Accuracy of Contrast-Enhanced Ultrasound in the Diagnosis of Bile Duct Obstruction

SIUMB recommendations on the use of ultrasound in neoplastic lesions of the gallbladder and extrahepatic biliary tract

Extrahepatic biliary tract and gallbladder neoplastic lesions are relatively rare and hence are often underrepresented in the general clinical recommendations for the routine use of ultrasound (US). Dictated by the necessity of updated summarized review of current literature to guide clinicians, this paper represents an updated position of the Italian Society of Ultrasound in Medicine and Biology (SIUMB) on the use of US and contrast-enhanced ultrasound (CEUS) in extrahepatic biliary tract and gallbladder neoplastic lesions such as extrahepatic cholangiocarcinoma, gallbladder adenocarcinoma, gallbladder adenomyomatosis, dense bile with polypoid-like appearance and gallbladder polyps.

Usefulness of contrast-enhanced ultrasonography for biliary tract disease

Conventional ultrasonography (US) for biliary tract disease shows high time and spatial resolution. In addition, it is simple and minimally invasive, and is selected as a first-choice examination procedure for biliary tract disease. Currently, contrast-enhanced US (CEUS), which facilitates the more accurate assessment of lesion blood flow in comparison with color and power Doppler US, is performed using a second-generation ultrasonic contrast agent. Such agents are stable and provide a timeline for CEUS diagnosis. Gallbladder lesions are classified into three types: gallbladder biliary lesion (GBL), gallbladder polypoid lesion (GPL), and gallbladder wall thickening (GWT). Bile duct lesions can also be classified into three types: bile duct biliary lesion (BBL), bile duct polypoid lesion (BDPL), and bile duct wall thickening (BDWT). CEUS facilitates the differentiation of GBL/BBL from tumorous lesions based on the presence or absence of blood vessels. In the case of GPL, it is important to identify a vascular stalk attached to the lesion. In the case of GWT, the presence or absence of a non-contrast-enhanced area, the Rokitansky-Aschoff sinus, and continuity of a contrast-enhanced gallbladder wall layer are important for differentiation from gallbladder cancer. In the case of BDWT, it is useful to evaluate the contour of the contrast-enhanced medial layer of the bile duct wall for differentiating IgG4-related sclerosing cholangitis from primary sclerosing cholangitis. CEUS for ampullary carcinoma accurately reflects histopathological findings of the lesion. Evaluating blood flow in the lesion, continuity of the gallbladder wall, and contour of the bile duct wall via CEUS provides useful information for the diagnosis of biliary tract disease.

Spatial analysis of hepatobiliary abnormalities in a population at high-risk of cholangiocarcinoma in Thailand

Cholangiocarcinoma (CCA) is a serious health challenge with low survival prognosis. The liver fluke, Opisthorchis viverrini, plays a role in the aetiology of CCA, through hepatobiliary abnormalities: liver mass (LM), bile duct dilation, and periductal fibrosis (PDF). A population-based CCA screening program, the Cholangiocarcinoma Screening and Care Program, operates in Northeast Thailand. Hepatobiliary abnormalities were identified through ultrasonography. A multivariate zero-inflated, Poisson regression model measured associations between hepatobiliary abnormalities and covariates including age, sex, distance to water resource, and history of O. viverrini infection. Geographic distribution was described using Bayesian spatial analysis methods. Hepatobiliary abnormality prevalence was 38.7%; highest in males aged > 60 years (39.8%). PDF was most prevalent (20.1% of males). The Standardized Morbidity Ratio (SMR) for hepatobiliary abnormalities was highest in the lower and upper parts of the Northeast region. Hepatobiliary abnormalities specifically associated with CCA were also more common in males and those aged over 60 years and distributed along the Chi, Mun, and Songkram Rivers. Our findings demonstrated a high risk of hepatobiliary disorders in Northeast Thailand, likely associated with infection caused by O. viverrini. Screening for CCA and improvement of healthcare facilities to provide better treatment for CCA patients should be prioritized in these high-risk areas.

Diagnostic value of contrast-enhanced ultrasound versus magnetic resonance imaging in extrahepatic cholangiocarcinoma

AIM

To compare the value of contrast-enhanced ultrasound and magnetic resonance imaging in the diagnosis of extrahepatic cholangiocarcinoma (EHCC).

METHODS

Forty-six patients with extrahepatic cholangiocarcinoma (ECHH group) diagnosed at our hospital from January 2015 to December 2017 were enrolled. Forty-six patients with extrahepatic bile duct stones (CBDS group) and 46 patients with pancreatic head carcinomas or duodenum papilla disease (PD group) were also included. All patients underwent B-mode ultrasonography (BUS), CEUS, and MRI. Using the pathological diagnosis as the "gold standard", the receiver operating characteristic (ROC) curves were plotted to compare the diagnostic efficacy (including diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value) of the three examination methods for EHCC.

RESULTS

There was no significant difference between CEUS and MRI in the arterial phase (χ² = 1.105, P = 0.602). CEUS showed low enhancement in 86.96% and 100.00% of patients in the portal phase and delayed phase, respectively, which were significantly higher than those of MRI (13.04% and 13.04%, respectively; χ² = 50.261, 70.769; P = 0.000, 0.000). The ROC curve analysis showed that the area under the curve (AUC) of MRI and CEUS for the diagnosis of EHCC was higher that of BUS (0.924, 0.897 vs 0.690). The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of BUS for EHCC were significantly lower than those of CEUS (χ² = 0.175, 0.066, 11.467, 37.260, 6.328; P = 0.000, 0.010, 0.001, 0.000, 0.012) and MRI (χ² = 0.227, 0.098, 13.378, 41.170, 9.082; P = 0.000, 0.002, 0.000, 0.000, 0.003). There was no significant difference in the diagnostic efficacy of CEUS and MRI for EHCC (χ² = 0.464, 0.383, 0.000, 0.001, 0.334; P = 0.496, 0.536, 1.000, 0.972, 0.563).

CONCLUSION

CEUS has high value in the diagnosis of EHCC and can be used as an important complement to MRI.