Early Results in Flow Diverter Sizing by Computational Simulation: Quantification of Size Change and Simulation Error Assessment

NARATA, ANA PAULA; BLASCO, JORDI; ROMAN, LUIS SAN; MACHO, JUAN MIGUEL; FERNANDEZ, HECTOR; MOYANO, RAQUEL KALE; WINZENRIETH, RENAUD; LARRABIDE, IGNACIO

Operative Neurosurgery

Oxfor University Press

Año: 2018

2332-4252

BACKGROUND: Sizing of flow diverters (FDs) stent in the treatment of intracranialaneurysms is a challenging task due to the change of stent length after implantation.OBJECTIVE: To quantify the size change and assess the error in length prediction in 82simulated FD deployments.METHODS: Eighty-two consecutive patients treated with FDs were retrospectivelyanalyzed. Implanted FD length was measured from angiographic images and comparedto the nominal sizes of the implanted device. Length change was obtained by subtractingthe nominal length from the real length and dividing by the nominal length. Implanteddevices were simulated on 3-dimensional models of each patient. Simulation error wasobtained by subtracting real length from simulated length and dividing by the real lengthof the FD. Subanalysis was done using ANOVA. Statistical significance was set to P < .05,and bootstrap resampling was used.RESULTS: When assessing the length change of the FD after implantation, changes of30% in average and up to 80% with reference to the nominal length of the device wereobserved. The simulation results showed a lower error of 3.52% in average with a maximumof 30%. Paired t-test showed nonsignificant differences between measured and real length(P = .07, with the mean of differences at 0.45 mm, 95% confidence interval [−0.950 0.038]).CONCLUSION: Nominal length is not an accurate sizing metric when choosing the size ofan FD irrespective of the brand and manufacturer. Good estimation of the final length ofthe stent after deployment as expressed by an error of 3.5% in average.