Fusion Imaging Reduces Radiation and Contrast Medium Exposure During Endovascular Revascularization of Iliac Steno-Occlusive Disease

Fusion Imaging Guidance Does Not Affect Radiation Exposure During Endovascular Procedures for Lower Extremity Arterial Disease: A Randomized Controlled Trial

PURPOSE

Radiation exposure for vascular interventionalists is still a concern. The aim of this study was to assess the value of advanced imaging guidance on radiation exposure and iodinated contrast volume during endovascular treatment of lower extremity arterial disease (LEAD).

MATERIALS AND METHODS

It was a prospective, randomized, monocentric, pilot, single-operator study, conducted from June 2018 to October 2019. Consecutive patients requiring a preoperative computed tomography angiography (CTA) for a symptomatic LEAD and scheduled for an iliac and/or femoropopliteal endovascular repair in a hybrid room were included. Patients were randomly assigned to the use of fusion imaging guidance (Vessel Navigator®, Philips) or not. The primary endpoint was the dose area product (DAP, Gy.cm²). Secondary endpoints were DAP for fluoroscopy, DAP for fluorography, Air Kerma, fluoroscopy time, volume of contrast, and number of digital subtraction angiography (DSA). Data were expressed in median [Q1-Q3].

RESULTS

In all, 64 of the 77 patients enrolled (34 in fusion group, 30 in control group, 82% men, 65.8 years [61-71]) were included. Groups were similar in terms of comorbidities, BMI (26 kg/cm2 [24-28]), but lesion location were not equally distributed (p=0.004). There was no significant difference between the groups regarding DAP (31.6 Gy.cm2 [23.4; 46.9] for fusion group vs 25.6[16.9; 34.0] Gy.cm2; p=0.07), Air Kerma (160 mGy [96;3365] vs 115 mGy [76;201]; p=0.12, fluoroscopy time (560 seconds [326;960] vs 454 seconds [228;1022]; p=0.44), contrast volume (60 ml [42;80] vs 50 ml [40;66]; p=0.10), or operative time (68 minutes [55;90] vs 46 minutes [30;80]; p=0.06). The median number of DSA was 14 [10-18] in the fusion group versus 11 [6-18]; p=0.049.

CONCLUSION

Fusion imaging guidance does not affect radiation exposure and contrast volume during endovascular revascularisation of iliac and femoropopliteal occlusive disease in a hybrid room environment.

Work and Training Conditions of German Residents and Young Radiologists in Interventional Radiology - A Nationwide Survey

INTRODUCTION

 With the increasing need for minimally invasive procedures based on lower complication rates, higher patient acceptance, and technical developments, there is a growing focus on the sound interventional training of young radiologists. This survey aimed to analyze the current situation in interventional radiology (IR) training in Germany to detect shortcomings and identify areas for improvement.

MATERIALS AND METHODS

 From November 1-30, 2020, an online questionnaire was distributed to representative radiological associations and societies with the request to forward it to radiology residents and radiologists < 40 years. The 44 questions covered six distinct areas from personal working conditions to the characterization of the IR department, training conditions, role of women in IR, and attendance at congresses/external training.

RESULTS

 A total of 330 participants completed the questionnaire. 77 % of participants expressed a high interest in IR, and 47 % could even imagine subspecializing in interventional radiology. Most institutions provided the necessary learning conditions and infrastructure. The rate of overall satisfaction with IR training conditions was 45 % (vs. a dissatisfaction rate of 39 %). However, females showed a lower satisfaction rate with their training environment than male participants (28 % vs. 51 %; P = 0.06). Positive correlations with work satisfaction were found for the presence and duration of the IR rotation, the number of partly independently/mentored performed interventions, and structured feedback. Moreover, the need for a structured training curriculum was expressed by 67 % of participants.

CONCLUSION

 Radiological residents and young radiologists expressed a high interest in interventional radiology, and they rate the infrastructure of German hospitals regarding IR as sufficient. However, they expressed the need for consistent IR rotations and better-structured resident and postgraduate education (curricula & interviews).

KEY POINTS

Interest in interventional radiology among radiological residents and young radiologists in Germany is high, but satisfaction with interventional radiology training leaves room for improvement. The most frequently mentioned aspects that can improve IR training were · organized rotations of at least 6 months. · structured curriculums with face-to-face feedback. · structured guidance by senior interventionists during procedures.

CITATION FORMAT

· Sieren M, Katoh M, Mahnken AH et al. Work and Training Conditions of German Residents and Young Radiologists in Interventional Radiology - A Nationwide Survey. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1853-8549.

Application of Vessel Navigator™ fusion imaging software in a complex transcatheter palliation of Tetralogy of Fallot with pulmonary atresia

Extreme pulmonary artery hypoplasia in cyanotic malformations precludes palliative surgeries. When aortopulmonary collaterals (APC) in such patients are also hypoplastic, their unifocalization to create a neopulmonary vasculature is also hampered. Stent angioplasty of the outflow or collateral arteries may reduce hypoxia but is challenging in tortuous and atretic tracts. Fusion imaging overlays anatomical data from computed tomography during adult structural interventions, but its use is not often reported in young children with complex cyanotic malformations. This report shows utility of fusion imaging in pulmonary atresia with extremely hypoplastic pulmonary arteries and stenotic APC to guide stenting of outflow tract and collaterals.

Efficacy of Fusion Imaging in Endovascular Revascularization of the Superficial Femoral Artery

BACKGROUND

The demand for endovascular revascularization (ER) to treat peripheral artery disease (PAD) has steadily increased. However, ER comes at the cost of increased contrast and radiation exposure, particularly in more complex cases. Fusion imaging is a new technology that may address these issues. The purpose of this study was to evaluate the efficacy of fusion imaging in ER of the superficial femoral artery (SFA).

METHODS

Patients with PAD undergoing ER of the SFA from February 2016 to July 2020 were retrospectively evaluated. A group of patients treated using fusion imaging was compared with a control group treated without fusion imaging. The primary end points were the contrast dose, fluoroscopy time, radiation dose, and operative time.

RESULTS

A total of 51 patients (fusion group, n = 26; control group, n = 25) underwent ER during the study period. Significantly lower iodinated contrast doses were observed in the fusion than in the control group (56.1 ± 23.7 vs. 87.9 ± 44.9 mL; P = 0.003), as well as significantly shorter fluoroscopy times (21.2 ± 11.1 vs. 44.9 ± 31.4 min; P = 0.001), lower radiation exposure (29.9 ± 8.9 vs. 122.2 ± 223.1 mGy; P = 0.04), and shorter operative times (88.3 ± 32.1 vs. 126.1 ± 66.8 min; P = 0.013).

CONCLUSIONS

The use of fusion imaging technology during ER of the SFA can significantly reduce the contrast dose, fluoroscopy time, radiation dose, and operative time.

Fusion imaging guidance for endovascular recanalization of peripheral occlusive disease

OBJECTIVE

Endovascular procedures are now the first line option for treatment of lower extremity arterial disease. Fusion imaging guidance has been reported to reduce radiation exposure and reintervention rates during fenestrated and branched endovascular repairs, but limited literature exists on its benefits during lower extremity arterial disease endovascular procedures, and more specifically peripheral occlusive disease (POD). This study aims to evaluate the radiation exposure and technical success benefits of fusion imaging guidance in a large cohort of patients treated endovascularly for complex POD.

METHODS

From January 2017 to September 2019, in a single center, all consecutive patients presenting symptomatic occlusions (Rutherford Baker categories 3 to 6) in the setting of POD and treated endovascularly were retrospectively assessed for inclusion. All procedures were performed under augmented fluoroscopy guidance (Vessel ASSIST, GE Healthcare), overlaying on live imaging the 3D path for transluminal recanalization based on the preoperative computed tomography angiography. Technical success, dose area product (DAP), total cumulated air kerma (CAK), and fluoroscopy time were collected. DAP results were compared with the literature.

RESULTS

During the study period, 179 patients were treated for iliac (n = 56) or femoropopliteal (n = 123) symptomatic arterial occlusions. Technical success was reported in 171 of 179 procedures (95.5%). The use of a re-entry catheter was required to achieve technical success in 11 patients (6.1%). Mean DAP and CAK were 15.44 Gy·cm² and 135 mGy, respectively, with a mean fluoroscopy time of 15.04 minutes. DAP and CAK were significantly higher in the iliac group when compared with the femoropopliteal group, although fluoroscopy time was not significantly different. DAP was lower than levels reported in the literature.

CONCLUSIONS

Routine use of fusion imaging guidance during POD endovascular treatment is associated with low radiation exposure, high technical success, and reduced need for re-entry systems.

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.

Automated Image Fusion Guidance during Endovascular Aorto-Iliac Procedures: A Randomized Controlled Pilot Study

BACKGROUND

The benefits of imaging guidance using a new fully automated fusion process (CYDAR) have been demonstrated during endovascular aortic aneurysm repair, but little is known about its use during aorto-iliac occlusive disease endovascular revascularization. The aim of this study was to evaluate the influence of CYDAR image fusion guidance during endovascular treatment of symptomatic aorto-iliac occlusive lesions, compared with control patients treated using standard 2D fluoroscopy alone.

METHODS

This is a single-center randomized controlled pilot study that recruited patients undergoing aorto-iliac endovascular revascularization.

RESULTS

Between January 2019 and February 2020, 37 patients with symptomatic aorto-iliac lesions were enrolled: 18 were assigned to the fusion group and 19 to the control group. Patients and lesions characteristics were well balanced between both study groups. The technical success of the procedure was 100% in the Fusion group and 94% in the control group. All radiation-related parameters were lower in the fusion compared to the control group, including: median DAP 18.5 Gy.cm2 vs. 21.8 Gy.cm2; Air Kerma 0.10 Gy vs. 0.12 Gy; fluoroscopy dose 4.2 Gy.cm² vs. 5.1 Gy.cm²; and number of DSA 7.5 vs. 8. The volume of iodinated contrast used was higher in the fusion group: 41 mL vs. 30 mL. The total procedure time was the same in both groups:60 min vs. 60 min.

CONCLUSIONS

The results of this pilot study suggest the use of fusion imaging in endovascular treatment of aorto-iliac disease results in reduction in radiation-related measured parameters with no change in procedure time and higher doses of iodinated contrast used. These results need to be further investigated in a larger, adequately powered study.

Digital Variance Angiography in Lower-Limb Angiography with Metal Implants

Purpose

The presence of metal implants may reduce angiographic image quality due to automated beam adjustments. Digital variance angiography (DVA) is reported to be superior to digital subtraction angiography (DSA) with increased contrast-to-noise ratio (CNR) and better image quality. The aim of the study was to evaluate whether DVA could counterbalance the image quality impairment of lower-limb angiographies with metal implants.

Materials and Methods

From November 2019 to January 2020, 85 raw lower-limb iodine contrast angiograms of 12 patients with metal implants were processed retrospectively with DVA analyses. For objective comparison, CNR of DSA and DVA images was calculated and the ratio CNR_DVA/CNR_DSA was determined. Visual image quality was evaluated in a paired comparison and by a five-grade Likert scale by three experienced radiologists.

Results

The CNR was calculated and compared in 1252 regions of interest in 37 image pairs containing metal implants. The median ratio of CNR_DVA/CNR_DSA was 1.84 with an interquartile range of 1.35–2.32. Paired comparison resulted in 84.5% in favour of DVA with an interrater agreement of 83.2% (Fleiss κ 0.454, p < 0.001). The overall image quality scores for DSA and DVA were 3.64 ± 0.08 and 4.43 ± 0.06, respectively (p < 0.001, Wilcoxon signed-rank test) with consistently higher individual ratings for DVA.

Conclusion

Our small-sample pilot study shows that DVA provides significantly improved image quality in lower-limb angiography with metal implants, compared to DSA imaging. The improved CNR suggest that this approach could reduce radiation exposure for lower-limb angiography with metal implants.

Level of Evidence

Level 4, case studies

Efficacy of three-dimensional road mapping by fusion of computed tomography angiography and fluoroscopy in endovascular treatment of aorto-iliac chronic total occlusion

The efficacy of multimodality image fusion road-mapping technique for endovascular therapy has been reported recently. Our aim was to evaluate the efficacy of endovascular therapy (EVT) with three-dimensional (3D) road mapping by fusing computed tomography (CT) and angiographical volumetric data for aorto-iliac chronic total occlusion (CTO). We retrospectively analyzed 36 patients with aorto-iliac CTO from June 2017 to November 2019 and classified them into two groups: EVT using a CT fused 3D roadmap (CTf3D-RM; 3D group, n = 14) and standard EVT (standard group, n = 22). Primary endpoint was wiring time and secondary endpoints were procedural success rate, number of guidewires, procedure time, radiation dose, contrast medium dose, and complications. Wiring time was significantly shorter in the 3D group than the standard group (3D, 15.6 ± 10.23 min vs. standard, 44.6 ± 35.3 min; p = 0.0052). Both groups had high procedural success rates (3D, 100% vs. standard, 100%) and low complication rates (3D, 0.0% vs. standard, 9.1%; p = 0.51). There were significantly fewer guidewires in the 3D group than the standard group (3D, 2.78 ± 1.31 vs. standard, 4.36 ± 2.01; p = 0.0138). The 3D group trended towards shorter procedural time (3D, 78.8 ± 32.5 min vs. standard, 107.5 ± 52.5 min; p = 0.076), lower radiation dose (3D, 28.6 ± 18.9 Gycm² vs. standard, 48.9 ± 49.2 Gycm²; p = 0.15), and lower contrast medium dose (3D, 102.2 ± 30.6 vs. standard, 127.5 ± 51.3; p = 0.11) than the standard group. Therefore, we concluded that EVT with CTf3D-RM is effective for aorto-iliac CTO. This method may improve the quality of aorto-iliac CTO interventions.

Biologically Inspired Catheter for Endovascular Sensing and Navigation

Minimally invasive treatment of vascular disease demands dynamic navigation through complex blood vessel pathways and accurate placement of an interventional device, which has resulted in increased reliance on fluoroscopic guidance and commensurate radiation exposure to the patient and staff. Here we introduce a guidance system inspired by electric fish that incorporates measurements from a newly designed electrogenic sensory catheter with preoperative imaging to provide continuous feedback to guide vascular procedures without additional contrast injection, radiation, image registration, or external tracking. Electrodes near the catheter tip simultaneously create a weak electric field and measure the impedance, which changes with the internal geometry of the vessel as the catheter advances through the vasculature. The impedance time series is then mapped to a preoperative vessel model to determine the relative position of the catheter within the vessel tree. We present navigation in a synthetic vessel tree based on our mapping technique. Experiments in a porcine model demonstrated the sensor’s ability to detect cross-sectional area variation in vivo. These initial results demonstrate the capability and potential of this novel bioimpedance-based navigation technology as a non-fluoroscopic technique to augment existing imaging methods.