A NEW AGE-BASED CUTOFF OF VISUAL RATING SCALES IN MRI: IMPROVING THE DIAGNOSTIC ACCURACY OF AD IN A CHINESE POPULATION

The omission diagnostic rate of the previous age-based medial temporal atrophy (MTA) cutoff score on magnetic resonance imaging (MRI) was relative high for detecting Alzheimer's disease (AD) in Chinese population. This study aimed to evaluate the diagnostic value of a new age-based cutoffs of visual rating scales (including medial temporal atrophy (MTA), posterior atrophy rating scale (PA), global cortical atrophy scale (GCA), and medial temporal-lobe atrophy index (MTAi) for discriminating AD patients in a Chinese population. This cross-sectional study collected data from a multicenter online case registration system from January 2013 to August 2017, the Chinese Alzheimer's disease Study and Evaluation project (CHASE). Total 585 subjects were diagnosed as normal cognition (NC)(n=87), amnestic mild cognitive impairment (aMCI)(n=141), and AD(n=68). Mean MTA, GCA, PA scores was determined by the visual rating scales, and MTAi was also calculated on magnetic resonance imaging (MRI). Receiver operating characteristic (ROC) curve analyses were used to determine diagnostic value of those scales. Correlations between scores of each visual rating scale and age, education and neuropsychological tests were evaluated. Scores of MTA, GCA and PA were correlated to age, the area under curve was 0.92 for MTA, 0.74 for GCA,0.46 for PA and 0.42 for MTAi, respectively(Figure 1), when used to detected AD from NC. A MTA cutoff score of 1.5 yielded an optimal sensitivity and specificity of 84.5% and 83.3% respectively for discriminating AD and NC, with a 15.5% of omission diagnostic rate. The discrimination between NC and AD stratified by age was also calculated, optimal MTA cut-off values for the age ranges 50-64, 65–74, 75-84 were≥1.0, ≥1.5, ≥ 2.0, the sensitivity and specificity were 92.3% and 68.4%; 90.4% and 85.2%, 70.8% and 82.3%, respectively(Table 1).