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Observations
and
Results
5. Observations & Results
A total of 724 women were enrolled for the study. For all the sonographic
studies, to rule out intra-observer variation, a second measurement was done after 1
hour. Student t test was applied for both these observations and only those
measurements where p value was <0.05(i.e. statistically no difference) were included in
the study for further statistical analysis.
Table 5A: Inter-observer brain volume assessment in study group
Parameter Mean difference Standard error (n=13) T Value P Value
Total BV ml 1.36 2.96 0.46 <0.05
Lt Hemicortex ml 1.1 1.15 0.96 <0.05
Rt Hemicortex ml 2.02 1.64 1.24 <0.05
Thalamic Volume ml 0.13 0.16 0.82 <0.05
Cerebellar Volume ml 0.24 0.51 0.43 <0.05
There was no statistically significant inter-observer variability seen in our study.
Page 36 of 84
5.1 Total Brain Volume measurements
5.1(A) Gestational Age and Total Brain Volume
5.1A (1) Correlation of Total Brain Volume with Gestational age
Pair of quantitative variables like gestational age and brain volume was analyzed
for correlation using Pearson’s correlation coefficient (r) as shown in the table below.
Progressing gestational age of fetus was correlated significantly with brain volume
between 20 weeks to 35 weeks of gestational period. (p<0.0001)
Table 5.1A (1): Correlation between gestational age and total brain volume in study
group
Correlation between GA and
Brain volume
r1 Value P Value
0.93 <0.0001
Graph 5.1A (1): Correlation between gestational age and total brain volume
1 r Value means correlation
Page 37 of 84
5.1A (2) Regression Analysis of Total Brain Volume versus Gestational age
Table 5.1A (2): Regression analysis between Gestational Age and Total Brain
Volume
ANOVA df SS MS F Significance F
Regression 1 2043403.9 2043403.9 4941.3 <0.0000001
Residual 723 298984.5 413.5
Total 724 2342388.4
Relationship of Gestational age and brain volume was also analysed
quantitatively as shown in the above table. The F value was 4941.3, which was very
highly significant (p<0.0001) Regression equation is developed and is correlated well
with gestational age [Total Brain Volume = 11.619(GA) - 202.95].
Graph5.1A (2): Regression Plot of Total brain volume versus Gestational age
Page 38 of 84
5.1A (3) Percentile chart and graph of Total Brain Volume with respect to gestational
age
Table 5.1A (3): Percentile chart of total brain volume with respect to gestational
age showing 90th
, 50th
, and 10th
percentile values
Gestational Age in Weeks
90th percentile 50th Percentile 10th percentile
20 47.2 35.6 29.64
21 56.43 45.6 30.4
22 63.6 53.45 41.9
23 73.72 65.9 52.96
24 95.86 78.4 64.72
25 116.68 88.2 69.9
26 124.38 97.3 73.2
27 148 116.3 96.9
28 150.27 112.3 95.54
29 175.89 136 110.65
30 187.3 159.2 124.14
31 170.77 151.15 127.69
32 196.55 166.6 146.1
33 221.3 180.6 146.6
34 216.6 193.7 162.6
35 277.68 202.3 169.4
Graph 5.1A (3): Total Brain Volume percentile
grap
Page 39 of 84
Correlation between EFWT and r Value P Value
Brain volume 0.93 <0.0001
5.1(B) Total Brain volume and estimated fetal weight
5.1 (B) (1) Correlation between Total Brain Volume and Estimated Fetal Weight
Pair of quantitative variables like estimated fetal weight and brain volume was
analysed for correlation using Pearson’s correlation coefficient(r) as shown in the table
below. Progressing fetal weight was correlated significantly with increasing brain
volume (p<0.0001).
Graph5.1B (1): Correlation between Estimated fetal weight and total brain volume
Table 5.1B (1): Correlation between Total Brain Volume and estimated fetal
weight
Page 40 of 84
5.1(B) (2) Regression analysis of Total brain volume versus Estimated fetal weight
Relationship of fetal weight and brain volume was also analysed quantitatively
as shown in the table below. The F value was 4021.2, which was statistically very
highly significant (p<0.000001).
Table 5.1B (2): Regression analysis of estimated fetal weight and Total Brain
Volume ANOVA df SS MS F Significance F
Regression 1.0 1985412.8 1985412.8 4021.2 <0.00000001
Residual 723.0 356975.7 493.7
Total 724.0 2342388.5
Graph 5.1B (2): Regression plot of estimated fetal weight versus total brain volume
with regression formula of Total brain volume in ml = 0.0764(EFWT) + 24.576
Page 41 of 84
5.2 Left Hemispheric Volume Measurements
5.2 (1) Correlation of Left Hemispheric Volume with Gestational age
Pair of quantitative variables like gestational age and left hemispheric volume
was analysed for correlation using Pearson’s correlation coefficient (r) as shown in the
table below. Progressing gestational age was correlated significantly with increasing
left hemicortex brain volume (p< 0.0001). There was increase in the volume of left
hemisphere in relation with the corresponding increase in the gestational age.
Table 5.2(1): Correlation between Gestational age and left hemispheric volume
Correlation between GA and
Left Hemisphere
r Value P Value
0.92 <0.0001
Graph 5.2(1): Correlation of Gestational age to the left hemispheric volume
Page 42 of 84
5.2 (2) Regression analysis of Left Hemispheric Volume versus Gestational Age
Relationship of gestational age and left hemispheric brain volume was also
analyzed quantitatively as shown in the table below. The F value was 4183.5, which
was statistically very highly significant (p<0.0001).
Table5.2 (2): Regression analysis of gestational age versus left hemispheric volume
regression formula left hemispheric volume in ml = 5.7803 (G.A.) – 100.9
ANOVA df SS MS F Significance F
Regression 1.0 505768.7 505768.7 4183.5 <0.0000001
Residual 723.0 87407.2 120.9
Total 724.0 593175.9
Graph 5.2(2): Regression plot of gestational age versus left hemispheric volume
Page 43 of 84
5.2 (3) Percentile chart and graph of Left Hemispheric Volume with respect to gestational age
Table 5.2 (3): Percentile chart of left hemispheric volume with respect to
gestational age showing 90th
, 50th
, and 10th
percentile values
Gestational Age in Weeks 90th percentile 50th Percentile 10th percentile
20 23.56 18.4 14.8
21 27.6 22.65 16.17
22 31.2 26.7 20.9
23 37.62 32.4 25.6
24 46.06 39.9 32.06
25 58.24 45.7 35.3
26 63.9 47.9 36.8
27 73.9 57.1 47.6
28 76.05 57.55 48.23
29 85.21 67.8 55.4
30 92.9 77.9 63.84
31 88.7 75.1 64.25
32 107.19 82.75 73.21
33 110.84 83.9 68.6
34 113.56 98.6 77.9
35 139.4 104.5 79.74
Graph 5.2 (3): Left Hemispheric Volume percentile graph
Page 44 of 84
5.3 Right Hemispheric Volume Measurements
5.3 (1): Correlation of Right Hemispheric Volume with Gestational age
Pair of quantitative variables like gestational age and right hemicortex volume
was analyzed for correlation using Pearson’s correlation coefficient (r) as shown in the
table and figure below. Progressing gestational age was correlated significantly with
increasing right hemicortex brain volume (p<0.0001).
Table 5.3 (1): Correlation between Gestational age and right hemispheric
volume in study group
Correlation between GA and r Value P Value
Right Hemicortex 0.92 <0.0001
Graph 5.3(1):Correlation between gestational age and right hemispheric volume
Page 45 of 84
5.3 (2) Regression analysis of Right Hemispheric Volume versus Gestational age
Relationship of gestational age and right hemispheric brain volume was also
analysed quantitatively as shown in the table below. The F value was 4561.02, which
was statistically very highly significant (p <0.00001).
Table 5.3(2): The regression on right hemispheric volume is Right
Hemispheric volume in ml = 5.7676(GA) - 100.62
ANOVA Df SS MS F Significance F
Regression 1.00 503541.46 503541.46 4561.02 <0.000001
Residual 723.00 79819.88 110.40
Total 724.00 583361.34
Graph 5.3(2): Regression plot of gestational age (GA) and right hemispheric
volume
Page 46 of 84
5.3 (3) Percentile chart and graph of Right Hemispheric Volume with respect to Gestational age
Table 5.3 (3): Percentile chart of right hemispheric volume with respect to
gestational age showing 90th
, 50th
, and 10th
percentile values
Gestational Age in Weeks 90th percentile 50th Percentile 10th percentile
20 22.88 17.9 14.54
21 28.5 23.2 15.24
22 32.9 26.65 20.05
23 38.26 34.8 26.8
24 47.36 39.5 31.98
25 57.42 42.9 35.9
26 64.9 51.3 36.2
27 74.78 58.7 47.3
28 77.29 55.9 46.72
29 89.89 68.75 52.6
30 95.2 78.2 60.3
31 89 74.25 62.2
32 104.22 85.3 71.6
33 112.02 89 75.4
34 111.62 96.3 82.04
35 139.6 100.7 83.9
Graph 5.3 (3): Right Hemispheric Volume percentile
graph
Page 47 of 84
5.4 Cerebellar volume measurements
5.4 (1) Correlation between Cerebellar Volume and Gestational Age
Pair of quantitative variables like gestational age and cerebellar volume was
analysed for correlation using Pearson’s correlation coefficient (r) as shown in the table
and figure below. Progressing gestational age was correlated significantly with
increasing cerebellar brain volume (p<0.0001).
Table5. 4(1): Correlation between Gestational age (GA) and Cerebellar Volume in study group Correlation between GA and
Cerebellar Volume
r Value P Value
0.845 <0.0001
Graph 5.4(1): Graph showing correlation between gestational age and cerebellar volume
Page 48 of 84
5.4 (2) Regression analysis of Cerebellar Volume versus Gestational age
Relationship of gestational age and cerebellar brain volume was also analysed
quantitatively as shown in the table and figure below. The F value was 1 8 1 4 . 4 ,
which was statistically very highly significant (p<0.0001).
Table5.4 (2): The regression equation of GA (gestational age) on Cerebellar
Volume is Cerebellar Volume in ml = 0.4754(GA) - 9.1648
ANOVA df SS MS F Significance F
Regression 1.0 3421.3 3421.3 1814.4 <0.0000001
Residual 723.0 1363.4 1.9
Total 724.0 4784.7
Graph 5.4(2): Regression plot of gestational age versus cerebellar volume regression formula cerebellar volume in ml =0.4754 -9.1648
Page 49 of 84
5.4 (3) Percentile chart and graph of Cerebellar Volume with respect to Gestational age
Table 5.4 (3): Percentile chart of cerebellar volume with respect to gestational age
showing 90th
, 50th
, and 10th
percentile values
Gestational Age in Weeks 90th percentile 50th Percentile 10th percentile
20 1.62 0.9 0.8
21 1.7 1.2 0.89
22 2.05 1.4 0.93
23 2.76 1.8 1.44
24 3.62 2.3 1.3
25 3.08 2.4 1.72
26 3.9 2.8 2.06
27 4.7 3.6 2.56
28 4.84 3.65 2.8
29 5.73 4.25 2.9
30 7.1 4.8 3.64
31 7 5.15 3.45
32 7.18 6.4 4.19
33 11.72 7.5 4.86
34 12.48 7.3 4.66
35 10.5 8.7 4.74
Graph 5.4 (3): Cerebellar Volume percentile graph
Page 50 of 84
5.5 Thalamic Volume measurements
5.5 (1) Correlation between Thalamic Volume and Gestational Age
Pair of quantitative variables like gestational age and thalamic volume was
analysed for correlation using Pearson’s correlation coefficient (r) as shown in the table
and figure below. Progressive gestational age was correlated significantly with
increasing thalamic brain volume (p<0.0001).
Table 5.5(1): Correlation between Gestational age and Thalamic Volume in study group
Correlation between GA and r Value P Value
Thalamic Volume 0.82 <0.0001
Graph 5.5(1): Graph showing correlation between gestational age and thalamic volume
Page 51 of 84
5.5 (2) Regression analysis of Thalamic volume versus Gestational age
Relationship of gestational age and thalamic brain volume were also analyzed
quantitatively as shown in the table and figure below. The F value was 1593.4, which
was statistically very highly significant (p<0.0001).
Table 5.5(2): The regression equation of GA on Thalamic Volume is:
FetalThalamic Volume in ml = 0.3594(GA) - 5.8454
ANOVA df SS MS F Significance F
Regression 1.0 1954.7 1954.7 1593.4 <0.00001
Residual 723.0 886.9 1.2
Total 724.0 2841.7
Figure 5.5(2): Regression plot of Gestational age versus thalamic volume
Page 52 of 84
5.5 (3) Percentile chart and graph of Thalamic volume with respect to Gestational age
Table 5.5 (3): Percentile chart of thalamic volume with respect to gestational age
showing 90th
, 50th
, and 10th
percentile values
Gestational Age in Weeks 90th percentile 50th Percentile 10th percentile
20 2.4 1.6 1.1
21 2.41 1.9 1.09
22 2.9 2 1.5
23 3.52 2.3 1.78
24 3.94 2.8 1.48
25 4.7 3.4 2.04
26 5.1 3.1 2.4
27 5.42 4.3 2.76
28 5.17 3.9 2.59
29 6.9 4.65 3.6
30 6.3 4.9 3.58
31 7.05 5.2 3.4
32 7.93 5.9 3.8
33 8.58 6.5 4.46
34 10.1 6 4.9
35 8.92 6.5 4
Graph 5.5 (3): Thalamic volume percentile graph
Page 53 of 84