Evaluation of model-based blood flow quantification from rotational angiography

For assessment of cerebrovascular diseases, it is beneficial to obtain three-dimensional (3D) information on vessel morphology and hemodynamics. Rotational angiography is routinely used to determine 3D geometry, and we recently outlined a method to estimate the blood flow waveform and mean volumetric flow rate from images acquired using rotational angiography. Our method uses a model of contrast agent dispersion to estimate the flow parameters from the spatial and temporal progression of the contrast agent concentration, represented by a flow map. Artifacts due to the rotation of the c-arm are overcome by using a reliability map. An attenuation calibration can be used to support our method, but it might not be available in clinical practice. In this paper, we analyze the influence of the attenuation calibration on our method. Furthermore, we concentrate on the validation of the proposed algorithm, with particular emphasis on the influence of parameters such as the length of the analyzed vessel segment, the frame rate of the acquisition, and the duration of the injection on accuracy. For the validation, rotational angiographic image sequences from a computer simulation and from a phantom experiment were used. With a mean error of about 10% for the mean volumetric flow rate and about 13% for the blood flow waveform from the phantom experiments, we conclude that the method has the potential to give quantitative estimates of blood flow parameters during cerebrovascular interventions which are accurate enough to be clinically useful.