Measurement in the angiography suite: evaluation of vessel sizing techniques.

ABSTRACT

BACKGROUND: Accurate vessel size measurement is important for neurointervention. Modern angiographic equipment offers various two-dimensional (2D) and 3D measurement methods that have not been systematically evaluated for accuracy and reliability. OBJECTIVE: To evaluate these methods using anthropomorphic vessel phantoms. MATERIALS AND METHODS: Tubing of known sizes (2-5 mm, 1 mm increments) was embedded in 3D-printed skulls to simulate the middle cerebral artery, internal carotid artery, and basilar artery. Each phantom was imaged to gain 3D DSA, 2D DSA, and DynaCT images. Three identical measurement locations were identified on each simulated vessel. Eight measurement methods (four 2D, three 3D, and one DynaCT) were evaluated. Measurements were performed by three independent experienced users on three separate occasions. Intraclass correlation and independent non-parametric analysis were carried out to evaluate the reliability and accuracy of these measurement methods. RESULTS: Better reliability was noted for the automatic measurement methods than for the corresponding manual measurement methods. The mean differences with the ground truth for all methods ranged from -0.12 to 0.03 with small SEs (0.02-0.03) and SDs (0.10-0.18). The smallest absolute mean differences were achieved in two automatic measurement methods based on 2D manual calibration and 3D images. In comparison with these two methods, results of measurements based on 2D autocalibration were statistically different. CONCLUSIONS: In our study, automatic analysis using 3D or 2D was the preferred measurement method. Manual calibration on 2D angiograms is necessary to improve the measurement accuracy. It is not known how our results may pertain to other angiographic systems.