Incremental contribution of size ratio as a discriminant for rupture status in cerebral aneurysms: comparison with size, height, and vessel diameter.

ABSTRACT

BACKGROUND: Aneurysm size ratio (SR), variably defined as the ratio of dome height (H) or maximal dimension (D(max)) over average parent vessel diameter (PV) diameter, has been proposed as a promising aneurysm rupture status predictor. OBJECTIVE: To evaluate the incremental contribution of SR to retrospective rupture status determination in a large high-resolution aneurysm database. METHODS: Measurements were performed on catheter 3D-rotational angiographic volumetric datasets for 267 aneurysms (98 ruptured). SR was computed both as H/PV (SR1) and as D(max)/PV (SR2), and its discriminant performance was evaluated on the whole dataset, on aneurysm-type subsets (bifurcation [BIF] vs sidewall [SW]), and at specific aneurysm locations. Univariate and multivariate statistical analyses were performed by the use of area under the curve (AUC) of the receiver-operating characteristics. RESULTS: Neither SR1 nor SR2 were statistically correlated to rupture status in the BIF group, where only PV (AUC = 0.61) achieved significance. All parameters were statistically significant in the combined group, but with modest performance (AUC range, 0.62-0.74). SR1 (AUC = 0.84) and SR2 (AUC = 0.78) were strong predictors in the SW group, similar to H (AUC = 0.83) and D(max) (AUC = 0.77). Multivariate statistics failed to support SR as an incremental independent parameter from PV, D(max), and H. CONCLUSION: SR provides an uneven performance that depends strongly on the BIF/SW distribution of the data and is not useful for bifurcation lesions. In the SW subset, the incremental contribution of the SR over its H or D(max) individual component measurements could not be validated, suggesting prior findings of its utility to be the result of aneurysm-type selection bias.