Intraoperative indocyanine green video angiography (ICG-VA) with FLOW 800 software in complex intracranial aneurysm surgery

Abstract

Background: Indocyanine green video angiography (ICG-VA) is a safe and effective instrument to assess changes in cerebral blood flow during cerebrovascular surgery. After ICG-VA, FLOW 800 provides a color-coded map to directly observe the dynamic distribution of blood flow and to calculate semiquantitative blood flow parameters later. The purpose of our study is to assess whether FLOW 800 is useful for surgery of complex intracranial aneurysms and to provide reliable evidence for intraoperative decision-making.

Methods: We retrospectively reviewed patients with complex aneurysms that underwent microsurgical and intraoperative evaluation of ICG-VA and FLOW 800 color-coded maps from February 2019 to May 2020. FLOW 800 data were correlated with patient characteristics, clinical outcomes, and intraoperative decision-making.

Results: The study included 32 patients with 42 complex aneurysms. All patients underwent ICG-VA FLOW 800 data provided semiquantitative data regarding localization, flow status in major feeding arteries; color maps confirmed relative adequate flow in parent, branching, and bypass vessels.

Conclusions: FLOW 800 is a useful supplement to ICG-VA for intraoperative cerebral blood flow assessment. ICG-VA and FLOW 800 can help to determine the blood flow status of the parent artery after aneurysm clipping and the bypass vessels after aneurysm bypass surgery.

Keywords: Aneurysm; Bypass; Clipping; FLOW 800; ICG-VA.

Fig. 1

A left internal carotid artery (ICA) C4 segment unruptured giant aneurysm (25 × 20 mm, blue arrow) with carotid-cavernous fistula (CCF, green arrow) was diagnosed by computed tomography (a), computed tomography angiography (b), digital subtraction angiography (c), and 3-dimensional rotational angiography (d). During surgery, the aneurysm was exposed (e). Then, conventional indocyanine green video angiography (ICG-VA) showed aneurysm (f, blue arrow), parent artery, and peripheral blood vessels. FLOW 800 provided a color-coded map that displayed the brain vessels in contrasting colors depending on the fluorescence appearance after ICG injection (arteries: red, cortical capillaries: yellow/green, veins: blue) (g). After high flow extracranial-to-intracranial (EC-IC) bypass (middle cerebral artery M3 segment-radial artery-ICA), we isolated aneurysm at ICA initial part and ICA before posterior communicating artery (PComA) branching (h). Another ICG-VA (I) and FLOW 800 analysis (j) showed the aneurysm disappeared (blue arrow) and the bypass vessel was fluent (green arrow)

Fig. 2

A left posterior communicating artery (PComA) aneurysm (4 × 3 mm, blue arrow) was diagnosed by computed tomography angiography (a), digital subtraction angiography (DSA) (b). DSA also indicated that the artery (blue arrow) was fetal-type posterior cerebral artery (c). During surgery, the lateral (d) and body (e) of aneurysm was exposed. The aneurysm neck was clipped with a cross-window aneurysm clip (f) and PComA (blue arrow) was visible (g). Conventional ICG-VA (h) and FLOW 800 analysis (i) showed clipping was satisfactory and the parent artery was unobstructed (blue arrow)

Fig. 3

A Right middle cerebral artery (MCA) M2 bifurcation unruptured large aneurysm (20 × 18 mm, blue arrow) with two M3 branches starting from the aneurysm was diagnosed by computed tomography (a, b) and computed tomography angiography (c, d). During surgery, we exposed the aneurysm and performed electrocoagulation to shrink it (e). Then, conventional indocyanine green video angiography (ICG-VA) showed aneurysm (f, blue arrow), parent artery including M2 (red arrow) and two M3 (green arrows). FLOW 800 provided a color-coded map that displayed the brain vessels in contrasting colors depending on the fluorescence appearance after ICG injection (arteries: red, cortical capillaries: yellow/green, veins: blue) (g). After low flow extracranial-to-intracranial (EC-IC) bypass (superficial temporal artery-M3), we isolated and resected the aneurysm (h, i, blue arrow). Another ICG-VA (j) and FLOW 800 analysis (k) showed the aneurysm disappeared and the bypass vessel was unobstructed (blue arrow)