Surveillance imaging after intracranial stent implantation: non-invasive imaging compared with digital subtraction angiography.

Abstract

Digital subtraction angiography (DSA) is the gold standard imaging for detection of in-stent restenosis (ISR) but there is limited literature on optimal non-invasive surveillance imaging. In this study, the ability of CT angiography (CTA) and MR angiography (MRA) compared with DSA in recognizing ISR was assessed. A single center database of patients treated with stent implantation for ICAD was accessed. All patients who underwent follow-up imaging with DSA paired with either MRA or CTA within 30 days were included. Two angiography readers and two non-invasive imaging readers measured restenosis with a submillimeter digital caliper. ISR was categorized as: none/minimal, mild (<50%), moderate (≥50-70%) or severe (≥70%). Analysis was performed with weighted κ statistics. 17 cases of individual stents that underwent surveillance imaging with paired DSA and CTA and five stents with paired DSA and MRA were identified. Of those undergoing DSA and CTA, inter-reader agreement produced κ=0.68 (95% CI 0.40 to 0.95) for DSA and κ=0.75 (95% CI 0.55 to 0.95) for CTA. Agreement across CTA and DSA was κ=0.36 (95% CI 0.26 to 0.52). Of those undergoing DSA and MRA, inter-reader agreement produced κ=0.71 (95% CI 0.27 to 1.00) for DSA and κ=1.00 (95% CI 1.00 to 1.00) for MRA. Agreement across MRA and DSA was κ=0.34 (95% CI 0.18 to 0.51). Good inter-reader agreement exists within DSA, CTA and MRA. However, when comparing non-invasive imaging (CTA and MRA) with DSA, only fair agreement exists. These data suggest that CTA and MRA are not comparable to DSA for evaluation of ISR.