Early Diagnosis of Alzheimer's Disease from MRI Images Using PNN

Here we propose a new method for the diagnosis of Alzheimer's disease from MRI images. The most prevalent, reliable and result-oriented methods for diagnosis of Alzheimer's disease are: Firstly, measuring the rate of atrophy of the hippocampus and total brain volume; Secondly, extracting information from the gray matter, white matter and cerebro spinal fluid (CSF) of the brain. In this work, different statistical features such as contrast, homogeneity, correlation, energy and also shape features are extracted from the MRI images. For every image a number of features are extracted and these are fed to the classifier. The images are classified into any of the three classes: Alzheimer's Disease (AD), Mild Cognitive Impairment (MCI) or Normal Control (NC). The proposed approach compares the performances of Probabilistic Neural Network (PNN), Support Vector Machines(SVM) and K-Nearest Neighbour (KNN) in terms of their accuracy, specificity and sensitivity. The MRI images are obtained from the ADNI database. ADNI is a clinically validated database of MRI, PET and FMRI images of subjects.

I. Introduction

Alzheimer's disease(AD) is a progressive brain disorder that gradually destroys memory, thinking abilities. It is an irreversible process which even destroys the intellectual abilities in later stages. The disease is first pointed out by Neyropathologist Alois Alzheimer in 1906 and is named after him[1]. Alzheimer's disease is the most well-known reason for dementia among individuals over the age of 65 years and it can't be considered as a typical sign of aging. It is a progressive neurological illness, which means that the condition deteriorates over time. Nerve cells in the brain also stops working, and brain signals that are vital for life fail to function properly. The disease often takes a specific pattern of brain damage as it progresses. One of the most affected areas is the hippocampus, which is thought to be the focal point of emotion and memory. Hippocampus plays a very important role in finding one's way around the environment and the events occuring there. The rate of shrinkage of the hippocampus takes place at an abnormal pace in an AD patient.