Comparison of 2D Digital Subtraction Angiography and 3D Rotational Angiography in the Evaluation of Dome-to-Neck Ratio

BACKGROUND AND PURPOSE: Dome-to-neck ratio of intracranial aneurysms is an important predictor of outcomes of endovascular coiling. 3D imaging techniques are increasingly used in evaluating the dome-to-neck ratio of aneurysms for intervention. The purpose of this study was to determine whether 3D rotational angiography (3DRA) can be used to determine accurately the dome-to-neck ratio of intracranial aneurysms when compared with conventional 2D digital subtraction angiography (2D DSA). MATERIALS AND METHODS: A retrospective analysis of 180 patients with 205 intracranial aneurysms who underwent both 2D DSA and 3DRA for evaluation of previously untreated aneurysms was conducted. Dome-to-neck ratios were compared between 2D DSA and 3DRA images. The mean difference in dome-to-neck ratios between 2D DSA and 3DRA was calculated. The proportions of "wide-neck" aneurysms seen on 2D DSA and 3DRA were compared by using 2 different definitions of "wide-neck," including < 1.5 and < 2.0. RESULTS: The average dome-to-neck ratio was 1.81 +/- 0.55 and 1.55 +/- 0.48 for 2D DSA and 3DRA, respectively (P <.0001). When we defined "wide-neck" as a dome-to-neck ratio < 1.5, sixty-nine (33.7%) aneurysms were wide-neck on 2D DSA compared with 119 (58%) on 3DRA (P <.0001) When we defined "wide-neck" as dome-to-neck ratio < 2.0, one hundred forty-two (69.3%) aneurysms were wide-neck on 2D DSA compared with 173 (84.4%) on 3DRA (P=.0004). CONCLUSIONS: In this retrospective study, 3DRA measurements resulted in significantly lower dome-to-neck ratios and significantly larger proportions of aneurysms defined as "wide-neck" compared with 2D DSA. Scrutiny of 2D DSA may offer substantial benefit over 3D techniques when imaging patients to or from endovascular therapy.