Article Figures & Data
Figures
- Fig 1.
Axial (left), coronal (middle), and sagittal (right) slices through a 3D structural MR imaging scan of a subject. The right hippocampus probabilistic VOI is superimposed on the image in native space.
- Fig 2.
Histogram of the voxels with nonzero probabilities on the VOI in Fig 1 (thin line) along with a fitted Gaussian mixture model (thick line) using the expectation-maximization algorithm. The automatically determined CSF threshold is shown as a vertical line approximately located at the intensity value of 70. The HPF is defined as the fraction of voxels in the VOI whose intensities are greater than the CSF threshold.
- Fig 3.
Predicted marginal means of the asymmetry index in different diagnostic groups. AI was found to be significantly different between the CN versus MCI (P < .001), CN versus AD (P < .001), and MCI versus AD (P = .03) groups. AI increased with increasing dementia severity. Error bars indicate 95% CI.
- Fig 4.
Predicted marginal means of the asymmetry index in men and women. The AI was found to be significantly higher in men (P < .01) after controlling for age, intracranial volume, and diagnostic group. Error bars indicate 95% CI.
- Fig 5.
Predicted marginal means of the HPF (averaged across hemispheres) in different diagnostic groups. The HPF was found to be significantly different between the CN versus MCI (P < .001), CN versus AD (P < .001), and MCI versus AD (P < .001) groups. The HPF decreased with increasing dementia severity. Error bars indicate 95% CI.
Tables
Group CN MCI AD CDR 0 0.5 1 (n = 28), 2 (n = 2) No. of subjects 98 70 30 Sex (female:male) 72:26 39:31 20:10 Age (yr) 75.9 ± 9.0 (60–94) 76.2 ± 7.2 (62–92) 78.0 ± 6.9 (65–96) Education (yr) 14.5 ± 2.9 (8–23) 13.8 ± 3.2 (6–20) 12.8 ± 3.2 (7–20) ICV (cm3) 1439 ± 150 (1132–1818) 1485 ± 187 (1171–1992) 1480 ± 118 (1274–1732) MMSE 29.0 ± 1.2 (25–30) 25.6 ± 3.5 (14–30) 21.2 ± 4.0 (15–29) Note:—CDR indicates Clinical Dementia Rating; MMSE, Mini-Mental State Examination.
↵a Values given are means and range.
- Table 2:
Definitions of all mathematic terms used in the mixed-effects model equation (Equation 4)
i Volume index i = 1, 2, ′, 775 j Subject identification index j = 1, 2, ′, 198 yi logit(HPF) or log(AI) for volume i as the response variable IDi Subject index of volume i where IDi ∈ (1, 2, ′, 198) Agei Age of subject IDi minus 76.34, the average age of all 198 subjects ICVi Estimated total intracranial volume of subject IDi minus 1461.5, the average ICV of all 198 subjects DXi Diagnostic group of subject IDi, a factor with 3 levels {CN, MCI, AD} Sexi Sex of subject IDi, a factor with 2 levels {Male, Female} I{statement} Indicator function that takes on values of 1 or 0 depending on whether the statement is true or false β0 ′ β7 Model fixed-effects parameters to be estimated and tested against null hypotheses of type Σakβk = 0 bj Model random effects assumed to be independent and identically distributed Gaussian with mean 0 and variance σb2 ei Random residuals assumed to be independent and identically distributed Gaussian with mean 0 and variance σe2
