Liver Tissue Characterization in Competitive Student Athletes by Quantitative MRI: Normal Values

Author

Lu Mao

Published

March 9, 2026

Statistical analysis

A placeholder for description of statistical methods.

Patient characteristics

Summary statistics for patient demographics and mean values of PDFF, R2*, T1, T2, and LIC are provided by sex and field strength in Table 1 and Table 2, respectively.

Table 1: Subject characteristics and measurements by sex.
Characteristic female, N = 761 male, N = 1351 Overall, N = 2111 p-value2
Age (years) 19.6 (18.9, 21.0) 20.1 (19.3, 21.4) 19.9 (19.1, 21.3) 0.021
AthleteType



    Basketball 3 (3.9%) 5 (3.7%) 8 (3.8%)
    Cross country 0 (0%) 3 (2.2%) 3 (1.4%)
    Diver 2 (2.6%) 0 (0%) 2 (0.9%)
    Football 0 (0%) 75 (56%) 75 (36%)
    Hockey 1 (1.3%) 1 (0.7%) 2 (0.9%)
    Ice Hockey 12 (16%) 12 (8.9%) 24 (11%)
    Rower 19 (25%) 10 (7.4%) 29 (14%)
    Soccer 7 (9.2%) 7 (5.2%) 14 (6.6%)
    Softball 9 (12%) 0 (0%) 9 (4.3%)
    Swimmer 3 (3.9%) 3 (2.2%) 6 (2.8%)
    Tennis 1 (1.3%) 1 (0.7%) 2 (0.9%)
    Track_endurance 1 (1.3%) 1 (0.7%) 2 (0.9%)
    Track_power 8 (11%) 8 (5.9%) 16 (7.6%)
    Volleyball 10 (13%) 0 (0%) 10 (4.7%)
    Wrestler 0 (0%) 9 (6.7%) 9 (4.3%)
Height (cm) 172.0 (165.0, 180.2) 188.0 (183.0, 193.0) 183.0 (173.7, 191.0) <0.001
Weight (kg) 70.0 (62.8, 77.0) 91.0 (81.1, 109.0) 84.0 (70.0, 99.0) <0.001
BMI 23.1 (21.7, 25.1) 26.6 (23.9, 30.7) 25.1 (22.5, 28.2) <0.001
Field strength


0.013
    1.5T 31 (41%) 79 (59%) 110 (52%)
    3T 45 (59%) 56 (41%) 101 (48%)
PDFF 1.8 (1.5, 2.3) 2.2 (1.7, 2.8) 2.1 (1.7, 2.6) 0.002
    (Missing) 9 19 28
R2s 36.8 (32.4, 42.1) 37.5 (33.5, 43.9) 37.1 (32.9, 43.6) 0.2
    (Missing) 9 19 28
T1 768.8 (594.0, 807.3) 600.6 (564.2, 745.1) 622.9 (577.1, 776.7) <0.001
    (Missing) 1 0 1
T2 45.2 (41.0, 49.5) 44.0 (40.8, 46.2) 44.1 (40.8, 47.0) 0.013
    (Missing) 12 21 33
LIC 0.566 (0.502, 0.669) 0.669 (0.584, 0.745) 0.639 (0.557, 0.732) <0.001
    (Missing) 9 19 28
1 Median (IQR); n (%)
2 Wilcoxon rank sum test; Pearson’s Chi-squared test
Table 2: Subject characteristics and measurements by field strength.
Characteristic 1.5T, N = 1101 3T, N = 1011 Overall, N = 2111 p-value2
Sex


0.013
    female 31 (28%) 45 (45%) 76 (36%)
    male 79 (72%) 56 (55%) 135 (64%)
Age (years) 20.0 (19.2, 21.4) 19.9 (19.1, 21.1) 19.9 (19.1, 21.3) 0.7
AthleteType



    Basketball 2 (1.8%) 6 (5.9%) 8 (3.8%)
    Cross country 2 (1.8%) 1 (1.0%) 3 (1.4%)
    Diver 0 (0%) 2 (2.0%) 2 (0.9%)
    Football 54 (49%) 21 (21%) 75 (36%)
    Hockey 1 (0.9%) 1 (1.0%) 2 (0.9%)
    Ice Hockey 13 (12%) 11 (11%) 24 (11%)
    Rower 16 (15%) 13 (13%) 29 (14%)
    Soccer 5 (4.5%) 9 (8.9%) 14 (6.6%)
    Softball 3 (2.7%) 6 (5.9%) 9 (4.3%)
    Swimmer 4 (3.6%) 2 (2.0%) 6 (2.8%)
    Tennis 2 (1.8%) 0 (0%) 2 (0.9%)
    Track_endurance 1 (0.9%) 1 (1.0%) 2 (0.9%)
    Track_power 3 (2.7%) 13 (13%) 16 (7.6%)
    Volleyball 2 (1.8%) 8 (7.9%) 10 (4.7%)
    Wrestler 2 (1.8%) 7 (6.9%) 9 (4.3%)
Height (cm) 185.4 (177.9, 193.0) 180.0 (172.0, 188.0) 183.0 (173.7, 191.0) 0.002
Weight (kg) 88.8 (71.6, 109.0) 79.0 (67.6, 87.0) 84.0 (70.0, 99.0) <0.001
BMI 26.3 (23.1, 30.9) 24.1 (22.3, 25.9) 25.1 (22.5, 28.2) <0.001
PDFF 2.3 (1.9, 2.8) 1.7 (1.4, 2.3) 2.1 (1.7, 2.6) <0.001
    (Missing) 13 15 28
R2s 33.5 (31.3, 35.5) 43.5 (39.6, 46.7) 37.1 (32.9, 43.6) <0.001
    (Missing) 13 15 28
T1 577.9 (556.8, 595.0) 783.5 (750.5, 804.2) 622.9 (577.1, 776.7) <0.001
    (Missing) 0 1 1
T2 46.2 (44.1, 48.9) 41.1 (38.4, 44.1) 44.1 (40.8, 47.0) <0.001
    (Missing) 16 17 33
LIC 0.713 (0.654, 0.764) 0.557 (0.504, 0.600) 0.639 (0.557, 0.732) <0.001
    (Missing) 13 15 28
1 n (%); Median (IQR)
2 Pearson’s Chi-squared test; Wilcoxon rank sum test

BMI

Table 3: Comparison of BMT by field strength within each sex.
Characteristic Female Male
1.5T, N = 311 3T, N = 451 p-value2 1.5T, N = 791 3T, N = 561 p-value2
BMI 23.05 (21.92, 24.87) 23.48 (21.60, 25.06) >0.9 28.2 (24.9, 32.0) 24.7 (22.8, 27.1) <0.001
1 Median (IQR)
2 Wilcoxon rank sum test

Comparison of markers by gender and field strength

Normal values (Median (IQR)) of PDFF, R2*, T1, T2, and LIC are summarized overall and by sex and field strength in Table 4 and shown graphically in Figure 1.

Table 4: Normal values by sex and field strength.
Female Male Overall
1.5T, N = 311 3T, N = 451 Overall, N = 761 1.5T, N = 791 3T, N = 561 Overall, N = 1351 1.5T, N = 1101 3T, N = 1011 Overall, N = 2111
PDFF 2.2 (1.8, 2.6) 1.5 (1.4, 1.8) 1.8 (1.5, 2.3) 2.4 (2.0, 2.9) 1.8 (1.5, 2.5) 2.2 (1.7, 2.8) 2.3 (1.9, 2.8) 1.7 (1.4, 2.3) 2.1 (1.7, 2.6)
R2s 32 (30, 35) 42 (38, 44) 37 (32, 42) 34 (32, 36) 44 (42, 49) 37 (33, 44) 34 (31, 35) 44 (40, 47) 37 (33, 44)
T1 588 (577, 600) 806 (791, 822) 769 (594, 807) 571 (552, 593) 755 (727, 783) 601 (564, 745) 578 (557, 595) 784 (750, 804) 623 (577, 777)
T2 49.4 (46.4, 52.2) 42.8 (38.9, 44.3) 45.2 (41.0, 49.5) 45.4 (43.3, 47.0) 40.9 (38.3, 43.4) 44.0 (40.8, 46.2) 46.2 (44.1, 48.9) 41.1 (38.4, 44.1) 44.1 (40.8, 47.0)
LIC 0.67 (0.61, 0.74) 0.53 (0.48, 0.56) 0.57 (0.50, 0.67) 0.72 (0.67, 0.79) 0.56 (0.53, 0.63) 0.67 (0.58, 0.74) 0.71 (0.65, 0.76) 0.56 (0.50, 0.60) 0.64 (0.56, 0.73)
1 Median (IQR)
Figure 1: Normal values (mean +- 2SD) by sex and field strength.

Note: There is an extreme outlier of Yca_074 with LIC = 3.39.

P-values comparing the normal values between sexes and fields strengths are tabulated in Table 5 and Table 6.

Table 5: P-values of t-test comparing 1.5T vs 3T by sex.
Overall female male
PDFF 0.003 0.338 0.003
R2s <0.001 <0.001 <0.001
T1 <0.001 <0.001 <0.001
T2 <0.001 <0.001 <0.001
LIC <0.001 <0.001 <0.001
Table 6: P-values of t-test comparing female vs male by field strength.
1.5T 3T Overall
PDFF 0.065 0.933 0.104
R2s 0.023 0.011 0.062
T1 0.039 <0.001 <0.001
T2 <0.001 0.124 0.013
LIC 0.023 0.011 <0.001

BMI correlations

Figure 2 plots PDFF, R2*, T1, T2, and LIC against BMI.

  • PDFF positively correlated with BMI for both 1.5T and 3T;
  • T1 negatively correlated with BMI for 3T only;
  • No correlation of R2* or LIC with BMI;
  • Can fit a regression line for 1.5/3T combined if desirable.
Figure 2: Measurements as a function of BMI.

By athletic group

Normal values (Mean \(\pm\) 2SD) of PDFF, R2*, T1, T2, and LIC are plotted in Figure 3 by sport. The size of the mean dot is proportional to the group size for the sport.

Figure 3: Normal values (mean +- 2SD) by sport.

Grouping of sports are considered below.

Type Sports
Power sport Diver, Track_power, Wrestler
Mixed sport Basketball, Football, Hockey, Ice Hockey, Soccer, Softball, Tennis, Volleyball
Endurance sport Cross country, Rower, Swimmer, Track_endurance

Number of subjects in each sex, field strength and sport type combination:

Type Total
Power sport Mixed sport Endurance sport
strata



    female-1.5T 1 17 13 31
    female-3T 9 26 10 45
    male-1.5T 4 65 10 79
    male-3T 13 36 7 56
Total 27 144 40 211
Table 7: Comparison of normal values between grouped sports by sex and field strength.
Strata Power sport Mixed sport Endurance sport
PDFF female-1.5T 3.89 (3.89, 3.89), N=1 2.17 (1.87, 2.58), N=17 2.15 (1.81, 2.53), N=13
female-3T 1.94 (1.74, 3.54), N=9 1.46 (1.21, 1.6), N=26 1.53 (1.46, 1.7), N=10
male-1.5T 1.93 (1.64, 2.19), N=4 2.46 (2.08, 3.21), N=65 2.12 (1.95, 2.53), N=10
male-3T 1.57 (1.27, 2.42), N=13 1.98 (1.48, 2.61), N=36 1.89 (1.73, 2.1), N=7
R2s female-1.5T 29.36 (29.36, 29.36), N=1 31.73 (28.5, 34.45), N=17 32.01 (31.01, 35.56), N=13
female-3T 50.91 (43.52, 57.2), N=9 39.19 (36.94, 43.07), N=26 40.19 (38.12, 43.35), N=10
male-1.5T 31.79 (31.7, 87.36), N=4 34.19 (32.14, 36.08), N=65 32.01 (31.08, 36.94), N=10
male-3T 43.81 (41.15, 46.97), N=13 45.54 (43.07, 51.31), N=36 43.84 (42.06, 45.03), N=7
T1 female-1.5T 584.35 (584.35, 584.35), N=1 594.13 (581.43, 602.66), N=17 584.81 (537.87, 593.9), N=13
female-3T 804.27 (769.42, 821.39), N=9 807.05 (793.98, 823.29), N=26 795.57 (787.67, 815.99), N=10
male-1.5T 548.06 (518.43, 574.54), N=4 566.82 (551.52, 589.4), N=65 593.5 (579.74, 597.81), N=10
male-3T 772.24 (752.98, 795.73), N=13 745.13 (706.91, 774.21), N=36 776.52 (758.28, 784.98), N=7
T2 female-1.5T 53.06 (53.06, 53.06), N=1 49.74 (46.82, 52.21), N=17 47.7 (45.8, 49.67), N=13
female-3T 40.47 (35.24, 43.85), N=9 42.96 (39.44, 44.39), N=26 41.09 (40.41, 46.56), N=10
male-1.5T 44.22 (40.21, 46.49), N=4 45.31 (43.18, 46.87), N=65 46.52 (45.3, 49.4), N=10
male-3T 41.03 (38.95, 43), N=13 40.28 (37.01, 44.24), N=36 40.07 (39.02, 42.56), N=7
LIC female-1.5T 0.6 (0.6, 0.6), N=1 0.67 (0.58, 0.74), N=17 0.67 (0.65, 0.77), N=13
female-3T 0.66 (0.56, 0.74), N=9 0.5 (0.47, 0.55), N=26 0.51 (0.48, 0.55), N=10
male-1.5T 0.67 (0.67, 2.11), N=4 0.73 (0.68, 0.78), N=65 0.67 (0.65, 0.8), N=10
male-3T 0.56 (0.53, 0.6), N=13 0.58 (0.55, 0.66), N=36 0.56 (0.54, 0.58), N=7
Figure 4: Normal values (mean +- 2SD) by grouped sports, sex and field strength.

Footballers alone

Normal values (Mean \(\pm\) 2SD) of PDFF, R2*, T1, T2, and LIC for football playes are summarized overall and by field strength in Table 8.

Table 8: Normal values by field strength for football players.
1.5T, N = 541 3T, N = 211 Overall, N = 751 p-value2
PDFF 2.6 (2.1, 3.5) 2.0 (1.5, 2.4) 2.3 (1.9, 2.9) 0.005
R2s 34 (32, 35) 46 (43, 52) 35 (33, 43) <0.001
T1 567 (554, 592) 733 (678, 769) 588 (562, 656) <0.001
T2 45.4 (43.3, 46.9) 40.3 (37.4, 42.9) 44.1 (42.2, 46.3) <0.001
LIC 0.72 (0.67, 0.76) 0.58 (0.55, 0.68) 0.69 (0.64, 0.75) 0.006
1 Median (IQR)
2 Welch Two Sample t-test