Four dimensional-flow magnetic resonance imaging analysis of carotid-cavernous fistula, dural arteriovenous fistula and spinal arteriovenous fistula: Detecting shunt point and diagnosing based on flow dynamics analysis

Background and purposeCarotid-cavernous fistulas (CCF), dural arteriovenous fistula (DAVF) and spinal arteriovenous fistula (SAVF) are rare vascular malformations that cause arteriovenous shunting. Detecting the shunt point and flow direction is necessary for shunt disease diagnosis and treatment. Hence, we propose a new shunt disease diagnostic way with four dimensional-flow magnetic resonance imaging (4D-flow MRI). Material and methodsThe 4D-flow MRI and the DSA (digital subtraction angiography) were performed on 23 patients, including 2 with CCF, 20 with intracranial DAVF, and 1 with SAVF. Catheter embolization was performed in 19 patients. The 4D-flow MRI assessment was conducted for pre- and post-treatment (n = 9), pretreatment only (n = 12) and post-treatment only (n = 2). We use two functions of 4D-flow imaging application, one is a two-dimensional (2D)-colormap, which indicates velocity distribution with color scale for detecting shunt point, and another one is a 2D-flow vector for diagnosing flow direction. ResultsShunt points are detected as red-colored lesions, with higher velocity compared with the surrounded area on 2D-colormap, with corresponding results to DSA findings. A 2D-flow vector indicates flow vectors of the main feeder, drainer, and influenced dural venous sinuses that could complement information obtained from other standard examinations. The post-therapeutic residual shunt flow analysis was consistent with DSA results except for one DAVF case. Conclusion2D-colormap helps detect the shunt point of vascular malformations. A 2D-flow vector makes it possible to diagnose CCF, DAVF and SAVF based on flow dynamic analysis. A 4D-flow MRI would be an additional measurement for shunt disease diagnoses.