Dynamic Contrast-Enhanced Ultrasound of Gastric Cancer: Correlation with Perfusion CT and Histopathology

Abstract

Objective: To assess the relationship between contrast-enhanced ultrasound (CEUS) parameters and perfusion CT (PCT) parameters of gastric cancers and their correlation with histologic features.

Materials and methods: This prospective study was approved by our Institutional Review Board. We included 43 patients with pathologically-proven gastric cancers undergoing CEUS using SonoVue® (Bracco) and PCT on the same day. Correlation between the CEUS parameters (peak intensity [PI], area under the curve [AUC], rise time [RT] from 10% to 90% of PI, time to peak [TTP_US], and mean transit time [MTT_US]) and PCT parameters (blood flow, blood volume, TTP_CT, MTT_CT, and permeability surface product) of gastric cancers were analyzed using Spearman's rank correlation test. In cases of surgical resection, the CEUS and PCT parameters were compared according to histologic features using Mann-Whitney test.

Results: CEUS studies were of diagnostic quality in 88.4% (38/43) of patients. Among the CEUS parameters of gastric cancers, RT and TTP_US showed significant positive correlations with TTP_CT (rho = 0.327 and 0.374, p = 0.045 and 0.021, respectively); PI and AUC were significantly higher in well-differentiated or moderately-differentiated tumors (n = 4) than poorly-differentiated tumors (n = 18) (p = 0.026 and 0.033, respectively), whereas MTT_CT showed significant differences according to histologic types (poorly cohesive carcinoma [PCC] vs. non-PCC), T-staging (≤ T2 vs. ≥ T3), N-staging (N0 vs. N-positive), and epidermal growth factor receptor expression (≤ faint vs. ≥ moderate staining) (p values < 0.05).

Conclusion: In patients with gastric cancers, CEUS is technically feasible for the quantification of tumor perfusion and may provide correlative and complementary information to that of PCT, which may allow prediction of histologic features.

Keywords: Contrast-enhanced ultrasound (CEUS); Histologic grade; Perfusion imaging; Stomach cancer.

Fig. 1. Calculation of perfusion parameters using CEUS.

AUC = area under curve, CEUS = contrast-enhanced ultrasound, MTT = mean transit time, PI = peak intensity, RT = rise time, TTP = time to peak

Fig. 2. Sixty-two-year-old male patient with surgically-proven pT2N0 gastric cancer of moderately-differentiated adenocarcinoma.

A. Preoperative contrast-enhanced CT image shows enhancing ulceroinfiltrative mass (arrow) at level of gastric mid body. B. CEUS image shows enhancing mass (arrow, green ROI) at corresponding location of water-distended stomach. C. Time-intensity curve analysis reveals PI of 2619 a.u. and AUC of 48820 a.u. ROI = region of interest

Fig. 3. Eighty-two-year-old female patient with surgically-proven pT3N0 gastric cancer of poorly-differentiated adenocarcinoma.

A. Axial CT image shows ulceroinfiltrative mass involving gastric low body and antrum (arrows). B. CEUS image reveals mass (arrows, green ROI) showing mild enhancement. C. Time-intensity curve analysis reveals PI of 36.9 a.u. and AUC of 342.0 a.u.