flow800 [Neurosurgery Wiki]

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FLOW800 is an intraoperative imaging tool developed by Carl Zeiss Meditec that works in combination with indocyanine green videoangiography (ICG-VA). It provides semi-quantitative hemodynamic analysis by converting ICG fluorescence video sequences into color-coded perfusion maps.

🧠 How It Works
ICG dye is injected intravenously.

The surgical microscope captures fluorescence signals as the dye circulates through cerebral vessels.

FLOW800 analyzes the fluorescence intensity over time and generates:

Time-to-peak maps (how fast the dye arrives)

Flow directionality

Intensity curves for user-defined regions

Color overlays on live images

⚙️ Clinical Utility in Neurosurgery
Visualizes arterial vs. venous phases in AVMs

Maps feeding arteries, nidus, and draining veins

Assists in real-time decision-making during vascular lesion resection

Potentially identifies residual nidus post-resection

Applied in bypass surgery, aneurysm clipping, AVMs, and tumor surgery

❌ Limitations
Not truly quantitative — flow values are relative, not absolute

Line-of-sight dependent — cannot image deep structures

Operator bias in region-of-interest (ROI) selection

No standard thresholds for defining "adequate" perfusion

Cannot replace DSA for diagnostic vascular imaging

🧠 In Summary:
FLOW800 is to ICG-VA what color Doppler is to grayscale ultrasound — a helpful overlay, but not a replacement for diagnostic angiography or sound surgical judgment. It enhances interpretability, not accuracy.