Contrast-enhanced agent detection imaging: Early experience in hepatocellular carcinoma

Hepatic malignancies: Correlation between sonographic findings and pathological features

Ultrasonography (US) findings are inevitably based on pathological features. Knowledge of the pathological features of hepatic malignancies such as hepatocellular carcinoma (HCC), liver metastasis and intrahepatic cholangiocarcinoma is essential for correct US diagnosis and appropriate management. One type of hepatocarcinogenesis is step-wise development from a low-grade dysplastic nodule (DN), high-grade DN, high-grade DN with malignant foci, and well-differentiated HCC, to classical HCC. The intranodular blood supply changes in accordance with this progression. Moreover, the malignant potential tends to change as the macroscopic configuration progresses. Therefore, typical US findings of advanced HCC are a mosaic pattern, septum formation, peripheral sonolucency (halo), lateral shadow produced by fibrotic pseudocapsule, posterior echo enhancement, arterial hypervascularity with dilated intratumoral blood sinusoids, and perinodular daughter nodule formation. Bull's eye appearance is a common presentation of metastases from gastrointestinal (GI) adenocarcinomas, and represents histological findings that show an area of central necrosis surrounded by a zonal area of viable tumor. Thick zonal area reflects the layer of viable cells that are fed by minute tumor vessels. US imaging features of liver metastases from the GI tract are as follows: Bull's eye appearance, multiple masses, irregular tumor border, arterial rim-like enhancement, and hypoenhancement in the late vascular phase. Most intrahepatic cholangiocarcinomas are ductal adenocarcinomas. The bile ducts peripheral to the tumor are usually dilated because of obstruction by tumors. US imaging features of mass-forming cholangiocarcinoma are as follows: peripheral bile duct dilatation, irregular tumor border, arterial enhancement due to minute intratumoral blood sinusoids, and hypoenhancement in the late vascular phase.

Differentiation between malignant and benign nodules in the liver: Use of contrast C3-MODE technology

AIM: To investigate the value of contrast-enhanced C³-MODE technology in differentiating malignant nodules of liver from the benign ones.

METHODS: Forty-six nodules in 36 patients (29 men and 7 women) were studied by contrast-enhanced C³-MODE technology and contrast-enhanced CT in 1 wk before the biopsy or operation. A low MI monitor and a high MI flash imaging were intermittently performed. After the injection of contrast agent, the period from 10 to 30 s and the time later than 100 s were respectively defined as early arterial phase and the late phase. The vascularities of the liver nodules in the two phases were combined for differential diagnosis. Corresponding to the pathological diagnosis, the accuracy, sensitivity and specificity of contrast-enhanced C³-MODE technology were compared to those of contrast-enhanced CT.

RESULTS: By C³-MODE technology, 33 of the 46 liver nodules were demonstrated as defected area in the late phase and were diagnosed as malignant tumors. Of them, 28 with hypervascularity in the early arterial phase were assessed as hepatocellular carcinoma, the other five nodules with rim-like enhancement in the early arterial phase were diagnosed as metastatic tumors. Thirteen nodules were shown as iso or hypervascularity in the late phase as well as centripetal filling in the early arterial phase and we made a diagnosis of hemangioma. Corresponding to the pathological results, the sensitivity, specificity and accuracy of contrast-enhanced C³-MODE technology in differentiating malignant and benign nodules in the liver were 97.0%, 92.3% and 95.7%, respectively. With comparison to those of contrast CT (sensitivity, 94.1%; specificity, 91.7%; accuracy, 93.5%), the difference was not significant.

CONCLUSION: Contrast-enhanced C³-MODE technology can effectively differentiate malignant liver tumors from the benign nodules. It highly agrees diagnostically with the pathology. We suggest that it provides a new approach for differential diagnosis of liver nodules in addition to contrast-enhanced CT.

Vascular flow patterns of hepatic tumors in contrast-enhanced 3-dimensional fusion ultrasonography using plane shift and opacity control modes

OBJECTIVE

This study was conducted to determine whether contrast-enhanced 3-dimensional (3D) fusion ultrasonography with combined use of the plane shift and opacity control modes can serve as a useful tool for identifying the vascular characteristics of hepatic tumors in 3D perspective.

METHODS

Contrast-enhanced 3D fusion ultrasonography was performed in 31 patients with hepatic tumors after the intravenous injection of contrast media. The shapes, courses, and distributions of tumor vessels, displayed in 3D perspective, were examined to identify the characteristic vascular flow patterns of various tumors. Images before and after contrast media administration were compared for evaluation of the effectiveness of contrast enhancement with regard to tumor diameter for various types of tumors. The images were interpreted in a blinded manner by 3 physicians specializing in abdominal ultrasonography, and vascular flow patterns were determined on the basis of consensus.

RESULTS

The characteristic vascular flow patterns observed in hepatocellular carcinomas are reticular flow within the tumor and flow showing a ringlike distribution surrounding the tumor. Metastatic tumors show a vascular flow pattern running between adjacent tumor nodules, and hemangiomas show localized nodular flow at the tumor margins. Contrast enhancement was found to be useful for showing the vascular flow patterns in small hepatocellular carcinomas and hemangiomas.

CONCLUSIONS

Contrast-enhanced 3D fusion ultrasonography makes it possible to display images combining the plane shift and opacity control modes to show tumor vessels, including minute vascular flow within hepatic tumors, in 3D perspective and to identify tumor-specific vascular flow patterns.