Third Ventricle Width is a Reliable and Clinically-Feasible Marker of Brain Atrophy in the Multiple Sclerosis Clinical Care Setting (P10-3.003)

Abstract

<h3>Objective:</h3> Examine reliability and clinical utility of third ventricle width (TVW) on standard-of-care MRIs as a marker of cerebral atrophy in real-world multiple sclerosis (MS) clinical care settings. <h3>Background:</h3> Cerebral atrophy is emerging as an important marker of MS disease progression, but clinically-feasible volumetric measurements remain elusive in clinical care settings. Research supports TVW as a reliable, valid, fast, and easy manual two-dimensional MRI estimate of cerebral atrophy that correlates with clinical disability and tracks with volumetric changes. Importantly, most TVW research has utilized standardized research MRIs; it is unclear how findings translate to standard-of-care (SoC) MRIs (i.e., variable field strengths and sequence parameters). We evaluated real-world clinical utility by examining reliability and clinical relevance of TVW measured from SoC (i.e., clinical) MRIs. <h3>Design/Methods:</h3> We measured TVW from SoC brain MRIs in 563 consecutive patients aged 18–65 years. Three trained raters blind to other patient data measured TVW in millimeters from midpoints of left and right boundaries of the third ventricle in axial T1-weighted images. TVWs were adjusted for demographic characteristics. Disability was assessed with the gold-standard MS Functional Composite (MSFC) evaluating cognition (SDMT), upper extremity coordination (NHPT), and gait (T25FW). GLM assessed TVW differences across level of level of impairment (number of MSFC components &lt;5^th percentile). <h3>Results:</h3> Interrater reliability of TVW measurement indicated excellent absolute-agreement (two-way mixed effects ICCs: single-rating 0.982; 95%CI: 0.958, 0.994; mean-rating <i>k</i>=3, 0.994; 0.986, 0.998). Medium-to-large difference in TVW across MSFC impairment (<i>p</i> for trend &lt;0.001; η_p²=0.089): TVW (mean [95%CI]) increased across patients impaired on no (n=245; 3.34 [3.14, 3.54]), one (n=155; 3.74 [3.45, 3.99]), two (n=106; 4.30 [4.00, 4.60]), and three (n=57; 4.81 [4.40, 5.22]) MSFC tasks. <h3>Conclusions:</h3> Measurement of TVW from standard-of-care MRIs is a highly-reliable and clinically-relevant marker of brain atrophy in MS that can be easily implemented into routine clinical care. <b>Disclosure:</b> Dr. Levy has nothing to disclose. Dr. Patel has nothing to disclose. Mr. Sumowski has nothing to disclose.