Table 4 Test/Retest variability measurements of CT-based organ volume of the selected key organs of interest.

From: Whole-Body [18F]FDG-PET/CT Imaging of Healthy Controls: Test/Retest Data for Systemic, Multi-Organ Analysis

Organ Volume

Test [mL]

Retest [mL]

Group

Subject

Δ%

t-test (paired)

 

ICC

t-value

p-value

(3,1)

CI95%

Δ%

Skeletal Muscle

816 ± 217

818 ± 207

0.3

−0.31

0.76

0.97

0.95–0.98

4.8

Subcutaneous Fat

795 ± 455

797 ± 467

0.3

−0.2

0.84

0.99

0.98–0.99

9.3

Visceral Fat

315 ± 228

309 ± 223

1.9

0.88

0.38

0.98

0.96–0.99

12.1

Heart Myocardium

116 ± 28

118 ± 28

1.5

−1.54

0.13

0.96

0.93–0.98

4.3

Brain

1377 ± 147

1378 ± 148

0.1

−2.09

0.04

1.00

1.0–1.0

0.2

Kidney (left)

129 ± 44

125 ± 42

3.5

2.17

0.04

0.95

0.91–0.97

8.7

Kidney (right)

132 ± 39

129 ± 39

1.8

1.46

0.15

0.96

0.93–0.98

6.6

Liver

1534 ± 283

1559 ± 267

1.6

−1.19

0.24

0.87

0.78–0.93

6.8

Lung (lower left)

613 ± 153

594 ± 131

3.2

1.55

0.13

0.83

0.71–0.9

10.4

Lung (lower right)

683 ± 176

669 ± 157

2.1

1.22

0.23

0.89

0.81–0.94

8.5

Lung (middle right)

323 ± 80

323 ± 80

0.1

0.08

0.93

0.97

0.94–0.98

4.9

Lung (upper left)

783 ± 235

770 ± 226

1.6

1.41

0.17

0.96

0.94–0.98

6.2

Lung (upper right)

636 ± 179

627 ± 173

1.4

1.4

0.17

0.97

0.95–0.98

5.4

Pancreas

79 ± 22

81 ± 22

1.5

−1.05

0.3

0.94

0.89–0.96

8.6

Spleen

186 ± 63

185 ± 65

0.6

0.39

0.7

0.95

0.91–0.97

7.3

  1. Δ% (group level) reflects the relative difference between the mean Test and Retest intensities across all subjects. Δ% (subject level) represents the average of individual Test-Retest percentage differences computed per subject. Repeatability was considered good for: Δ% < 3.5% on the group level, Δ% < 13% on the subject level (thresholds were determined by: mean Δ% + 2 SD), and statistical significance of p > 0.05. Values not meeting these criteria are highlighted in bold text. The group-level Δ% was < 3.5% for nearly all organs. Statistically significant group-level differences were observed in the brain and kidneys (both p = 0.04), but these did not compromise overall repeatability, as ICC(3,1) values remained > 0.95 in most regions. Slightly lower ICCs were seen in the liver and lung lobes, and subject-level differences were more pronounced in organs sensitive to weight fluctuations and respiration, such as visceral fat (Δ% = 12.1%) and lungs.
Back to article page