Role of DWI and MRS in diagnosis of Alzheimer’s and pre-Alzheimer’s disease

Alzheimer’s disease (AD) is a major cause of dementia in elderly affecting about 30% above the age of 85 years, while mild cognitive impairment (MCI) is the impairment in cognitive functions with intact daily life activities which is described as the preclinical phase of AD. To evaluate the role of DWI and MRS in prediction of pre-Alzheimer’s patients and differentiating them from those with AD. This study included 37 patients (24 males and 13 females) with age ranged from 50 to 73years (mean age=61.6years). They were divided into two main groups, the first group pre-Alzheimer’s (MCI) included 24 patients, and the second group (AD) included 13 patients. All patients underwent DWI and MRS using 1.5 T system. In our study, males were more commonly affected by the two diseases, the mean age was 61.6 years and memory dysfunction followed by depression was the most common clinical symptom. Regarding DWI study, there were statistically higher ADC values in AD (0.97 and 0.94) than in MCI (0.90 and 0.79) in the hippocampal and temporal regions respectively. The NAA/Cr ratio was significantly higher in MCI (1.74 and 1.58) than in AD (1.41 and 1.05) in the hippocampal, temporal regions respectively. Regarding mI/Cr ratio, it was significantly higher in AD (1.51 and 1.47) than in MCI (1.10 and 1.11). The Cho/Cr ratio also was significantly higher in AD (1.27 and 1.38) than in MCI (1.02 and 0.99) in the same regions respectively. From the ROC curve analysis the NAA/Cr ratio was the most sensitive and specific in both regions. Mild cognitive impairment is a term used to describe the pre-Alzheimer’s stage. Later, most of MCI patients develop Alzheimer’s dementia. The combination of DWI and MRS is promising tool for the detection of early structural changes occurring in MCI patients before the full manifestation of dementia syndrome starts to appear. DWI and MRS help in early prediction, follow-up, and treatment of patients with pre-Alzheimer’s disease.