A total of 51 gastric cancer patients were included in our final analysis. The clinical characteristics of the included patients are summarized in Table 1.
Table 1 Clinical characteristics of 51 patients with gastric adenocarcinoma
Characteristics
|
Statistics(mean,range)
|
Cancer peoples
|
51
|
Gender(M/F)
|
36/15
|
Age(years)
|
63(44-82)
|
Tumor thickness(cm)
|
1.6(0.8-3.4)
|
Tumor site
|
|
Fundus
|
7(13.8%)
|
Body
|
12(23.5%)
|
Autrum
|
32(62.7%)
|
Histological differentiation degree
|
|
Highly differentiated adenocarcinoma
Moderately differentiated adenocarcinoma
|
6(11.7%)
16(31.4%)
|
Poorly differentiated adenocarcinoma differentiation
|
29(56.9%)
|
LNM
|
|
Yes
|
33(64.7%)
|
No
|
18(35.3%)
|
N-staging
|
|
N0
|
18(35.3%)
|
N1
|
7(13.7%)
|
N2
|
11(21.6%)
|
N3
|
15(29.4%)
|
Comparison of Zeff, nZeff, ID, nID regarding sex, age, location, thickness, differentiation degree, and LN metastasis of gastric adenocarcinoma
The Zeff, nZeff, ID and nID values were slightly higher in male patients than in female patients (P = 0.577, P = 0.507, P = 0.476, and P = 0.342, respectively) (Table 2). However, these differences were not statistically significant. Patients were classified into a young group (age ≤ 63 years) and an old group (age > 63 years). There was no significant difference in Zeff, nZeff, ID and nID values between the two age groups (P = 0.800, P = 0.707, P = 0.778, and P = 0.450, respectively). In addition, patients were divided into a small tumor group (≤ 1.6 cm) and a large tumor group (> 1.6 cm) according to the mean tumor thickness of 1.6 cm. The Zeff, nZeff, ID and nID values of the large tumor group were slightly higher than those of the small tumor group, but these differences were not statistically significant (P = 0.059, P = 0.075, P = 0.163, and P = 0.147, respectively). Similarly, there were no significant differences in Zeff, nZeff, ID and nID values among the three tumor location groups (P = 0.248, P = 0.212, P = 0.237, and P = 0.247, respectively). In addition, due to the limited number of cases, the moderately and highly differentiated gastric adenocarcinoma groups were combined into one group identified as the well-differentiated tumor group (n=6). As shown in Figure 2 and 3, the values of Zeff, nZeff, ID and nID in the poorly differentiated adenocarcinoma group were significantly higher than those in the well-differentiated group (P < 0.001). Moreover, the values of Zeff, nZeff, ID and nID in the group with LN metastasis were significantly higher than those in the group without LN metastasis (P < 0.001).
Table 2 Comparison of venous phase Zeff, nZeff, ID and nID in gastric adenocarcinoma with respect to sex, age, location, thickness, degree of differentiation and lymph node metastasis
|
Clinical features
|
Number of cases
|
Zeff
|
nZeff
|
ID mg/ml
|
nID
|
|
Gender
|
|
|
|
|
|
|
Male
|
36
|
(8.22±0.27)
|
(0.86±0.04)
|
(1.67±0.59)
|
(0.35±0.12)
|
|
Female
|
15
|
(8.18±0.27)
|
(0.85±0.03)
|
(1.54±0.55)
|
(0.31±0.11)
|
|
T value
|
|
-0.565
|
-0,672
|
-0.723
|
-0.968
|
|
P value
|
|
>0.05
|
>0.05
|
>0.05
|
>0.05
|
|
Age
|
|
|
|
|
|
|
Young(≤63 y)
|
26
|
(8.20±0.26)
|
(0.86±0.04)
|
(1.61±0.55)
|
(0.35±0.11)
|
|
Older (>63 y)
|
25
|
(8.22±0.28)
|
(0.86±0.04)
|
(1.66±0.61)
|
(0.32±0.12)
|
|
T value
|
|
-0.283
|
0.378
|
-0.283
|
0.761
|
|
P value
|
|
>0.05
|
>0.05
|
>0.05
|
>0.05
|
|
Thickness
|
|
|
|
|
|
|
Small(≤1.6 cm)
|
31
|
(8.14±0.26)
|
(0.85±0.40)
|
(1.54±0.58)
|
(0.32±1.23)
|
|
Large(> 1.6 cm)
|
20
|
(8.31±0.25)
|
(0.87±0.28)
|
(1.77±0.56)
|
(0.37±0.10)
|
|
T value
|
|
-2.445
|
-1.974
|
-1.428
|
-1.540
|
|
P value
|
|
>0.05
|
>0.05
|
> 0.05
|
> 0.05
|
|
Sites
|
|
|
|
|
|
|
Fundus
|
7
|
(8.34±0.28)
|
(0.89±0.03)
|
(1.95±0.67)
|
(0.40±0.12)
|
|
Body
|
12
|
(8.24±0.23)
|
(0.86±0.04)
|
(1.67±0.48)
|
(0.34±0.12)
|
|
Antrum
|
32
|
(8,17±0.28)
|
(0.85±0.04)
|
(1.55±0.57)
|
(0.31±0.11)
|
|
F value
|
|
1.436
|
1.603
|
1.485
|
1.441
|
|
P value
|
|
> 0.05
|
> 0.05
|
> 0.05
|
> 0.05
|
|
Differentiation degree
|
|
|
|
|
|
|
Well-differentiated
|
22
|
(8.01±0.13)
|
(0.83±0.03)
|
(1.21±0.25)
|
(0.24±0.07)
|
|
Poorly
|
29
|
(8.36±0.25)
|
(0.88±0.02)
|
(1.96±0.54)
|
(0.41±0.09)
|
|
T value
|
|
5.920
|
6.041
|
6.023
|
7.232
|
|
P value
|
|
< 0.001
|
< 0.001
|
< 0.001
|
< 0.001
|
|
Lymph node metastasis
|
|
|
|
|
|
|
No
|
18
|
(8.00±0.19)
|
(0.83±0.04)
|
(1.24±0.41)
|
(0.24±0.10)
|
|
With
|
33
|
(8.32±0.24)
|
(0.87±0.02)
|
(1.84±0.54)
|
(0.39±0.09)
|
|
T value
|
|
-5.312
|
-4.842
|
-4.095
|
-5.435
|
|
P value
|
|
< 0.001
|
< 0.001
|
< 0.001
|
< 0.001
|
Abbreviations: Zeff, effective atomic number; nZeff, normalized effective atomic number; ID, iodine density; nID, normalized iodine density.
Efficacy of Zeff, nZeff, ID and nID in diagnosing the differentiation degree of gastric cancer in the venous phase
The AUCs of the Zeff, nZeff, ID and nID in the venous phase for diagnosing the differentiation of gastric adenocarcinoma were 0.909, 0.888, 0.905 and 0.916, respectively. The AUC of nID in the venous phase was slightly higher than the remaining values (Table 3, Fig. 4). In addition, the sensitivities of Zeff, nZeff, ID and nID were 93.10%, 93.10%, 89.70% and 86.20%, respectively, with Zeff, and nZeff having the highest sensitivity. The specificities were 81.80%, 86.40%, 81.80% and 86.20%, respectively, with a slightly higher specificity of nZeff. Moreover, the optimal cutoff values for Zeff, nZeff, ID and nID were 8.080, 0.856, 1.365 and 0.320 mg/mL, respectively.
Table 3 ROC curve results of Zeff, nZeff, ID and nID for gastric cancer differentiation in the venous phase
ROC
|
Zeff
|
nZeff
|
ID
|
nID
|
Differentiation degree
|
|
|
|
|
AUC
|
0.909
|
0.888
|
0.905
|
0.916
|
sensitivity
|
93.10%
|
93.10%
|
89.70%
|
86.20%
|
specificity
|
81.80%
|
86.40%
|
81.80%
|
90.90%
|
Optimum cutoff values
|
8.080
|
0.856
|
1.365mg/ml
|
0.320
|
Youden index
|
0.749
|
0.795
|
0.715
|
0.771
|
Abbreviations: ROC, receiver operating characteristic curve; Zeff, effective atomic number; nZeff, normalized effective atomic number; ID, iodine density; nID, normalized iodine density
Diagnostic efficacy of Zeff, nZeff, ID and nID in predicting LN metastasis of gastric adenocarcinoma in venous phase
The venous phase AUC values of Zeff, nZeff, ID and nID for predicting LN metastasis of gastric adenocarcinoma were 0.888, 0.824, 0.828 and 0.892, respectively, with higher Zeff and nID (Table 4, Fig 5). In addition, the sensitivities of Zeff, nZeff, ID and nID were 87.90%, 84.80%, 84.80% and 97.0%, respectively, while the specificities were 83.30%, 72.20%, 83.30% and 72.20%. Furthermore, the optimal cut-off values for Zeff, nZeff, ID and nID were 8.060, 0.845, 1.325 and 0.245 mg/mL, respectively.
Table 4 Results of ROC of venous phase Zeff, nZeff, ID and nID in predicting LN metastasis in gastric adenocarcinoma
ROC
|
Zeff
|
nZeff
|
ID
|
nID
|
Lymph node metastasis
|
|
|
|
|
AUC
|
0.888
|
0.824
|
0.828
|
0.892
|
sensitivity
|
87.90%
|
84.80%
|
84.80%
|
97.00%
|
specificity
|
83.30%
|
72.20%
|
83.30%
|
72.20%
|
Optimum cutoff values
|
8.060
|
0.845
|
1.325
|
0.245
|
Youden index
|
0.712
|
0.571
|
0.682
|
0.692
|
Abbreviations: ROC, receiver operating characteristic curve; Zeff, effective atomic number; nZeff, normalized effective atomic number; ID, iodine density; nID, normalized iodine density
Correlation of Zeff, nZeff, ID, nID with N stage in gastric adenocarcinoma lesions
Spearman rank correlation was used to analyze the correlation between Zeff, nZeff, ID, nID and N stage of gastric cancer lesions. The results showed that Zeff, nZeff, ID, nID in the venous phase of gastric adenocarcinoma lesions were positively correlated with the N stage (rs=0.684, rs=0.539, rs=0.591, rs=0.644, P<0.05). The venous phase Zeff of gastric cancer lesions had the best correlation with N staging.