This could facilitate clinical translation of qDSA for standardizing treatment endpoints in blood flow altering procedures.
Monday, March 6
Abstract No. 112, Genicular Artery Embolization for Treatment of Knee Osteoarthritis: A Prospective Pilot Trial
Taslakian,1 T. Mabud,1 E. Alaia,1 R. Kijowski,1 J. Samuels,1 M. Attur,1 W. Macaulay,1 R. Hickey1; 1New York University Grossman School of Medicine
Purpose: To evaluate the safety and effectiveness of genicular artery embolization (GAE) in reducing knee pain and improving function and quality of life in patients with knee osteoarthritis (OA), as determined by validated patient-reported outcome measures. Minimal clinically important difference (MCID) will be used to determine clinical success. Imaging data and disease-specific biomarkers will be evaluated.
Materials and Methods: This is a prospective, single-arm clinical trial. Patients with mild to severe (Kellgren-Lawrence grade 2-4) symptomatic knee OA, who failed conservative therapy for at least 3 months were enrolled. Knee imaging, patient-reported outcome measures (KOOS, WOMAC, VAS, QOL), and knee OA-specific serum biomarkers were evaluated. Each patient underwent transcatheter arterial embolization of one or more genicular arteries in the target knee using 250-μm microspheres (Embozene, Varian). Patients were followed up at 1-, 3-, and 12-month post GAE. The primary outcome was the proportion of patients with clinical success (defined as 20% decrease in WOMAC pain score at 12 months [achieving MCID]). Baseline and follow-up outcomes were compared using paired Wilcoxon signed-rank tests.
Results: A total of 13 patients (10 male; mean age 69 ± 6 years) were included. Technical success was 100%. Clinical success rate was 75%. There were no major adverse events. Transient skin changes involving the target knee were seen in 50% of cases. VAS pain scores decreased from 69.2 ± 4.8 to 33.4 ± 25.4, 21.3 ± 24.3, 9 ± 10.5 at 1, 3, 12 months follow up (P = 0.0004); WOMAC pain scores decreased from 8.5 ± 3.6 to 5.1 ± 2.7, 4 ± 3.3, 4 ± 3.1 (P = 0.06). WOMAC physical function scores decrease from 30.6 ± 12.8 to 11.7 ± 8.1 at 12 months. QOL index value and KOOS QOL scores improved from 0.65 ± 0.18 and 30.4 ± 14.7 at baseline to 0.88 ± 0.08 and 68.75 ± 19.8 at 12 months, respectively. Hyaluronic Acid (HA) levels decreased from 93.7 ± 65.4 to 52.5 ± 17.2 at 12 months (P = 0.022).
Conclusion: GAE is safe and efficacious treatment option for patients with knee pain secondary to OA, with high clinical success rate, no major adverse events, and significant improvement in knee pain, physical function, and quality of life.
Abstract No. 121, Viable Disc Allograft Supplementation in Patients with Chronic Low Back Pain (VAST Trial): Interim 36-Month Results of an Open-Label Extension Study
Beall,1 I. Fayed1; 1Clinical Radiology of Oklahoma
Purpose: Available treatment for discogenic back pain has limited effectiveness and durability. Previously reported at 12 months, clinical improvements in pain and function were achieved in both the investigational allograft and saline groups of the VAST randomized controlled trial. An open-label extension study is in progress. We report outcomes in patients who completed the 36-month follow-up.
Materials and Methods: The study was conducted in 218 patients with 1or 2 level degenerative lumbar disc disease and refractory chronic low back pain. At 12 months, patients could continue in an open-label extension study for up to 36 months, with an interim visit at 24 months. In this interim analysis, we assessed mean change from baseline in VAS and ODI scores and categorical responder status. To minimize confounding, we compared these 36-month data with results from prior time points in this population only.
VIVEX Biologics, Inc. sponsored this study and contributed to study design, data monitoring, statistical analysis, and reporting of results and paid for independent data collection, core laboratory, and EDC services. All authors had complete access to data and were provided all analyses requested.
Results: Nine of 12 sites participated in the extension; outcome data were entered for 50 patients at 36 months (allograft-treated, n = 46; saline-treated, n = 4). The 36-month completer population within each study arm was similar to the intent-to-treat population in age, sex, race, ethnicity, body mass index, and smoking status. In the allograft-treated group, change from baseline in VAS score (mean [95% CI]) at month 36 was -35.35 (± 25.39). Success rates in the allograft-treated group show that patients continued to have clinically meaningful benefits through 36 months in both pain and function, with 60% of patient reporting ≥ 50% improvement in pain and more than 70% of the patients had a ≥ 20 point reduction in ODI in VAS at 36 months.
Conclusion: Patients treated with viable disc tissue allograft for degenerated lumbar discs showed sustained clinical benefits at 3 years following treatment. This interim analysis suggests that viable disc tissue allograft might be a durable, nonsurgical treatment for patients with chronically painful degenerated lumbar discs.
Abstract No. 139, Transarterial Chemoperfusion Treatment of Unresectable Pleural Mesothelioma: A Phase 2 Prospective Study
Kis,1 M. Pereira,1 J. Kim,1 G. El-Haddad,2 J. Choi,1 J. Fontaine,1 A. Saltos,1 B. Creelan,1 T. Tanvetyanon1; 1H. Lee Moffitt Cancer Center; 2Moffitt Cancer Center and Research Institute
Purpose: Transarterial chemoperfusion treatment selectively delivers relatively high concentration of chemotherapy to the targeted tissue’s arterial bed maximizing antitumoral effect and minimizing systemic side effects. Advanced malignant pleural mesothelioma (MPM) carries a very poor prognosis. The current prospective study (ClinicalTrials.gov Identifier: NCT02611037) investigated the disease control rate, overall survival and adverse events of transarterial chemoperfusion treatment in patients with relapsed unresectable MPM.
Materials and Methods: 32 patients, 5 female and 27 males (age 71.7 ± 6.9 years), with MPM were enrolled between 3/2016-4/2021. ECOG performance status was 0 and 1 (12.5% and 87.5%, respectively). Patients had transarterial chemoperfusion treatment in every 4 weeks with cisplatin (35 mg/m2), methotrexate (100 mg/m2) and gemcitabine (1000 mg/m2) via the ipsilateral internal mammary artery and/or descending thoracic aorta. All patients had received and progressed on prior chemotherapy. 5 patients also had prior radiation therapy and 3 patients had pleurectomy. The number of prior systemic chemo- and immunotherapy was 1.96 ± 1.3 (range, 1-6). Response rate was evaluated by modified RECIST for mesothelioma.
Results: At the data cutoff date (October 10, 2022) 30 of the 32 patients had died. A total of 199 chemoperfusion treatments were performed. The median number of treatments was 3/patient (range, 1-53). The disease control rate was 75% (1 PR, 23 SD, 8 PD). Median progression-free survival from the enrollment was 4.7 months (95% CI 2.5-7.4). Median OS was 8.9 months (95% CI 5.7-15). OS at 6, 12, 18, 24 and 36 months were 69%, 41%, 14%, 7%, and 5%, respectively. There was no treatment related mortality. Major complication rate (grade 3 adverse events) was 1% (2 events). The most common grade 1 or 2 adverse events were nausea and anemia (both occurred in 47% of patients), followed by hypomagnesemia (44%), hyperkalemia (41%) and lymphopenia (31%).
Conclusion: Transarterial chemoperfusion treatment with cisplatin, methotrexate and gemcitabine in every 4 weeks is feasible and safe. The treatment has promising disease control rate and OS in this group of heavily pretreated patients with relapsed MPM.
Tuesday, March 7
Abstract No. 166, Bariatric Arterial Embolization is Associated with Significant Muscle-Sparing Weight Loss Detected by Whole-Body Magnetic Resonance Imaging Anthropometry
Giraldo Herrera,1 A. Khalil,1 T. Garg,1 T. Mehta,2 J. Linge,3 C. Weiss4; 1Johns Hopkins Medicine; 2Johns Hopkins Hospital; 3AMRA Medical AB; 4Johns Hopkins University School of Medicine
Purpose: To evaluate the early effects of bariatric arterial embolization (BAE) on multi-compartment fat and muscle body composition.
Materials and Methods: This report is the pilot phase of the BEATLES trial Bariatric Embolization of ArTeries with imaging visibLe EmbolicS. BEATLES is an IRB and FDA-approved physician-initiated investigational device exemption study that evaluates tightly calibrated 100-200μm radiopaque microspheres (BT-001933-01, Boston Scientific Corporation).
Adult participants with obesity (BMI ≥35kg/m2) were scanned at 0 (baseline), 3 and 6-months post-BAE from neck to knees in a Siemens Skyra 3T MRI system using a dual-echo Dixon water-fat Vibe protocol, and a single-slice multi-echo Dixon proton liver density acquisition. Anthropometrics were obtained using AMRA Researcher (AMRA Medical AB, Linköping, Sweden), a semi-automated cloud-based MRI segmentation tool.1 Statistical testing was performed via repeated measures correlation (Rrm).2
Results: Seven patients (mean age, 39.6 ± 11.0 years, 6 females) with CDC class II-III obesity underwent BAE. At 0, 3, and 6-months, mean body weight was 125.9 ± 24.4, 113.5 ± 21.2, and 110.7 ± 23.3 kg (Rrm = -0.694 [95% CI -0.921 to -0.113], P = 0.012). Weight-to-thigh muscle volume ratios were 10.3 ± 1.9 10.0 ± 0.5, and 9.2 ± 1.3 kg/L (Rrm = 0.89 [95% CI 0.64-0.97], P value = 0.001), respectively. Postprocedural anthropometry is summarized in Table 1.
Conclusion: BAE using 100-200 μm microspheres is associated with significant post-procedural muscle-sparing weight loss via subcutaneous and intra-muscular fat reduction.
Abstract No. 188, Thoracic Duct Venous Junction Lymphoplasty: Initial Experience and Outcomes
Gurevich,1 M. Asher,1 G. Nadolski,2 M. Itkin1; 1Division of Interventional Radiology, Department of Radiology, Perelman School of Medicine at the University of Pennsylvania; 2Penn Image-Guided Interventions (PIGI) Lab, Hospital of the University of Pennsylvania, Division of Interventional Radiology
Purpose: Lymphatic system is a complex network of tissues and vessels that transport lymphatic fluid from peripheral interstitium back into the venous circulation via the thoracic duct (TD). Recent advancements in interventional lymphatic management have revolutionized the treatment of traumatic and nontraumatic lymphatic leaks, but upstream obstructions of the TD present a novel challenge. Obstruction of TD outflow increases lymphatic pressures, leading to several conditions such as lymphedema, chylous and non-chylous ascites, abdominal pain, and more. Herein we describe our early experience with Thoracic Duct Venous Junction Lymphoplasty (TDVL) for lymphatic decompression.
Materials and Methods: Review of internal prospectively collected database was performed to identify patients who underwent TDVL between September 2020 and May 2022. Patient demographics, baseline pathological characteristics, imaging findings, procedural details, and follow-up information was collected. Procedural outcomes were stratified into complete resolution, partial resolution, temporary resolution, and failure.
Results: Database review identified 23 patients (13M, 10F; average age of 57.3y ± 12.5y) who underwent technically successful TDVL. All patients demonstrated signs of lymphovenous junction obstruction/stenosis on dynamic contrast-enhanced MR lymphangiography and TD lymphography. Indication for TDVL were 11 (47.8%) ascites, bloating, and abdominal pain, 5 (21.7%) lower abdomen/extremities edema, 3 (13%) protein losing enteropathy (PLE), 2 (8.7%) neck swelling, 1 (4.3%) chest wall swelling, and 1 (4.3%) chylothorax. 6 (26.1%) patients had complete symptomatic resolution, 3 (13%) patients had partial resolution, 13 (56.5%) patients had temporary resolution of symptoms with median symptom-free duration of 14 days (ranging 5 to 180 days), and 1 (4.3%) patient had no improvement.
Conclusion: In patients with imaging findings of lymphatic obstruction and above-mentioned clinical presentations, TDVL was effective in alleviating symptoms for 19 of 23 (82.6%) patients, proving the pathophysiological mechanism of these diseases. High symptomatic recurrence rate commands further improvement of the TD venous decompression methods.
Abstract No. 193, Selective Lymphatic Embolization for Treatment of Lymphatic Conduction Disorders in Children
Srinivasan,1 G. Krishnamurthy,1 F. Escobar,1 C. Smith,1 Y. Dori1; 1Children's Hospital of Philadelphia
Purpose: The importance of preserving the thoracic duct (TD) when treating patients with lymphatic conduction disorders has been increasingly recognized. We present our experience with selective lymphatic embolization (SLE) in these patients, with focus on technical aspects and outcomes.
Materials and Methods: Clinical and lymphangiogram records of 39 patients (18 females; median age 6.5 y, IQR 9.3 y; median weight 20.5 kg, IQR 33 kg) who underwent SLE for thoracic lymphatic conduction disorders from 2015-2022 were analyzed; 36 patients presented with chylothorax and 15 with plastic bronchitis. Relevant clinical and imaging data, including technical aspects of the procedure, complications, and outcomes, were collated.
Results: Etiology of conduction disorders included palliation of single-ventricle heart disease in 28 patients (72%), vascular malformation/aneuploidy in 9 (23%), and trauma in 2 (5%). 39 procedures were performed after initial planning dynamic contrast-enhanced MR lymphangiogram. SLE of abnormal branches via microcatheter in the TD was performed in in 35 patients (90%), and an articulating steerable microcatheter was used for selection in 22 of 35 cases (63%). Initial TD access was antegrade in 24 of 35 (69%), retrograde in 1 of 35 (3%), and both in 10 of 35 (29%). A dextrose flood technique, requiring placement of 2 catheters in the TD, was used during embolization in 21 cases (54%). In 12 of 39 cases (31%), SLE was performed by direct needle puncture of target channels.
Adjunct procedures included balloon occlusion of the TD confluence in 5 cases, balloon occlusion of Fontan fenestration in 4, selective coil embolization in 2, and balloon dilation of duct stenosis with resolution of pressure gradient in 3 cases.
Inadvertent extension of glue into the TD was seen in 8 cases. In all cases, glue was cleared by flushing, snaring, or balloon maceration. Cerebral embolization after venous extension of glue occurred in 1 patient with a Glenn shunt, without neurologic sequela. The TD was confirmed to be patent in all cases.
Median follow-up was 571 days (IQR, 324 d; range, 42-2318 d). Presenting symptoms were resolved in 32 patients (82%), improved in 4 (10%), and unchanged in 1 (3%); 2 patients were lost to follow-up.
Conclusion: We show that selective lymphatic embolization, with appropriate attention to technique, can be performed safely, and that it is effective in the treatment of lymphatic conduction disorders. Importantly, selective techniques preserve the patency of the thoracic duct in these patients.
Abstract No. 194, Percutaneous Cholecystocholangiography for Early Exclusion of Biliary Atresia: A Single-Center 5-Year Experience
Todd,1 F. Nowakowski,2 K. Garcia-Reyes,1 V. Bishay,3 D. Shilo,3 E. Kim,4 A. Fischman,4 R. Lookstein,5 R. Patel6; 1Icahn School of Medicine at Mount Sinai; 2Mount Sinai Medical System; 3Mount Sinai; 4Mount Sinai Health System; 5Mount Sinai Hospital; 6Mount Sinai Medical Center
Purpose: To evaluate the clinical safety and effectiveness of ultrasound (US)-guided percutaneous cholecystocholangiography (PCC) at the time of liver biopsy for early exclusion of biliary atresia (BA) in infants with congenital cholestasis and liver disease.
Materials and Methods: A single-center retrospective review from December 2017 and August 2022 of all US-guided PCC done in infants under 100 days old with concern for biliary atresia at one academic institution. Pre-procedural data and procedural details including demographic information, CBC and LFTs were collected. Post-procedural outcomes including technical success, complications, pathology findings, and ultimate treatment course were also assessed.
Results: 22 infants (15 male, 7 female; age range, 27 to 98 days) were referred to the radiology department for PCC with suspected BA. A diagnosis of BA was excluded when contrast material was visualized in the gallbladder, biliary tree, and duodenum. US or fluoroscopic-guided liver biopsies were also performed at the time of PCC. Patients diagnosed with BA underwent the Kasai procedure. Of the 20 patients in whom PCC was attempted, technical success was achieved in 16. Of those, BA was excluded in 14, with the following diagnoses: neonatal hepatitis (n = 6), bile duct paucity of unknown cause (n = 5), A1AT deficiency (n = 1), total parenteral nutrition-associated cholestasis (n = 1), and CMV hepatitis (n = 1). BA was diagnosed from PCC in two patients and confirmed at surgery. In four cases of failed PCC, BA (n = 1), vanishing bile duct (n = 1), neonatal hepatitis (n = 1), and Alagille syndrome (n = 1) was diagnosed. BA was also diagnosed in the two infants for whom PCC was not attempted due to lack of visualization of the gallbladder on US.
Conclusion: Percutaneous cholecystocholangiography is a safe and clinically effective technique that allows for the quick exclusion of biliary atresia at the time of biopsy without the need for a potential second invasive intraoperative cholangiogram or pathology results.
Wednesday, March 8
Abstract No. 241, MRI Monitoring Transcatheter Intraarterial Delivery of Clinical Magnetically Labeled Natural Killer Adoptive Immunotherapy
Zhang,1 A. Eresen,1 Z. Chen,2 Z. Yu,3 N. Abi-Jaoudeh,4 V. Yaghmai,1 Z. Zhang1; 1University of California, Irvine; 2University of Southern California; 3University of Washington; 4University of California
Purpose: The purposes of our study were to test the following hypotheses in a rat model with liver tumor: (1) transcatheter intrahepatic arterial (IHA) natural killer (NK) infusion improves NK cell homing efficacy in targeted tumors compared with intravenous (IV) injection, and (2) serial MRI monitoring of NK cell migration in targeted tumors can serve as an early biomarker for prediction of longitudinal response.
Materials and Methods: This study used a clinically applicable approach combining FDA-approved drugs heparin (H), protamine (P), and ferumoxytol (F) to form HPF nanocomplexes for magnetic NK labeling, allowing visualization of NK cell biodistribution in vivo with advanced MRI. NK cells (LNK cell line) were labeled with clinically applicable HPF nanocomplexes. Twenty-four rat HCC models (buffalo rats with McA-RH7777 liver tumor implantation) were assigned to three groups: transcatheter IHA saline infusion control group, transcatheter IHA NK infusion group, and IV NK infusion group. T2*-weighted MRI studies were performed at baseline, 24 h, 48 h, and 8 days following transcatheter IHA local delivery and IV injection. Two-tailed Student t-test was used to evaluate pairwise significance among the groups.
Results: There was a significant difference in tumor R2* values between baseline and 24 h following the selective transcatheter IHA NK delivery to the tumors (P = 0.04) compared with that of IV NK infusion (P = 0.803). At 8 days post-infusion, there were significant differences in tumor volumes between the control, IV, and IHA NK infusion groups (control vs. IV, P = 0.12; control vs. IHA, P = 0.001; and IV vs. IHA, P = 0.001). Moreover, there was a strong correlation between the change in tumor R2* value (∆R2*) at 24 h post-infusion and the change in tumor volume (∆volume) at 8 days in the IHA group (R2 = 0.704, P = 0.003).
Conclusion: MRI can track clinically applicable labeled NK cells with a 12 h labeling time. Transcatheter IHA infusion improves NK cell homing efficacy and immunotherapeutic efficiency. The change in tumor R2* value 24 h post-infusion is a crucial early biomarker for predicting longitudinal response.
Abstract No. 251, Cost-Effectiveness Analysis of Interventional Liver-Directed Therapies for Downstaging of Hepatocellular Carcinoma Before Liver Transplant
Wu,1 A. Kwong,2 M. Heller,1 R. Lokken,3 N. Fidelman,1 N. Mehta1; 1University of California, San Francisco; 2Stanford Healthcare; 3UCSF Department of Radiology
Purpose: To perform a cost-effectiveness analysis comparing the two most commonly used modalities, transarterial chemoembolization (TACE) and transarterial radioembolization (TARE) for downstaging of hepatocellular carcinoma (HCC) before liver transplant (LT).
Materials and Methods: A cost-effectiveness analysis was performed comparing TACE and TARE downstaging HCC over a 5-year time horizon from a payer’s perspective. The clinical course, including both successful downstaging leading to LT and failure of downstaging with possible disease progression, were from the United Network for Organ Sharing. The median number of treatments needed for downstaging was from the MERITS-LT consortium (2 in TARE and 3 in TACE cohorts). Costs and effectiveness were measured in US dollars and quality-adjusted life years (QALYs). Probabilistic and deterministic sensitivity analyses were performed.
Results: TARE achieved a higher effectiveness 2.49 QALY (TACE: 2.31 QALY) at a higher cost $172,965 (TACE: $157,687), with the incremental cost-effectiveness ratio of $85,517 /QALY, making TARE the more cost-effective strategy. The difference in outcome was equivalent to 84.4 days (nearly 3 months) in compensated cirrhosis state. Probabilistic sensitivity analyses showed TARE was more cost-effective in 64.92% of 10,000 Monte Carlo simulations.
TACE was more effective if greater than 84% of patients who received TACE as the initial LRT could receive liver transplant per year (base case: 74.6% from pooled analysis of multiple published cohorts). TARE became more cost-effective when the cost of TACE exceeded $10,638 (base case: $12,722) or when the cost of TARE was lower than $34,023 (base case: $30,609). Subgroup analyses TARE be the more cost-effective strategy if this cohort required one fewer LRT than the TACE cohort.
Conclusion: TARE is the more cost-effective downstaging strategy for patients with HCC exceeding Milan criteria when compared with TACE.
Abstract No. 274, Predicting the Safety and Effectiveness of Inferior Vena Cava Filters (PRESERVE): Outcomes at 12 Months
Johnson,1 J. Spies,2 K. Scott,3 B. Kato,3 X. Mu,3 J. Rectenwald,4 R. White,5 M. Khaja,6 D. Zuckerman,7 T. Casciani,1 D. Gillespie8; 1Indiana University; 2Georgetown University Medical Center; 3Healthcore; 4University of Wisconsin; 5University of California Los Angeles; 6University of Michigan; 7Yale; 8Southcoast Health
Purpose: To characterize the current practice of vena cava filter use in the United States, including indications, safety and effectiveness.
Materials and Methods: PRESERVE was a multicenter, prospective, open-label, non-randomized longitudinal evaluation of subjects in whom commercially available vena cava filters from seven manufacturers were implanted at 54 sites in the United States between October 10, 2015, and March 31, 2019.
Subjects were evaluated at procedure, discharge, and 3, 6, 12, 18, and 24 months post-procedure. Follow-up imaging was performed at 3 and 12 months. Subjects from whom vena cava filters were removed were followed for 1 month post-retrieval. The composite primary safety endpoint was freedom from perioperative significant adverse events and freedom from clinically significant perforation, filter embolization, caval thrombotic occlusion, and/or new deep vein thrombosis within the first twelve months following placement, assessed in subjects with filters at twelve months; Composite primary effectiveness endpoint: procedural success and freedom from new clinically significant pulmonary embolus at twelve months or one-month post-retrieval.
Results: Filters were implanted in 1421 subjects. Of these, 1019 (71.7%) had current deep vein thrombosis and/or pulmonary embolus. Anticoagulation was contraindicated or had failed in 1159 (81.6%). One hundred twenty six vena cava filters were placed as prophylaxis. Filters were removed from 632 (44.5%) subjects. The primary safety endpoint (89.4%) and primary effectiveness endpoint (96.4%) were both achieved. Procedural complications were uncommon and usually mild, but one subject died during attempted filter removal. Clinically significant vena cava filter-related adverse events were rare. Post-filter deep vein thrombosis (80 events in 74 subjects [5.2%]), pulmonary embolus (23 events in 23 subjects [1.6%]), and/or caval thrombotic occlusions (15 events in 15 subjects [1.1%]), none fatal, occurred in 93 subjects (6.5%). No pulmonary embolus occurred in subjects following prophylactic placement.
Conclusion: Implantation of vena cava filters in patients with venous thromboembolism and contraindication to or complication or failure of anticoagulation is associated with few adverse events and is effective in preventing clinically significant pulmonary embolus. Prophylactic use is associated with very few adverse events and is effective in preventing clinically significant pulmonary embolus.
