Operative Neurosurgery 30:250–259, 2026
This clinical study evaluates intraoperative indocyanine green videoangiography with FLOW 800 software to quantify hemodynamic changes during cranial and spinal dural arteriovenous fistula (dAVF) microsurgical obliteration. Using four FLOW 800 metrics across venous regions of interest, the authors compare pre- and post-obliteration measurements confirmed by intraoperative digital subtraction angiography.
Key findings identify increased Delay Time and decreased Speed as consistent, significant markers of successful dAVF obliteration, supported by nonparametric tests, logistic and Bayesian regression, and PCA visualization. The study suggests FLOW 800 as a practical adjunct to intraoperative imaging, while acknowledging limitations from small sample size and ROI selection variability.
Key Hemodynamic Parameters: Intraoperative FLOW 800 analysis of indocyanine green videoangiography quantifies four hemodynamic parameters—Delay Time, Speed, Time to Peak, and Rise Time—across venous drainage regions before and after dAVF (dural arteriovenous fistula) obliteration.
Most Sensitive Indicators: Delay Time (time for dye to reach ROI) and Speed (rate of dye flow) are the most sensitive and consistent hemodynamic indicators of successful dAVF obliteration, with Delay Time increasing and Speed decreasing significantly post-obliteration.
Statistical Significance: Delay Time increased from a median of 2.07s to 7.86s (P = .020), and Speed decreased from 13.5 s⁻¹ to 5.5 s⁻¹ (P = .029), both changes being statistically significant; Time to Peak and Rise Time showed no significant association.
Predictive Value: A 50% increase in Delay Time is associated with 2.16 times higher odds of achieving obliteration (OR = 4.59), while a 50% decrease in Speed is associated with 1.28 times higher odds; Delay Time and Speed are the strongest predictors in regression analyses.
Clinical Utility: FLOW 800 provides real-time, semiquantitative intraoperative feedback, supporting its use as a noninvasive adjunct to traditional imaging (like intraoperative DSA) for confirming dAVF obliteration, especially where DSA is unavailable.
Study Limitations: The study is limited by small sample size (8 patients, 14 ROIs), single-center design, and possible variability in ROI selection; findings require validation in larger, multicenter studies.
Practical Considerations: Complete visualization of venous outflow is necessary for FLOW 800 utility; current evidence supports its use as a complementary tool rather than a replacement for DSA.
Clinical Outcome: All patients in the study had successful dAVF obliteration confirmed by intraoperative DSA, no complications or recurrences at median 19.4 months follow-up, and FLOW 800 changes were consistent with successful surgical outcomes.
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