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HIPPOCAMPAL ATROPHY: AUTOMATED VOLUMETRY VS VISUAL EXAMINATION–AN ARG ADNI COHORT ANALYSIS

      Background: Hippocampal atrophy is one of the earliest findings in Alzheimer Disease (AD). MRI volumetry is a low-cost in vivo study to quantify brain atrophy Our goal is to analyze MRI brain volumetry in Arg._ADNI cohort in order to determine the clinical usefullness. As a secondary objective a comparation between visual and automated analysis of the hippocampal atrophy was performed.
      Methods: 45 patients of the Argentina-ADNI database were included (12 controls, 12 early mild cognitive impairment (eMCI), 13 late MCI and 8 dementia AD). Neuropsichological assessment, labs, CSF biomarkers, fdg-PET and PiB-PET were performed. All of them had a MRI Brain Volumetry including Absolute Hippocampal volume, whole brain volume and a hippocampal/whole brain ratio (Hi/WBV). Study of correlation between hippocampal visual and automated examination was performed on 49 patients between cognitive neurologist and neuroradiologist.
      Results: Whole brain volume was similar between groups, but hippocampal volume was inversely related to clinical impairment. Specially Hi/WBV ratio. 88% of AD, 46% of LMCI and 42% of eMCI were below a cutoff point of 0.0025. In addition, 92% of control patients had a Hi/WBV superior to 0.0025 value. On the other hand, 68.4% of patients who had Hi/WBV<0.0025 had another positive AD biomarker (FDG-PET, Pib-PET or CSF profile) versus 34,6% of those >0.0025. With a specificity of 0.72, sensitivity 0.61, PPV 0.68 and NPV 0.66. A visual examination of hippocampal atrophy showed low concordance in the control group and a high influence of the years of training.
      Conclusions: A reliable cutoff point to measure hypocampal atrophy could be determined using MRI volumetry, this finding correlates with clinical impairment and the presence of other AD biomarkers. Visual examination of MRI seems to be insufficient to assess hyppocampal atrophy in the early stages of the disease even for a specialist in neuroradiology or cognitive neurology.