Article Figures & Data
Figures
- Fig 1.
A, Representative coronal control (control C2) and AD (patient AD4) images are shown from the sections for region-of-interest analysis. The proton images demonstrate the anatomy of the brain in the corresponding sodium sections and were part of the dataset used for hippocampal volume determination. The sodium images are normalized to the ventricular signal intensity, scaled as shown with the color bar on the right, which is also used for B. The images were normalized to the brightest areas of intensity in the center of the image, seen clearly in these images as the lateral ventricles. The hippocampal volumes from the proton sets were coregistered to the sodium images and used to mask the hippocampuses as described in the methods. B, Shown is the corresponding section from a B1 map calculated from a spherical sodium phantom with contour lines added for each 10th percentile. This indicates excellent homogeneity over the areas of interest. The units are in B1 relative to the maximum in that section scaled to the same color bar. The maximum is found at the edges of the phantom near the struts of the birdcage.
- Fig 2.
For each subject, the proton images underwent 3D co-registration and resectioning to match the sodium position for that subject and sodium voxel size. The top 3 images show from left to right: 1 section of the original proton volume, the corresponding section of the co-registered and resectioned (Morphed) proton volume, and the corresponding section of the sodium volume for that subject. The hippocampal volumes were computed from manual hippocampal masking on a section-by-section basis. The middle left image shows the hippocampal mask for the section of brain shown above. The transformation matrix obtained from the co-registration and resection of the proton volume was applied to the hippocampal mask to yield the mask in the center image for that morphed section. This was performed on a 3D basis, and the bottom line shows that transformation in 3D. The entire hippocampal volume mask is shown as a 3D rendering of the surface from a tilted superior-inferior perspective. The morphed hippocampal volume mask (bottom center) was applied to the sodium volume, and those pixels were averaged to obtain sodium enhancement.
- Fig 3.
Compared is sodium enhancement with diagnosis (r2 = 0.53; P = .006). Sodium enhancement is taken as the average sodium enhancement of the right and left medial temporal lobes relative to ventricle. The vertical error bars represent the 95% confidence interval.
- Fig 4.
Compared is diagnosis with mean hippocampal volume per subject normalized to total intracranial volume (r2 = 0.42; P = .034). The vertical error bars represent the 95% confidence interval.
- Fig 5.
Plotted is unnormalized hippocampal volume against sodium enhancement for each brain hemisphere (20 hemispheres from 10 subjects; overall r2 = 0.50; P < .01). The square data points represent control hemispheres, and the circles represent AD hemispheres. The center solid line indicates the linear overall regression. The dashed lines indicate the linear regressions for the control (left: r2 = 0.24; P < .01) and AD (right: r2 = 0.40; P < .01) data points. Although a moderate correlation is observed for all groups, sodium enhancement still correlates with disease state even when controlling for hippocampal volumes.
Tables
Cohort data summary
Patient S Age Sodium Proton RMTL SD LMTL SD RHV Norm LHV Norm TIV C1 M 75 66.60 9.80 62.25 11.8 3.38 4.06 4.07 4.89 1330 C2 M 76 64.77 10.1 61.04 11.6 3.77 3.59 3.89 3.71 1680 C3 M 74 58.28 8.12 56.17 10.8 4.29 4.24 4.39 4.35 1620 C4 M 81 59.30 6.26 59.52 9.8 4.64 4.19 4.68 4.22 1770 C5 F 66 61.17 4.73 58.41 4.5 3.44 3.39 3.24 3.19 1630 Average/cohort SD 60.75/2.9 HV 3.91/0.45 Norm HV 3.98/0.5 AD1 F 75 73.58 9.01 69.18 12.78 2.68 3.09 2.67 3.07 1390 AD2 M 75 66.00 10.5 61.77 9.12 3.99 3.88 3.93 3.82 1640 AD3 M 64 64.33 8.00 67.76 10.37 3.69 3.47 3.23 3.04 1700 AD4 F 77 71.57 9.76 65.06 9.23 2.89 3.25 2.99 3.36 1420 AD5 M 77 74.85 9.67 68.49 8.53 3.26 2.87 2.85 2.51 1810 Average/cohort SD 68.25/3.4 HV 3.22/0.5 Norm HV 3.24/0.4 1600 P value .006 HV .052 Norm HV .034 Note:—Analysis of the hippocampal signal normalized to ventricular signal is shown for 5 patients with mild AD and 5 control patients. Patient age (years) and sex (S) are indicated. RMTL indicates the right medial temporal lobe; LMTL, the left medial temporal lobe enhancement as a percentage of ventricle enhancement, an internal control; SD, for either inside that region of interest or for the entire cohort (Cohort SD). The hippocampal volumes (HV, cm3) for the right (RHV) and left (LHV) sides are shown, and next to those are the volumes normalized (Norm) to total intracranial volume (TIV, cm3). The pooled averages of the left and right averaged measurements for each subject are shown in the Average/cohort SD lines.
