Prediction of lymphovascular invasion in rectal cancer based on multimodal magnetic resonance imaging radiomics model

Table 1 Patient baseline characteristics, n (%)/mean ± SD/median (interquartile range)

Characteristic	Overall (n = 278)	Training set (n = 222)	Test set (n = 56)	LVI-negative (n = 157)	LVI-positive (n = 121)	Test statistic	P value
Age (years)	62.5 ± 11.8	62.3 ± 11.9	63.2 ± 11.4	61.8 ± 12.2	63.4 ± 11.2	1.148	0.254
Gender						4.651	0.031
Male	164 (59.0)	131 (59.0)	33 (58.9)	85 (54.1)	79 (65.3)
Female	114 (41.0)	91 (41.0)	23 (41.1)	72 (45.9)	42 (34.7)
Maximum tumor diameter (cm)	4.2 ± 1.6	4.1 ± 1.5	4.5 ± 1.8	3.8 ± 1.4	4.7 ± 1.7	4.982	< 0.001
CEA (ng/mL)	8.4 (3.2-21.6)	8.1 (3.1-20.8)	9.2 (3.5-24.1)	5.8 (2.8-15.2)	14.2 (5.7-35.8)	4.521	< 0.001
CA19-9 (U/mL)	18.3 (8.7-42.5)	17.9 (8.5-41.2)	19.8 (9.2-45.7)	15.1 (7.8-28.6)	25.8 (12.4-58.9)	2.947	0.003
Differentiation grade						22.184	< 0.001
Well-differentiated	45 (16.2)	37 (16.7)	8 (14.3)	35 (22.3)	10 (8.3)
Moderately-differentiated	198 (71.2)	158 (71.2)	40 (71.4)	115 (73.2)	83 (68.6)
Poorly-differentiated	35 (12.6)	27 (12.2)	8 (14.3)	7 (4.5)	28 (23.1)
T stage						28.756	< 0.001
T1-T2	67 (24.1)	54 (24.3)	13 (23.2)	52 (33.1)	15 (12.4)
T3	156 (56.1)	124 (55.9)	32 (57.1)	92 (58.6)	64 (52.9)
T4	55 (19.8)	44 (19.8)	11 (19.6)	13 (8.3)	42 (34.7)
N stage						18.942	< 0.001
N0	142 (51.1)	114 (51.4)	28 (50.0)	98 (62.4)	44 (36.4)
N1	98 (35.3)	78 (35.1)	20 (35.7)	47 (29.9)	51 (42.1)
N2	38 (13.7)	30 (13.5)	8 (14.3)	12 (7.6)	26 (21.5)
Perineural invasion						24.317	< 0.001
Negative	201 (72.3)	161 (72.5)	40 (71.4)	132 (84.1)	69 (57.0)
Positive	77 (27.7)	61 (27.5)	16 (28.6)	25 (15.9)	52 (43.0)

CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9; LVI: Lymphovascular invasion.

Table 2 Radiomics feature selection results

Selection step	FS-T2WI	DWI	T1CE	Total
Initial features	1425	1385	1390	4200
After ICC screening (> 0.75)	1182	1143	1198	3523
After variance screening	1094	1048	1129	3271
After correlation screening (|r| < 0.9)	674	638	691	2003
After univariate screening (P < 0.05)	121	94	135	350
After LASSO screening	8	6	9	23

FS-T2WI: Fat-suppressed T2-weighted imaging; DWI: Diffusion-weighted imaging; T1CE: T1-weighted contrast-enhanced imaging; ICC: Intraclass correlation coefficient; LASSO: Least absolute shrinkage and selection operator.

Table 3 Logistic regression analysis of lymphovascular invasion predictors

Variable	Univariate analysis		Multivariate analysis
	OR (95%CI)	P value	OR (95%CI)	P value
Gender (male vs female)	1.590 (1.037-2.438)	0.032	1.421 (0.859-2.351)	0.168
Tumor diameter (≥ 4 cm vs < 4 cm)	2.834 (1.781-4.504)	< 0.001	2.142 (1.251-3.668)	0.006
CEA (≥ 5 ng/mL vs < 5 ng/mL)	2.953 (1.712-5.088)	< 0.001	2.261 (1.224-4.191)	0.009
CA19-9 (≥ 37 U/mL vs < 37 U/mL)	1.892 (1.181-3.031)	0.008	1.354 (0.782-2.334)	0.284
Differentiation (poor vs well/moderate)	4.571 (2.451-8.529)	< 0.001	3.824 (1.912-7.654)	< 0.001
T stage (T3-4 vs T1-2)	3.421 (1.889-6.194)	< 0.001	2.581 (1.329-5.003)	0.005
N stage (N1-2 vs N0)	2.903 (1.831-4.604)	< 0.001	2.314 (1.381-3.872)	0.001
Perineural invasion (positive vs negative)	3.984 (2.318-6.837)	< 0.001	2.951 (1.612-5.406)	< 0.001

CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9; OR: Odds ratio; CI: Confidence interval.

Table 4 Performance of different models on training and test sets

Model	Training set			Test set
	AUC (95%CI)	Sensitivity	Specificity	AUC (95%CI)	Sensitivity	Specificity
FS-T2WI	0.756 (0.693-0.819)	0.729	0.714	0.742 (0.615-0.869)	0.720	0.710
DWI	0.721 (0.655-0.787)	0.687	0.698	0.708 (0.574-0.842)	0.680	0.677
T1CE	0.789 (0.730-0.848)	0.771	0.730	0.775 (0.654-0.896)	0.760	0.742
Multimodal radiomics	0.847 (0.796-0.898)	0.823	0.794	0.835 (0.732-0.938)	0.840	0.774
Clinical model	0.798 (0.738-0.858)	0.750	0.762	0.782 (0.660-0.904)	0.720	0.774
Combined model	0.883 (0.840-0.926)	0.844	0.825	0.867 (0.778-0.956)	0.840	0.806

AUC: Area under the curve; CI: Confidence interval; FS-T2WI: Fat-suppressed T2-weighted imaging; DWI: Diffusion-weighted imaging; T1CE: T1-weighted contrast-enhanced imaging.