Contribution of DECT in detecting serosal invasion of gastric cancer

A quantitative model using multi-parameters in dual-energy CT to preoperatively predict serosal invasion in locally advanced gastric cancer

OBJECTIVES

To develop and validate a quantitative model for predicting serosal invasion based on multi-parameters in preoperative dual-energy CT (DECT).

MATERIALS AND METHODS

A total of 342 LAGC patients who underwent gastrectomy and DECT from six centers were divided into one training cohort (TC), and two validation cohorts (VCs). Dual-phase enhanced DECT-derived iodine concentration (IC), water concentration, and monochromatic attenuation of lesions, along with clinical information, were measured and collected. The independent predictors among these characteristics for serosal invasion were screened with Spearman correlation analysis and logistic regression (LR) analysis. A quantitative model was developed based on LR classifier with fivefold cross-validation for predicting the serosal invasion in LAGC. We comprehensively tested the model and investigated its value in survival analysis.

RESULTS

A quantitative model was established using IC, 70 keV, 100 keV monochromatic attenuations in the venous phase, and CT-reported T4a, which were independent predictors of serosal invasion. The proposed model had the area-under-the-curve (AUC) values of 0.889 for TC and 0.860 and 0.837 for VCs. Subgroup analysis showed that the model could well discriminate T3 from T4a groups, and T2 from T4a groups in all cohorts (all p < 0.001). Besides, disease-free survival (DFS) (TC, p = 0.015; and VC1, p = 0.043) could be stratified using this quantitative model.

CONCLUSION

The proposed quantitative model using multi-parameters in DECT accurately predicts serosal invasion for LAGC and showed a significant correlation with the DFS of patients.

CRITICAL RELEVANCE STATEMENT

This quantitative model from dual-energy CT is a useful tool for predicting the serosal invasion of locally advanced gastric cancer.

KEY POINTS

Serosal invasion is a poor prognostic factor in locally advanced gastric cancer that may be predicted by DECT. DECT quantitative model for predicting serosal invasion was significantly and positively correlated with pathologic T stages. This quantitative model was associated with patient postoperative disease-free survival.

Quantitative parameters in novel spectral computed tomography: Assessment of Ki-67 expression in patients with gastric adenocarcinoma

BACKGROUND

The level of Ki-67 expression has served as a prognostic factor in gastric cancer. The quantitative parameters based on the novel dual-layer spectral detector computed tomography (DLSDCT) in discriminating the Ki-67 expression status are unclear.

AIM

To investigate the diagnostic ability of DLSDCT-derived parameters for Ki-67 expression status in gastric carcinoma (GC).

METHODS

Dual-phase enhanced abdominal DLSDCT was performed preoperatively in 108 patients with gastric adenocarcinoma. Primary tumor monoenergetic CT attenuation value at 40-100 kilo electron volt (kev), the slope of the spectral curve (λ_HU), iodine concentration (IC), normalized IC (nIC), effective atomic number (Z^eff) and normalized Z^eff (nZ^eff) in the arterial phase (AP) and venous phase (VP) were retrospectively compared between patients with low and high Ki-67 expression in gastric adenocarcinoma. Spearman’s correlation coefficient was used to analyze the association between the above parameters and Ki-67 expression status. Receiver operating characteristic (ROC) curve analysis was performed to compare the diagnostic efficacy of the statistically significant parameters between two groups.

RESULTS

Thirty-seven and 71 patients were classified as having low and high Ki-67 expression, respectively. CT_{40 kev-VP}, CT_{70 kev-VP}, CT_{100 kev-VP}, and Z^eff-related parameters were significantly higher, but IC-related parameters were lower in the group with low Ki-67 expression status than the group with high Ki-67 expression status, and other analyzed parameters showed no statistical difference between the two groups. Spearman’s correlation analysis showed that CT_{40 kev-VP}, CT_{70 kev-VP}, CT_{100 kev-VP}, Z^eff, and nZ^eff exhibited a negative correlation with Ki-67 status, whereas IC and nIC had positive correlation with Ki-67 status. The ROC analysis demonstrated that the multi-variable model of spectral parameters performed well in identifying the Ki-67 status [area under the curve (AUC) = 0.967; sensitivity 95.77%; specificity 91.89%)]. Nevertheless, the differentiating capabilities of single-variable model were moderate (AUC value 0.630 - 0.835). In addition, the nZ^eff_VP and nIC_VP (AUC 0.835 and 0.805) showed better performance than CT_{40 kev-VP}, CT_{70 kev-VP} and CT_{100 kev-VP} (AUC 0.630, 0.631 and 0.662) in discriminating the Ki-67 status.

CONCLUSION

Quantitative spectral parameters are feasible to distinguish low and high Ki-67 expression in gastric adenocarcinoma. Z^eff and IC may be useful parameters for evaluating the Ki-67 expression.

Quantitative parameters in novel spectral computed tomography: Assessment of Ki-67 expression in patients with gastric adenocarcinoma

BACKGROUND

The level of Ki-67 expression has served as a prognostic factor in gastric cancer. The quantitative parameters based on the novel dual-layer spectral detector computed tomography (DLSDCT) in discriminating the Ki-67 expression status are unclear.

AIM

To investigate the diagnostic ability of DLSDCT-derived parameters for Ki-67 expression status in gastric carcinoma (GC).

METHODS

Dual-phase enhanced abdominal DLSDCT was performed preoperatively in 108 patients with gastric adenocarcinoma. Primary tumor monoenergetic CT attenuation value at 40-100 kilo electron volt (kev), the slope of the spectral curve (λ_HU), iodine concentration (IC), normalized IC (nIC), effective atomic number (Z^eff) and normalized Z^eff (nZ^eff) in the arterial phase (AP) and venous phase (VP) were retrospectively compared between patients with low and high Ki-67 expression in gastric adenocarcinoma. Spearman’s correlation coefficient was used to analyze the association between the above parameters and Ki-67 expression status. Receiver operating characteristic (ROC) curve analysis was performed to compare the diagnostic efficacy of the statistically significant parameters between two groups.

RESULTS

Thirty-seven and 71 patients were classified as having low and high Ki-67 expression, respectively. CT_{40 kev-VP}, CT_{70 kev-VP}, CT_{100 kev-VP}, and Z^eff-related parameters were significantly higher, but IC-related parameters were lower in the group with low Ki-67 expression status than the group with high Ki-67 expression status, and other analyzed parameters showed no statistical difference between the two groups. Spearman’s correlation analysis showed that CT_{40 kev-VP}, CT_{70 kev-VP}, CT_{100 kev-VP}, Z^eff, and nZ^eff exhibited a negative correlation with Ki-67 status, whereas IC and nIC had positive correlation with Ki-67 status. The ROC analysis demonstrated that the multi-variable model of spectral parameters performed well in identifying the Ki-67 status [area under the curve (AUC) = 0.967; sensitivity 95.77%; specificity 91.89%)]. Nevertheless, the differentiating capabilities of single-variable model were moderate (AUC value 0.630 - 0.835). In addition, the nZ^eff_VP and nIC_VP (AUC 0.835 and 0.805) showed better performance than CT_{40 kev-VP}, CT_{70 kev-VP} and CT_{100 kev-VP} (AUC 0.630, 0.631 and 0.662) in discriminating the Ki-67 status.

CONCLUSION

Quantitative spectral parameters are feasible to distinguish low and high Ki-67 expression in gastric adenocarcinoma. Z^eff and IC may be useful parameters for evaluating the Ki-67 expression.

Gastrointestinal Applications of Iodine Quantification Using Dual-Energy CT: A Systematic Review

Dual-energy computed tomography (DECT) can estimate tissue vascularity and perfusion via iodine quantification. The aim of this systematic review was to outline current and emerging clinical applications of iodine quantification within the gastrointestinal tract using DECT. The search was conducted with three databases: EMBASE, Pubmed and The Cochrane Library. This identified 449 studies after duplicate removal. From a total of 570 selected studies, 30 studies were enrolled for the systematic review. The studies were categorized into four main topics: gastric tumors (12 studies), colorectal tumors (8 studies), Crohn’s disease (4 studies) and miscellaneous applications (6 studies). Findings included a significant difference in iodine concentration (IC) measurements in perigastric fat between T1–3 vs. T4 stage gastric cancer, poorly and well differentiated gastric and colorectal cancer, responders vs. non-responders following chemo- or chemoradiotherapy treatment among cancer patients, and a positive correlation between IC and Crohn’s disease activity. In conclusion, iodine quantification with DECT may be used preoperatively in cancer imaging as well as for monitoring treatment response. Future studies are warranted to evaluate the capabilities and limitations of DECT in splanchnic flow.

Radiologic serosal invasion sign as a new criterion of T4a gastric cancer on computed tomography: diagnostic performance and prognostic significance in patients with advanced gastric cancer

PURPOSE

To investigate the diagnostic performance and prognostic significance of a new criterion for radiologic T4a staging on computed tomography (CT) in patients with advanced gastric cancer (AGC).

METHODS

Between January 2010 and April 2019, 101 patients with pathologically confirmed gastric cancer were collected. Among them, 53 patients with pathologic T3 and T4a cancers were included in this study. Three reviewers assessed preoperative CT scans for radiologic T staging in two sessions, independently and in consensus at a 2-week interval, while blinded about the pathologic T stage. The radiologic serosal invasion sign was defined as a nodular extension from the outer gastric wall reaching beyond the perigastric vascular plane and adopted as a new CT criterion for T4a cancer. We evaluated the diagnostic performance, interobserver agreement, and prognostic significance of this sign for the postoperative recurrence.

RESULTS

There were 46 pathologic T3 cancers (86.7%) and seven pathologic T4a cancers (13.2%). The diagnostic performance of the radiologic serosal invasion sign in the differentiation between T3 and T4a cancers was as follows: sensitivity, 91.3%; specificity, 71.43%; and accuracy, 88.68% for R1 and sensitivity, 78.26%; specificity, 85.71%; and accuracy, 79.25% for R2. The k-value was 0.64. Among the clinical and pathologic variables, radiologic T4a sign [hazard ratio (HR): 7.96; 95% confidence interval (CI) 2.36-26.86, p = 0.001], pathologic T4a (HR 9.82, 95% CI 2.35-40.95, p = 0.002), tumor size (HR 1.18, 95% CI 1.02-1.35, p = 0.026), and lymphovascular invasion (HR 6.39, 95% CI 1.42-28.75, p = 0.015) were the significant factors for postoperative recurrence.

CONCLUSIONS

Radiologic serosal invasion sign is reliable as a new CT criterion for T4a cancer staging in patients with advanced gastric cancer, demonstrating 80% to 88% accuracy. Radiologic serosal invasion sign can also serve as a prognostic factor for postoperative recurrence as well as pathologic T4a stage.