The correlation of hippocampal T2-mapping with neuropsychology test in patients with Alzheimer's disease.

OBJECTIVES: 1) To deduce T2, the inverse of the transverse relaxation rate (R2), in the hippocampus of healthy adults; 2) to investigate the brain iron deposition in Alzheimer's disease (AD) patients and age-matched healthy controls using T2-values. METHODS: T2-weighted data from the bilateral-hippocampi of ten AD patients and sixty healthy controls were collected at six echo time points using multi-slice multi-echo turbo spin echo (MSME-TSE) imaging on a 3.0 T MR-scanner, followed by the neuropsychological testing. The correlations between T2-values and Mini-Mental State Examination (MMSE) scores were investigated on group-wise basis (covariates in the group-wise analyses: gender, age, side and healthy/AD). RESULTS: There were no significant differences in hippocampal T2-values on intra-gender and inter-gender basis (P > 0.05). Hippocampal T2-values of both sides were similar (right: 85.2±2.4 milliseconds; left: 85.3±2.5 milliseconds). The bilateral hippocampal T2 values correlated moderately with age (right: r = -0.59; left: -0.58; P < 0.001). The AD-group had significantly lower T2-values in the hippocampus when compared to normal controls (P < 0.001) and such low T2-values had a strong positive correlation with the MMSE score (R (2) = 0.97; P < 0.05). CONCLUSION: Patients with AD showed significantly lower T2 values, which can be attributed to the increased iron depositions in the hippocampus. A positive correlation between T2-values and cognition scores suggests that quantitative T2 can be used in the early diagnosis of AD and in the monitoring of the treatment response

T₂-weighted images at various echo time-points and resultant T₂-map.

<p>Row 1 & Row 2 consist of six T₂-weighted images, taken at echo times of 20, 40, 60, 80, 100, and 120 ms, covering the entire hippocampus of an AD patient and an elderly control. The single image in Row 3 is the corresponding T₂ map. The bilateral hippocampal atrophy was visually found accompanied with a varied degree of decreased T₂ values (or increased R₂ values) in the AD patient. Illustration of the ROI selection on the representative spin-echo images (TE = 60, 80, 100 and 120 milliseconds) of a patient with AD and an elderly control. The hippocampal region for which T₂ data were acquired is shown as representative regions of interest. Note: ROIs required include the hippocampal contours to be as large as possible but not involving its boundaries, and avoiding visible cystic areas and CSF in the hippocampal fissure.</p

Scatter plot of T₂ (or R₂)-values of hippocampus vs. MMSE score.

<p>Scatter plot shows the T₂ (or R₂)-values of the hippocampus and the MMSE score in AD patients were positively (or negatively) correlated with a coefficient of determination of 0.97 (or 0.95) (<i>P</i> < 0.05 for both) controlling for the age related bias.</p

Scatter plots of T₂-values in bilateral hippocampus of normal controls at various ages.

<p>Scatter plots illustrate T₂ values on both sides of hippocampus correlated moderately with age in normal controls. The correlation coefficients are -0.59 and -0.58 for right side (A) and left side (B), respectively at <i>P</i> < 0.001.</p