Experimental multiparametric magnetic resonance imaging characterization of iliocaval venous thrombosis pathological changes

OBJECTIVE

Iliocaval thrombotic obstruction is a challenging condition, especially because thrombus age and corresponding pathological remodeling at presentation are unknown, which directly impacts management. Our aim was to assess the ability of magnetic resonance imaging (MRI) in determining age thresholds of experimentally created inferior vena cava (IVC) thrombosis in pigs.

METHODS

We used a previously described swine model of IVC thrombosis. The animals underwent MRI at baseline, immediately after thrombosis creation, and after a follow-up period extending from 2 to 28 days. Thirteen pigs were divided into three groups according to disease chronicity: acute group (AG; n = 5), subacute group (SAG; n = 4), and chronic group (CG; n = 4), with a mean thrombosis age of 6.4 ± 2.5 days, 15.7 ± 2.8 days, and 28 ± 5.7 days, respectively. A T1-weighted volumetric interpolated breath-hold examination sequence was used to anatomically delineate IVC thrombus as a region of interest. Three other MRI sequences were used to assess the thrombus signal.

RESULTS

The Kruskal-Wallis test showed a statistically significant difference in T1 relaxation times after contrast injection (P = .026) between the three groups of chronicity. The AG (360.2 ± 102.5 ms) was significantly different from the CG (336.7 ± 55.2 ms; P = .003), and the SAG (354.1 ± 89.7 ms) was significantly different from the AG (P = .027). There was a statistically significant difference in native T2 relaxation times (P = .038) between the three groups. The AG (160 ± 86.7 ms) was significantly different from the SAG (142.3 ± 55.4 ms; P = .027), and the SAG was significantly different from the CG (178.4 ± 11.7 ms; P = .004).

CONCLUSIONS

This study highlighted MRI characteristics in a swine model that might have the potential to significantly differentiate subacute and chronic stages from an acute stage of deep vein thrombosis in humans. Further clinical studies in humans are warranted.

CLINICAL RELEVANCE

In addition to providing a better understanding of venous thrombosis remodeling over time, magnetic resonance imaging has the potential to be a tool that could allow us to characterize the composition of venous thrombus over an interval, allowing for a refined analysis of the local evolution of venous thrombosis. We propose a noninvasive and innovative method to characterize different thresholds of chronicity with magnetic resonance imaging features of central deep vein thrombosis of the inferior vena cava experimentally obtained using a totally endovascular in vivo swine model, mimicking human pathophysiology. Being able to determine these features noninvasively is critical for vascular specialists when it comes to choosing between fibrinolytic therapy, percutaneous thrombectomy, or surgical management.

Added Value of Selective Intra-arterial Cone-Beam CT Angiography in the Management of Visceral Artery Aneurysms

PURPOSE

The aim of this study is to evaluate the value of selective intra-arterial cone-beam computed tomography angiography (CBCTA) relative to conventional computed tomography angiography (CTA) in understanding visceral artery aneurysm (VAA) morphology, and its impact on treatment planning.

MATERIALS AND METHODS

Between January 2017 and August 2021, all patients who had a diagnosis of VAA and underwent intraoperative CBCTA imaging were retrospectively reviewed. Impact on treatment decisions, optimal C-arm angulations derived from CBCTA, and additional radiation exposure were reported. Two blinded independent reviewers qualitatively reviewed CBCTA and conventional CTA images. A 5-point Likert scale (1=poor image quality, 5=excellent image quality) was used to assess the overall image quality of each modality. Number of vessels arising from the aneurysm sac was counted.

RESULTS

A total of 16 patients had a diagnosis of VAA during the study period, of whom 10 patients had intraoperative CBCTA and conventional CTA available for review. Out of 10 patients, 7 underwent successful endovascular treatment, 2 were deemed not amenable for endovascular embolization based on intraoperative CBCTA findings, and 1 had resolved pseudoaneurysm. Total fluoroscopy time and radiation dose (dose area product [DAP] and skin dose) for all procedures were 27.7 ± 19.9 minutes, 28 362 (±18 651) µGy*m2, and 1879 (±1734) mGy, respectively. Radiation exposure from CBCTA (DAP and skin dose) was 5703 (±3967) µGy*m2 and 223.6 (±141.3) mGy, respectively. In patients who underwent endovascular treatment, the proportional DAP from CBCTA was 18.3% (±15.3%) of the total procedural radiation dose. Qualitative rating of overall image quality of CBCTA images was superior to CTA images (mean score: 4.55 vs 3, p<0.001). More branch vessels arising from the VAA were identified by all reviewers in CBCTA as compared with conventional CTA (median, min-max: 3, 0-4 vs 2,1-3 vessels).

CONCLUSION

Intraoperative CBCTA after selective intra-arterial contrast injection, with better spatial resolution, provided better delineation of visceral aneurysm morphology as compared with conventional, intravenous CTA and enabled optimal treatment planning at a reasonable additional radiation exposure.

CLINICAL IMPACT

Visceral artery aneurysms (VAA) are often diagnosed incidentally by conventional computed tomographic angiography (CTA). Endovascular treatment typically requires selective angiographies at multiple projections to better understand aneurysm morphology, location, and efferent branch vessels. Intra-arterial cone-beam CT angiography (CBCTA) for VAA has the advantage of selective contrast opacification, better spatial resolution, and three-dimensional/multi-planar visualization of aneurysm morphology. In addition, CBCTA enables identification of optimal C-arm working projection for subsequent endovascular treatment. The aim of this study is to evaluate the value of intraoperative CBCTA relative to conventional CTA in understanding visceral artery aneurysm morphology and its impact on treatment planning.

"Octafen": A Noninvestigational Alternative Endograft Configuration for the Treatment of Thoracoabdominal Aortic Aneurysms

PURPOSE

To demonstrate the feasibility of Octafen technique, a novel endovascular configuration for the treatment of thoracoabdominal aortic aneurysms (TAAA).

TECHNIQUE

Two patients with complex TAAA and high surgical risk were treated with Octafen endograft configuration in a hybrid operating room with computed tomography (CT)-fluoroscopy image fusion guidance, using 3D-3D fusion techniques to facilitate procedural success. The procedure is a modification of the previously-described Octopus technique for endovascular repair of TAAA. The main advantage of this technique is the ability to use devices to repair a TAAA with the combination of off-the-shelf and noninvestigational custom-made devices. The devices used are readily available to most practicing vascular surgeons, which provides an alternative treatment in case of limited access to investigational devices, in time-sensitive cases, and in patients with limited functional capacity who cannot undergo open repair. In the modification described herein, we use a combination of standard bifurcated endovascular aneurysm repair (EVAR) devices (Excluder; W.L. Gore & Associates, Flagstaff, Arizona) in combination with a 2-vessel renal fenestrated device (Z-Fen; Cook Medical, Bloomington, Indiana). The article describes a step-by-step approach to this technique to elucidate pitfalls, benefits, and advantages.

CONCLUSION

The Octafen technique might offer an alternative option for thoracoabdominal aneurysm treatment circumventing the need for access to custom-made, investigational devices.

CLINICAL IMPACT

In this manuscript, we describe a technique for endovascular repair of thoraco-abdominal aortic aneurysms that involves the combination of off-the-shelf and non-investigational, custom-made devices. The 'Octafen' technique provides a treatment alternative in case of limited access to investigational devices and can be adjusted according to patient anatomy.

Endovascular retrieval of a fractured Optease inferior vena cava filter using endobronchial forceps and intraoperative cone-beam computed tomography guidance

Endovascular retrieval of fractured inferior vena cava (IVC) filters after the manufacturer recommended indwelling time can be challenging and require advanced retrieval techniques. We describe an endovascular retrieval technique of a fractured Optease IVC filter in a 57-year-old woman using endobronchial forceps and intraoperative cone-beam computed tomography guidance. Following incomplete filter retrieval, the location and orientation of fractured strut was confirmed by cone-beam computed tomography venography. The embedded filter fragment was then successfully removed using endobronchial forceps via a transjugular venous approach. In the present report, we highlight the additional value of intraoperative cross-sectional imaging, in conjunction with advanced endovascular techniques, for retrieval of challenging IVC filters.

Cadaveric aortic aneurysm creation: A life-like model for training endovascular repair

The recent decline in RAAA incidence and the fast paced scenario with associated challenges regarding training calls for initiative for a better training environment to maximize learning. This led us to the creation of a pulsatile human cadaveric RAAA model. Fresh frozen cadaver was used to create RAAA with BioTissue in hybrid suite with ability to perform CBCTA for sizing. As a proof of concept, the model was used to perform REVAR with proximal CODA balloon control. The model proved to be feasible and we believe it is a better environment to train and gain adequate proficiency in RAAA management.

Emerging Applications for Computer Vision and Artificial Intelligence in Management of the Cardiovascular Patient

Artificial intelligence and telemedicine promise to reshape patient care to an unprecedented extent, leading to a safer and more sustainable work environment and improved patient care. In this article, we summarize how these emerging technologies can be used in the care of cardiovascular patients in such ways as fall detection and prevention, virtual nursing, remote case support, automation of instrument counts in the operating room, and efficiency optimization in the cardiovascular suite.

Dynamic, Time-Resolved CT Angiography After EVAR: A Quantitative Approach to Accurately Characterize Aortic Endoleak Type and Identify Inflow Vessels

PURPOSE

Our purpose was to study the accuracy of dynamic computed tomography angiography (d-CTA) in characterizing endoleak type, inflow vessels as compared with digital subtraction angiography (DSA) using qualitative and quantitative analysis.

METHODS

Between March 2019 and January 2021, all patients who underwent d-CTA imaging after EVAR were retrospectively reviewed. Two blinded independent reviewers qualitatively reviewed d-CTA and DSA images. Quantitative region of interest (ROI) analysis was performed by measuring time-resolved contrast enhancement within the aorta and endoleak lesion(s) in the aneurysm sac. Differences between time-to-peak enhancement (Δ TTP) across different ROIs were quantified.

RESULTS

A total of 48 patients underwent d-CTA during the study period, of whom 24 patients had abdominal EVAR and DSA imaging for comparison. Qualitative review of DSA imaging showed type I (n=4), type II (n=16), and type III (n=2) and no endoleak (n=2). In 23 of 24 patients (95.8%), d-CTA findings correlated with DSA findings for endoleak type. One patient had a type III endoleak that was demonstrated only in d-CTA (arising from defect in polymer sealing ring of Ovation stent graft) imaging. In type II endoleak cases, d-CTA identified more inflow vessels than DSA imaging (33 vs 21 vessels, p=0.010). Quantitative analysis showed mean (±SD) Δ TTP values for type I endoleak as 1.8 (±1.8) seconds, type II as 9.6 (±3.5) seconds, and for type III endoleak as 5.6 (±1.3) seconds.

CONCLUSION

Dynamic CTA can accurately characterize aortic endoleak type, inflow vessels as compared with DSA imaging. Quantitative parameters such as Δ TTP enhancement can help better differentiate endoleak types and provide an objective approach to endoleak diagnosis.

Dynamic Imaging of Aortic Pathologies: Review of Clinical Applications and Imaging Protocols

The past decade has seen significant advances in dynamic imaging of the aorta. Today's vascular surgeons have the opportunity to choose from a wide array of imaging modalities to evaluate different aortic pathologies. While vascular ultrasound and aortography are considered to be the bread and butter imaging modalities, newer dynamic imaging techniques provide time-resolved information in various aortic pathologies. However, despite growing evidence of their advantages in the literature, they have not been routinely adopted. In order to understand the role of these emerging modalities, one must understand their principles, advantages, and limitations in the context of various clinical scenarios. In this review, we provide an overview of dynamic imaging techniques for aortic pathologies and describe various dynamic computed tomography and magnetic resonance imaging protocols, clinical applications, and potential future directions.

Single-Center Experience With Aortic Coarctation Stenting in Adult Patients

OBJECTIVE

Endovascular repair of aortic coarctation (CoA) has become an important tool in the treatment of an expanding patient population. In this study, we present our 10-year experience with endovascular repair of CoA.

METHODS

Between January 2012 and January 2022, a total of 15 patients were treated at our Institution for CoA with catheter-based techniques. Demographics, intraprocedural data, and follow-up data were retrospectively collected from institutional databases and analyzed. The primary endpoint was technical success and secondary endpoints were intraoperative complications and short-, mid-, and long-term follow-up.

RESULTS

Mean age was 44.87 ± 15.52 years (range, 15-64) and 12 patients (80%) were male. Fourteen patients (93.3%) were hypertensive, and 4 patients (26.7%) had a bicuspid aortic valve. Three patients (20%) had undergone open repair in the pediatric age. Fourteen patients (93.3%) received stenting of CoA and 1 patient (6.7%) received thoracic endovascular aortic repair and left subclavian artery stenting for proximal pseudoaneurysmatic dilation and symptomatic restenosis. Mean pretreatment trans-stenotic gradient was 23.25 ± 11.16 mm Hg and posttreatment trans-stenotic gradient was 1.3 ± 1.33 mm Hg. Primary technical success was achieved in 15 cases (100%). One right inguinal hematoma (6.7%) was observed. One patient (6.7%) had an aortic rupture at the left subclavian artery origin after poststent dilation. Mean follow-up time was 34.75 ± 34.38 months. A total of 2 patients had an increased trans-stenotic gradient at long-term follow-up, and 1 reintervention (6.7%) for somatic growth was performed.

CONCLUSIONS

Endovascular repair of CoA is effective and safe, with excellent mid-term and long-term success rates.

Advanced intraoperative imaging guidance for inside-out central venous recanalization using a novel catheter access system

BACKGROUND

The novel Surfacer Inside-Out recanalization technique facilitates right-sided central venous access in occluded vessels but carries a risk of arterial and pleural injuries. This article demonstrates how an advanced intraoperative imaging protocol can help to avoid these potential complications.

METHODS

This retrospective review included patients undergoing the Surfacer Inside-Out central venous recanalization procedure between December 2017 and October 2021. The study sample comprised patients included in the SAVE-US trial at our site as well as patients treated after US Food and Drug Administration approval of the device. All procedures were performed using intraoperative cone-beam computed tomography (CBCT) angiography to map out the trajectory of the device through the mediastinum and supraclavicular space with fusion imaging for guidance. Procedures were aborted if CBCT findings predicted injury to arterial or respiratory structures. The intraoperative coronal and sagittal orientation of the device was compared to preoperatively predicted trajectory.

RESULTS

A total of 17 procedures were performed in 16 patients with end-stage renal disease and a mean age of 61 ± 11 years. Most patients presented a type 3 central venous occlusion (9/15). Successful recanalization was achieved in 14 of the 17 cases (82.4%) with no intraoperative complications. The procedure had to be aborted in 3 of the 17 cases based on intraoperative CBCT findings, which projected the device to perforate the right pleural space in one patient, the trachea and right subclavian artery in another, and the innominate artery in the third patient. The total radiation dose per procedure was 753 ± 346 mGy and the mean procedural time was 101.6 ± 29.7 minutes. A median of 2 (range, 1-5) intraoperative CBCT scans were performed per patient and accounted for 70% of the total radiation dose. Statistical analysis showed intraoperative CBCT findings to differ significantly from preoperative predicted values.

CONCLUSIONS

The nonsteerable and penetrating nature of the Surfacer device may lead to serious complications when performed under fluoroscopic guidance alone. Intraoperative CBCT with fusion overlay enhances the safety and effective use of this device and inside out crossing technique.

Dynamic CT angiography is more accurate in diagnosing endoleaks than standard triphasic CT angiography and enables targeted embolization

PURPOSE

The primary objective was to compare the accuracy of dynamic CT angiography (d-CTA) with standardized triphasic contrast enhanced CT angiography (t-CTA) in diagnosing endoleak type after endovascular aortic repair (EVAR) using digital subtraction angiography (DSA) as reference standard. The secondary objective was to study the impact of d-CTA on image-fusion guided endoleak embolization.

MATERIALS AND METHODS

Retrospective review of patients who underwent d-CTA imaging after EVAR between March 2019 and July 2021 was performed. De-identified images were independently reviewed by two-two blinded readers to document endoleak type and target vessels. Impact of d-CTA-guided embolization was evaluated by number of planning angiograms, radiation exposure and accuracy of target vessel overlay.

RESULTS

During the study period, 52 patients underwent d-CTA, 19 had all three modalities available for analysis. DSA imaging confirmed 4(21.0%) type-I, 14(73.7%) type-II and 1(5.3%) type-III endoleak. Findings from d-CTA matched with DSA in 19/19 cases (100%), whereas t-CTA matched in 14/19 cases (73.7%). In type-II endoleaks, number of target vessels identified by d-CTA, t-CTA and DSA were 23, 17 and 16 respectively. Mean dose-length product from d-CTA and t-CTA was 1445±551 and 1612±530 mGy*cm (p=0.26). Nine patients underwent d-CTA-guided type-II endoleak embolization, using a median of 1(range:1-4) planning angiogram before embolization utilizing 21.6(±8.7)% of total procedural radiation dose. Target vessel overlay was accurate in 9/9(100%) cases.

CONCLUSION

Dynamic, time-resolved CTA is more accurate compared to standardized triphasic contrast enhanced CTA in diagnosing endoleak type after EVAR. In type-II endoleak, d-CTA better identified target vessels and enabled safe, targeted embolization.

Diagnostic accuracy of FDG PET for the identification of Vascular Graft Infection

BACKGROUND

Fluorodeoxyglucose (FDG) positron emission tomography (FDG PET/CT) can be used to identify and localize infection in patients with vascular graft infections (VGI). We aimed to evaluate the diagnostic accuracy of 18F-FDG PET/CT by defining thresholds for standardized uptake value (SUV) and tissue-to-background ratio (TBR) that would accurately identify the presence of vascular graft infection.

METHODS

Patients with suspected VGI were prospectively recruited and underwent 18F-FDG PET/CT scans. Diagnosis was based on clinical, laboratory and radiologic findings, and blinded to the results of the PET/CT scan. Receiver operator characteristics (ROC) curve analysis was done to determine optimal thresholds for SUV and TBR.

RESULTS

Our final cohort consisted of 28 patients with suspected VGI (mean±SD age 67±10 years, 61% men), of which 15 patients (54%) had definitive VGI. The cohort included 61% prosthetics grafts and 39% stent-grafts. The type of graft included in this study were biologic (4%), Dacron (64%) and Polytetrafluoroethylene (32%). The location of the implanted grafts were aortic (54%) and peripheral arterial reconstruction (46%). The location of the peripheral graft was 77% in lower extremity and 23% in the upper extremity (arterio-venous grafts for dialysis access). Using ROC analysis, SUV max of 4.5, SUV mean of 3.7, and a TBR of 1.6 gave the best balance between sensitivity and specificity (93%/92%, 100%/92% and 93%/92% respectively). All thresholds had an area under the curve ≥0.93 and correct reclassification rate ≥93%.

CONCLUSION

Our data suggests that FDG PET/CT can be used to reliably and accurately diagnose VGI. The dual anatomic-physiologic information from FDG PET/CT can complement clinical diagnosis particularly in uncertain cases.

Endovascular Porcine Model of Iliocaval Venous Thrombosis

OBJECTIVE

To develop a large animal model of iliocaval deep venous thrombosis (DVT), which enables development and evaluation of interventional management and existing imaging modalities.

METHODS

The experimental protocol consisted of a total endovascular approach. Pigs were percutaneously accessed through the right internal jugular and bilateral femoral veins. Three balloon catheters were inflated to induce venous stasis in the infrarenal inferior vena cava (IVC) and bilateral common iliac veins (CIVs). Hypercoagulability was induced by injecting 10 000 IU of thrombin. After 2.5 hours, the balloon catheters were removed before animal recovery. After seven, 14, 21, 28, or 35 days, animals were euthanised; the IVC and CIV were harvested en bloc, cross sectioned and prepared for histological examination. Multimodal imaging was performed before and after thrombus creation, and before animal euthanasia.

RESULTS

Thirteen female domestic pigs with a mean weight of 59.3 kilograms were used. The mean maximum IVC diameter and area were 16.4 mm and 1.2 cm², respectively. The procedure was successful in 12 animals with occlusive venous thrombosis in the region of interest on immediate post-operative magnetic resonance venography and a mean thrombus volume of 19.8 cm³. Clinical pathology results showed platelet consumption, D dimer increase, and inflammatory response. Histological evaluation demonstrated a red cell, fibrin, and platelet rich thrombus on day 1, with progressive inflammatory cell infiltration from day 7. Collagen deposition appeared in week 2 and neovascularisation in week 3.

CONCLUSION

Endovascular occlusion combined with thrombin infusion is a reliable minimally invasive approach to produce acute and subacute DVT in a large animal model.

Giant right coronary artery to coronary sinus fistula

BACKGROUND

We describe a giant right coronary artery (RCA) to coronary sinus (CS) fistula in a 59-year-old woman who presented to our institution with right heart enlargement.

METHODS

Investigation revealed an ectatic 22mm RCA draining into an enlarged CS, and a Qp:Qs of 2.0. We proceeded with surgery. After initiating cardiopulmonary bypass and electrical arrest, the distal RCA was opened. An opening into the CS was confirmed and closed with a bovine pericardium patch. The RCA origin was triply ligated. Anastomoses of a saphenous vein graft to the posterior descending artery and the right ventricular marginal artery were performed, followed by anastomosis to the ascending aorta.

RESULTS

Post-operatively, mixed venous oxygen saturation was 76%. Six months later the patient was doing well.

CONCLUSION

Coronary artery fistulas are rare congenital anomalies for which the ideal management strategies remain under study, with surgical repair being the mainstay of treatment in complex, aneurysmal fistulas.

Transcarotid access for remote robotic endovascular neurointerventions: a cadaveric proof-of-concept study

OBJECTIVE

The purpose of this proof-of-concept study was to demonstrate the setup and feasibility of transcarotid access for remote robotic neurointerventions in a cadaveric model.

METHODS

The interventional procedures were performed in a fresh-frozen cadaveric model using an endovascular robotic system and a robotic angiography imaging system. A prototype remote, robotic-drive system with an ethernet-based network connectivity and audio-video communication system was used to drive the robotic system remotely. After surgical exposure of the common carotid artery in a cadaveric model, an 8-Fr arterial was inserted and anchored. A telescopic guiding sheath and catheter/microcatheter combination was modified to account for the "workable" length with the CorPath GRX robotic system using transcarotid access.

RESULTS

To simulate a carotid stenting procedure, a 0.014-inch wire was advanced robotically to the extracranial internal carotid artery. After confirming the wire position and anatomy by angiography, a self-expandable rapid exchange nitinol stent was loaded into the robotic cassette, advanced, and then deployed robotically across the carotid bifurcation. To simulate an endovascular stroke recanalization procedure, a 0.014-inch wire was advanced into the proximal middle cerebral artery with robotic assistance. A modified 2.95-Fr delivery microcatheter (Velocity, Penumbra Inc.) was loaded into the robotic cassette and positioned. After robotic retraction of the wire, it was switched manually to a mechanical thrombectomy device (Solitaire X, Medtronic). The stentriever was then advanced robotically into the end of the microcatheter. After robotic unfolding and short microcatheter retraction, the microcatheter was manually removed and the stent retriever was extracted using robotic assistance. During intravascular navigation, the device position was guided by 2D angiography and confirmed by 3D cone-beam CT angiography.

CONCLUSIONS

In this proof-of-concept cadaver study, the authors demonstrated the setup and technical feasibility of transcarotid access for remote robot-assisted neurointerventions such as carotid artery stenting and mechanical thrombectomy. Using transcarotid access, catheter length modifications were necessary to achieve "working length" compatibility with the current-generation CorPath GRX robotic system. While further improvements in dedicated robotic solutions for neurointerventions and next-generation thrombectomy devices are necessary, the transcarotid approach provides a direct, relatively rapid access route to the brain for delivering remote stroke treatment.

Time-resolved, Cardiac-gated Computed Tomography after Endovascular Ascending Aortic and Arch Repair

PURPOSE

Better time-resolved imaging of stent grafts in ascending aorta and arch accounting for cardiac motion is necessary to understand device-related complications and endoleaks. We describe a novel dynamic time-resolved computed tomography-angiography (d-CTA) and its combination with electrocardiography-gating (d-gated-CTA) to image stent grafts in ascending aorta and to better characterize endoleaks.

DESCRIPTION

d-CTA involves multiple scans acquired at different timepoints along contrast enhancement curve. d-gated-CTA involves concomitant electrocardiography-gating in a pre-defined cardiac phase minimizing motion induced artifacts.

EVALUATION

We illustrate the utility of d-CTA and d-gated-CTA in two clinical scenarios. d-CTA demonstrated type 1A endoleak in a patient with aortic arch aneurysm treated by total arch debranching and thoracic stent graft. d-gated-CTA demonstrated type 1A endoleak in a patient with ascending aortic pseudo-aneurysm treated by aortic cuff placement.

CONCLUSIONS

Dynamic, cardiac-gated CTA enables time-resolved angiographic imaging of ascending aorta and arch without any cardiac motion related artifacts. Such advanced imaging techniques help with better characterization of endoleaks after stent-graft deployment in the ascending aorta and arch.

Time-Resolved, Dynamic Computed Tomography Angiography for Characterization of Aortic Endoleaks and Treatment Guidance via 2D-3D Fusion-Imaging

In the United States, more than 80% of all abdominal aortic aneurysms are treated by endovascular aortic aneurysm repair (EVAR). The endovascular approach warrants good early results, but adequate follow-up imaging after EVAR is imperative to maintain long-term positive outcomes. Potential graft-related complications are graft migration, infection, fraction, and endoleaks, with the last one being the most common. The most frequently used imaging after EVAR is computed tomography angiography (CTA) and duplex ultrasound. Dynamic, time-resolved computed tomography angiography (d-CTA) is a reasonably new technique to characterize the endoleaks. Multiple scans are done sequentially around the endograft during acquisition that grants good visualization of the contrast passage and graft-related complications. This high diagnostic accuracy of d-CTA can be implemented into therapy via image fusion and reduce additional radiation and contrast material exposure. This protocol describes the technical aspects of this modality: patient selection, preliminary image review, d-CTA scan acquisition, image processing, qualitative and quantitative endoleak characterization. The steps of integrating dynamic CTA into intra-operative fluoroscopy using 2D-3D fusion-imaging to facilitate targeted embolization are also demonstrated. In conclusion, time-resolved, dynamic CTA is an ideal modality for endoleak characterization with additional quantitative analysis. It can reduce radiation and iodinated contrast material exposure during endoleak treatment by guiding interventions.

Cone-Beam CT and Image Fusion-Guided Percutaneous Recanalization of Occluded Central Venous Stent

We describe an 81-year-old man with end-stage renal disease and central venous occlusion who was referred for dialysis access creation. This case illustrates a novel percutaneous image fusion–guided recanalization of an occluded right subclavian vein and brachiocephalic vein stent in a patient with limited remaining dialysis access sites. (Level of Difficulty: Advanced.)

Dynamic, Time-Resolved Computed Tomography Angiography Technique to Characterize Aortic Endoleak Type, Inflow and Provide Guidance for Targeted Treatment

PURPOSE

To illustrate dynamic, time-resolved CTA (d-CTA) imaging technique in characterizing aortic endoleak type/inflow using quantitative parameters and its value in providing image guidance for targeted treatment approach.

TECHNIQUE

Dedicated endoleak protocol involved acquiring multiple time-resolved contrast enhanced scans using third-generation CT scanner (Somatom Force^®, Siemens Healthineers). Parameters such as scan field of view (FOV), kV, number/timing of scans were customized based on patient's body-mass-index, timing bolus, and prior imaging findings. D-CTA image datasets were evaluated qualitatively and quantitatively using time-attenuation curves (TAC) analysis after motion correction using a dedicated software (syngo.via^®, Siemens). D-CTA findings from 4 illustrative cases demonstrating type I, type II (inferior mesenteric and lumbar artery inflow), and type III endoleak were illustrated. TAC analysis with time to peak parameter enabled better characterization of endoleak type and inflow. During endoleak intervention, target vessels from d-CTA images were electronically annotated and overlaid on fluoroscopy using 2D-3D image fusion to provide image guidance for targeted treatment.

CONCLUSION

D-CTA imaging with TAC analysis characterizes aortic endoleak type and inflow, in addition to providing image guidance for targeted endoleak treatment. Such dynamic, time-resolved imaging techniques may provide further insights into understanding aortic endoleak that remains an Achilles heel for endovascular aortic aneurysm repair.

CT-Fluoroscopy Image-Fusion Guidance for Embolization of Aortopulmonary Collaterals

BACKGROUND

In adults with congenital heart disease, anatomically complex culprit collateral vessels may cause life-threatening hemoptysis and require catheter-based embolization. Techniques using conventional 2-dimensional (2D) fluoroscopy can be challenging.

TECHNIQUE

We describe a technique using 2D/3-dimensional (3D) image fusion for intraprocedural guidance to embolize aortopulmonary collaterals. Two fluoroscopic images of the thorax at least 30° apart with pigtail catheter in the ascending aorta were used for image fusion with preprocedural computed tomography (CT) angiography using the spine and pigtail catheter as landmarks. 3D planning information was overlaid on 2D fluoroscopy for cannulation and embolization.

RESULTS

Between November 2018 and June 2019, a total of 6 sessions of aortopulmonary collateral embolization using CT-fluoroscopy image-fusion guidance were conducted in 3 patients with adult congenital heart disease. In 3/6 sessions, the indication for embolization was hemoptysis. Common target vessels were left and right bronchial arteries (4 and 3 sessions, respectively). The spine and a pigtail catheter in the aorta were frequently used as landmarks for image fusion (67%). Particle embolization was used in 100% of cases. Mean procedure and fluoroscopy times were 3 hours, 23 minutes and 1 hour, 3 minutes, respectively. On average, 169 mL (350 mg iodine/mL) of contrast material was used in each session and total skin dose of radiation exposure was 1538 mGy. Successful collateral embolization was confirmed by postprocedure angiography that showed negligible or no flow through culprit collaterals.

CONCLUSION

Use of CT-fluoroscopy image-fusion guidance can aid in embolization of aortopulmonary collaterals with complex anatomy in 3D space.

Successful coil embolization of a large right coronary artery-coronary sinus fistula causing a significant left-to-right shunt: a case report

Background

This case reviews a challenging but successful transcatheter coil embolization of a large congenital coronary artery fistula (CAF) causing a significant left-to-right shunt.

Case summary

A 51-year-old female with no significant prior history presented with symptoms of dyspnoea and chest discomfort. Extensive evaluation revealed a large CAF between a tortuous right coronary artery (RCA) and the coronary sinus (CS) composed of three aneurysmal pseudochambers. Closure of the RCA-CS fistula was attempted through coil deployment into the fistula neck. However, due to the brisk flow through the fistula, both coils embolized into the fistula sac. An alternative location was subsequently identified on three-dimensional rendering of a computed tomography angiography scan, which revealed a sharp bend in the RCA prior to the fistula neck and distal to the posterior descending artery (PDA) takeoff. Repeat attempt at embolization was accomplished using a telescoping system to reach and occlude the targeted bend. The coil mass remained stable and angiography demonstrated reduced flow through the fistula and preserved patency of the PDA. The decreased residual flow through the fistula secondary to the initial embolization attempt likely aided the successful deployment of coils in the second and final attempt. At 1 year, the patient was doing well with resolution of her symptoms and no clinical symptoms of coronary ischaemia.

Discussion

We suggest that an initial unsuccessful attempt at transcatheter embolization of a CAF should not preclude subsequent attempts for closure when there exists an appropriate indication.

Impact of network performance on remote robotic-assisted endovascular interventions in porcine model

Remote robotic-assisted endovascular interventions require real-time control of the robotic system to conduct precise device navigation. The delay (latency) between the input command and the catheter response can be affected by factors such as network speed and distance. This study evaluated the effect of network latency on robotic-assisted endovascular navigation in three vascular beds using in-vivo experimental model. Three operators performed femoral, carotid, and coronary endovascular robotic navigation blinded from the hybrid room with the prototype remote-enabled CorPath GRX system in a porcine model. Navigation was performed to different targets with randomly assigned network latencies from 0 to 1000 ms. Outcome measurements included navigation success, navigation time, perceived lag (1 = imperceptible, 5 = too long), and procedural impact scored by the operators (1 = no impact, 5 = unacceptable). Robotic-assisted remote endovascular navigation was successful in all 65 cases (9 femoral, 38 external carotid, 18 coronary). Guidewire times were not significantly different across the simulated network latency times. Compared to 0 ms added latency, both the procedural impact and perceived lag scores were significantly higher when the added latency was 400 ms or greater (< 0.01). Remote endovascular intervention was feasible in all studied anatomic regions. Network latency of 400 ms or above is perceptible, although acceptable to operators, which suggests that remote robotic-assisted femoral, carotid or coronary arterial interventions should be performed with network latency below 400 ms to provide seamless remote device control.

CT-Guided Endovascular Exclusion of Pseudoaneurysmal Subclavian Bypass After Early-Age Surgical Correction of Complex Aortic Coarctation

We describe a 64-year-old woman with subclavian pseudoaneurysm after aortic coarctation repair, treated using a hybrid approach involving true three-dimensional analysis and image fusion-guided placement of thoracic endovascular aortic repair stents. This case illustrates the potential complications of coarctation repair and need for lifelong surveillance in these patients. (Level of Difficulty: Advanced.)

Torque device suture technique to achieve hemostasis in large-bore venous access

Objectives

To describe and compare a novel technique using a torque device to manage figure‐of‐eight suture tension for venous access hemostasis in patients who have undergone atrial septal defect (ASD) or patent foramen ovale (PFO) closure.

Background

Large bore venous access has become increasingly important in transcatheter procedures, but management of hemostasis can be time‐consuming and/or resource intensive. As such, various techniques have sought to provide cost effective and safe alternatives to manual compression. We describe a modification of the figure‐of‐eight suture technique wherein we apply a torque device to manage variable suture tension instead of tying a knot and compare it to the standard figure‐of‐eight suture technique.

Methods

We performed a retrospective study of 40 consecutive patients who underwent ASD or PFO closure, 20 of whom underwent standard figure‐of‐eight technique and 20 of whom underwent figure‐of‐eight with torque device modification. Bleeding Academic Research Consortium definitions were used to categorize bleeding events.

Results

The groups were similar in age, gender, weight, aspirin use, platelet count, procedure time, hemoglobin, and international normalized ratio. Standard figure‐of‐eight suture had seven patients with bleeding, with six classified as BARC II and one as BARC I. Figure‐of‐eight plus torque device had three patients with bleeding, with two classified BARC II and one as BARC I. There were no incidences of hematoma in either group.

Conclusion

The torque device suture technique is a unique modification of the figure‐of‐eight suture technique to achieve venous hemostasis. In addition, the modification allows secure and variable suture tension as well as easy removal by nursing staff.

Intraoperative Imaging and Image Fusion for Venous Interventions

Advanced imaging for intraoperative evaluation of venous pathologies has played an increasingly significant role in this era of evolving minimally invasive surgical and interventional therapies. The evolution of dedicated venous stents and other novel interventional devices has mandated the need for advanced imaging tools to optimize safe and accurate device deployment. Most venous interventions are typically performed using a combination of standard 2-dimensional (2D) fluoroscopy, digital-subtraction angiography, and intravascular ultrasound imaging techniques. Latest generation computer tomography (CT) and magnetic resonance imaging (MRI) scanners have been shown to provide high-resolution 3D and 4D information about venous vasculature. In addition to morphological imaging, novel MRI techniques such as 3D time-resolved MR venography and 4D flow sequences can provide quantitative information and help visualize intricate flow patterns to better understand complex venous pathologies. Moreover, the high-fidelity information from multiple imaging techniques can be integrated using image fusion to overcome the limitations of current intraoperative imaging techniques. For example, the limitations of standard 2D fluoroscopy and luminal angiography can be compensated for by perivascular and soft-tissue information from MRI during complex venous interventions using image fusion techniques. Intraoperative dynamic evaluation of devices such as venous stents and real-time understanding of changes in flow patterns during venous interventions may be routinely available in future interventional suites with integrated multimodality CT or MR imaging capabilities. The purpose of this review is to discuss the outlook for intraoperative imaging and multimodality image fusion techniques and highlight their value during complex venous interventions.