Application value of multiphase contrast-enhanced computed tomography radiomics in preoperative evaluation of peritoneal metastasis in gastric cancer

Table 1 Comparison of basic characteristics of gastric cancer patients

Characteristic	Total (n = 200)	No peritoneal metastasis (n = 128)	Peritoneal metastasis (n = 72)	Statistical value	P value
Age (years)	63 (55, 71)	61 (53, 69)	66 (58, 74)	Z = -2.162	0.031
Gender				χ2 = 0.892	0.345
Male	134 (67.0)	89 (69.5)	45 (62.5)
Female	66 (33.0)	39 (30.5)	27 (37.5)
BMI (kg/m2)	22.8 (20.5, 25.2)	23.1 (20.8, 25.4)	22.3 (19.9, 24.8)	Z = -1.423	0.155
Clinical symptoms
Abdominal pain	156 (78.0)	97 (75.8)	59 (81.9)	χ2 = 1.098	0.295
Abdominal distension	89 (44.5)	52 (40.6)	37 (51.4)	χ2 = 2.284	0.131
Weight loss	124 (62.0)	74 (57.8)	50 (69.4)	χ2 = 2.745	0.098
Anemia	98 (49.0)	58 (45.3)	40 (55.6)	χ2 = 2.070	0.150
Blood routine indicators
Hemoglobin (g/L)	118 (102, 135)	124 (108, 142)	108 (94, 126)	Z = -2.648	0.008
White blood cell count (× 109/L)	6.8 (5.2, 8.9)	6.3 (4.9, 8.1)	7.6 (5.8, 9.8)	Z = -2.035	0.042
Platelet count (× 109/L)	285 (218, 356)	268 (205, 338)	312 (248, 389)	Z = -2.314	0.021
Liver and kidney function indicators
ALT (U/L)	28 (18, 45)	24 (16, 38)	35 (22, 58)	Z = -2.187	0.029
AST (U/L)	32 (21, 48)	28 (19, 42)	38 (26, 61)	Z = -2.458	0.014
Total bilirubin (μmol/L)	18.6 (12.4, 26.8)	16.2 (11.8, 23.4)	22.8 (15.7, 32.1)	Z = -2.319	0.020
Creatinine (μmol/L)	78 (65, 94)	74 (62, 89)	85 (71, 102)	Z = -2.108	0.035
Blood urea nitrogen (mmol/L)	5.8 (4.2, 7.6)	5.4 (4.0, 7.1)	6.5 (4.8, 8.9)	Z = -1.892	0.058
Laboratory indicators
CEA (ng/mL)	8.5 (3.2, 22.1)	5.8 (2.6, 14.3)	18.9 (8.7, 45.2)	Z = -5.834	< 0.001
CA19-9 (U/mL)	45.2 (18.7, 126.8)	28.4 (15.2, 78.6)	89.7 (42.3, 234.1)	Z = -4.921	< 0.001
CA72-4 (U/mL)	12.6 (4.8, 35.7)	7.9 (3.8, 21.4)	28.4 (12.1, 68.9)	Z = -5.127	< 0.001
Tumor differentiation degree				χ2 = 12.358	0.002
Well differentiated	23 (11.5)	20 (15.6)	3 (4.2)
Moderately differentiated	89 (44.5)	64 (50.0)	25 (34.7)
Poorly differentiated	88 (44.0)	44 (34.4)	44 (61.1)
Lauren classification				χ2 = 15.942	< 0.001
Intestinal type	78 (39.0)	61 (47.7)	17 (23.6)
Diffuse type	95 (47.5)	52 (40.6)	43 (59.7)
Mixed type	27 (13.5)	15 (11.7)	12 (16.7)
HER-2 expression				χ2 = 5.624	0.018
Negative	142 (71.0)	85 (66.4)	57 (79.2)
Positive	58 (29.0)	43 (33.6)	15 (20.8)

Data was showed as n (%) or median (Q1, Q3). BMI: Body mass index; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9; CA72-4: Carbohydrate antigen 72-4; HER-2: Human epidermal growth factor receptor-2.

Table 2 Dataset division and feature consistency assessment

Item	Training set (n = 140)	Validation set (n = 60)	Statistical value	P value
Peritoneal metastasis	51 (36.4)	21 (35.0)	χ2 = 0.038	0.845
Age (years)	63 (54, 71)	64 (56, 72)	Z = -0.687	0.492
Gender (male)	94 (67.1)	40 (66.7)	χ2 = 0.004	0.948
Features with ICC ≥ 0.75	3771/3920 (96.2)
Mean ICC (95%CI)	0.892 (0.856-0.921)
Distribution of excluded features
Shape features	2/14 (14.3)
First-order statistical features	15/54 (27.8)
Texture features	38/225 (16.9)
Filter features	94/3627 (2.6)

Data wea showed as n (%) or median (Q1, Q3). ICC: Intraclass correlation coefficient; 95%CI: 95% confidence interval.

Table 3 Radiomics feature selection results

Selection step	Number of features	Selection criteria/method
Feature extraction	3920	All extracted features
Consistency assessment	3771	ICC ≥ 0.75
Univariate screening	628	P < 0.05 (Mann-Whitney U)
Collinearity testing	443	|r|≤ 0.9
LASSO selection results for each model
Arterial phase model	12	λ = 0.024
Venous phase model	15	λ = 0.031
Delayed phase model	11	λ = 0.028
Multiphase combined model	18	λ = 0.019

LASSO: Least absolute shrinkage and selection operator.

Table 4 Performance comparison of different radiomics models (%)

Model	SMOTE-processed training set (n = 178)						Validation set (n = 60)
	AUC (95%CI)	Sensitivity	Specificity	Accuracy	PPV	NPV	AUC (95%CI)	Sensitivity	Specificity	Accuracy	PPV	NPV
Arterial phase	0.801 (0.738-0.857)	73.0	75.3	74.2	74.7	73.6	0.781 (0.661-0.874)	71.4	74.4	73.3	60.0	82.9
Venous phase	0.859 (0.798-0.910)	79.8	80.9	80.3	80.7	80.0	0.834 (0.727-0.915)	76.2	82.1	80.0	69.6	86.5
Delayed phase	0.826 (0.762-0.882)	75.3	77.5	76.4	77.0	75.8	0.806 (0.692-0.894)	71.4	79.5	76.7	65.2	83.8
Multiphase combined	0.894 (0.842-0.936)	85.4	83.1	84.3	83.5	85.1	0.876 (0.783-0.941)	81.0	84.6	83.3	73.9	89.2

SMOTE: Synthetic minority oversampling technique; 95%CI: 95% confidence interval; AUC: Area under the curve; PPV: Positive predictive value; NPV: Negative predictive value.

Table 5 DeLong test comparison of area under the curve between different models

Model comparison	SMOTE-processed training set (n = 178)		Validation set (n = 60)
	AUC difference	P value	AUC difference	P value
Multiphase vs arterial phase	0.093	0.009	0.095	0.025
Multiphase vs venous phase	0.035	0.042	0.042	0.038
Multiphase vs delayed phase	0.068	0.018	0.070	0.032
Venous phase vs arterial phase	0.058	0.028	0.053	0.041
Venous phase vs delayed phase	0.033	0.044	0.028	0.046
Delayed phase vs arterial phase	0.025	0.135	0.025	0.158

SMOTE: Synthetic minority oversampling technique; AUC: Area under the curve.

Table 6 Model calibration and clinical net benefit assessment

Assessment indicator	Multiphase combined model	Venous phase model	Arterial phase model	Delayed phase model
SMOTE-processed training set (n = 178)
H-L test χ2	5.842	8.726	11.245	9.324
H-L test P value	0.664	0.365	0.187	0.316
Calibration curve slope	0.94	0.89	0.85	0.87
Calibration curve intercept	0.08	0.12	0.18	0.15
Validation set (n = 60)
H-L test χ2	4.926	6.542	8.734	7.658
H-L test P value	0.765	0.587	0.365	0.468
Calibration curve slope	0.91	0.86	0.82	0.84
Calibration curve intercept	0.11	0.16	0.21	0.19
Clinical net benefit
Net benefit at threshold probability 0.25	0.224	0.192	0.158	0.176
Avoidable unnecessary surgeries (%)	33.7	28.5	23.2	25.6

SMOTE: Synthetic minority oversampling technique.