Subtraction CTA: An Alternative Imaging Option for the Follow-Up of Flow-Diverter-Treated Aneurysms?

Abstract

BACKGROUND AND PURPOSE: This was a pilot study to explore the diagnostic accuracy and safety of subtraction CTA combined with a single-energy metal artifact reduction algorithm (SEMAR) compared to DSA for the evaluation of intracranial aneurysm occlusion after flow diverter treatment. MATERIALS AND METHODS: We included patients treated with a flow diverter for an unruptured intracranial aneurysm between November 2015 and November 2016. The patient cohort comprised 2 groups: those who underwent follow-up imaging 1 month after flow-diverter treatment and those with a known residual intracranial aneurysm after flow diverter treatment who underwent imaging at regular follow-ups. Full-brain subtraction CTA was performed on a 320-detector row CT system. A low-dose non-enhanced volume acquisition was followed by a contrast-enhanced volume CTA. Iterative and noise-reduction filters, SEMAR, and SURE Subtraction algorithms were applied. DSA was performed on a flat panel C-arm angiography system. Standard posteroanterior, lateral, 3D, and detailed 2D acquisitions were performed. Imaging was independently scored by 2 clinicians. Aneurysm occlusion (Raymond scale) was our primary outcome parameter. RESULTS: Thirteen intracranial aneurysms were evaluated with subtraction CTA and DSA. Nine aneurysm remnants were demonstrated by both subtraction CTA and DSA. The sensitivity and specificity of subtraction CTA for the detection of aneurysm occlusion were 100% (95% CI, 82.41%-100%) and 100% (95% CI, 67.55%-100%), respectively. Agreement between readers was perfect (ϭ 1.0). The smallest neck remnant detected on subtraction CTA was 1.2 mm. No complications occurred. CONCLUSIONS: Subtraction CTA with single-electron metal artifact reduction is effective in the reduction of metal artifacts of flow diverters and might therefore be a viable alternative in the assessment of intracranial aneurysm occlusion after flow diverter treatment.

Evaluation of Intra-Aneurysmal Residual Blood Flow with the iMSDE T1-Black Blood Imaging after Flow Diverter Treatment

“… 25) Duarte Conde et al proposed subtraction CTA combined with a single-energy metal artifact reduction algorithm as FD-treated aneurysms; however, no usefulness for FDs other than Surpass FD (Stryker Neurovascular, Fremont, CA, USA) was demonstrated. 26) …”

Postinterventional Assessment after Stent and Flow-Diverter Implantation Using CT: Influence of Spectral Image Reconstructions and Different Device Types

“…3 Despite relevant technical improvements across the years, complications can occur after stent-assisted coiling and flow-diverter implantation, the most important of which are aneurysm remnants, aneurysm recanalization, and in-stent constriction. 4,5 DSA represents the criterion standard to evaluate vessel patency and aneurysm occlusion. 5 However, DSA is an invasive procedure with a low-but-not-negligible complication rate.…”

“…4,5 DSA represents the criterion standard to evaluate vessel patency and aneurysm occlusion. 5 However, DSA is an invasive procedure with a low-but-not-negligible complication rate. 5 A noninvasive and time-saving option for follow-up imaging with lower radiation exposure would therefore be desirable.…”

“…5 However, DSA is an invasive procedure with a low-but-not-negligible complication rate. 5 A noninvasive and time-saving option for follow-up imaging with lower radiation exposure would therefore be desirable. In contrast, CTA is noninvasive and less time-consuming and has a lower radiation exposure; however, stent-associated artifacts hamper the assessment of the adjacent vessel and aneurysm sac, resulting in a lower diagnostic sensitivity for in-stent stenosis and aneurysm remnants.…”

“…In contrast, CTA is noninvasive and less time-consuming and has a lower radiation exposure; however, stent-associated artifacts hamper the assessment of the adjacent vessel and aneurysm sac, resulting in a lower diagnostic sensitivity for in-stent stenosis and aneurysm remnants. 5 These artifacts result from various mechanisms, including beam-hardening, scatter effects, and Poisson noise, with beam-hardening being considered the main factor. 6 In this context, the extent of the artifacts depends, in particular, on the individual stent type, stent material, and the corresponding x-ray attenuation.…”