Article Figures & Data
Figures
- Fig 1.
Phase maps (upper row) and thresholded low-phase voxels used in mean phase of low-phase voxel (MP-LPV) calculation (bottom row) of subcortical deep gray matter structures. MP-LPV was determined by thresholding the phase images to retain only those voxels with phase values lower than 2 standard deviations below reference group. Upper and lower rows show the same subjects, and each column contains a representative subject from each age group (left to right, <25 years, 25–39 years, 40–55 years, >55 years).
- Fig 2.
Scatterplots showing significant interaction effects between sex and the mean phase of low-phase voxels (MP-LPV) of the putamen and substantia nigra.
Tables
- Table 1:
Demographic characteristics and global volumetric MRI measures of study participants
Total Male Female P n (%) 210 89 (42.4) 121 (57.6) Age (SD) median 39.8 (15.5) 41 38 (16.1) 38 41.1 (14.9) 44 .202 Race, n (%) of available cases White 139 (87.4) 58 (87.9) 81 (87.1) .617 African American 13 (8.2) 5 (7.6) 8 (8.6) Other 7 (4.4) 3 (4.5) 4 (4.3) Education, n (%) of available cases No high school 15 (9.7) 7 (11.3) 8 (8.7) .893 High school 24 (15.6) 11 (17.7) 13 (14.1) Some college 32 (20.8) 14 (22.6) 18 (19.6) Associate/technical 22 (14.3) 7 (11.3) 15 (16.3) Bachelor level 36 (23.4) 12 (19.4) 24 (26.1) Graduate level 23 (14.9) 10 (16.1) 13 (14.1) Postgraduate 2 (1.3) 1 (1.6) 1 (1.1) MRI volumes in cm3, mean (SD) WM hyperintensities 1.26 (4.47) 1.74 (6.50) 0.87 (1.29) .160 GM 791.93 (65.56) 787.64 (69.36) 795.02 (62.81) .525 Cortical GM 644.30 (56.33) 637.10 (62.11) 649.56 (51.36) .181 WM 761.95 (41.39) 771.66 (39.57) 754.97 (41.41) .008 Lateral ventricles 31.66 (12.70) 33.46 (13.36) 30.35 (12.07) .136 Note:—Differences between men and women were assessed by means of the χ2 test (race and education) and Student t test (age and normalized volumes).
- Table 2:
Sex differences of mean phase, mean phase of low-phase voxels, and normalized volume values of subcortical deep gray matter structures
Mean Phase MP-LPV Normalized Volume Male (n = 89) Female (n = 121) P Male (n = 89) Female (n = 121) P Male (n = 89) Female (n = 121) P Total SDGM −.012 (.014) −.016 (.014) .036 −.144 (.022) −.149 (.027) .573 49.209 (5.474) 44.442 (3.551) <.001 Caudate −.054 (.017) −.064 (.018) .001 −.170 (.016) −.167 (.014) .525 7.398 (1.079) 6.832 (.890) <.001 Putamen −.018 (.028) −.027 (.029) .028 −.175 (.039) −.183 (.047) .487 10.471 (1.386) 9.426 (.914) <.001 Globus pallidus −.016 (.025) −.015 (.024) .643 −.184 (.033) −.183 (.042) .348 3.809 (.442) 3.431 (.399) <.001 Thalamus .005 (.008) .003 (.009) .210 −.095 (.015) −.091 (.013) .157 16.474 (1.923) 14.661 (1.188) <.001 Pulvinar −.042 (.030) −.042 (.028) .657 −.139 (.017) −.140 (.018) .689 .456 (.092) .419 (.090) .010 Hippocampus .024 (.032) .031 (.039) .073 −.161 (.044) −.165 (.049) .822 7.559 (.956) 6.981 (.817) <.001 Amygdala .011 (.039) −.007 (.066) .086 −.214 (.051) −.210 (.075) .086 2.634 (.424) 2.326 (.307) <.001 Accumbens −.179 (.140) −.230 (.163) .035 −.744 (.203) −.80 (.252) .298 .865 (.199) .784 (.189) .006 Red nucleus −.050 (.057) −.059 (.051) .331 −.238 (.027) −.232 (.026) .225 .179 (.023) .162 (.022) <.001 Substantia nigra −.097 (.056) −.096 (.057) .765 −.305 (.039) −.308 (.041) .574 .305 (.048) .282 (.053) .005 Note:—Results are shown as mean (standard deviation); volume measurements are expressed in cubic centimeters. Mean phase and mean phase of low-phase tissue (MP-LPV) measurements are expressed in radians. Statistical analyses were carried out by use of independent-samples t test and Mann-Whitney U test.
- Table 3:
Linear regression analyses assessing the association between age and mean phase, mean phase of low-phase tissue, and normalized volumes, adjusted for sex
Mean phasea MP-LPVa Normalized Volume β P β P β P Total SDGM −.102 .057 −.255 <.001 −.245 <.001 Caudate −.102 .068 −.350 <.001 −.247 <.001 Putamen −.208 <.001 −.193 <.001 −.239 <.001 lobus pallidus .210 <.001 −.273 <.001 .049 .352 Thalamus −.178 <.001 −.521 <.001 −.299 <.001 Pulvinar nucleus −.384 <.001 −.340 <.001 −.105 .059 Hippocampus −.027 .645 .033 .589 −.075 .163 Amygdala .039 .525 −.029 .631 .069 .197 Accumbens −.051 .376 .112 .043 −.271 <.001 Red nucleus −.301 <.001 −.252 <.001 −.195 <.001 Substantia nigra −.207 .006 −.256 <.001 .023 .687 ↵a Adjusted for the effects of normalized volume.
- Table 4:
Proportion of structural low-phase voxels versus structural normalized volume within age groups, adjusted for sex
Age (years) P <25 n = 43 25–39 n = 56 40–55 n = 72 ≥55 n = 39 Total SDGM .29 (.04) .32 (.03) .34 (.04) .35 (.04) <.001 Caudate .27 (.09) .33 (.08) .36 (.07) .35 (.08) <.001 Putamen .17 (.08) .26 (.06) .33 (.07) .32 (.09) <.001 Globus pallidus .42 (.07) .40 (.06) .38 (.06) .35 (.06) <.001 Thalamus .40 (.03) .43 (.03) .44 (.04) .43 (.04) <.001 Pulvinar nucleus .11 (.08) .24 (.16) .28 (.15) .29 (.14) <.001 Hippocampus .15 (.08) .19 (.09) .18 (.07) .18 (.07) .319 Amygdala .17 (.14) .18 (.10) .17 (.10) .16 (.08) .738 Accumbens .15 (.14) .14 (.14) .12 (.13) .13 (.16) .703 Red nucleus .05 (.05) .13 (.12) .21 (.13) .17 (.11) <.001 Substantia nigra .17 (.11) .23 (.11) .27 (.11) .24 (.14) .002 General linear modeling comparing the proportion of structural low-phase voxels versus structural normalized volume between age groups. Results are presented as mean (standard deviation).
