Endovascular treatment of pancreaticoduodenal aneurysm with braided stent-assisted coil embolization using intraoperative cone-beam computed tomography guidance

Pancreaticoduodenal arterial arcade aneurysms are rare but are prone to rupture. We report the case of a 60-year-old woman with an asymptomatic pancreaticoduodenal artery aneurysm and concomitant celiac trunk occlusion that was treated using an endovascular approach. After percutaneous transfemoral access and superior mesenteric artery cannulation, intraoperative cone-beam computed tomography angiography was performed to better understand the aneurysm morphology and provide image guidance. On selecting the optimal working projection, the aneurysm and distal parent vessel were cannulated and treated by braided stent (low-profile visualized intraluminal support; MicroVention)-assisted coil embolization. Completion angiography and cone-beam computed tomography confirmed successful exclusion of the aneurysm sac and a patent pancreaticoduodenal arcade with a well-apposed stent.

Pancreaticoduodenal artery aneurysms (PDAAs) are rare entities classified under visceral aneurysms and often identified incidentally or when the aneurysm ruptures. 1 Treatment of PDAAs should be considered, irrespective of their size, using open surgical repair and endovascular embolization strategies. 2,3 Understanding the three-dimensional (3D) morphology of the aneurysm, efferent vessels, and collateral pathways is critical to deciding on the optimal treatment options. 4 This requires better preprocedural 3D planning and/or multiple two-dimensional (2D) angiograms in different C-arm angulations. Intraprocedural 3D imaging techniques such as rotational angiography and cone-beam computed tomography angiography (CBCTA) are routinely performed during neurointerventions for a better understanding of the aneurysm morphology and treatment guidance. [5][6][7] Recently, new generation stents have revolutionized the management of complex intracranial aneurysms with efferent branches and reconstruction of the parent vessel. 8,9 Clinical experience with treating visceral aneurysms using these novel stents has also been evolving. [10][11][12] The low-profile visualized intraluminal support (LVIS) system (MicroVention Terumo, Aliso Viejo, CA) is a braided stent designed to assist coil embolization.
The purpose of our report was to describe a case of an inferior pancreaticoduodenal aneurysm treated by braided stent-assisted coil embolization, highlighting the additional value of intraoperative CBCTA guidance. The patient provided written informed consent for the report of her case details and imaging studies.

CASE REPORT
A 60-year-old woman with a history of hypertension, obesity (body mass index, 41 kg/m 2 ) had undergone a routine abdominal CT imaging study for evaluation of hematuria and lower back pain. CT demonstrated a 1.7-cm Â 1.1-cm pancreaticoduodenal artery aneurysm with concomitant celiac occlusion (Fig 1). The patient was taken to a hybrid operating room equipped with a robotic angiography system (Artis Pheno VE10B;   Coil embolization of the aneurysm sac was performed using framing coils (6-mm Â 19-cm HydroFrame; MicroVention Terumo), followed by filling coils (7-mm Â 20-cm HydroFil; Microvention Terumo) and microcoils (8 mm Â 24 cm, Galaxy G3; Cardiva Medical Inc, Santa Clara, CA; Fig 3, C). Next, the braided coil-assisted stent (4.5-mm Â 32-mm LVIS device, Microvention Terumo) was deployed in the pancreaticoduodenal artery using road mapping and image guidance (Fig 4, A and B). After deployment, stent foreshortening was not observed. 2D angiography confirmed aneurysm exclusion and a patent pancreaticoduodenal arcade (Fig 4, C). Follow On the first postoperative day, the patient was discharged with a prescription for clopidogrel monotherapy. At her 3-month follow-up visit, the patient was asymptomatic, and follow-up CTA showed a patent pancreaticoduodenal arcade and complete exclusion of the PDAA (Fig 5, B; Supplementary Video 5).

DISCUSSION
The current recommendation for PDAA management is intervention, regardless of its size. 3 An association between celiac trunk stenosis and PDAA has been reported, with a speculated flow-related causal relationship for both stenosis-first and aneurysm-first scenarios. 13 Our patient had had celiac artery occlusion with collateralization from the SMA, which had prompted our decision to treat the PDAA first. Given the better spatial resolution and intra-arterial contrast injection, CBCTA was performed to better understand the PDAA morphology and delineate the treatment options. Despite the additional radiation, CBCTA was helpful in planning the optimal C-arm working projection without the need for multiple 2D angiograms with the resultant contrast injections. The vessel markers from CBCTA overlaid on the fluoroscopic images were useful for gross navigational guidance under breath-hold to facilitate stent positioning. Although CTA with intravenous contrast can provide such information on aneurysm morphology, CBCTA with intra-arterial contrast injection serves as a better intraprocedural 3D imaging tool, even more so in the setting of ruptured visceral aneurysms.
The endovascular treatment options for PDAAs have been evolving with a high success rate, 14 with recent availability of flexible microcatheters, softer framing and filling coils, and braided stents. 15 Angiographic assessment of the collateral circulation in the presence of celiac artery or SMA stenosis is also critical in deciding the optimal endovascular treatment option. Coil embolization of the aneurysm with preservation of the patency of the distal parent vessel is important, especially in the setting of celiac or SMA stenosis. 3,14,16 The tortuosity of the pancreaticoduodenal arcade can be a challenge in delivering a standard covered stent to treat PDAAs. The lower profile and excellent trackability of these braided stents make these stents suitable for treating such complex aneurysms with robust parent vessel reconstruction. Reported case series have shown encouraging results using flow-diverting stents to treat visceral aneurysms. 10,11 These devices provide a scaffold to alter flow toward the parent vessels of the aneurysm. This scaffold was initially designed to assist with coil embolization but, later, evolved into multilayer, braided stents composed of cobalt/chromium and/or nitinol with differing porosity and pore densities. 17 However, the long-term follow-up and durability of this novel treatment option in the visceral segment remain to be determined. In addition, these novel stents and microcatheters add a reasonable cost. Owing to the relationship between the hemodynamics and pathogenesis of PDAAs, closer imaging follow-up after endovascular embolization is required in the presence of celiac occlusion or median arcuate ligament syndrome. 18

CONCLUSIONS
PDAAs can be treated using braided stent-assisted coil embolization. Intraoperative CBCTA can help with better procedural planning, image guidance, and assessment of vessel wall apposition after stent deployment.