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Abstract
Introduction The use of flow diverters has emerged as an effective treatment of aneurysm. One of the major limitations of flow diverters is the need to put patients on dual anti-platelet therapy (DAPT). The exposure of bare metal struts leads to platelet activation. A method to assess the degree of neointimal tissue ingrowth over the surface of the device could permit patient-specific tailoring of DAPT. Currently, the standard of follow-up for flow diverter patients is digital subtraction angiography (DSA); however, it has been previously reported DSA appearance of complete aneurysm occlusion is not always reliable with continued aneurysm growth.1 There have been reported cases of very delayed complications after DAPT has been stopped,2 although rare, such complications can be catastrophic.
High Frequency Optical Coherence Tomography (HF-OCT) is a novel intravascular imaging technique designed for use in cerebrovascular anatomy with a spatial resolution approaching 10 microns. In this study, we sought to compare HF-OCT with state-of-the-art DSA for the in vivo evaluation of complete aneurysm occlusion.
Methods Flow diverters were implanted in 15 rabbits, at least 21 days after a standard elastase aneurysm creation. Six of the rabbits were imaged at 15 days post implant, including both DSA and HF-OCT to assess healing of the aneurysm. The remaining 9 rabbits were allowed to heal for 60 days, at which point they also received HF-OCT. Finally, the rabbits were euthanized, perfused with formalin, and the aneurysms were explanted for histological analysis.
Results Fifteen days following implant, one aneurysm was seen to be fully occluded on DSA, but HF-OCT demonstrated an aneurysm remnant, and the struts remained uncovered (figure 1D-E). At 60 days post-implant, another aneurysm appeared fully healed on DSA, yet HF-OCT demonstrated that the aneurysm remained in communication with the parent artery (figure 1A-B). This observation was later confirmed on SEM (figure C).
Top row: DSA of a 60-day follow up, showing a fully occluded aneurysm (A). Corresponding HF-OCT, showing that the aneurysm was in fact not occluded (B); the aneurysm remnant is visible between 11 and 2 o’clock (*). SEM of the neck of the aneurysm, confirming the HF-OCT results (C) Bottom row: DSA at 15 days follow up of a fully occluded aneurysm (D). Corresponding HF-OCT showing evidence that the aneurysm is not occluded (E). The two arrows indicate two small remnants at the shoulders of the aneurysm’s neck.
Conclusions Preliminary evidence is presented showing that DSA alone is insufficient to confirm complete aneurysm occlusion. HF-OCT may reliably show parent artery remodeling and inform patient-specific decisions regarding duration of DAPT.
References
AJNR June 2012;33(6):1150–1155.
J Neurosurg 2016;125:929–935.
Disclosures R. King: None. M. Marsofoi: None. E. Langan: None. M. Shazeeb: None. G. Ughi: 4; C; Gentuity LLC. 5; C; Gentuity LLC. C. Raskett: None. A. Puri: None. M. Gounis: None.