# Quantitative TOF-MRA using SYNAPSE VINCENT predicts neointimal formation after stent-assisted coiling of intracranial aneurysms

## TL;DR

This study shows that quantitative TOF-MRA using SYNAPSE VINCENT can predict neointimal formation after stent-assisted coiling of intracranial aneurysms.

## Contribution

The study introduces a novel method using quantitative TOF-MRA signal measurements to predict neointimal formation after stent-assisted coiling.

## Key findings

- TOF-SIR change was independently associated with the presence of the white-collar sign (WCS) at 1 year.
- WCS-positive aneurysms showed a significantly greater increase in TOF-SIR over 12 months.
- Quantitative TOF-MRA using SYNAPSE VINCENT may serve as a reliable alternative to DSA for monitoring aneurysm healing.

## Abstract

Metallic susceptibility artifacts limit the reliability of time-of-flight MR angiography (TOF-MRA) for evaluating aneurysm healing after stent-assisted coiling (SAC). This study investigated whether quantitative TOF-MRA signal measurements at the aneurysm neck, analyzed using SYNAPSE VINCENT software, correlate with the angiographic white-collar sign (WCS), a surrogate marker of neointimal formation.

Eighty-three internal carotid artery aneurysms in 81 patients treated with the Neuroform Atlas stent between January 2019 and December 2023 were retrospectively analyzed. Patients were categorized according to the presence or absence of WCS on 1-year digital subtraction angiography (DSA). The TOF-MRA signal intensity ratio (TOF-SIR) was defined as the ratio of signal intensity at the stented ICA neck to that at the distal M1 segment. TOF-SIR changes over 12 months were compared between groups. The primary outcome was the association between TOF-SIR change and WCS positivity; the secondary outcome evaluated longitudinal TOF-SIR trajectories within each group.

Of the 83 aneurysms, 39 (47%) demonstrated WCS positivity at 1 year. Complete occlusion rates were higher in the WCS-positive group immediately after SAC (23% vs. 11%, p = 0.031) and at 1 year (100% vs. 50%, p < 0.001). The increase in TOF-SIR from postoperative day 1 to 1 year was significantly greater among WCS-positive aneurysms (p = 0.004). ROC analysis identified a TOF-SIR change threshold of 0.03 as predictive of WCS positivity (sensitivity 80%; specificity 61%; AUC 0.69). After adjustment for confounders, TOF-SIR change remained independently associated with WCS development (OR 68.4; 95% CI 1.54–3,040). TOF-SIR increased progressively over time in WCS-positive aneurysms (ρ = 0.24, p = 0.002), whereas no significant longitudinal trend was observed in WCS-negative cases (ρ = 0.035, p = 0.65).

A greater increase in TOF-SIR over 1 year was independently associated with WCS positivity, indicating that quantitative TOF-MRA using SYNAPSE VINCENT may serve as a robust surrogate marker of neointimal formation after SAC. This approach has the potential to reduce reliance on DSA and to function as a practical adjunct in long-term follow-up of aneurysm healing.