Medial temporal lobe atrophy on MRI predicts dementia in patients with mild cognitive impairment.

Background: Although detailed volumetric MRI assessment of medial temporal lobe atrophy (MTA) can predict dementia in patients with mild cognitive impairment (MCI), it is not easily applied to routine clinical practice.

Objective: To test the predictive accuracy of visually assessed MTA in MCI patients using a standardized visual rating scale.

Methods: Seventy-five MCI patients (mean age 63 years) underwent a coronal three-dimensional magnetization-prepared rapid gradient echo brain MRI sequence. MTA was rated visually using a 5-point rating scale.

Results: The mean follow-up period for the cohort was 34 months. At follow-up, 49% of the enrolled MCI patients fulfilled criteria for dementia. MTA assessed using a standardized visual rating scale was significantly associated with dementia at follow-up, with a hazard ratio of 1.5 for every point increase in atrophy score (p < 0.001) and of 3.1 for the presence of atrophy based on the dichotomized atrophy score (p = 0.003). The predictive accuracy of visually assessed MTA was independent of age, gender, education, Mini-Mental State Examination score, Clinical Dementia Rating Sum of Boxes score, Verbal Delayed Recall, and the presence of hypertension, depression, the APOE epsilon4 allele, and white matter hyperintensities.

Conclusions: Visual assessment of MTA on brain MRI using a standardized rating scale is a powerful and independent predictor of conversion to dementia in relatively young MCI patients. As overlap existed in MTA scores between patients with and without dementia at follow-up, the results should be interpreted in the light of the odds for the individual patient.