Multiparameter magnetic resonance imaging-based radiomics model for the prediction of rectal cancer metachronous liver metastasis

Table 1 Patient baseline characteristics and magnetic resonance imaging radiomics parameters, n (%)

Variables	Overall (n = 301)	MLM (n = 49)	Non-MLM (n = 252)	P value
Age [median (IQR)]	46.00 (31.00, 58.00)	51.00 (32.00, 60.00)	44.50 (30.00, 57.00)	0.074
Gender
Male	136 (45.2)	22 (44.9)	114 (45.2)	1.000
Female	165 (54.8)	27 (55.1)	138 (54.8)
BMI, kg/m2 [median (IQR)]	23.50 (20.80, 26.10)	22.90 (20.70, 26.60)	23.55 (20.80, 26.02)	0.870
Smoking
Yes	140 (46.5)	26 (53.1)	114 (45.2)	0.396
No	161 (53.5)	23 (46.9)	138 (54.8)
Drinking
Yes	142 (47.2)	22 (44.9)	120 (47.6)	0.847
No	159 (52.8)	27 (55.1)	132 (52.4)
MTD, cm
≤ 4	147 (48.8)	25 (51.0)	122 (48.4)	0.859
> 4	154 (51.2)	24 (49.0)	130 (51.6)
Pathological grade
I-II	142 (47.2)	17 (34.7)	125 (49.6)	0.079
III	159 (52.8)	32 (65.3)	127 (50.4)
Pathological type
Infiltrating	38 (12.6)	4 (8.2)	34 (13.5)	0.700
Ulcerative	111 (36.9)	18 (36.7)	93 (36.9)
Cauliflower	74 (24.6)	12 (24.5)	62 (24.6)
Uplift	78 (25.9)	15 (30.6)	63 (25.0)
MRF
Yes	162 (53.8)	23 (46.9)	139 (55.2)	0.368
No	139 (46.2)	26 (53.1)	113 (44.8)
EMVI
Yes	154 (51.2)	26 (53.1)	128 (50.8)	0.893
No	147 (48.8)	23 (46.9)	124 (49.2)
Node
Yes	133 (44.2)	26 (53.1)	107 (42.5)	0.226
No	168 (55.8)	23 (46.9)	145 (57.5)
Spicule
Yes	164 (54.5)	28 (57.1)	136 (54.0)	0.801
No	137 (45.5)	21 (42.9)	116 (46.0)
AFP, ng/mL [median (IQR)]	2.81 (2.25, 3.41)	2.69 (2.16, 3.32)	2.82 (2.27, 3.42)	0.334
CA199, U/mL [median (IQR)]	9.61 (6.60, 12.66)	9.83 (6.64, 11.47)	9.59 (6.54, 12.73)	0.856
CEA, ng/mL [median (IQR)]
0-5	167 (55.5)	14 (28.6)	153 (60.7)	< 0.001
≥ 5	134 (44.5)	35 (71.4)	99 (39.3)
pT stage
T2	158 (52.5)	30 (61.2)	128 (50.8)	0.237
T3	143 (47.5)	19 (38.8)	124 (49.2)
N stage
N0	94 (31.2)	16 (32.7)	78 (31.0)	0.936
N1	102 (33.9)	17 (34.7)	85 (33.7)
N2	105 (34.9)	16 (32.7)	89 (35.3)
Character 1 [median (IQR)]	0.46 (0.31, 0.63)	1.65 (1.44, 1.98)	0.41 (0.28, 0.55)	< 0.001
Character 2 [median (IQR)]	8.70 (7.70, 9.60)	13.00 (11.80, 14.80)	8.30 (7.57, 9.10)	< 0.001
Character 3 [median (IQR)]	169.30 (140.90, 198.10)	167.80 (145.20, 194.70)	172.25 (139.95, 198.25)	0.976
Character 4 [median (IQR)]	1.70 (1.20, 2.40)	4.50 (3.60, 5.10)	1.60 (1.10, 2.10)	< 0.001
Character 5 [median (IQR)]	3.60 (2.90, 4.20)	6.70 (4.80, 8.80)	3.40 (2.70, 4.00)	< 0.001
Character 6 [median (IQR)]	32.30 (22.30, 42.50)	29.80 (23.00, 39.30)	32.75 (22.08, 43.00)	0.364
Character 7 [median (IQR)]	4.20 (2.80, 5.30)	7.20 (5.90, 8.10)	3.75 (2.60, 4.80)	< 0.001

MLM: Metachronous liver metastasis; IQR: Interquartile range; BMI: Body mass index; MTD: Maximum tumor diameter; MRF: Mesenteric fascia; EMVI: Extramural venous invasion; AFP: Alpha fetoprotein; CA199: Carbohydrate antigen 199; CEA: Carcinoembryonic antigen; Character 1: T2_wavelet.LHL_firstorder_RobustMeanAbsoluteDeviation; Character 2: T1_log.sigma10.mm.3D_firstorder_Kurtosis; Character 3: T1_lbp.3D.m1_firstorder_Skewness; Character 4: ADC_wavelet.LHL_gldm_LargeDepenceHighGrayLevelEmphasis; Character 5: ADC_wavelet.HLL_glrlm_LongRunHighGrayLeveEmphasis; Character 6: T1_log.sigma30.mm.3D_glrlm_GrayLevelNonUniformity; Character 7: T1_wavelet.HHL_glszm_GrayLevelNonUniformity.

Table 2 Selection of metachronous liver metastasis predictive variables based on logistic regression

Variables	Univariate			Multivariate
	OR	95%CI	P value	OR	95%CI	P value
Age [median (IQR)]	1.02	0.55-1.72	> 0.05
Gender
Male	1.00
Female	0.86	0.23-1.02	> 0.05
BMI, kg/m2 [median (IQR)]	1.21	0.78-1.87	> 0.05
Smoking
Yes	1.00
No	0.79	0.18-1.16	> 0.05
Drinking
Yes	1.00
No	0.81	0.23-2.57	> 0.05
MTD, cm
≤ 4	1.00
> 4	1.16	0.77-3.98	> 0.05
Pathological grade
I-II	1.00
III	1.23	0.91-2.26	> 0.05
Pathological type
Infiltrating	1.00
Ulcerative	0.63	0.12-1.16	> 0.05
Cauliflower	0.78	0.23-1.65	> 0.05
Uplift	1.12	0.88-2.37	> 0.05
MRF
Yes	1.00
No	0.63	0.22-1.19	> 0.05
EMVI
Yes	1.00
No	0.67	0.11-1.59	> 0.05
Node
Yes	1.00
No	0.82	0.41-2.16	> 0.05
Spicule
Yes	1.00
No	0.58	0.21-2.26	> 0.05
AFP, ng/mL [median (IQR)]	1.23	0.88-1.77	> 0.05
CA199, U/mL [median (IQR)]	1.15	0.91-1.65	> 0.05
CEA, ng/mL [median (IQR)]	2.13	1.03-4.57	< 0.05	2.11	1.01-4.12	< 0.05
pT stage
T2	1.00
T3	1.13	0.75-2.16	> 0.05
N stage
N0	1.00
N1	1.13	0.86-1.87	> 0.05
N2	1.21	0.99-2.14	> 0.05
Character 1 [median (IQR)]	1.23	0.77-1.96	< 0.05	1.19	0.87-2.16	< 0.05
Character 2 [median (IQR)]	2.67	1.12-4.13	< 0.05	2.58	1.14-3.99	< 0.05
Character 3 [median (IQR)]	1.58	0.88-2.03	> 0.05
Character 4 [median (IQR)]	1.06	0.56-1.87	< 0.05	1.13	0.61-1.94	< 0.05
Character 5 [median (IQR)]	0.98	0.23-1.56	< 0.05	0.91	0.19-2.06	< 0.05
Character 6 [median (IQR)]	1.87	1.02-2.76	> 0.05
Character 7 [median (IQR)]	2.23	1.11-3.87	< 0.05	2.09	1.05-3.55	< 0.05

OR: Odds ratio; CI: Confidence interval; IQR: Interquartile range; BMI: Body mass index; MTD: Maximum tumor diameter; MRF: Mesenteric fascia; EMVI: Extramural venous invasion; AFP: Alpha fetoprotein; CA199: Carbohydrate antigen 199; CEA: Carcinoembryonic antigen; Character 1: T2_wavelet.LHL_firstorder_RobustMeanAbsoluteDeviation; Character 2: T1_log.sigma10.mm.3D_firstorder_Kurtosis; Character 3: T1_lbp.3D.m1_firstorder_Skewness; Character 4: ADC_wavelet.LHL_gldm_LargeDepenceHighGrayLevelEmphasis; Character 5: ADC_wavelet.HLL_glrlm_LongRunHighGrayLeveEmphasis; Character 6: T1_log.sigma30.mm.3D_glrlm_GrayLevelNonUniformity; Character 7: T1_wavelet.HHL_glszm_GrayLevelNonUniformity.

Table 3 Evaluation of predictive performance of metachronous liver metastasis prediction model based on receiver operating characteristic

Prediction model	Training set				International set
	AUC	95%CI	PPV	NPV	AUC	95%CI	PPV	NPV
RFM	0.919	0.868-0.970	0.94	0.99	0.901	0.850-0.952	0.94	0.99
GLRM	0.765	0.710-0.820	0.75	0.98	0.767	0.712-0.822	0.64	0.94

AUC: Area under the curve; CI: Confidence interval; PPV: Positive predictive value; NPV: Negative predictive value; RFM: Random forest model; GLRM: Generalized linear regression.