Cinematic Rendering of Twig‐Like Middle Cerebral Artery

A 48-year-old woman presented with intermittent headaches for 3 years. Cerebral computed tomography angiography showed irregular vessels resembling a moyamoya pattern involving the left middle cerebral artery (MCA), and found an aneurysm in the ophthalmic segment of the right internal carotid artery (Fig 1A). Digital subtraction angiography showed the absence of the normal left M1 segment, replaced by a serpentine vascular tangle that connects the carotid termination to the normal distal M1 segment, consistent with twig-like MCA (T-MCA; Fig 1B). This structure differs from the moyamoya pattern, and may be related to the persistence of the fetal arterial network that ultimately developed into the main trunk of the MCA. Cinematic rendering of computed tomography angiography provides a clear depiction of T-MCA anatomy, facilitating communication between the doctor and the patient, and adding value to existing medical images in preoperative planning (Fig 1C, Video S1). In general, aneurysms associated with T-MCA should be prioritized for targeted therapy, especially ruptured aneurysms. In T-MCA with recurrent stroke, bypass intervention may be a last resort. T-MCA can be found incidentally, or it can present with hemorrhagic or ischemic stroke, but most patients with T-MCA in previous studies have had hemorrhagic stroke. Hemorrhagic stroke in T-MCA may be related to rupture of aneurysms, the twig-like network, or other abnormal collateral vessels. Ischemic stroke in T-MCA may be mainly caused by hemodynamic compromise, artery-to-artery embolism, or a combination of both. Although aneurysm formation, hemorrhage, and ischemia are known clinical consequences, many cases of T-MCAs may remain clinically and radiologically stable for at least several years.1 Therefore, given the absence of hemorrhagic or severe ischemic complications, the patient in the present study was treated conservatively and underwent regular imaging monitoring. T-MCA is a rare vascular anomaly characterized by a plexiform network of small vessels replacing the M1 segment of the MCA.1 The incidence of T-MCA has been widely assessed in Asian populations, ranging from 0.11% to 1.17% in angiographic studies.2 However, due to the similarity of the imaging manifestations of T-MCA and moyamoya disease, up to 69% of patients with T-MCA are initially diagnosed with moyamoya disease.3 Moyamoya is a progressive, predominantly bilateral steno-occlusive disorder that typically involves the internal carotid artery termini with involvement of the proximal anterior cerebral artery and MCA. However, T-MCA does not involve the distal internal carotid artery. Although typical moyamoya disease is angiographically bilateral and symmetric, T-MCA is a unilateral anomaly. Additionally, in T-MCAs, there are no transdural collateral vessels, as are seen in most cases of moyamoya disease. In moyamoya disease, distal MCA vessels have the appearance of a “puff of smoke.” However, in T-MCA, the caliber of the distal MCA and flow are maintained. This is the most important difference from moyamoya disease.4 Cinematic rendering techniques have significantly improved the ability to generate photorealistic 3D images from computed tomography data, providing a remarkable level of realism that better shows the imaging characteristics of T-MCA, thereby reducing misdiagnosis rates, and avoiding unnecessary evaluation and treatment. Both authors contributed to the conception and design of the study; the acquisition and analysis of data; and drafting the text and preparing the figure. We thank Siemens Healthineers engineer, Dr X. Zhao, for his support in rendering film technology. Nothing to report. Video S1. Cinematic rendering from CT angiography in a 48-year-old woman with a twig-like left middle cerebral artery. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.