Imaging of Pulsatile Tinnitus.

Tinnitus is a common complaint that approximately three-fourths of adults will experience at some point in their life. While for many it is a mild nuisance, for some it can be debilitating, affecting cognition and quality of life, increasing stress, and leading to anxiety, depression, and in severe circumstances even suicide. Pulsatile tinnitus refers to the perception of a heartbeat-like sound without external stimulus. Although less common than nonpulsatile tinnitus, pulsatile tinnitus raises concern for underlying disease that can have a high risk of causing the patient harm if undiagnosed, and most of these patients will have positive findings at imaging. While these findings are often subtle, identifying them can have a meaningful impact on the patient's quality of life. The literature on pulsatile tinnitus is changing rapidly with improved imaging techniques and novel minimally invasive treatment options. A careful history and physical examination together with appropriate imaging are therefore critical in identifying the underlying cause. With emerging surgical, endovascular, and supportive technologies, the vast majority of patients with bothersome pulsatile tinnitus can be cured or have their symptoms ameliorated. The objective of this narrative review is to present a comprehensive analysis of the currently available literature on pulsatile tinnitus, with a focus on understanding its pathophysiologic mechanisms, diagnostic pathways, imaging findings, and the spectrum of available management strategies and ultimately to propose a structured framework that aids radiologists as well as clinicians in identifying an underlying diagnosis and guiding management of these patients. ©RSNA, 2024 Supplemental material is available for this article.

Imaging biomarkers of vascular and axonal injury are spatially distinct in chronic traumatic brain injury.

Traumatic Brain Injury (TBI) is associated with both diffuse axonal injury (DAI) and diffuse vascular injury (DVI), which result from inertial shearing forces. These terms are often used interchangeably, but the spatial relationships between DAI and DVI have not been carefully studied. Multimodal magnetic resonance imaging (MRI) can help distinguish these injury mechanisms: diffusion tensor imaging (DTI) provides information about axonal integrity, while arterial spin labeling (ASL) can be used to measure cerebral blood flow (CBF), and the reactivity of the Blood Oxygen Level Dependent (BOLD) signal to a hypercapnia challenge reflects cerebrovascular reactivity (CVR). Subjects with chronic TBI (n = 27) and healthy controls (n = 14) were studied with multimodal MRI. Mean values of mean diffusivity (MD), fractional anisotropy (FA), CBF, and CVR were extracted for pre-determined regions of interest (ROIs). Normalized z-score maps were generated from the pool of healthy controls. Abnormal ROIs in one modality were not predictive of abnormalities in another. Approximately 9-10% of abnormal voxels for CVR and CBF also showed an abnormal voxel value for MD, while only 1% of abnormal CVR and CBF voxels show a concomitant abnormal FA value. These data indicate that DAI and DVI represent two distinct TBI endophenotypes that are spatially independent.