Image Fusion Guidance for In Situ Laser Fenestration of Aortic Stent graft for Endovascular Repair of Complex Aortic Aneurysm: Feasibility, Efficacy and Overall Functional Success

Assessment of Bridging Stents in In Situ Laser Fenestrations of Aortic Endografts With Intravascular Ultrasound

Objective

Treatment of complex aortic aneurysms with the in situ laser fenestration (ISLF) technique involves implantation of a balloon expandable stent graft (bSG) in the created fenestration. Adequate expansion of this bSG is of importance both to achieve seal and to ensure target vessel stability. This experimental study assessed the expansion rate of different bSGs in the ISLF setting using intravascular ultrasound (IVUS).

Methods

A commercially available aortic endograft was used to test the laser fenestration technique (Zenith Alpha, Cook Medical LLC, Bloomington, IN, USA). The ISLF was stented with the following bSGs: two Gore Viabahn VBX balloon expandable endoprostheses (WL Gore & Associates, Bloomington, IL, USA), three BeGraft Peripheral and three BeGraft Plus (Bentley InnoMed GmbH; Hechingen, Germany), and three Advanta V12 (Atrium, Hudson, NH, USA). The bSGs were expanded in three steps: (1) nominal, (2) rated burst pressure, and (3) dilation with a non-compliant balloon at 15 atmospheres. After each step, an IVUS assessment of the bSG minimum diameter and the area at the fenestration (FA) and in a fully expanded segment distal to the fenestration (SA) was performed. A mean of the three IVUS measurements was used as the value for comparison. An insufficient bSG expansion was defined as a mean of FA/SA of <0.8 (i.e., <80% expansion).

Results

The VBX was the only bSG that could be expanded to its intended diameter (i.e., at least 80%) at nominal pressure. The BeGraft Peripheral and BeGraft Plus had the lowest degree of expansion after nominal and rated burst pressure. All bSGs that were tested reached a sufficient expansion degree after using a higher pressure balloon.

Conclusion

In this ex vivo experiment, dilation up to nominal pressure showed satisfactory expansion only for the VBX. The consistency of the results when applied to the different types of stent grafts that were analysed reflects structural stent graft specific issues to consider when choosing the right device in cases of ISLF.

Image fusion guidance for left subclavian artery in situ fenestration during thoracic endovascular repair

OBJECTIVES

To evaluate the feasibility and clinical benefit of utilizing image fusion for thoracic endovascular repair (TEVAR) with in situ fenestration (ISF-TEVAR).

MATERIALS AND METHODS

Between January 2020 and December 2020, we prospectively collected 18 consecutive cases with complex thoracic aortic lesions who underwent image fusion guided ISF-TEVAR. As a control group, 18 patients were collected from historical medical records from June 2019 to December 2019. The fusion group involved the use of 3D fusion of CTA and fluoroscopic images for real-time 3D guidance, and the control group involved the use of only regular fluoroscopic images for guidance. The total contrast medium volume, hand-injected contrast medium volume, overall operative time, radiation dose and fluoroscopy time were compared between the two groups. Accuracy was measured based on preoperative CTA and intraoperative digital subtraction angiography.

RESULTS

3D fusion imaging guidance was successfully implemented in all patients in the fusion group. Hand-injected contrast medium volume and overall operative time were significantly lower in the fusion group than in the control group (p = .028 and p = .011). Compared with the control group, the fusion group showed a significant reduction in time and radiation dose-area product (DAP) for fluoroscopy (p = .004 and p = .010). No significant differences in total radiation dose (DAP) or total contrast medium volume were observed (p = .079 and p = .443). Full accuracy was achieved in 8 cases (44%), with a mean deviation of 2.61 mm ± 3.1 (range 0.0-8.4 mm).

CONCLUSIONS

3D image fusion for ISF-TEVAR was associated with a significant reduction in hand-injected contrast medium, time and radiation exposure for fluoroscopy and overall operative time. The image fusion guidance showed potential clinical benefits towards improved treatment safety and accuracy for complex thoracic endovascular interventions.

Fusion imaging for pulmonary artery embolization: impact on fluoroscopy duration and contrast agent exposure

OBJECTIVES

To assess the impact of fusion imaging guidance on fluoroscopy duration and volume of contrast agent used for pulmonary artery embolization.

METHODS

Thirty-four consecutive patients who underwent pulmonary artery embolization for pulmonary arterio-venous malformation (n = 28) or hemoptysis (n = 6) were retrospectively included. In the experimental group (n = 15), patients were treated using fusion imaging with 2D/3D registration. In the control group (n = 19), no fusion imaging has been used. Fluoroscopy duration and amount of contrast used were measured and intergroup comparison was performed.

RESULTS

The average volume of contrast agent used for embolization in the fusion group (118.3 ml) was significantly lower than in the control group (285.3 ml) (p < 0.002). The mean fluoroscopy duration was not significantly different between both groups (19.5 min in the fusion group vs 31.4 min in the control group (p = 0.10)). No significant difference was observed regarding the average X-ray exposure (Air Kerma) (p = 0.68 in the univariate analysis). Technical success rate was 100% for both groups.

CONCLUSION

Fusion imaging significantly reduces contrast medium volumes needed to perform pulmonary artery embolization. The fluoroscopy duration and the X-ray exposure did not vary significantly.

ADVANCES IN KNOWLEDGE

CTA-based fusion imaging using 2D-3D registration is a valuable tool for performing pulmonary artery embolization, helpful for planning and guiding catheterization.Compared to the traditional imaging guidance, fusion imaging reduces the volume of contrast agent used.

Mechanical Comparison between Fenestrated Endograft and Physician-Made Fenestrations

INTRODUCTION

A fenestrated endograft (FE) is the first-line endovascular option for juxta and pararenal abdominal aortic aneurysms. A physician-modified stent-graft (PMSG) and laser in situ fenestration (LISF) have emerged to circumvent manufacturing delays, anatomic standards, and the procedure's cost raised by FE. The objective was to compare different fenestrations from a mechanical point of view.

METHODS

In total, five Zenith Cook fenestrations (Cook Medical, Bloomington, IN, USA) and five Anaconda fenestrations (Terumo Company, Inchinnan, Scotland, UK) were included in this study. Laser ISF and PMSG were created on a Cook TX2 polyethylene terephthalate (PET) cover material (Cook Medical, Bloomington, IN, USA). In total, five LISFs and fifty-five PMSG were created. All fenestrations included reached an 8 mm diameter. Radial extension tests were then performed to identify differences in the mechanical behavior between the fenestration designs. The branch pull-out force was measured to test the stability of assembling with a calibrated 8 mm branch. Fatigue tests were performed on the devices to assess the long-term outcomes of the endograft with an oversized 9 mm branch.

RESULTS

The results revealed that at over 2 mm of oversizing, the highest average radial strength was 33.4 ± 6.9 N for the Zenith Cook fenestration. The radial strength was higher with the custom-made fenestrations, including both Zenith Cook and Anaconda fenestrations (9.5 ± 4.7 N and 4.49 ± 0.28 N). The comparison between LISF and double loop PMSG highlighted a higher strength value compared with LISF (3.96 N ± 1.86 vs. 2.7 N ± 0.82; p= 0.018). The diameter of the fenestrations varied between 8 and 9 mm. As the pin caliber inserted in the fenestration was 9 mm, one could consider that all fenestrations underwent an "elastic recoil" after cycling. The largest elastic recoil was observed in the non-reinforced/OC fenestrations (40%). A 10% elastic recoil was observed with LISF.

CONCLUSION

In terms of mechanical behavior, the custom-made fenestration produced the highest results in terms of radial and branch pull-out strength. Both PMSG and LISF could be improved with the standardization of the fenestration creation protocol.

Emergent endovascular treatment options for thoracoabdominal aortic aneurysm

For a long time, parallel grafting, physician-modified endografts, and, more recently, in situ fenestration were the only go-to endovascular options for ruptured thoracoabdominal aortic aneurysm, offered mixed results, and depended mainly on the operator's and center's experience. As custom-made devices have become an established endovascular treatment option for elective thoracoabdominal aortic aneurysm, they are not a viable option in the emergency setting, as endograft production can take up to 4 months. The development of off-the-shelf (OTS) multibranched devices with a standardized configuration has allowed the treatment of ruptured thoracoabdominal aortic aneurysm with emergent branched endovascular procedures. The Zenith t-Branch device (Cook Medical) was the first readily available graft outside the United States to receive the CE mark (in 2012) and is currently the most studied device for those indications. A new device, the E-nside thoracoabdominal branch endoprosthesis OTS multibranched endograft (Artivion), has been made commercially available, and the GORE EXCLUDER thoracoabdominal branch endoprosthesis OTS multibranched endograft (W. L. Gore and Associates) is expected to be released in 2023. Due to the lack of guidelines on ruptured thoracoabdominal aortic aneurysm, this review summarizes the available treatment options (ie, parallel grafts, physician-modified endografts, in situ fenestrations, and OTS multibranched devices), compares the indications and contraindications, and points out the evidence gaps that should be filled in the next decade.

Midterm Outcomes of Antegrade In Situ Laser Fenestration of Polyester Endografts for Urgent Treatment of Aortic Pathologies Involving the Visceral and Renal Arteries

OBJECTIVE

Aortic endografting and antegrade in situ laser fenestration of visceral arteries (LFEVAR) may be considered as an alternative to open surgery for the emergency repair of complex abdominal aortic aneurysms (AAA) in fragile patients. The aim of this article was to evaluate the midterm results of LFEVAR performed with polyester endografts.

METHODS

From August 2015 to December 2020, all consecutive LFEVAR performed for non-deferrable treatment of complex AAA were analysed. Polyester endografts were deployed and subsequently fenestrated using an atherectomy laser probe; the fenestrations were enlarged using cutting and semicompliant balloons before implantation of balloon expandable bridging stents into the target vessels. Prospectively collected midterm survival, patency, and re-intervention rates were analysed.

RESULTS

Forty four procedures were performed for 11 type 1a endoleaks, five thoraco-abdominal aneurysms, 20 pararenal aneurysms, four segmental renal artery (RA) preservations, three anastomotic aneurysms, and one aortic dissection. One hundred and eight laser fenestrations were performed (26 for the superior mesenteric artery [SMA], 13 for the coeliac trunk, 33 and 31 for the right and left RA, respectively). The median ischaemia duration was 7, 48, 48, and 45 minutes, respectively. The technical success rate was 97%, with no open surgical conversions. The 30 day mortality was 4.5% (n = 2). No spinal cord ischaemia events were observed nor early stent related complications. Kaplan-Meier overall survival at two years was 73%, the aortic related re-intervention free survival was 70%, and the stent related re-intervention free survival was 90.6%. Four target vessel thromboses were detected, of which three were rescued. Three type IIIc endoleaks, one RA false aneurysm, and one SMA stenosis, required re-intervention during a median follow up of 24.7 months.

CONCLUSION

Antegrade LFEVAR is feasible, safe, and provides satisfactory early and midterm outcomes for non-deferrable treatment of aortic pathologies involving the visceral segment. Long term data are mandatory to confirm the usefulness of this promising off label technique.

A Systematic Review of Contemporary Outcomes from Aortic Arch In Situ Laser Fenestration During Thoracic Endovascular Aortic Repair

BACKGROUND

In situ laser fenestrated endovascular aortic repair (L-FEVAR) is a novel and creative solution for complex aortic pathologies in the urgent and emergency setting. Outcomes of this technique, however, are poorly reported. We sought to evaluate the efficacy, safety, and outcomes of L-FEVAR in aortic arch pathologies.

METHODS

A systematic literature review and analysis were conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses and Cochrane guidelines. A search was conducted using Google, PubMed, and Scopus to identify studies evaluating L-FEVAR. Two independent reviewers determined study inclusion. Case reports and series including < 10 patients were excluded. Reviewers also assessed the methodological quality and extracted data regarding outcomes. A meta-analysis of endoleak event rates was conducted using a fixed-effect model due to small sample size.

RESULTS

Eight studies met inclusion criteria between 2013 and 2021. Most studies were retrospective (87.5%) with median follow-up duration of 12.5 months (range 10-42). There were 440 patients included (range 15-148), mostly men (64%). Mean age was 61 years (range 53-68). Included patients were all symptomatic with L-FEVAR being technically successful in 93.3% of cases. The main indication for aortic arch intervention was aortic dissection. Single fenestrations occurred most frequently (68%), followed by triple (22%) then double fenestrations (9%). Meta-analysis of 8 studies (n = 440) demonstrated an endoleak event rate of 0.06 (95% confidence interval 0.04-0.09, P < 0.001) with no observed statistically significant heterogeneity of effects (Q = 7.91, P = 0.34). The median operative time was 162 min (range 53-252) with median length of stay of 10 days (range 7-17). Primary branch patency was 96.6%. Secondary patency rate was 97%. Pooled complication rates such as endoleak occurred in 4.8%, stroke in 2.0%, spinal cord ischemia in 0.2%, retrograde dissection in 0.9%, and 30-day death in 2.0%. Access complications occurred in 0.4%. Antiplatelet regimen was poorly reported in the study cohort.

CONCLUSIONS

In situ laser fenestration is a feasible, safe, and effective approach to treat aortic arch disease in patients who are unsuitable for open or custom-made endovascular means. High technical success and excellent short-term branch patency can be achieved. These single-institution series exhibit promising short-term outcomes. In a similar paradigm to investigational device exemptions studies for custom-made and physician modified endografts, these preliminary data make a persuasive argument for larger long-term multi-institutional prospective study of this promising technique.

In Situ Laser Fenestrations of Aortic Endografts for Emergent Aortic Disease

BACKGROUND

In situ laser fenestration (ISLF) is a novel endovascular technique which allows customization of a standard stent graft to a patient's anatomy. While most reported cases involve revascularization of the left subclavian artery (LSA), some centers have now reported their initial experience treating branches of the visceral aorta for aortic aneurysms. The aim of this study is to examine the adoption of ISLF in emergent aortic pathology at a specialized aortic center.

METHODS

Between December 2020 and February 2022, all patients who underwent ISLF as part of endovascular intervention for complex aortic pathology at a university hospital were identified. Cases were collected from a prospective aortic database with additional information obtained from a retrospective review of electronic hospital records.

RESULTS

Fifteen patients (11 men and 4 women) underwent emergency ISLF, with a median age of 76 years. Eleven presented with symptomatic or ruptured aortic aneurysms, three with acute complicated aortic dissections and 1 aortic traumatic transection. Most aortic aneurysms were thoraco-abdominal (n = 7), with 1 arch, 1 thoracic, 1 supra-renal, and one-juxta-renal aortic aneurysm. ISLF was performed to revascularize the LSA in 8 cases, and branches of the reno-visceral aorta in 7 cases. All LSA ISLF cases had left brachial artery exposure. Femoral access was percutaneous in 14 of 15 cases. Technical success was 96.3% (26/27)). Median ischemic times were: superior mesenteric artery 7 min, renal arteries 22 min, and celiac trunk 43.5 min. There were 2 early aortic/fenestration related reinterventions. There was no stroke and 1 death caused by heparin-induced thrombocytopenia within 30 days. The majority of patients did not require intensive care admission (n = 8). The median intensive care unit stay was 0 days and hospital length of stay 18 days. There was no fenestration endoleak or reintervention post discharge with a median follow-up of 168 days.

CONCLUSIONS

ISLF is a promising new technique that can show excellent technical results in experienced aortic centers, even during the learning curve. While custom-made devices with reinforced fenestrations are preferred in nonemergent situations, ISLF is a feasible option for complex aortic pathology in the acute setting when open surgery is not feasible.

A patient-specific multi-modality abdominal aortic aneurysm imaging phantom

Purpose

Multimodality imaging of the vascular system is a rapidly growing area of innovation and research, which is increasing with awareness of the dangers of ionizing radiation. Phantom models that are applicable across multiple imaging modalities facilitate testing and comparisons in pre-clinical studies of new devices. Additionally, phantom models are of benefit to surgical trainees for gaining experience with new techniques. We propose a temperature-stable, high-fidelity method for creating complex abdominal aortic aneurysm phantoms that are compatible with both radiation-based, and ultrasound-based imaging modalities, using low cost materials.

Methods

Volumetric CT data of an abdominal aortic aneurysm were acquired. Regions of interest were segmented to form a model compatible with 3D printing. The novel phantom fabrication method comprised a hybrid approach of using 3D printing of water-soluble materials to create wall-less, patient-derived vascular structures embedded within tailored tissue-mimicking materials to create realistic surrounding tissues. A non-soluble 3-D printed spine was included to provide a radiological landmark.

Results

The phantom was found to provide realistic appearances with intravascular ultrasound, computed tomography and transcutaneous ultrasound. Furthermore, the utility of this phantom as a training model was demonstrated during a simulated endovascular aneurysm repair procedure with image fusion.

Conclusion

With the hybrid fabrication method demonstrated here, complex multimodality imaging patient-derived vascular phantoms can be successfully fabricated. These have potential roles in the benchtop development of emerging imaging technologies, refinement of novel minimally invasive surgical techniques and as clinical training tools.

Antegrade in situ laser fenestration of aortic stent graft during endovascular aortic repair: A case report

BACKGROUND

The endovascular repair of juxtarenal abdominal aortic aneurysms (JAAA) usually requires combination treatment with various stent graft modifications to preserve side branch patency. As a feasible technique, according to the situation, antegrade in situ laser fenestration still needs to be improved.

CASE SUMMARY

This report describes a case that was successfully treated with endovascular repair facilitated by antegrade in situ laser fenestration while maintaining renal arterial flow. Laser fenestration was performed using a steerable sheath positioned in the stent graft lumen in front of the renal artery ostium. With the bare stent region unreleased, renal artery perfusion could be maintained and accurate positioning could be achieved by angiography in real time.

CONCLUSION

This study suggests the feasibility and short-term safety of this novel antegrade in situ laser fenestration technique for select JAAA patients.

A systematic review of experimental and clinical studies reporting on in situ laser fenestration of aortic endografts

OBJECTIVE

To summarize available in-situ laser fenestration (ISLF) literature, including experimental studies with their subsequent recommendations regarding optimal fenestration technique and fabric; as well as the short and mid-term results of clinical studies.

METHODS

A systematic review of English articles was performed in MEDLINE, the Cochrane Database and EMBASE, following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines by two researchers. The search period was without starting date until the 31^st August 2020, and search terms included were in situ, laser, fenestration, and endograft. Quality assessment of the studies was performed using the Newcastle-Ottawa scale by two other independent researchers.

RESULTS

A total of 19 clinical studies were included, with a total of 428 patients (390 supra-aortic trunk ISLF, 38 visceral vessel ISLF). The technical success was 96.9% and 95.6% supra-aortic and visceral vessel ISLF, respectively. Most studies have less than 12-month follow-up, and the longest available follow-up (in one study) was 5-years for left-subclavian fenestration and 17-months for visceral vessel ISLF. Overall, the quality of the evaluated clinical studies was low. Six experimental studies were included, with the highest level of evidence suggesting fenestration of multifilament polyethylene terephthalate grafts, followed by dilation with either a 6- or 8-mm non-compliant balloon.

CONCLUSION

Experimental studies favour the use of multifilament polyethylene terephthalate , followed by dilation with non-compliant balloons as the most durable "in-vitro" technique for ISLF. Short-term outcomes for arch and visceral vessel revascularization are promising, with low rates of in-hospital mortality, stroke, and end-organ ischemia. Nonetheless, the long-term durability of ISLF is yet to be determined and they should be limited to selected symptomatic or urgent cases.

Transjugular intrahepatic portosystemic shunt placement: portal vein puncture guided by 3D/2D image registration of contrast-enhanced multi-detector computed tomography and fluoroscopy

Background

To assess the technical feasibility, success rate, puncture complications and procedural characteristics of transjugular intrahepatic portosystemic shunt (TIPS) placement using a three-dimensional vascular map (3D-VM) overlay based on image registration of pre-procedural contrast-enhanced (CE) multi-detector computed tomography (MDCT) for portal vein puncture guidance.

Materials and methods

Overall, 27 consecutive patients (59 ± 9 years, 18male) with portal hypertension undergoing elective TIPS procedure were included. TIPS was guided by CE-MDCT overlay after image registration based on fluoroscopic images. A 3D-VM of the hepatic veins and the portal vein was created based on the pre-procedural CE-MDCT and superimposed on fluoroscopy in real-time. Procedural characteristics as well as hepatic vein catheterization time (HVCT), puncture time (PT), overall procedural time (OPT), fluoroscopy time (FT) and the dose area product (DAP) were evaluated. Thereafter, HVCT, PT, OPT and FT using 3D-VM (61 ± 9 years, 14male) were compared to a previous using classical fluoroscopic guidance (53 ± 9 years, 21male) for two interventional radiologist with less than 3 years of experience in TIPS placement.

Results

All TIPS procedure using of 3D/2D image registered 3D-VM were successful with a significant reduction of the PSG (p < 0.0001). No clinical significant complication occurred. HVCT was 14 ± 11 min, PT was 14 ± 6 min, OPT was 64 ± 29 min, FT was 21 ± 12 min and DAP was 107.48 ± 93.84 Gy cm². HVCT, OPT and FT of the interventionalist with less TIPS experience using 3D/2D image registered 3D-VM were statistically different to an interventionalist with similar experience using fluoroscopic guidance (p_HVCT = 0.0022; p_OPT = 0.0097; p_FT = 0.0009). PT between these interventionalists was not significantly different (p_PT = 0.2905).

Conclusion

TIPS placement applying registration-based CE-MDCT vessel information for puncture guidance is feasible and safe. It has the potential to improve hepatic vein catherization, portal vein puncture and radiation exposure.

Combination of Quadruple Antegrade and Retrograde In Situ Stent-Graft Laser Fenestration in the Management of a Complex Abdominal Aortic Aneurysm

BACKGROUND

We report a case of juxtarenal abdominal aortic aneurysm-anatomically unsuitable for conventional endovascular repair because of narrow distal aorta-successfully treated by endovascular repair facilitated by in situ laser fenestration.

METHODS AND RESULTS

An aortic stent graft was inserted to exclude a juxtarenal aneurysm: under image fusion guidance, antegrade in situ laser fenestration allowed to perfuse superior mesenteric artery and both renal arteries. After complementary insertion of an extended aortouni-iliac stent graft, retrograde in situ laser fenestration was performed to perfuse the contralateral left iliac artery, in order to overcome a narrow distal aorta. Postoperative course was uneventful. Six month's CT showed an excluded aneurysm, patency of the inserted stents and the absence of endoleak.

CONCLUSIONS

In situ laser fenestration seems to be an effective solution for endovascular therapy of complex juxtarenal aneurysms. In this case of narrow distal aorta it was a suitable alternative to overcome endovascular aneurysm repair anatomical restrictions and to prevent other additional open surgical interventions.

CBCT-Based Image Guidance for Percutaneous Access: Electromagnetic Navigation Versus 3D Image Fusion with Fluoroscopy Versus Combination of Both Technologies-A Phantom Study

PURPOSE

We set out to compare three types of three-dimensional CBCT-based imaging guidance modalities in a phantom study: image fusion with fluoroscopy (IF), electromagnetic navigation (EMN) and the association of both technologies (CEMNIF).

MATERIALS AND METHODS

Four targets with a median diameter of 11 mm [first quartile (Q1): 10; third quartile (Q3): 12] with acute angle access (z-axis < 45°) and four targets of 10 mm [8-15] with large angle access (z-axis > 45°) were defined on an abdominal phantom (CIRS, Meditest, Tabuteau, France). Acute angle access targets were punctured using IF, EMN or CEMNIF and large angle access targets with EMN by four operators with various experiences. Efficacy (target reached), accuracy (distance between needle tip and target center), procedure time, radiation exposure and reproducibility were explored and compared.

RESULTS

All targets were reached (100% efficacy) by all operators. For targets with acute angle access, procedure times (EMN: 265 s [236-360], IF: 292 s [260-345], CEMNIF: 320 s [240-333]) and accuracy (EMN: 3 mm [2-5], IF: 2 mm [1-3], CEMNIF: 3 mm [2-4]) were similar. Radiation exposure (EMN: 0; IF: 708 mGy.cm² [599-1128]; CEMNIF: 51 mGy.cm² [15-150]; p < 0.001) was significantly higher with IF than with CEMNIF and EMN. For targets with large angle access, procedure times (EMN: 345 s [259-457], CEMNIF: 425 s [340-473]; p = 0.01) and radiation exposure (EMN: 0, CEMIF: 159 mGy.cm² [39-316]; p < 0.001) were significantly lower with EMN but with lower accuracy (EMN: 4 mm [4-6] and CEMNIF: 4 mm [3, 4]; p = 0.01). The operator's experience did not impact the tested parameters regardless of the technique.

CONCLUSION

In this phantom study, EMN was not limited to acute angle targets. Efficacy and accuracy of puncture for acute angle access targets with EMN, IF or CEMNIF were similar. CEMNIF is more accurate for large angle access targets at the cost of a slightly higher procedure time and radiation exposure.