Value of 18F-FDG PET-CT in surveillance of postoperative colorectal cancer patients with various carcinoembryonic antigen concentrations

Table 1 Characteristics of patients in the study

Characteristic	n
Male/female	71/35
Age (yr, median)	27-75 (56)
Primary site
Colon	42
Rectum	64
Pathological type
Adenocarcinoma	94
Adenosquamous carcinoma	2
Squamous cell carcinoma	1
Mucinous adenocarcinoma	9
Therapy
Operation	21
Operation and chemotherapy	13
Operation and radiotherapy	37
Operation, chemotherapy and radiotherapy	35

Table 2 Intersections of positron emission tomography/computerized tomography and computerized tomography diagnoses

CT (n = 106)	PET/CT (n = 106)
	TP (n = 79)	FP (n = 4)	TN (n = 19)	FN (n = 4)
TP (n = 67)	67
FP (n = 6)		4	2
TN (n = 17)			17
FN (n = 16)	12			4

PET: Positron emission tomography; CT: Computerized tomography; TP: Ture positive, FP: False positive; TN: True negative; FN: False negative.

Table 3 Diagnostic performance comparisons in case-based and lesion-based analyses

	PET/CT and CT in all patients		PET/CT in patients with different CEA levels
	PET/CT	CT	PET/CT (CEA ≤ 3.4 ng/mL)	PET/CT (CEA > 3.4 ng/mL)
Case-based analysis
Sensitivity (%)	95.2 (79/83)1	80.7 (67/83)1	83.3 (10/12)	97.2 (69/71)
Specificity (%)	82.6 (19/23)	73.9 (17/23)	85.7 (12/14)	77.8 (7/9)
Accuracy (%)	92.5 (98/106)2	79.3 (84/106)2	84.6 (22/26)	95 (76/80)
Lesion-based analysis
Sensitivity (%)	96.1 (146/152)3	83.1 (118/142)3	81.3 (13/16)5	97.8 (133/136)5
Specificity (%)	81.4 (35/43)	73.5 (25/34)	80 (16/20)	82.6 (19/23)
Accuracy (%)	92.8 (181/195)4	81.3 (143/176)4	80.6 (29/36)6	95.6 (152/159)6

¹χ² = 8.186, P = 0.004;

²χ² = 6.201, P = 0.013;

³χ² = 13.445, P = 0.000;

⁴χ² = 11.194, P = 0.001;

⁵χ² = 6.432, P = 0.011;

⁶χ² = 7.837, P = 0.005. PET: Positron emission tomography; CT: Computerized tomography; CRC: Colorectal cancer.

Table 4 Diagnostic performance of positron emission tomography/computerized tomography and computerized tomography in patients with various carcinoembryonic antigen levels

CEA level (ng/mL)	CT (%)			PET/CT (%)
	Sensitivity	Specificity	Accuracy	Sensitivity	Specificity	Accuracy
≤ 3.4 (n = 26)	57.1 (8/14)	75 (9/12)	65.4 (17/26)	83.3 (10/12)	85.7 (12/14)	84.6 (22/26)
3.4-10 (n = 29)	78.3 (18/23)	66.7 (4/6)	75.9 (22/29)	96 (24/25)	75 (3/4)	93.1 (27/29)
10-30 (n = 34)	86.7 (26/30)	75 (3/4)	85.3 (29/34)	96.7 (29/30)	75 (3/4)	94.1 (32/34)
> 30 (n = 17)	93.8 (15/16)	100 (1/1)	94.1 (16/17)	100 (16/16)	100 (1/1)	100 (17/17)

PET: Positron emission tomography; CT: Computerized tomography; CRC: Colorectal cancer; CEA: Carcinoembryonic antigen.

Table 5 Positron emission tomography/computerized tomography scan and change of management

	Surgery	Radiotherapy	Chemotherapy	Chemoradiotherapy
Added cases (n = 23)	6	3	9	5
Reduced cases (n = 15)	8	2	3	2
Total (n = 38)	14	5	12	7

PET: Positron emission tomography; CT: Computerized tomography.