Gastroenterol Res

Gastroenterology Research, ISSN 1918-2805 print, 1918-2813 online, Open Access

Article copyright, the authors; Journal compilation copyright, Gastroenterol Res and Elmer Press Inc

Journal website https://gr.elmerpub.com

Original Article

Volume 19, Number 3, June 2026, pages 136-146

Computed Tomography-Based Assessment of Sarcopenia and Disease Progression in Pancreatic Ductal Adenocarcinoma: A Radiomics and Machine Learning Approach

↓ Figure 2. Sex-specific development of PMI values over time. As the number of evaluated patients decreased markedly at t3 (12 months), this follow-up time point is not shown. Values for all time points are provided in Table 5. PMI: psoas muscle index.

↓ Figure 3. Selected features of the second logistic regression model (LogReg). Intensity range and minimum histogram gradient are the strongest predictors.

↓ **Table 1.** Cohort-Derived Quartile Thresholds for Psoas Muscle Index (PMI) at Different Time Points for the Present Study Cohort
Time points	PMI in cm²/m², female	PMI in cm²/m², male
t0	3.6	5.0
t1	3.4	4.6
t2	3.1	4.7
t3	3.4	4.5

↓ Table 1. Cohort-Derived Quartile Thresholds for Psoas Muscle Index (PMI) at Different Time Points for the Present Study Cohort

Time points

PMI in cm²/m², female

PMI in cm²/m², male

3.6

5.0

3.4

4.6

3.1

4.7

3.4

4.5

↓ **Table 2.** Settings of the Radiomics Feature Extraction
Setting	Determination
FBN: fixed bin number; LoG: Laplacian of Gaussian.
Bin method	FBN
Bin amount	32
LoG filter	0
LoG sigma	2
Matrix aggregation	3D average
Method	Directions
Resample filter	1
Resample spacing X	1
Resample spacing Y	1
Resample spacing Z	1
Second-order distance	1
Threshold filter	0

↓ Table 2. Settings of the Radiomics Feature Extraction

Setting

Determination

FBN: fixed bin number; LoG: Laplacian of Gaussian.

Bin method

FBN

Bin amount

LoG filter

LoG sigma

Matrix aggregation

3D average

Method

Directions

Resample filter

Resample spacing X

Resample spacing Y

Resample spacing Z

Second-order distance

Threshold filter

↓ **Table 3.** Patients’ Demographic at the Time of Diagnosis
	Absolute number	Relative (%)
Number of patients	62	100
Sex
Female	24	38.7
Male	38	61.3
Mean age (years)
Total (min.–max.)	64 (41–84)
Female	66 (52–79)
Male	63 (41–84)

↓ Table 3. Patients’ Demographic at the Time of Diagnosis

Absolute number

Relative (%)

Number of patients

100

Sex

Female

38.7

Male

61.3

Mean age (years)

Total (min.–max.)

64 (41–84)

Female

66 (52–79)

Male

63 (41–84)

↓ **Table 4.** Patients’ Clinical Characteristics at the Time of Diagnosis Including Age, TNM Stage Distribution, Type of Therapy, and Disease Course
	Absolute number	Relative (%)
Additional information about patients’ therapy and disease course is provided. The third column shows the corresponding relative frequencies of patients. T: primary tumor; N: lymph nodes; M: metastasis; UICC: Union Internationale Contre le Cancer; PD: progressive disease.
T stage
Tx	2	3.2
T0	0	0
T1	3	4.8
T2	16	25.8
T3	35	56.5
T4	6	9.7
N stage
Nx	10	16.1
N0	5	8.1
N1	45	72.6
N2	2	3.2
M stage
Mx	3	4.8
M0	26	41.9
M1	33	53.2
UICC-stadium
IA	3	4.8
IB	2	3.2
IIA	0	0
IIB	16	25.8
III	5	8.1
IV	33	53.2
Unknown	3	4.8
Therapy
Resection + chemotherapy	18	29.0
Resection only	5	8.1
Chemotherapy only	39	62.9
Disease course (n = 62)
1 = no PD at t2	37	59.7
2 = PD at t2, no PD at t1	18	29.0
3 = PD at t2, PD at t1	7	11.3
Disease course (n = 35)
1 = no PD at t3	16	45.7
2 = PD at t3, no PD at t2	13	37.1
3 = PD at t3, PD at t2	6	17.1

↓ Table 4. Patients’ Clinical Characteristics at the Time of Diagnosis Including Age, TNM Stage Distribution, Type of Therapy, and Disease Course

Absolute number

Relative (%)

Additional information about patients’ therapy and disease course is provided. The third column shows the corresponding relative frequencies of patients. T: primary tumor; N: lymph nodes; M: metastasis; UICC: Union Internationale Contre le Cancer; PD: progressive disease.

T stage

3.2

4.8

25.8

56.5

9.7

N stage

16.1

8.1

72.6

3.2

M stage

4.8

41.9

53.2

UICC-stadium

4.8

3.2

IIA

IIB

25.8

III

8.1

53.2

Unknown

4.8

Therapy

Resection + chemotherapy

29.0

Resection only

8.1

Chemotherapy only

62.9

Disease course (n = 62)

1 = no PD at t2

59.7

2 = PD at t2, no PD at t1

29.0

3 = PD at t2, PD at t1

11.3

Disease course (n = 35)

1 = no PD at t3

45.7

2 = PD at t3, no PD at t2

37.1

3 = PD at t3, PD at t2

17.1

↓ **Table 5.** Characteristics and Measurements From t0 to t3
	t0	t1	t2	t3
The percentage values marked with (*) refer, for better comparability, to the subset of the respective category that contained values. PMI: psoas muscle index; SD: standard deviation.
Patients	62	100	56	90.3	62	100	35	56.5
PMI (cm²/m²), mean ± SD
Total	5.45 ± 1.65	5.05 ± 1.45	4.96 ± 1.69	5.05 ± 1.52
Female	4.22 ± 0.78	3.90 ± 0.89	3.62 ± 0.80	3.87 ± 0.64
Male	6.22 ± 1.59	5.69 ± 1.31	5.81 ± 1.55	5.59 ± 1.50
Sarcopenia according to lowest quartile
Total	16	25.8*	14	25.0*	16	25.8*	9	25.7*
Female	6	25.0*	5	25.0*	6	25.0*	3	27.3*
Male	10	26.3*	9	25.0*	10	26.3*	6	25.0*
Sarcopenia according to reference values
Total	19	30.6*	27	48.2*	31	50.0*	17	48.6*
Female	7	29.2*	10	50.0*	15	62.5*	5	45.5*
Male	12	31.6*	17	47.2*	16	42.1*	12	50.0*

↓ Table 5. Characteristics and Measurements From t0 to t3

Absolute

h (%)

Absolute

h (%)

Absolute

h (%)

Absolute

h (%)

The percentage values marked with (*) refer, for better comparability, to the subset of the respective category that contained values. PMI: psoas muscle index; SD: standard deviation.

Patients

100

90.3

100

56.5

PMI (cm²/m²), mean ± SD

Total

5.45 ± 1.65

5.05 ± 1.45

4.96 ± 1.69

5.05 ± 1.52

Female

4.22 ± 0.78

3.90 ± 0.89

3.62 ± 0.80

3.87 ± 0.64

Male

6.22 ± 1.59

5.69 ± 1.31

5.81 ± 1.55

5.59 ± 1.50

Sarcopenia according to lowest quartile

Total

25.8*

25.0*

25.8*

25.7*

Female

25.0*

27.3*

Male

26.3*

25.0*

26.3*

25.0*

Sarcopenia according to reference values

Total

30.6*

48.2*

50.0*

48.6*

Female

29.2*

50.0*

62.5*

45.5*

Male

31.6*

47.2*

42.1*

50.0*

↓ **Table 6.** ROC-AUC for the Three Prediction Algorithms
	t0	t1	t2	t3
Acc: accuracy; CI: confidence interval; dt: decision tree; KNN: k-nearest neighbor; M: mean; rf: random forest; ROC-AUC: receiver operating characteristics area under the curve; SD: standard deviation.
Acc_M_rf	0.73 ± 0.05	0.76 ± 0.07	0.79 ± 0.12	0.72 ± 0.08
Acc_95% CI_rf	0.72–0.74	0.74–0.78	0.76–0.82	0.69–0.75
Auc_M_rf	0.81 ± 0.09	0.83 ± 0.07	0.84 ± 0.11	0.74 ± 0.14
Auc_95% CI_rf	0.79–0.83	0.81–0.85	0.81–0.87	0.69–0.79
F₁_M_rf	0.53 ± 0.21	0.70 ± 0.13	0.75 ± 0.06	0.71 ± 0.10
F₁_95% CI_rf	0.48–0.58	0.67–0.73	0.74–0.76	0.68–0.74
Acc_M_KNN	0.65 ± 0.08	0.45 ± 0.09	0.45 ± 0.08	0.47 ± 0.13
Acc_95% CI_KNN	0.63–0.67	0.43–0.47	0.43–0.47	0.43–0.51
Auc_M_KNN	0.58 ± 0.10	0.54 ± 0.09	0.54 ± 0.10	0.56 ± 0.20
Auc_95% CI_KNN	0.56–0.60	0.52–0.56	0.52–0.56	0.49–0.62
F₁_M_KNN	0.47 ± 0.28	0.53 ± 0.13	0.73 ± 0.09	0.59 ± 0.13
F₁_95% CI_KNN	0.40–0.54	0.50–0.56	0.71–0.75	0.55–0.63
Acc_M_dt	0.67 ± 0.07	0.66 ± 0.07	0.70 ± 0.05	0.76 ± 0.10
Acc_95% CI_dt	0.65–0.69	0.64–0.68	0.69–0.71	0.73–0.79
Auc_M_dt	0.68 ± 0.10	0.64 ± 0.07	0.72 ± 0.05	0.76 ± 0.10
Auc_95% CI_dt	0.66–0.70	0.62–0.66	0.71–0.73	0.73–0.79
F₁_M_dt	0.31 ± 0.12	0.71 ± 0.14	0.55 ± 0.10	0.54 ± 0.12
F₁_95% CI_dt	0.28–0.34	0.67–0.75	0.53–0.57	0.50–0.58

↓ Table 6. ROC-AUC for the Three Prediction Algorithms

Acc: accuracy; CI: confidence interval; dt: decision tree; KNN: k-nearest neighbor; M: mean; rf: random forest; ROC-AUC: receiver operating characteristics area under the curve; SD: standard deviation.

Acc_M_rf

0.73 ± 0.05

0.76 ± 0.07

0.79 ± 0.12

0.72 ± 0.08

Acc_95% CI_rf

0.72–0.74

0.74–0.78

0.76–0.82

0.69–0.75

Auc_M_rf

0.81 ± 0.09

0.83 ± 0.07

0.84 ± 0.11

0.74 ± 0.14

Auc_95% CI_rf

0.79–0.83

0.81–0.85

0.81–0.87

0.69–0.79

F₁_M_rf

0.53 ± 0.21

0.70 ± 0.13

0.75 ± 0.06

0.71 ± 0.10

F₁_95% CI_rf

0.48–0.58

0.67–0.73

0.74–0.76

0.68–0.74

Acc_M_KNN

0.65 ± 0.08

0.45 ± 0.09

0.45 ± 0.08

0.47 ± 0.13

Acc_95% CI_KNN

0.63–0.67

0.43–0.47

0.43–0.51

Auc_M_KNN

0.58 ± 0.10

0.54 ± 0.09

0.54 ± 0.10

0.56 ± 0.20

Auc_95% CI_KNN

0.56–0.60

0.52–0.56

0.49–0.62

F₁_M_KNN

0.47 ± 0.28

0.53 ± 0.13

0.73 ± 0.09

0.59 ± 0.13

F₁_95% CI_KNN

0.40–0.54

0.50–0.56

0.71–0.75

0.55–0.63

Acc_M_dt

0.67 ± 0.07

0.66 ± 0.07

0.70 ± 0.05

0.76 ± 0.10

Acc_95% CI_dt

0.65–0.69

0.64–0.68

0.69–0.71

0.73–0.79

Auc_M_dt

0.68 ± 0.10

0.64 ± 0.07

0.72 ± 0.05

0.76 ± 0.10

Auc_95% CI_dt

0.66–0.70

0.62–0.66

0.71–0.73

0.73–0.79

F₁_M_dt

0.31 ± 0.12

0.71 ± 0.14

0.55 ± 0.10

0.54 ± 0.12

F₁_95% CI_dt

0.28–0.34

0.67–0.75

0.53–0.57

0.50–0.58