Quantitative analysis tool for clinical functional MRI in mild traumatic brain injury

Functional magnetic resonance imaging (fMRI) has been available commercially for clinical diagnostic use for many years. However, both clinical interpretation of fMRI by a neuroradiologist and quantitative analysis of fMRI data can require significant personnel resources that exceed reimbursement. In this report, a fully automated computer-based quantification methodology (Enumerated Auditory Response, EAR) has been developed to provide an auditory fMRI assessment of patients who have suffered a mild traumatic brain injury. Fifty-five study participants with interpretable auditory fMRI sequence data were assessed by EAR analysis, as well as both clinical radiologist fMRI interpretation and voxelwise general linear model (GLM) analysis. Comparison between the clinical interpretation and the two computer analysis methods resulted in 67% concordance (identical), 32% nearconcordance (one level difference), and 1% discordant. Comparison between the clinical computer-based quantification (EAR) and GLM analysis yielded significant correlations in right and left ear responses (p⟨0.05) for the full subject group. Automated fMRI quantification analysis equivalent to EAR might be appropriate for both future research projects with constrained resources, as well as possible routine clinical use.

Central auditory processing disorders after mild traumatic brain injury

Auditory processing disorders are common following mild traumatic brain injury (mTBI), but the neurocircuitry involved is not well understood. The present study used functional MRI to examine auditory cortex activation patterns during a passive listening task in a normative population and mTBI patients with and without clinical central auditory processing deficits (APD) as defined by the SCAN-3:A clinical battery. Patients with mTBI had overall patterns of lower auditory cortex activation during the listening tasks as compared to normative controls. A significant lateralization pattern (pairwise t-test; p⟨0.05) was observed in normative controls and in those with mTBI and APD during single-side stimulation. Additionally, baseline connectivity between left and right auditory cortices was lower in mTBI patients than in controls (p=0.01) and significantly reduced in the mTBI with APD group (p=0.008). Correlation was also observed between bilateral task-related activation and competing words subscore of the SCAN-3:A. These findings suggest the passive listening task is well suited to probe auditory function in military personnel with an mTBI diagnosis. Further, the study supports the use of multiple approaches for detecting and assessing central auditory deficits to improve monitoring of short- and long-term outcomes.