Multi-modal radiomics model to predict treatment response to neoadjuvant chemotherapy for locally advanced rectal cancer

Table 1 Clinical characteristics of patients in training and validation cohorts, n (%)

Variable	Training cohort, n = 70			Validation cohort, n = 48
	Response, n = 48	Non-response, n = 22	P value	Response, n = 32	Non-response, n = 16	P value
T3	9 (18.8)	0 (0)	0.002	9 (28.1)	0 (0)	0.03
T4a	31 (64.6)	10 (45.5)		16 (50)	8 (50)
T4b	8 (16.7)	12 (54.6)		7 (21.9)	8 (50)
N0	8 (16.7)	1 (4.6)	0.4	6 (18.8)	2 (12.5)	0.6
N1	26 (54.2)	13 (59.1)		13 (40.6)	9 (56.3)
N2	14 (29.2)	8 (36.4)		13 (40.6)	5 (31.3)
Site: Ultralow	2 (4.2)	1 (4.55)	0.2	4 (12.5)	1 (6.3)	0.01
Site: Low	34 (70.8)	12 (54.6)		21 (65.6)	5 (31.3)
Site: High	12 (25)	9 (40.9)		7 (21.9)	10 (62.5)
EMVI positive	33 (68.8)	5 (22.7)	< 0.001	24 (75)	2 (12.5)	< 0.001
EMVI negative	15 (31.3)	17 (77.3)		8 (25)	14 (87.5)
Female	14 (29.2)	10 (45.5)	0.2	9 (28.1)	6 (37.5)	0.5
Male	34 (70.8)	12 (54.6)		23 (71.9)	10 (62.5)
CEA ≤ 3.4	32 (66.7)	14 (63.6)	0.8	21 (65.6)	12 (75)	0.5
CEA > 3.4	16 (33.3)	8 (36.4)		11 (34.4)	4 (25)
CA199 ≤ 22	39 (81.3)	19 (86.4)	0.6	29 (90.6)	14 (87.5)	0.7
CA199 > 22	9 (18.8)	3 (13.6)		3 (9.4)	2 (12.50)
Age in yr	59.2 ± 9.7	54.8 ± 10.5	0.09	60.8 ± 9.6	55.3 ± 11.1	0.08
BMI in kg/m2	22.9 ± 3.2	23.1 ± 3.2	0.8	22.8 ± 3.4	23.3 ± 2.9	0.6
Hb in g/L	134.8 ± 20.5	127.9 ± 19.5	0.2	131.4 ± 19.5	127.1 ± 22.2	0.5

Site: Ultralow: Lower margin of tumor involves anal canal; Site low: Lower margin of tumor is below peritoneal reflection; Site: High: Lower margin of tumor is above peritoneal reflection; EMVI: Extramural venous invasion; CEA: Carcinoembryonic antigen; CA199: Carbohydrate antigen199; BMI: Body mass index; Hb: Hemoglobin.

Table 2 Performance of optimal radiomic signatures

Characteristic	AUC	95%CI	Cut-off	ACC	Specificity	Sensitivity
EMVI
Training	0.73	0.619-0.842	0.331	0.714	0.688	0.773
Validation	0.578	0.426-0.731		0.583	0.594	0.562
CT
Training	0.809	0.745-0.872	0.5	0.818	0.875	0.742
Validation	0.766	0.632-0.899		0.792	0.844	0.688
DCE-T1
Training	0.848	0.79-0.907	0.5	0.818	0.875	0.742
Validation	0.812	0.688-0.937		0.854	0.938	0.688
HR-T2WI
Training	0.845	0.786-0.903	0.5	0.857	0.932	0.758
Validation	0.859	0.746-0.973		0.896	0.969	0.75
ADC
Training	0.847	0.789-0.904	0.5	0.844	0.83	0.864
Validation	0.828	0.71-0.946		0.833	0.844	0.812
CRM
Training	0.921	0.842-1	0.318	0.886	0.854	0.955
Validation	0.908	0.823-0.994		0.812	0.812	0.812
MRM
Training	0.925	0.845-1	0.447	0.886	0.896	0.864
Validation	0.93	0.86-1		0.875	0.875	0.875

EMVI: Extramural venous invasion; CT: Computed tomography; DCE-T1: Dynamic contrast enhanced T1 images; HR-T2WI: High resolution T2-weighted imaging; ADC: Apparent diffusion coefficient; CRM: Combined radiomic model; MRM: Multi-modal radiomics model; AUC: Area under the curve; CI: Confidence interval; ACC: Accuracy.