醫學研究

Intravenous C-arm conebeam CT angiography following long-term flow-diverter implantation: Technologic evaluation and preliminary results

Yu SC, Lee KT, Lau TW, Wong GK, Pang VK, Chan KY. AJNR Am J Neuroradiol. 2016 Mar;37(3):481-6. doi: 10.3174/ajnr.A4558. Epub 2015 Nov 19. PMID: 26585252; PMCID: PMC7960118.

Abstract

Background and purpose: A noninvasive investigation with high spatial resolution and without metal artifacts is necessary for long-term imaging follow-up after flow-diverter implantation. We aimed to evaluate the diagnostic value of conebeam CT angiography with intravenous contrast enhancement in the assessment of vascular status following implantation of the Pipeline Embolization Device and to analyze the preliminary results of vascular status following long-term Pipeline Embolization Device implantation.

Materials and methods: This was an ongoing prospective study of consecutive patients with intracranial aneurysms treated with the Pipeline Embolization Device. Patients with a modified Rankin Scale score of 4-5 were excluded. The median and interquartile range of the time interval of Pipeline Embolization Device implantation to conebeam CT angiography with intravenous contrast enhancement were 56.6 and 42.9-62.4 months, respectively. Conebeam CT angiography with intravenous contrast enhancement was performed with the patient fully conscious, by using a C-arm CT with a flat panel detector.

Results: There were 34 patients and 34 vascular segments. In all 34 cases, contrast effect and image quality were good and not substantially different from those of intra-arterial conebeam CTA. Metal artifacts occurred in all 14 cases with coil masses; the Pipeline Embolization Device was obscured in 3 cases. In all 34 cases, there was no residual aneurysm, no vascular occlusion, 1 vascular stenosis (50%), good Pipeline Embolization Device apposition to the vessel, and no Pipeline Embolization Device-induced calcification. All 28 Pipeline Embolization Device-covered side branches were patent.

Conclusions: Conebeam CT angiography with intravenous contrast enhancement is potentially promising and useful for effective evaluation of the vascular status following intracranial flow diverters. The Pipeline Embolization Device for intracranial aneurysms is probably safe and promising for long-term placement, with favorable morphologic outcome and without delayed complications.

Figure 1.   CBCTA with intra-arterial contrast shows the absence of motion artifacts and good contrast opacification of the vascular structures. The same image quality is also observed with IVCBCTA. A, Metal artifacts (asterisk) and the origin of ophthalmic artery (white arrow) are depicted on intra-arterial CBCTA. B, Features of contrast enhancement within the internal carotid artery and the hypoattenuated wall of the internal carotid artery (white arrow) within the enhanced cavernous sinus are indistinguishable from those depicted on intravenous CBCTA. C, In a 59-year-old man who underwent implantation of 1 PED 68 months ago, IVCBCTA shows the presence of metal artifacts (white asterisk) not affecting the PED-paved vascular segment to be assessed. Focal calcification can be depicted near the lower end of the PED (white arrow). The ophthalmic artery covered by the PED is well-preserved and well-depicted (white arrowheads).

Figure 2.  How the PED-paved vascular segment can still be depicted in the presence of coil-induced metal artifacts is illustrated in the following 2 cases. A, In a 67-year-old woman who had a giant aneurysm at C6 and received coil embolization 4 times with 23 coils (total length, 275 cm), including 1 stent-assisted coil embolization, the aneurysm recurred and was treated with 2 PEDs implanted at C4–6. IVCBCTA was performed 55 months after PED implantation. Although the large coil mass in close proximity induced intense metal artifacts, the PED-paved vascular segment is not affected because it lies outside the plane of metal artifacts (white asterisks) parallel to the direction of the conebeam x-ray. The PED is seen well-apposed to the vessel wall and conforming to the vascular curvature. The hypoattenuated wall of the internal carotid artery (white arrow) allows the vessel to be differentiated from the contrast-enhanced cavernous sinus. B, In a 57-year-old man who underwent coil embolization (total length, 20 cm) for a cerebral aneurysm and subsequently underwent PED implantation at C6 for aneurysm recurrence, IVCBCTA was performed 72 months afterward, which showed the PED-paved vascular segment unaffected by metal artifacts (white asterisk), despite the presence of the coil mass (white arrow) in close proximity. The PED is seen well-apposed to the vessel wall and conforming to the vascular curvature.

Figure 3.  In a 68-year-old woman with a 21-mm saccular aneurysm located at the ophthalmic segment (C6) of the internal carotid artery as shown on DSA (A), follow-up IVCBCTA 56 months after PED implantation shows no evidence of residual cavity or wall of the aneurysm (white asterisk, B). In a 69-year-old woman with a 13-mm saccular aneurysm located at the communicating segment (C7) of the internal carotid artery as shown on DSA (C), follow-up IVCBCTA 52 months after PED shows no evidence of a residual cavity of the aneurysm but evidence of a residual wall of the aneurysm (white arrows, D).

Figure 4.  The only case of vascular stenosis occurred in a 79-year-old man who underwent implantation of 1 PED at 40 months before IVCBCTA. The stenosis (white arrow) can be well-depicted between the PED and the contrast-enhanced arterial lumen when the vascular segment C6 is examined in cross-sections perpendicular to the long axis (A) or in a longitudinal section (B).

Figure 5.  Good PED apposition to the vessel wall, good PED conformity to the vascular curvature, and preservation of the covered side branch can be illustrated in the following 3 patients. In a 66-year-old woman who underwent implantation of 1 PED 42 months ago, IVCBCTA (A) shows good PED apposition to the vessel wall and good conformity to the vascular curvature, with focal calcification at the wall of C5 outside the PED (white arrow). B, Good PED apposition to the vessel wall and focal calcification are shown again at another cross-sectional plane, in which the ophthalmic artery covered by the PED is well-preserved and well-depicted (white arrowheads). C, In a 68-year-old woman who underwent implantation of 1 PED 52 months ago, IVCBCTA shows good PED apposition to the vessel wall and good conformity to the vascular curvature. The hypoattenuated wall of the internal carotid artery (white arrow) allows the vessel to be differentiated from the contrast-enhanced cavernous sinus. D, In an 81-year-old woman who underwent implantation of 1 PED 51 months ago, IVCBCTA shows good PED apposition to the vessel wall and good conformity to the vascular curvature. The ophthalmic artery covered by the PED is well-preserved and well-depicted (white arrowheads).

Citation:

https://pubmed.ncbi.nlm.nih.gov/26585252/