Elzbieta Trypka

Multimodal imaging in diagnosis of Alzheimer's disease and amnestic mild cognitive impairment: value of magnetic resonance spectroscopy, perfusion, and diffusion tensor imaging of the posterior cingulate region.

The purpose of this study was to assess metabolic, perfusion, and microstructural changes within the posterior cingulate area in patients with Alzheimers disease (AD) and amnestic mild cognitive impairment (aMCI) using advanced MR techniques such as: spectroscopy (MRS), perfusion weighted imaging (PWI), and diffusion tensor imaging (DTI). Thirty patients with AD (mean age 71.5 y, MMSE 18), 23 with aMCI (mean age 66 y, MMSE 27.4), and 15 age-matched normal controls (mean age 69 y, MMSE 29.5) underwent conventional MRI followed by MRS, PWI, and DTI on 1.5 Tesla MR unit. Several metabolite ratios (N-acetylaspartate [NAA]/creatine [Cr], choline [Ch]/Cr, myoinositol [mI]/Cr, mI/NAA, mI/Cho) as well as parameters of cerebral blood volume relative to cerebellum and fractional anisotropy were obtained in the posterior cingulate region. The above parameters were correlated with the results of neuropsychological tests. AD patients showed significant abnormalities in all evaluated parameters while subjects with aMCI showed only perfusion and diffusion changes in the posterior cingulate area. Only PWI and DTI measurements revealed significant differences among the three evaluated subject groups. DTI, PWI, and MRS results showed significant correlations with neuropsychological tests. DTI changes correlated with both PWI and MRS abnormalities. Of neuroimaging methods, DTI revealed the highest accuracy in diagnosis of AD and aMCI (0.95, 0.79) followed by PWI (0.87, 0.67) and MRS (0.82, 0.47), respectively. In conclusion, AD is a complex pathology regarding both grey and white matter. DTI seems to be the most useful imaging modality to distinguish between AD, aMCI, and control group, followed by PWI and MRS.

Does perfusion CT enable differentiating Alzheimer's disease from vascular dementia and mixed dementia? A preliminary report

UNLABELLED The purpose of the study was to evaluate the usefulness of perfusion CT (pCT) in differentiating Alzheimers disease (AD) from vascular dementia (VaD) and mixed dementia (MixD). pCT was performed in 41 patients (mean age, 68.3 years): 24 with AD, 8 with VaD, and 9 with MixD. Regional perfusion parameters (rCBF, rCBV, and rMTT) were calculated from 31 ROIs in the grey and white matter of the frontal and temporal lobes, basal ganglia, and internal capsules bilaterally. The obtained data for the subgroups of AD, VaD, and MixD patients were compared statistically. CONCLUSIONS On the basis of rCBF and rCBV values, pCT may be a valuable method of distinguishing between AD and VaD but it seems to be of little significance in differentiating MixD from VaD and of no usefulness in distinguishing between AD and MixD.

Evaluation of the Posterior Cingulate Region with FDG-PET and Advanced MR Techniques in Patients with Amnestic Mild Cognitive Impairment: Comparison of the Methods

BACKGROUND The posterior cingulate region is an area of the earliest pathological changes in amnestic mild cognitive impairment (aMCI). The utility of FDG-PET imaging in dementia is already well established. OBJECTIVES The aim of the study was to compare FDG-PET with advanced MR measurements: MR spectroscopy (MRS), perfusion weighted imaging (PWI), and diffusion tensor imaging (DTI) within the posterior cingulate region in patients with aMCI. METHODS Fifty-five patients diagnosed with aMCI (66.5 y) and 20 age-matched controls (69 y) underwent MR examination including MRS, PWI, and DTI followed by FDG-PET scanning. Values of MRS metabolite ratios (NAA/Cr, Cho/Cr, mI/Cr), PWI cerebral blood volume (rCBV), and DTI fractional anisotropy (FA) were compared to the FDG-PET rates of glucose metabolism. RESULTS Compared to controls, aMCI patients showed significant (p < 0.05) glucose hypometabolism, and lower rCBV and FA values. FDG-PET results correlated significantly with rCBV values. Compared to FDG-PET, PWI showed similar and DTI greater accuracy in distinguishing aMCI from controls. According to FDG-PET findings, two groups of aMCI patients were established: those with lower (PET-positive) and normal (PET-negative) glucose uptake. PET-positive aMCI subjects showed normal MRS findings, lower rCBV and FA values, while PET-negative patients revealed normal MRS and PWI results but significantly lower FA values. CONCLUSIONS Advanced MR techniques such as PWI and particularly DTI may be regarded as competitive techniques to FDG-PET. DTI was the only method to show alterations in aMCI patients with normal FDG-PET, PWI, and MRS findings. DTI seems to be a very sensitive biomarker of early degeneration in aMCI.

Quantitative Evaluation of Changes in the Selected White Matter Tracts Using Diffusion Tensor Imaging in Patients with Alzheimer's Disease and Mild Cognitive Impairment

This study evaluated the damage to the extensive range of white matter tracts in patients with Alzheimers disease (AD) and mild cognitive impairment (MCI). Thirty-four patients with AD (mean age 71.5 yrs, MMSE 17.6), 23 patients with MCI (mean age 66 yrs, MMSE 27.4) and 15 normal controls (mean age 69 yrs, MMSE 29.8) were enrolled. Diffusion tensor imaging (DTI) was performed in 25 directions on 1.5 T MR scanner. Fractional anisotropy (FA) values were obtained with a small ROI method in several association tracts including posterior cingulum fibers, in commissural tracts (genu and splenium of corpus callosum) and projection tracts (middle cerebellar peduncles and posterior limbs of internal capsules). In MCI significant reductions of FA were found in the inferior longitudinal fascicles, left superior longitudinal fascicle and posterior cingulum fibers compared to normal controls. In AD significantly decreased FA values were detected in the same fascicles as in MCI and additionally in inferior fronto-occipital tracts and commissural tracts. In both AD and MCI the most severe changes were found within posterior cingulum fibers. No abnormalities were detected in projection tracts in both groups. Accuracy of DTI in detecting AD and MCI reached 0.95 and 0.79, respectively. FA measurements strongly correlated with neuropsychological tests. DTI is capable of depicting microstructural changes within white matter fiber tracts in dementia and may aid the differential diagnosis of AD and MCI.

The Value of Cognitive Screening Tests in Patients with Amnestic and Non-amnestic MCI.

Introduction Although the original diagnostic criteria for mild cognitive impairment (MCI) highlighted the importance of memory impairment, more recently the MCI classification was expanded to encompass other cognitive domains, allowing the diagnosis of amnestic or non-amnestic MCI. Objective The primary aim of this study was to identify cognitive tests and illustrate a neuropsychological profile of cognitive subtests of persons with amnestic MCI (aMCI) and non-amnestic MCI (naMCI). Material and Methods: The study used a cross-sectional design. The study group consisted of 35 aMCI and 16 naMCI subjects matched for age, sex and years of education. The groups did not differ according to CDR. All subjects underwent a wide range of psychological tests including MMSE, TYM, DemTect, FAS, CDT, IADL and GDS. The following tests were completed to measure episodic memory, working memory, executive functions, perception and language. The analysis of variance (ANOVA) was used to analyze the differences between group means. Results The statistical analysis illustrated that total scores of MMSE, TYM, DemTect and FAS to differentiate the aMCI from naMCI subjects. Compared to naMCI, aMCI subjects scored lower in MMSE (p=0.0104) and in DemTect (p=0.0002) while they had higher scores in TYM (p=0.0067) and FAS (p=0.0427). Conclusions This study shows that cognitive screening tests provide valuable information regarding the differential diagnosis of aMCI versus naMCI. MMSE and DemTect may be seen as superior screening tests in aMCI, while TYM and FAS in naMCI subjects.

Searching for Correlations Between Results of Psychological Tests and FDG-PET as Well as Spectroscopic Metabolites From Posterior Cingulate Gyrus in Patients with MCI.

Background The aim of the study was to search for correlations between the results of psychological tests and FDG-PET as well as spectroscopic metabolites from the posterior cingulate gyrus (PCG) in patients with amnestic (aMCI) and non-amnestic MCI (naMCI). Material and Methods The study group consisted of 35 aMCI, 16 naMCI and 20 control subjects matched for age, sex and years of education. All subjects underwent a wide range of psychological tests including MMSE, CDR, TYM, DEMTEC, CDR, FAS, IADL and GDS as well neuroimaging brain studies including FDG-PET with the evaluation of glucose metabolism and magnetic resonance spectroscopy (MRS) with the evaluation of several metabolites such as NAA (neuronal marker), choline (marker of myelin turnover) and myoinositol (marker of gliosis). The results of FDG-PET and the levels of MRS metabolites obtained from PCG were compared between the subject groups and then correlated with the scores of psychological tests using Pearson’s coefficient. Results Compared to CG, both aMCI and naMCI subjects showed significantly lower levels of glucose metabolism and NAA within PCG. In the aMCI subgroup the results of FDG-PET studies revealed significant negative correlations with the scores of TYM (p=0.17, r= -0.48) while in the naMCI subgroup lower levels of NAA correlated with lower scores in DEMTEC. Conclusions In both aMCI and naMCI metabolic changes within PCG such as glucose hipometabolism and decreased neuronal activity correlate with the results of single psychological test.