C-arm Angulation Research Articles

Enhancing Visualization of the Foramen Ovale in Percutaneous Microcompression: A Preoperative Image Simulation Technique

Introducing a preoperative image simulation technique to streamline the visualization of the foramen ovale in percutaneous microcompression. Twenty-five trigeminal neuralgia patients were included in the study. Preoperative cranial computed tomography scans were processed with 3D Slicer software to create simulated fluoroscopic skulls. The angulations required for precise visualization of the foramen ovale were established via simulated anteroposterior imaging. These simulations informed the C-arm's angulations for foramen ovale targeting during surgery. The preoperative simulations accurately forecasted skull rotation angulations, aligning closely with intraoperative observations with negligible discrepancies (0-2 degrees). In 17 patients, the foramen ovale was distinctly visible, while in 8 patients, it was partially obscured yet discernible using the simulated angles. Nonvisible of the foramen ovale did not occur. Postoperative pain relief and complications were recorded. Based on our initial findings, the application of preoperative image simulation shows significant referential value in achieving accurate visualization of the foramen ovale in percutaneous microcompression for trigeminal neuralgia.

Cardiac magnetic resonance imaging for preprocedural planning of percutaneous left atrial appendage closure.

Percutaneous closure of the left atrial appendage (LAA) facilitates stroke prevention in patients with atrial fibrillation. Optimal device selection and positioning are often challenging due to highly variable LAA shape and dimension and thus require accurate assessment of the respective anatomy. Transesophageal echocardiography (TEE) and x-ray fluoroscopy (XR) represent the gold standard imaging techniques. However, device underestimation has frequently been observed. Assessment based on 3-dimensional computer tomography (CTA) has been reported as more accurate but increases radiation and contrast agent burden. In this study, the use of non-contrast-enhanced cardiac magnetic resonance imaging (CMR) to support preprocedural planning for LAA closure (LAAc) was investigated. CMR was performed in thirteen patients prior to LAAc. Based on the 3-dimensional CMR image data, the dimensions of the LAA were quantified and optimal C-arm angulations were determined and compared to periprocedural data. Quantitative figures used for evaluation of the technique comprised the maximum diameter, the diameter derived from perimeter and the area of the landing zone of the LAA. Perimeter- and area-based diameters derived from preprocedural CMR showed excellent congruency compared to those measured periprocedurally by XR, whereas the respective maximum diameter resulted in significant overestimation (p < 0.05). Compared to TEE assessment, CMR-derived diameters resulted in significantly larger dimensions (p < 0.05). The deviation of the maximum diameter to the diameters measured by XR and TEE correlated well with the ovality of the LAA. C-arm angulations used during the procedures were in agreement with those determined by CMR in case of circular LAA. This small pilot study demonstrates the potential of non-contrast-enhanced CMR to support preprocedural planning of LAAc. Diameter measurements based on LAA area and perimeter correlated well with the actual device selection parameters. CMR-derived determination of landing zones facilitated accurate C-arm angulation for optimal device positioning.

Centerline depth world for left atrial appendage orifice localization using reinforcement learning.

Left atrial appendage (LAA) occlusion (LAAO) is a minimally invasive implant-based method to prevent cardiovascular stroke in patients with non-valvular atrial fibrillation. Assessing the LAA orifice in preoperative CT angiography plays a crucial role in choosing an appropriate LAAO implant size and a proper C-arm angulation. However, accurate orifice localization is hard because of the high anatomic variation of LAA, and unclear position and orientation of the orifice in available CT views. With the major research focus being on LAA segmentation, the only existing computational method for orifice localization utilized a rule-based decision. Nonetheless, using such a fixed rule may yield high localization error due to the varied anatomy of LAA. While deep learning-based models usually show improvements under such variation, learning an effective localization model is difficult because of the tiny orifice structure compared to the vast search space of CT volume. In this paper, we propose a centerline depth-based reinforcement learning (RL) world for effective orifice localization in a small search space. In our scheme, an RL agent observes the centerline-to-surface distance and navigates through the LAA centerline to localize the orifice. Thus, the search space is significantly reduced facilitating improved localization. The proposed formulation could result in high localization accuracy compared to the expert annotations. Moreover, the localization process takes about 7.3s which is 18 times more efficient than the existing method. Therefore, this can be a useful aid to physicians during the preprocedural planning of LAAO.

Computed tomography vs. cinefluoroscopy for the assessment of mechanical prosthetic valve leaflet motion.

Evaluation of mechanical prosthetic valve function is based on echocardiography, but adequate assessment of leaflet motion is limited by acoustic shadowing. Cinefluoroscopy is a standard method to assess leaflet motion, while computed tomography (CT) has been suggested as an alternative. We sought to compare the feasibility of leaflet motion assessment by cinefluoroscopy vs. CT. In 35 prospectively enrolled patients, leaflet motion was assessed in 43 bileaflet mechanical prostheses (29 mitral and 14 aortic) by cinefluoroscopy and non-contrast CT. Assessment was considered feasible when the 'in profile' projection (with the radiographic beam parallel to both the valve ring plane and the tilting axis of discs) could be achieved. Overall feasibility of fluoroscopic assessment was 74% (mitral, 66% vs. aortic, 93%; p = 0.071), while feasibility of CT assessment was 100% (p = 0.003). Among prostheses with unfeasible fluoroscopic assessment, CT suggested an extreme C-arm angulation to achieve the "in profile" projection (RAO: 76.0 ± 5.8°, LAO: 122.7 ± 32.5°, CRA: 51.4 ± 16.0°, CAU: 57.0 ± 18.2°). Among prostheses with feasible assessment by both techniques, fluoroscopy and CT yielded similar opening and closing angles (intraclass correlation coefficient, 0.959-0.998) with lower irradiation with CT as compared with fluoroscopy (26.2[21.1-29.3] vs. 289[179-358] mGy, p < 0.001). While CT scan took 8.7 ± 0.5s, fluoroscopy required 2.64 ± 1.56min to achieve and record the "in profile" projection. Non-contrast CT provides a higher feasibility and a quicker evaluation of mechanical prosthetic valve leaflet motion with less irradiation than fluoroscopy, especially in mitral valve position.

Evaluation of Robotic-Assisted Carotid Artery Stenting in a Virtual Model Using Motion-Based Performance Metrics

Purpose: Robotic-assisted carotid artery stenting (CAS) cases have been demonstrated with promising results. However, no quantitative measurements have been made to compare manual with robotic-assisted CAS. This study aims to quantify surgical performance using tool tip kinematic data and metrics of precision during CAS with manual and robotic control in an ex vivo model. Materials and Methods: Transfemoral CAS cases were performed in a high-fidelity endovascular simulator. Participants completed cases with manual and robotic techniques in 2 different carotid anatomies in random order. C-arm angulations, table position, and endovascular devices were standardized. Endovascular tool tip kinematic data were extracted. We calculated the spectral arc length (SPARC), average velocity, and idle time during navigation in the common carotid artery and lesion crossing. Procedural time, fluoroscopy time, movements of the deployed filter wire, precision of stent, and balloon positioning were recorded. Data were analyzed and compared between the 2 modalities. Results: Ten participants performed 40 CAS cases with a procedural success of 100% and 0% residual stenosis. The median procedural time was significantly higher during the robotic-assisted cases (seconds, median [interquartile range, IQR]: 128 [49.5] and 161.5 [62.5], p=0.02). Fluoroscopy time differed significantly between manual and robotic-assisted procedures (seconds, median [IQR]: 81.5 [32] and 98.5 [39.5], p=0.1). Movement of the deployed filter wire did not show significant difference between manual and robotic interventions (mm, median [IQR]: 13 [10.5] and 12.5 [11], p=0.5). The postdilation balloon exceeded the margin of the stent with a median of 2 [1] mm in both groups. Navigation with robotic assistance showed significantly lower SPARC values (–5.78±3.14 and –8.63±3.98, p=0.04) and higher idle time values (8.92±8.71 and 3.47±3.9, p=0.02) than those performed manually. Conclusions: Robotic-assisted and manual CAS cases are comparable in the precision of stent and balloon positioning. Navigation in the carotid artery is associated with smoother motion and higher idle time values. These findings highlight the accuracy and the motion stabilizing capability of the endovascular robotic system. Clinical Impact Robotic assistance in the treatment of peripheral vascular disease is an emerging field and may be a tool for radiation protection and the geographic distribution of endovascular interventions in the future. This preclinical study compares the characteristics of manual and robotic-assisted carotid stenting (CAS). Our results highlight, that robotic-assisted CAS is associated with precise navigation and device positioning, and smoother navigation compared to manual CAS.

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.

478 Pre-tavi Aortic Annulus Sizing: Comparison Between Manual And Semi-automated New Generation Software Measurements

Introduction: TAVI Planning requires important information and CT is used to help determine aortic annulus size, to guide selection of appropriate valve, provide dimensions of the entire aorta and give guidance for C-arm angulation for deployment of the device. This requires accurate and time-consuming manual measurements performed by experienced operators. Semi-automatic software can aid the CT reconstructions reducing the time needed for multiple measurements assessment. Aim of this study is to compare manual and semi-automatic measurements for aortic annulus assessment in terms of accuracy, agreement and time among different operators with different experience in cardiovascular CT reconstruction

Non-contrast computed tomography versus cinefluoroscopy for the assessment of mechanical prosthetic valve leaflet motion

Introduction: valve replacement remains the definitive treatment of most cases with severe valvular heart disease. Mechanical prosthetic valves remain the main option in younger patients. Objective: evaluation of mechanical prosthetic valve function by comparing the feasibility of leaflet motion assessment by cinefluoroscopy vs. CT. Materials and methods: Leaflet motion was assessed in 30 bileaflet mechanical prostheses (21 mitral and 9 aortic) by cinefluoroscopy and non-contrast CT. Assessment was considered feasible when the ‘in profile’ projection (with the radiographic beam parallel to both the valve ring plane and the tilting axis of discs) could be achieved. Results: Overall feasibility of fluoroscopic assessment was 74% (mitral, 66% vs. aortic, 93%; p=0.071), while feasibility of CT assessment was 100% (p=0.003). Among prostheses with unfeasible fluoroscopic assessment, CT suggested an extreme C-arm angulation to achieve the “in profile” projection (RAO: 76.0±5.8°, LAO: 122.7±32.5°, CRA: 51.4±16.0°, CAU: 57.0±18.2°). Among prostheses with feasible assessment by both techniques, fluoroscopy and CT yielded similar opening and closing angles (intraclass correlation coefficient, 0.959 - 0.998) with lower irradiation with CT as compared with fluoroscopy (26.2[21.1-29.3] vs. 289[179-358] mGy, p&lt;0.001). While CT scan took 8.7±0.5 seconds, fluoroscopy required 2.64±1.56 minutes to achieve and record the “in profile” projection.

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

BackgroundThis 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 methodsA 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.Results3D-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.ConclusionIn 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.

Radiation Awareness for Endovascular Abdominal Aortic Aneurysm Repair in the Hybrid Operating Room: An Instant Operator Risk Chart for Daily Practice

Introduction: While the operator radiation dose rates are correlated to patient radiation dose rates, discrepancies may exist in the effect size of each individual radiation dose predictors. An operator dose rate prediction model was developed, compared with the patient dose rate prediction model, and converted to an instant operator risk chart. Materials and Methods: The radiation dose rates (DRoperator for the operator and DRpatient for the patient) from 12,865 abdomen X-ray acquisitions were selected from 50 unique patients undergoing standard or complex endovascular aortic repair (EVAR) in the hybrid operating room with a fixed C-arm. The radiation dose rates were analyzed using a log-linear multivariable mixed model (with the patient as the random effect) and incorporated varying (patient and C-arm) radiation dose predictors combined with the vascular access site. The operator dose rate models were used to predict the expected radiation exposure duration until an operator may be at risk to reach the 20 mSv year dose limit. The dose rate prediction models were translated into an instant operator radiation risk chart. Results: In the multivariate patient and operator fluoroscopy dose rate models, lower DRoperator than DRpatient effect size was found for radiation protocol (2.06 for patient vs 1.4 for operator changing from low to medium protocol) and C-arm angulation. Comparable effect sizes for both DRoperator and DRpatient were found for body mass index (1.25 for patient and 1.27 for the operator) and irradiated field. A higher effect size for the DRoperator than DRpatient was found for C-arm rotation (1.24 for the patient vs 1.69 for the operator) and exchanging from femoral access site to brachial access (1.05 for patient vs 2.5 for the operator). Operators may reach their yearly 20 mSv year dose limit after 941 minutes from the femoral access vs 358 minutes of digital subtraction angiography radiation from the brachial access. Conclusion: The operator dose rates were correlated to patient dose rate; however, C-arm angulation and changing from femoral to brachial vascular access site may disproportionally increase the operator radiation risk compared with the patient radiation risk. An instant risk chart may improve operator dose awareness during EVAR.

Scatter radiation reduction with a radiation-absorbing pad in interventional radiology examinations

PurposeRadiation-absorbing pads are an additional possibility to reduce scattered radiation at its source. The goal of this study is to investigate the efficacy of a new reusable radiation-absorbing pad at its origin in an experimental setup. Material and methodsAll measurements were carried out using a clinical angiography system with a standardized fluoroscopy protocol, different C-arm angulations and an anthropomorphic torso phantom as a scattering body. An ionization chamber was used to measure the radiation exposure at five different heights of a simulated operator during a simulated transfemoral angiography intervention. Measurements were carried out with and without radiation-absorbing pads with lead equivalents of 0.25 and 0.5 mm placed onto the scattering body. For all measurements a mobile acrylic shield and an under-table lead curtain was used. ResultsAt all operator heights from 100 to 165 cm a significant radiation dose reduction of up to 80.6 % (p < 0.01) using the radiation-absorbing pad was measured, when compared to no radiation-absorbing pad. At the height of 165 cm the radiation-absorbing pad with a lead equivalence of 0.5 mm showed a significant radiation dose reduction (51.4 %, p < 0.01) in comparison to a lead equivalence of 0.25 mm. ConclusionThe addition of a radiation-absorbing pad to the standard protection means results in a significant dose reduction for the operator, particularly for upper body parts.

Pre-tavi Aortic Annulus Sizing: Comparison Between Manual And Semi-automated New Generation Software Measurements. Preliminary Experience

Introduction: TAVI Planning requires important information and CT is used to help determine aortic annulus size, to guide selection of appropriate valve, provide dimensions of the entire aorta and give guidance for C-arm angulation for deployment of the device. This requires accurate and time-consuming manual measurements performed by experienced operators. Semi-automatic software can aid the CT reconstructions reducing the time needed for multiple measurements assessment. Aim of this study is to compare manual and semi-automatic measurements in terms of accuracy, agreement and time.

MDCT planning of trans catheter aortic valve implantation (TAVI): determination of optimal c-arm angulation.

A fluoroscopic view perpendicular to the aortic valve annulus is required during transcatheter aortic valve implantation (TAVI) for obtaining an optimal deployment of the bioprosthesis. By predicting c-arm angulation, pre-procedural MDCT could decrease the number of aortograms, shorten the time of the procedure and reduce the amount of intra-arterial contrast agent. The aim of our study was to assess the accuracy of MDCT in predicting c-arm angulation at the cath. lab. In this single center study, we investigated MDCT prediction of c-arm angulation in patients having undergone a TAVI procedure using SAPIEN 3® (Edwards Lifesciences, USA). Prior to the procedure, an experienced radiologist had reported the angulation using dedicated software (CTreport). After the procedure, a blinded experienced radiologist retrospectively measured the angles using the same method (CTstudy). Interobserver variability was drawn from the comparison between CTreport and CTstudy. Then, the mean angular difference between the predicted MDCT angles (CTstudy) was compared to the working view recorded at the cath. lab. Seventy-nine patients (M/F = 0.65; mean age: 85.2years ± 5.3) were included. Interobserver variability was 5.9 ± 6.1°. The mean absolute difference between MDCT and fluoroscopy was 8.8 ± 7.1°. The present study showed that MDCT could predict the coplanar fluoroscopic angles prior to TAVI using a balloon-expandable bioprosthesis Sapien 3® placed via a transfemoral approach with a mean angular difference of 8.8 ± 7.1°. Reproducibility was considered good as the mean difference between two independent measures was 5.9 ± 6.1°.

Iliac Artery Deformation During Abdominal EVAR has Consequences for Choice of Iliac Limbs, Optimal C-arm Angulation and Image Fusion Guidance.

Iliac Artery Deformation During Abdominal EVAR has Consequences for Choice of Iliac Limbs, Optimal C-arm Angulation and Image Fusion Guidance.

Invited commentary

In this article, the authors have identified endovascular aneurysm repair (EVAR) as a potential risk factor for subsequent development of intra-abdominal cancer. When stratified for computed tomography (CT) vs non-CT surveillance, the cohort undergoing CT surveillance did not have an additional cancer risk, implying that the cancer risk is related to the fluoroscopy exposure from the EVAR procedure itself. Whereas much has been written lately about the short- and long-term risks of radiation exposure, the long-term risk of cancer from a single exposure is thought provoking. In its early days, EVAR was typically offered to higher risk patients not believed to be suitable operative candidates because of concerns about device durability. As durability issues have become less of a concern, EVAR has generally become the standard of care for all anatomically suitable patients regardless of age or risk factors. This paper injects some caution into this approach, particularly in younger, healthier patients with long life expectancy. One could potentially argue about the relevance of statistical vs clinical significance. Because of the large numbers studied, close to 40,000 patients, the cancer difference was statistically significant; however, the hazard ratio was only 1.14 for development of abdominal cancer and 1.11 for any cancer, and absolute differences between the groups were small, but for an outcome as potentially severe as cancer, even small differences need to be taken seriously. I doubt the numbers will be startling enough to significantly change practice patterns. However, efforts to minimize radiation exposure during EVAR need to be continuously emphasized and improved. Because of the nature of the administrative database, the authors are not able to quantify the amount of radiation received during EVAR; however, given the stochastic nature of radiation-induced malignant neoplasms, it is reasonable to assume that there is no safe dose and that every effort to minimize radiation exposure should be employed. This is increasingly relevant as EVAR becomes more complicated and potentially time-consuming with the expansion of fenestrated and branched EVAR. The authors mention some measures, such as C-arm angulation, frame rate, table position, and use of protective materials. Other important adjuncts include expanded use of intravascular ultrasound, two-dimensional and three-dimensional fusion imaging, and use of newer imaging systems with radiation-reducing software packages.1Hertault A. Maurel B. Midulla M. Bordier C. Desponds L. Saeed Kilani M. et al.Minimizing radiation exposure during endovascular procedures: basic knowledge, literature review, and reporting standards.Eur J Vasc Endovasc Surg. 2015; 50: 21-36Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar, 2Mohapatra A. Greenburg R.K. Mastracci T.M. Eagleton M.J. Thornsberry B. Radiation exposure to operating room personnel and patients during endovascular procedures.J Vasc Surg. 2013; 58: 702-709Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar Whereas this article focuses on the patient risk, risks to the operating surgeons and other operating room personnel cannot be ignored. Radiation risk, both deterministic and stochastic, should also be a standard part of the informed consent process. Anecdotally, I have noted that our younger trainees are often the most aggressive in terms of using protective radiation shielding during procedures. This is encouraging and clearly should become endemic practice in our profession. The opinions or views expressed in this commentary are those of the author and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery. A population-based cohort study examining the risk of abdominal cancer after endovascular abdominal aortic aneurysm repairJournal of Vascular SurgeryVol. 69Issue 6PreviewEndovascular aneurysm repair (EVAR) has increasingly been used as the primary treatment approach for abdominal aortic aneurysm (AAA). This study examined the hypothesis that EVAR leads to an increased risk of abdominal cancer within the radiation field compared with open AAA repair. Full-Text PDF Open Archive

Intraoperative contrast-enhanced ultrasound for early diagnosis of endoleaks during endovascular abdominal aortic aneurysm repair

BackgroundThe aim of this study was to evaluate the feasibility and utility of intraoperative contrast-enhanced ultrasound (CEUS) for early detection of endoleaks (ELs) during endovascular abdominal aortic aneurysm repair (EVAR) compared with completion digital subtraction angiography. MethodsPatients undergoing elective EVAR from January 2017 to April 2018 were consecutively enrolled in this prospective study. After endograft deployment, two-digital subtraction angiography (2DSA) with orthogonal C-arm angulations (anteroposterior and sagittal view) were routinely performed. After the endovascular treatment of clear, high-flow type I/III ELs detected by 2DSA, intraoperative CEUS was carried out in sterile conditions on the surgical field before guidewire removal. Presence and type of EL were evaluated with 2DSA and CEUS. CEUS was performed with the vascular surgeon blinded to the 2DSA findings. The primary end point was the level of agreement between 2DSA and CEUS to detect any type of EL and type II EL. Agreement between two diagnostic methods was calculated using Cohen's kappa. The secondary end point was utility of CEUS for intraoperative adjunctive procedure guidance. ResultsSixty patients were enrolled (mean age, 78 ± 6 years; 90% male). 2DSA revealed 11 ELs (18%; 1 type IA, 10 type II), and CEUS 25 ELs (42%; 2 type IA, 23 type II). 2DSA and CEUS were in agreement in 39 cases (65%; 32 no ELs, 7 type II ELs). CEUS detected 17 ELs not identified by 2DSA (28%; 2 type IA, 15 type II); 2DSA detected three ELs not identified by CEUS (5%; 3 type II). In one case, 2DSA and CEUS detected type II and type IA ELs, respectively. For EL and type II EL detection, Cohen's kappa was 0.255 and 0.250, respectively (both “fair agreement”). Intraoperative adjunctive sac embolization was performed under CEUS control in 4 cases and technical success was 100%. ConclusionsIntraoperative CEUS during EVAR is feasible and can detect a greater number of ELs than 2DSA, in particular type II ELs. Further studies are necessary to assess the reliability of this intraoperative diagnostic examination. In type II ELs, CEUS may represent an additional, useful tool for intraoperative sac embolization guidance.

Optimizing Staff Dose in Fluoroscopy-Guided Interventions by Comparing Clinical Data with Phantom Experiments

PurposeTo evaluate conditions for minimizing staff dose in interventional radiology, and to provide an achievable level for radiation exposure reduction. Materials and MethodsComprehensive phantom experiments were performed in an angiography suite to evaluate the effects of several parameters on operator dose, such as patient body part, radiation shielding, x-ray tube angulation, and acquisition type. Phantom data were compared with operator dose data from clinical procedures (n = 281), which were prospectively acquired with the use of electronic real-time personal dosimeters (PDMs) combined with an automatic dose-tracking system (DoseWise Portal; Philips, Best, The Netherlands). A reference PDM was installed on the C-arm to measure scattered radiation. Operator exposure was calculated relative to this scatter dose. ResultsIn phantom experiments and clinical procedures, median operator dose relative to the dose-area product (DAP) was reduced by 81% and 79% in cerebral procedures and abdominal procedures, respectively. The use of radiation shielding decreased operator exposure up to 97% in phantom experiments; however, operator dose data show that this reduction was not fully achieved in clinical practice. Both phantom experiments and clinical procedures showed that the largest contribution to relative operator dose originated from left-anterior-oblique C-arm angulations (59%–75% of clinical operator exposure). Of the various x-ray acquisition types used, fluoroscopy was the main contributor to procedural DAP (49%) and operator dose in clinical procedures (82%). ConclusionsAchievable levels for radiation exposure reduction were determined and compared with real-life clinical practice. This generated evidence-based advice on the conditions required for optimal radiation safety.

Iliac artery deformation during EVAR.

Objectives To quantify the deformation of the common iliac artery caused by stiff guide wires and delivery systems during abdominal endovascular aortic repair (EVAR). Methods Twenty-two patients treated with abdominal EVAR were included. The following three image data-sets were acquired for each patient: (1) a preoperative computed tomography angiography (CTA), (2) an intraoperative contrast-enhanced cone beam CT (CBCT) obtained after the main trunk of the bifurcated stent graft was released and both iliac limbs were engaged with stiff guide wires, and (3) the first postoperative CTA. These data-sets were merged and compared in an image analysis work station. The length and the tortuosity index of the common iliac artery, the Euclidian displacement of the aortic and the iliac bifurcations, and the optimal C-arm angulation for projection of the iliac bifurcation were computed. Results The common iliac artery was on average 6.4 mm shorter ( p &lt; 0.001) and tortuosity index was lower ( p = 0.003) in the intraoperative images compared to preoperative. Some of the foreshortening was reversed postoperatively, remaining mean length difference was 2.9 mm ( p = 0.007) compared to preoperative. Intraoperatively, the aortic bifurcation was mostly displaced in a cranial direction (100%) and the iliac bifurcation in a ventral direction (93%). The optimal lateral C-arm angulation for projection of the iliac bifurcation changed. Anterior contralateral angle increased from median 42° (IQR, 27–63) in the preoperative CTA to 62 (49–74) in the intraoperative CBCT ( p = 0.02). Optimal cranio-caudal angulation did not change. Conclusion Stiff guide wires and delivery systems cause significant deformation of the common iliac arteries during EVAR. The aortic bifurcation is more cranial, the common iliac arteries are shorter, and optimal C-arm angulation is more contralateral oblique when the iliac limbs are to be deployed compared to baseline measurements from preoperative CTA. This affects image fusion accuracy and stent graft selection.

Effectiveness of a new radiation protection system in the interventional radiology setting

ObjectivesThe goal of this study was to examine a new weightless-like radiation protection garment regarding its radiation protection efficacy and to compare it to a conventional two-piece apron suit plus thyroid collar and standard ancillary shields. Material and MethodsAll measurements were carried out using a clinical angiography system with a standardized fluoroscopy protocol for different C-arm angulations. An anthropomorphic torso phantom served as a scattering body. In addition, an ionization chamber was used to measure the radiation exposure on five different representative heights and at two different positions of an examiner during a typical fluoroscopic-guided intervention. ResultsThe new weightless-like radiation protection garment and the conventional protection concept showed a mean dose reduction of 98.1% (p < 0.01) and 90.1% (p < 0.01) when compared to no shielding, respectively. By adding ancillary shields to both systems, an average reduction of 99.0% (p < 0.01) and 98.2% (p < 0.01) was found. In addition, the efficacy of both systems varied depending on the height, the C-arm angulation and position of the examiner. ConclusionCombined with ancillary shields as an overall protection system, the recently introduced weightless-like radiation protection garment showed a significant better radiation protection efficacy when compared to conventional radiation protection measures.

IP009. Intraoperative Contrast-Enhanced Ultrasound for Early Diagnosis and Treatment of Endoleaks During Endovascular Abdominal Aortic Aneurysm Repair∗

The objective of this study was to evaluate the feasibility of intraoperative contrast-enhanced ultrasound (CEUS) to detect and to treat endoleaks (EL) during endovascular aneurysm repair (EVAR). Patients undergoing elective EVAR from January to December 2017 were consecutively enrolled. After endograft deployment, two completion angiography studies (2CAs) with orthogonal C-arm angulation (anteroposterior and 90-degree left anterior oblique) were routinely performed. Intraoperative CEUS was performed in sterile conditions on the surgical field before guidewire removal. Presence and type of EL at the 2CAs and CEUS were evaluated and prospectively collected. CEUS was performed by a vascular surgeon blinded to the findings of the 2CAs. The primary end point was the agreement between the 2CAs and CEUS for detection of any EL and type II EL (Cohen κ). The secondary end point was evaluation of number and type of intraoperative adjunctive procedures performed as a result of CEUS findings. Forty-four patients were enrolled (mean age, 77 ± 6 years; male, 91%). The 2CAs revealed 9 ELs (21%; type IA, 1; type II, 8; Table), and CEUS revealed 18 ELs (41%; type IA, 2; type II, 16; Fig). The 2CAs and CEUS showed the same findings in 28 cases (64%; no EL, 23; type II EL, 5). CEUS detected 12 ELs unidentified by the 2CAs (27%; type IA, 2; type II, 10). The 2CAs discovered three ELs unseen at CEUS (7%; type II, three). For EL and type II EL detection, Cohen κ was 0.236 and 0.175, respectively. On the basis of CEUS findings, adjunctive intraoperative procedures were performed in five patients (11%): Palmaz stent was deployed for a type IA EL in one case; sac embolization with coils was performed under CEUS control in four cases according to the preoperatively planned procedure. Intraoperative CEUS during EVAR detected a higher number of ELs than the 2CAs and allowed more precise identification of EL type. CEUS is a useful tool in intraoperative sac embolization for type II EL.TableEndoleaks (ELs) detected with two completion angiography studies (2CAs) and contrast-enhanced ultrasound (CEUS) in 44 patientsCEUSTotal+−2CAs+639−122335Total182644 Open table in a new tab