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

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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

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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

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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

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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

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