Correlation between baseline magnetic resonance imaging features and serum carcinoembryonic antigen levels in patients with primary rectal cancer

Table 1 Baseline characteristics of patients

Characteristic	n	Percentage
Age (years)	42-78
Average value (mean ± SD)	62.3 ± 8.7
Gender
Male	44	55.0
Female	36	45.0
Body mass index (kg/m²)	18.5-29.6
Average value (mean ± SD)	24.1 ± 3.4
Tumor location
Upper rectum	12	15.0
Middle rectum	34	42.5
Lower rectum	34	42.5

Table 2 Univariate analysis of magnetic resonance imaging features and serum carcinoembryonic antigen levels

Magnetic resonance imaging feature	n	Serum carcinoembryonic antigen level (ng/mL) (mean ± SD)	r value	P value
Tumor size (cm)			0.456	< 0.01
≤ 4	40	5.2 ± 1.8
> 4	40	8.3 ± 2.5
T-stage			0.387	< 0.01
T1-T2	30	4.8 ± 1.6
T3-T4	50	8.1 ± 2.9
Circumferential resection margin			0.325	< 0.05
Positive	28	8.9 ± 3.3
Negative	52	5.2 ± 2.1
Extramural vascular invasion			0.298	< 0.05
Yes	35	7.8 ± 2.7
No	45	5.3 ± 2.3
Lymph node metastasis			0.356	< 0.01
Yes	40	8.5 ± 2.8
No	40	4.9 ± 1.9

Table 3 Multivariate logistic regression analysis of factors associated with serum carcinoembryonic antigen levels

Independent variable	B	SE	Wald	Odds ratio	95%CI	P value
Tumor size	0.942	0.256	13.578	2.563	1.562-4.208	< 0.01
T-stage	0.629	0.201	9.745	1.875	1.236-2.847	< 0.01
Circumferential resection margin status	0.212	0.198	1.146	1.234	0.856-1.782	> 0.05
Extramural vascular invasion	0.145	0.205	0.503	1.156	0.789-1.697	> 0.05
Lymph node metastasis	0.521	0.239	4.736	1.684	1.057-2.685	< 0.05

B: Regression coefficient.

Table 4 Construction process of the prediction model and performance analysis indicators

Indicator	Value
Sensitivity (%)	76.5
Specificity (%)	82.3
Area under the curve	0.856
95%CI	0.782-0.930
P value of Hosmer-Lemeshow test	0.765

Table 5 Performance analysis of the prediction model in different subgroups

Subgroup	n	Area under the curve	95%CI
Stage T1-T2 and no lymph node metastasis	18	0.735	0.623-0.847
Stage T1-T2 and with lymph node metastasis	12	0.802	0.698-0.906
Stage T3-T4 and no lymph node metastasis	21	0.834	0.721-0.947
Stage T3-T4 and with lymph node metastasis	19	0.912	0.835-0.989