Computed tomography angiography-fluoroscopy image fusion allows visceral vessel cannulation without angiography during fenestrated endovascular aneurysm repair

Real-time 3D-3D image fusion of CTA/CBCT roadmap fluoroscopy in the transcatheter mitral intervention

Absence of periprocedural visualization of three-dimensional (3D) left heart anatomy and its surrounding structures in fluoroscopy may reduce the rate of successful transcatheter mitral valve repair. We proposed a multimodal imaging strategy based on 3D computed tomography (CT) angiography and 3D cone beam CT fusion images, which enabled real-time visual inspection of 3D cardiac structures on fluoroscopy, to optimize transcatheter mitral intervention. This new image fusion technology, together with standard transesophageal echocardiography guidance, improved the efficiency and safety of the procedure, and could be considered as a new workflow for transcatheter mitral valve intervention.

Automated image fusion during endovascular aneurysm repair: a feasibility and accuracy study

PURPOSE

Image fusion merges preoperative computed tomography angiography (CTA) with live fluoroscopy during endovascular procedures to function as an overlay 3D roadmap. However, in most current systems, the registration between imaging modalities is performed manually by vertebral column matching which can be subjective, inaccurate and time consuming depending on experience. Our objective was to evaluate feasibility and accuracy of image-based automated 2D-3D image fusion between preoperative CTA and intraoperative fluoroscopy based on vertebral column matching.

METHODS

A single-center study with offline procedure data was conducted in 10 consecutive patients which had endovascular aortic repair in which we evaluated unreleased automated fusion software provided by Philips (Best, the Netherlands). Fluoroscopy and digital subtraction angiography images were collected after the procedures and the vertebral column was fused fully automatically. Primary endpoints were feasibility and accuracy of bone alignment (mm). Secondary endpoint was vascular alignment (mm) between the lowest renal artery orifices. Clinical non-inferiority was defined at a mismatch of < 1 mm.

RESULTS

In total, 87 automated measurements and 40 manual measurements were performed on vertebrae T12-L5 in all 10 patients. Manual correction was needed in 3 of the 10 patients due to incomplete visibility of the vertebral edges in the fluoroscopy image. Median difference between automated fusion and manual fusion was 0.1 mm for bone alignment (p = 0.94). The vascular alignment was 4.9 mm (0.7-17.5 mm) for manual and 5.5 mm (1.0-14.0 mm) for automated fusion. This did not improve, due to the presence of stiff wires and stent graft.

CONCLUSION

Automated image fusion was feasible when all vertebral edges were visible. Accuracy was non-inferior to manual image fusion regarding bone alignment. Future developments should focus on intraoperative image-based correction of vascular alignment.

A State-of-the-Art Review of Intra-Operative Imaging Modalities Used to Quality Assure Endovascular Aneurysm Repair

Endovascular aortic aneurysm repair (EVAR) is the preferred method for elective abdominal aortic aneurysm (AAA) repair. However, the success of this technique depends greatly on the technologies available. Intra-operative imaging is essential but can come with limitations. More complex interventions lead to longer operating times, fluoroscopy times, and greater contrast doses. A number of intra-operative imaging modalities to quality assure the success of EVAR have been developed. A systematic literature search was performed with separate searches conducted for each imaging modality in the study: computed tomography (CT), digital subtraction angiography (DSA), fusion, ultrasound, intra-operative positioning system (IOPS), and non-contrast imaging. CT was effective at detecting complications but commonly resulted in increased radiation and contrast dose. The effectiveness of DSA can be increased, and radiation exposure reduced, through the use of adjunctive technologies. We found that 2D-3D fusion was non-inferior to 3D-3D and led to reduced radiation and contrast dose. Non-contrast imaging occasionally led to higher doses of radiation. Ultrasound was particularly effective in the detection of type II endoleaks with reduced radiation and contrast use but was often operator dependent. Unfortunately, no papers made it past full text screening for IOPS. All of the imaging techniques discussed have advantages and disadvantages, and clinical context is relevant to guide imaging choice. Fusion and ultrasound in particular show promise for the future.

Updates in Endovascular Procedural Navigation In Canadian Journal of Cardiology

There have been significant advancements in endovascular technology over the past decade. Increasingly complex disease processes are being addressed in a less invasive fashion, while still relying on standard two-dimensional, gray-scale fluoroscopy imaging to guide the procedures. With the advent of flat panel detectors as standard on fluoroscopy units and the utilization of fluoroscopy cone-beam computed tomography, the development of improved imaging tools has occurred which will help improve the imaging modalities used to perform these endovascular procedures. . Fusion imaging, the overlay of pre-operative 3-dimensional computed tomography images helps interventionalists perform endovascular procedures. Building on this technology, improvements in its function and utilization have occurred with the additional application of artificial intelligence and machine learning - allowing the images to independently accommodate to changes in the visualized anatomy. Corresponding development of navigation systems, allowing for the tracking of endovascular tools within these images using either fiberoptics of electromagnetic field generators, are looking to improve the accuracy of the procedures while reducing the need for radiation and contrast agents. These tools are making a dramatic change in our ability to perform complex endovascular procedures, and are the future gold standard. Ultimately, these will allow procedures to occur more quickly and more safely.

Completion of Target Vessel Stenting After FEVAR via Snare Technique in a Patient with Tortuous Right Renal Artery

Target vessel catheterization remains challenging in patients with complex anatomies. Fenestrated endovascular aneurysm repair (FEVAR) is an established technique to treat aortic aneurysms. In this case report, we treated a juxtarenal aneurysm using FEVAR. Initial attempts to complete the target vessel stenting were unsuccessful because of an unfavorable orifice and tortuosity of the right renal artery. The completion of FEVAR was achieved with a bifemoral approach using a snare system, which aligned the tip of a steerable sheath at the level of the fenestration for the right renal artery to create a stable condition. Control angiography and computed tomography confirmed a successful stenting of the target vessel and the sealing of the fenestration without an endoleak.

Accuracy of registration techniques and vascular imaging modalities in fusion imaging for aortic endovascular interventions: a phantom study

Background

This study aimed to assess the error of different registration techniques and imaging modalities for fusion imaging of the aorta in a standardized setting using a anthropomorphic body phantom.

Materials and methods

A phantom with the 3D printed vasculature of a patient suffering from an infrarenal aortic aneurysm was constructed. Pulsatile flow was generated via an external pump. CTA/MRA of the phantom was performed, and a virtual 3D vascular model was computed. Subsequently, fusion imaging was performed employing 3D-3D and 2D-3D registration techniques. Accuracy of the registration was evaluated from 7 right/left anterior oblique c-arm angulations using the agreement of centerlines and landmarks between the phantom vessels and the virtual 3D virtual vascular model. Differences between imaging modalities were assessed in a head-to-head comparison based on centerline deviation. Statistics included the comparison of means ± standard deviations, student’s t-test, Bland-Altman analysis, and intraclass correlation coefficient for intra- and inter-reader analysis.

Results

3D-3D registration was superior to 2D-3D registration, with the highest mean centerline deviation being 1.67 ± 0.24 mm compared to 4.47 ± 0.92 mm. The highest absolute deviation was 3.25 mm for 3D-3D and 6.25 mm for 2D-3D registration. Differences for all angulations between registration techniques reached statistical significance. A decrease in registration accuracy was observed for c-arm angulations beyond 30° right anterior oblique/left anterior oblique. All landmarks (100%) were correctly positioned using 3D-3D registration compared to 81% using 2D-3D registration. Differences in accuracy between CT and MRI were acceptably small. Intra- and inter-reader reliability was excellent.

Conclusion

In the realm of registration techniques, the 3D-3D method proved more accurate than did the 2D-3D method. Based on our data, the use of 2D-3D registration for interventions with high registration quality requirements (e.g., fenestrated aortic repair procedures) cannot be fully recommended. Regarding imaging modalities, CTA and MRA can be used equivalently.

Image Fusion During Standard and Complex Endovascular Aortic Repair, to Fuse or Not to Fuse? A Meta-analysis and Additional Data From a Single-Center Retrospective Cohort

PURPOSE

To determine if image fusion will reduce contrast volume, radiation dose, and fluoroscopy and procedure times in standard and complex (fenestrated/branched) endovascular aneurysm repair (EVAR).

MATERIALS AND METHODS

A search of the PubMed, Embase, and Cochrane databases was performed in December 2019 to identify articles describing results of standard and complex EVAR procedures using image fusion compared with a control group. Study selection, data extraction, and assessment of the methodological quality of the included publications were performed by 2 reviewers working independently. Primary outcomes of the pooled analysis were contrast volume, fluoroscopy time, radiation dose, and procedure time. Eleven articles were identified comprising 1547 patients. Data on 140 patients satisfying the study inclusion criteria were added from the authors' center. Mean differences (MDs) are presented with the 95% confidence interval (CI).

RESULTS

For standard EVAR, contrast volume and procedure time showed a significant reduction with an MD of -29 mL (95% CI -40.5 to -18.5, p<0.001) and -11 minutes (95% CI -21.0 to -1.8, p<0.01), respectively. For complex EVAR, significant reductions in favor of image fusion were found for contrast volume (MD -79 mL, 95% CI -105.7 to -52.4, p<0.001), fluoroscopy time (MD -14 minutes, 95% CI -24.2 to -3.5, p<0.001), and procedure time (MD -52 minutes, 95% CI -75.7 to -27.9, p<0.001).

CONCLUSION

The results of this meta-analysis confirm that image fusion significantly reduces contrast volume, fluoroscopy time, and procedure time in complex EVAR but only contrast volume and procedure time for standard EVAR. Though a reduction was suggested, the radiation dose was not significantly affected by the use of fusion imaging in either standard or complex EVAR.

Improved 3D Catheter Shape Estimation Using Ultrasound Imaging for Endovascular Navigation: A Further Study

OBJECTIVE

Two-dimensional fluoroscopy is the standard guidance imaging method for closed endovascular intervention. However, two-dimensional fluoroscopy lacks depth perception for the intervention catheter and causes radiation exposure for both surgeons and patients. In this paper, we extend our previous study and develop the improved three-dimensional (3D) catheter shape estimation using ultrasound imaging. In addition, we perform further quantitative evaluations of endovascular navigation.

METHOD

First, the catheter tracking accuracy in ultrasound images is improved by adjusting the state vector and adding direction information. Then, the 3D catheter points from the catheter tracking are further optimized based on the 3D catheter shape optimization with a high-quality sample set. Finally, the estimated 3D catheter shapes from ultrasound images are overlaid with preoperative 3D tissue structures for the intuitive endovascular navigation.

RESULTS

the tracking accuracy of the catheter increased by 24.39%, and the accuracy of the catheter shape optimization step also increased by approximately 17.34% compared with our previous study. Furthermore, the overall error of catheter shape estimation was further validated in the catheter intervention experiment of in vitro cardiovascular tissue and in a vivo swine, and the errors were 2.13 mm and 3.37 mm, respectively.

CONCLUSION

Experimental results demonstrate that the improved catheter shape estimation using ultrasound imaging is accurate and appropriate for endovascular navigation.

SIGNIFICANCE

Improved navigation reduces the radiation risk because it decreases use of X-ray imaging. In addition, this navigation method can also provide accurate 3D catheter shape information for endovascular surgery.

Current utilization and future directions of robotic-assisted endovascular surgery

INTRODUCTION

Endovascular surgery has become the standard of care to treat most vascular diseases using a minimally invasive approach. The CorPath system further enhances the potential and enables surgeons to perform robotic-assisted endovascular procedures in interventional cardiology, peripheral vascular surgery, and neurovascular surgery. With the introduction of this technique, the operator can perform multiple steps of endovascular interventions outside of the radiation field with high precision movements even from long-geographical distances.

AREAS COVERED

The first and second-generation CorPath systems are currently the only commercially available robotic devices for endovascular surgery. This review article discusses the clinical experiences and outcomes with the robot, the advanced navigational features, and the results with recent hardware and software modifications, which enables the use of the system for neurovascular interventions, and long-distance interventional procedures.

EXPERT OPINION

A high procedural success was achieved with the CorPath robotic systems in coronary and peripheral interventions, and the device seems promising in neurovascular procedures. More experience is needed with robotic neurovascular interventions and with complex peripheral arterial cases. In the future, long-distance endovascular surgery can potentially transform the management and treatment of acute myocardial infarction and stroke, with making endovascular care more accessible for patients in remote areas.

Safety and Feasibility of Performing Fenestrated Endovascular Abdominal Aneurysm Repair Using a Portable C-arm Without Fusion Technology: A Single-Center Experience

Objective Most centers performing fenestrated endovascular aneurysm repair (F-EVAR) use hybrid rooms with fusion technology for mapping. We present our experience of successfully performing F-EVAR using C-arm without fusion technology. Methods During the period of January 2016 to October 2018, data were collected from a prospectively maintained F-EVAR database at our tertiary care institute. The primary endpoint was technical success, and the secondary outcomes measured were short- and midterm clinical success (both defined by the Society for Vascular Surgery reporting standards), blood loss, radiation dose, operative time, postoperative endoleaks, aneurysm rupture, endograft patency, and complications. Results We performed 11 F-EVARs during the study period in five (45.5%) males and six (54.5%) females, with a mean age of 75+8 years. All procedures were performed under general anesthesia using OEC 9900 Elite Mobile C-arm (GE Healthcare, Chicago, IL, USA) without the use of fusion technology. Three patients had planned preoperative open procedures for access due to prior cutdown or bypass. Technical success was achieved in all 11 (100%) cases. The mean length of stay was 5+2 days, and the mean follow-up was 7.5+6.5 months. The mean procedure time was 301+167 minutes, and the mean blood loss was 361+233 mL. Mean fluoroscopy time was 72+31 minutes, and the mean radiation exposure time was 2,160+930 mGy. No patients required intraoperative transfusion. Thirty-day (short term) clinical success was achieved in 10 (90.0%), cases whereas six-month (midterm) clinical success was achieved in 7 (77.7%) patients. Branch vessel patency was 11 (100%) at 30 days and 9 (81.8%) at six months, and primary endograft patency was 100% (11) at six months. We had no perioperative mortality or major adverse cardiac event at 30 days. Thirty-day postoperative morbidity included readmission for pulmonary edema from cardiac failure in one patient. Two patients had clinically insignificant silent cardiac enzyme elevation. Three patients had re-interventions performed during the mean follow-up period. Two patients developed renal stent thrombosis resulting in renal insufficiency, which is defined as an increase in creatinine concentration ≥0.5 mg/dL, without the need for dialysis. One type II endoleak was identified postoperatively that required trans-lumbar embolization. No type I or III endoleaks were identified during the study period. Asymptomatic common femoral artery thrombosis was seen on follow-up imaging in one patient. Conclusions We conclude that F-EVAR can be safely performed using C-arm without the use of fusion technology. Its utility can be expanded to centers with appropriate skill set but no hybrid technology.

The role of fEVAR, chEVAR and open repair in treatment of juxtarenal aneurysms: a systematic review

INTRODUCTION

Open repair (OR), fenestrated endovascular aneurysm repair (fEVAR) and endovascular exclusion using parallel graft (chEVAR) are complementary procedures used for treatment of juxtarenal abdominal aortic aneurysm (jrAAA). The aim of our study was to assess available literature and analyze dispersion of OR, fEVAR and chEVAR procedures among reported papers related to treatment of jrAAA.

EVIDENCE ACQUISITION

The PubMed database was systematically searched using predefined strategy and key words related to treatment of jrAAA on September 28th, 2019. Studies were assessed for eligibility using the inclusion and exclusion criteria with at least five patients treated with at least one of the procedures while systematic reviews, meta-analysis, reviews, comments, editorials and letters were excluded as well as studies without clear classification of the location of the aneurysm, studies not specifying the number of patients treated with each of the techniques or not discriminated between aortic pathologies (juxtarenal, paravisceral and thoracoabdominal), hybrid procedures, endoanchors or with branched stent-graft.

EVIDENCE SYNTHESIS

Overall, 1533 papers were identified while papers that met inclusion criteria were either representing experience of single institution (87 papers) or from multicenter studies (6 papers), national or international registries (18 papers). In the period between January 1977 and December 2017, treatment of 5664 patients with jrAAA was reported in 87 papers as a single institution report. Out of them 2531 (45%) were treated with OR, 2592 (46%) with fEVAR and 541 (9%) with chEVAR. Out of 29 institutions reporting OR, there were 11 (37.9%) with more than 100 treated patients while 21 (41.1%) out of 51 institutions that reported more than 50 jrAAA treated with fEVAR. Only four institutions reported results of all three treatment modalities.

CONCLUSIONS

Based on the results reported in the literature, regardless of its complexity and costs, fEVAR for jrAAA has been accepted in substantial number of hospitals worldwide, while number of reported procedures is reaching OR.

Peroperative Intravascular Ultrasound for Endovascular Aneurysm Repair versus Peroperative Angiography: A Pilot Study in Fit Patients with Favorable Anatomy

BACKGROUND

The aim of this study was to compare intravascular ultrasound (IVUS) assistance for endovascular aortic aneurysm repair (EVAR) to standard assistance by angiography.

METHODS

From June 2015 to June 2017, 173 consecutive patients underwent EVAR. In this group, 69 procedures were IVUS-assisted with X-ray exposure limited to completion angiography for safety purposes because an IVUS probe does not yet incorporate a duplex probe (group A), and 104 were angiography-assisted procedures (group B). All IVUS-assisted procedures were performed by vascular surgeons with basic duplex ultrasound (DUS) training. The primary study endpoints were mean radiation dose, duration of fluoroscopy, amount of contrast media administered, procedure-related outcomes, and renal clearance expressed as the glomerular filtration rate (GFR) before and after the procedure. Secondary endpoints were operative mortality, morbidity, and arterial access complications.

RESULTS

Mean duration of fluoroscopy time was significantly lower for IVUS-assisted procedures (24 ± 15 min vs. 40 ± 30 min for angiography-assisted procedures, P < 0.01). Moreover, mean radiation dose (Air KERMA) was significantly lower in IVUS-assisted procedures (76m Gy [44-102] vs. 131 mGy [58-494]), P < 0.01. IVUS-assisted procedures required fewer contrast media than standard angiography-assisted procedures (60 ± 20 mL vs. 120 ± 40 mL, P < 0.01). The mean duration of the procedure was comparable in the two groups (120 ± 30 min vs. 140 ± 30 min, P = 0.07). No difference in renal clearance before and after the procedure was observed in either of the two groups (99.0 ± 4/97.8 ± 2 mL/min in group A and 98.0 ± 3/97.6 ± 5 mL/min in group B) (P = 0.28). The mean length of follow-up was nine months (6-30 months). No postoperative mortality, morbidity, or arterial access complications occurred. No type 1 endoleak was observed. Early type II endoleaks were observed in 21 patients (11%), 12 in the angiography-assisted group (11%) and nine in the IVUS-assisted group (12%). They were not associated with sac enlargement ≥5 mm diameter and therefore did not require any additional treatment.

CONCLUSIONS

Compared with standard angiography-assisted EVAR, IVUS significantly reduces renal load with contrast media, fluoroscopy time, and radiation dose while preserving endograft deployment efficiency. Confirmation from a large prospective study with improved IVUS probes will be required before IVUS-assisted EVAR alone can become standard practice.

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.

Performance of a feature-based algorithm for 3D-3D registration of CT angiography to cone-beam CT for endovascular repair of complex abdominal aortic aneurysms

BACKGROUND

A crucial step in image fusion for intraoperative guidance during endovascular procedures is the registration of preoperative computed tomography angiography (CTA) with intraoperative Cone Beam CT (CBCT). Automatic tools for image registration facilitate the 3D image guidance workflow. However their performance is not always satisfactory. The aim of this study is to assess the accuracy of a new fully automatic, feature-based algorithm for 3D3D registration of CTA to CBCT.

METHODS

The feature-based algorithm was tested on clinical image datasets from 14 patients undergoing complex endovascular aortic repair. Deviations in Euclidian distances between vascular as well as bony landmarks were measured and compared to an intensity-based, normalized mutual information algorithm.

RESULTS

The results for the feature-based algorithm showed that the median 3D registration error between the anatomical landmarks of CBCT and CT images was less than 3 mm. The feature-based algorithm showed significantly better accuracy compared to the intensity-based algorithm (p < 0.001).

CONCLUSION

A feature-based algorithm for 3D image registration is presented.