Simplified volume embolization ratio calculation method in endovascular coiling for unruptured cerebral aneurysms

ObjectiveVolume embolization ratio (VER) is an important factor involved in recurrence rates in endovascular coiling for cerebral aneurysms. However, there is no method to clearly understand it during surgery. We report our simplified aneurysm VER calculation method and discuss the outcomes.MethodsWe performed treatment by calculating the aneurysm volume and coil length using the formula D(length of coil inserted to achieve 100% packing in cm) = 2 V(aneurysm volume in mm³). The volume and VER calculated by our simplified method were denoted as simplified volume (sV) and simplified VER (sVER). The volume and VER were also calculated by the application Angiosuite Neuro Edition, which were denoted as aV and aVER. The volume of the coil calculated by Angiosuite Neuro Edition divided by sV was called simplified Angiosuite VER (saVER). Comparisons were made between the averages of sVER and aVER, and sVER and saVER. Postoperative follow-up was performed by magnetic resonance angiography (MRA) or DSA 3 or 6, and 12 months, and Raymond Roy occlusion classification (RROC) was evaluated.ResultsT-test results were not significantly different between sVER and aVER (P = 0.06) or sVER and saVER (P = 0.9), the difference in VER due to the calculation method was within the margin of error. Eight of the 18 patients had improved RROC at 12 months, and there were no cases of worsening of the score.ConclusionWe presented simplified VER calculation method which can be performed in real time and clinically acceptable approximation without the need for a smartphone app.