Evaluation of blood flow signal in small hepatic nodules by color Doppler ultrasonography

Dynamic changes in ultrasound characteristics of nodules in cirrhotic liver and their implications in surveillance for malignancy

OBJECTIVE

To investigate whether there are ultrasound characteristics that can suggest HCC in ultrasound surveillance of nodules in cirrhotic liver.

METHODS

Data from 277 patients with hepatitis B virus-related nodules in cirrhotic liver undergoing ultrasound surveillance of the nodules for malignancy were reviewed. Size of the nodules ranged 6-23 mm. The nodules were followed by color Doppler ultrasound at 3- to 6-month intervals, with focus on size, shape, echogenicity, margin, halo sign, and vasculature. Suspicious malignant nodules underwent contrast-enhanced CT/MRI, and some indeterminate nodules underwent biopsy.

RESULTS

Nodules in 189 patients were hypo/isoechoic/faint high echoic, 23 were hyperechoic, and 65 were both hypo/isoechoic/faint high echoic and hyperechoic. Forty-two patients developed hepatocellular carcinoma: 35 from nodules and 7 from background parenchyma. Fourteen nodules recessed (size >10 mm), 11 new nodules emerged (size >10 mm), and the total number of nodules increased over 5 years. All hepatocellular carcinomas developed from hypo/isoechoic/faint high echoic nodules, and no typical hyperechoic nodules developed into hepatocellular carcinomas. The size increased significantly when the nodules developed into hepatocellular carcinomas. No nodule presented an overt halo, seven hepatocellular carcinomas developed from nodules with a halo, and ill-defined margins of 16 nodules became well defined when they developed into hepatocellular carcinomas. No vasculature was detectable in the nodules, while it was detectable in eight hepatocellular carcinomas. No significant change occurred in nodules without malignancy.

CONCLUSION

The characteristics for dynamic surveillance of nodules in cirrhotic liver for malignancy should include nodule growth, margin, halo, and vasculature. Apart from evident growth, an ill-defined margin becoming a well-defined margin, a newly emerged halo, and newly detectable vasculature are strongly suggestive of nodule malignancy.

Resistance index in differential diagnosis of liver lesions by color doppler ultrasonography

AIM: To investigate the specific value of resistance index (RI) in color Doppler ultrasonography in the diagnosis of focal hepatic lesions.

METHODS: Eight hundred patients with 893 hepatic solid lesions were studied with color Doppler flow imaging (CDFI) and pulsed Doppler, including 644 malignant cases (596 primary malignant liver tumors, and 48 metastatic liver tumors), 156 benign cases. All were confirmed by operation and pathology.

RESULTS: The detection rate of arterial flow in malignant tumors was 92%, and 52% in benign lesions. Doppler spectrum analysis showed that the resistance index in primary malignant tumors was 0.75 ± 0.12, 0.73 ± 0.09 in metastatic tumors, and was below 0.6 in benign lesions. The difference was significant (P < 0.001). This difference was related with its histopathologic structure.

CONCLUSION: The arterial flow with RI ≥0.6 identified by CDFI within the liver lesion can be regarded as a criterion of malignant tumors, RI < 0.6 can be regarded as benign disorders. RI is useful in differential diagnosis of liver neoplasms.

Contrast enhancement patterns of hepatic tumours during the vascular phase using coded harmonic imaging and Levovist to differentiate hepatocellular carcinoma from other focal lesions

The purpose of the study was to assess contrast enhancement patterns of hepatic tumours during the vascular phase using contrast-enhanced ultrasound and Levovist to differentiate hepatocellular carcinoma from other hepatic tumours. 89 hepatic tumours in 82 consecutive patients were evaluated using coded harmonic ultrasound imaging. The procedure used a phase inversion harmonic technique and coded technology. We observed images for 2 min from the beginning of the administration as the vascular phase using continuous transmission and intermittent transmissions of 1 s or 2 s. The contrast agent Levovist was administered intravenously as a bolus infusion of 2.5 g. Tumour vessels with flow spreading into the tumour and/or homogeneously stained hyperechoic images were observed in 34 of the 41 hepatocellular carcinomas (sensitivity, 82.9%; specificity, 93.8%). Peripheral enhancements were characteristic of intrahepatic cholangiocarcinoma and metastatic hepatic tumours (sensitivity, 60.0% and 83.3%; specificity, 65.5% and 76.4%, respectively). Pooling at the periphery or throughout the tumour was apparent only in haemangioma (sensitivity, 76.5%; specificity, 100%). A tortuous feeding artery and spoke-like vascularization were evident only in the two focal nodular hyperplasias. Contrast-enhanced ultrasound using coded harmonic ultrasound imaging and Levovist provided detailed information about tumour vascularity and contrast enhancement patterns in hepatic tumours.

Visualization of blood flow in hepatic vessels and hepatocellular carcinoma using B-flow sonography

PURPOSE

A B-flow sonographic technique was recently developed to provide direct visualization of blood flow with gray-scale sonography. Compared with color Doppler sonography, B-flow imaging has wideband resolution and a high frame rate. The purpose of this study was to evaluate the usefulness of B-flow sonography for visualizing blood flow in hepatic vessels and tumor vascularity in patients with liver cirrhosis or hepatocellular carcinoma (HCC).

METHODS

Twenty-five patients with liver cirrhosis, including 15 with HCC, were studied by B-flow and color Doppler sonography. Blood-flow detection rates in portal veins and hepatic arteries and tumor vascularity in HCC were analyzed, and the 2 methods were compared.

RESULTS

Using B-flow, blood flow was visualized in the portal vein in 23 (92%) of 25 patients and was visualized in the hepatic artery separately from the portal vein in 9 (36%) of 25 patients. The blood-flow signals were visualized only within vessels, never "bleeding" outside the vessel's lumen. Blood flow in the portal vein was observed with color Doppler sonography in all 25 patients, but the hepatic artery was never clearly separated from the portal vein. Vascularity within the HCC tumor was detected in 9 (60%) of 15 nodules with B-flow imaging, and fine arteries flowing into the tumor were observed in 6 nodules. Color Doppler sonography detected blood flow in 13 (87%) of the 15 HCC nodules.

CONCLUSIONS

Blood flow in hepatic vessels and tumor vessels of HCC were visualized with B-flow sonography. B-flow sonography is a potentially useful technique for the evaluation of liver vascularity and intratumoral vessels.

Assessment of arterial tumor vascularity in small hepatocellular carcinoma. Comparison between color doppler ultrasonography and radiographic imagings with contrast medium: dynamic CT, angiography, and CT hepatic arteriography

Hepatocellular carcinoma (HCC) is characterized by tumor vascularization from the hepatic artery. The objective of our work was to compare color Doppler ultrasonography (CDU), including power Doppler ultrasonography (PDU) with radiographic imagings with contrast medium in regard to the detection of the arterial tumor vascularity of small hepatocellular carcinomas (HCC). We examined 42 small HCC lesions 2 cm or less in diameter in 37 patients for arterial tumor vascularity by conventional CDU, PDU, dynamic computed tomography (dCT), digital subtraction angiography (DSA), and CT hepatic arteriography (CTA). Color images were detected in 25 (59.5%) and 28 (66.7%) of the 42 lesions with conventional CDU and PDU, respectively, and tumor vascularity was detected in 26 (61.9%) by dCT, 23 (54.8%) by DSA, and 29 (69.0%) by CTA. Tumor vascularity could be detected in 51.9% by PDU and CTA, more than by conventional CDU, dCT, and DSA (44.4, 44.4, and 33.3%, respectively) in well-differentiated HCC, whereas the detection rates by these techniques were almost equal (86.7% by CDU, 93.3% by PDU, dCT, and DSA, 100% by CTA, respectively) in moderately and poorly differentiated HCC. PDU is superior to CDU, dCT and DSA and equal to CTA for the detection of tumor vascularity in small HCC, particularly in well-differentiated HCC.

Power Doppler sonography for hepatocellular carcinoma: factors affecting the power Doppler signals of the tumors

AIMS/BACKGROUND

A recent advancement in Doppler ultrasonography (US) is power Doppler for detecting low-velocity blood flow at the microvascular level with angle independence. The present study was performed to characterize the factors contributing to the power Doppler signals of hepatocellular carcinoma (HCC).

METHOD

Correlation of Doppler signals of HCC in 114 patients with 178 HCC nodules was analyzed in relation to the findings of CT and angiography, tumor characteristics (size, echo pattern, and histological differentiation of tumor), viral markers and severity of liver disease.

RESULTS

The sensitivity of power Doppler US was superior to that of CT and angiography (each p<0.05; McNemar's test). The detection rate of power Doppler signal was significantly higher in tumors with diameter > or =2 cm (vs <2 cm in diameter), and with low/mixed echo pattern (vs high echo appearance), and with moderately/poorly differentiated HCC (vs well-differentiated HCC). Univariate analysis revealed that echo pattern, tumor size and histological differentiation of HCC in addition to CT and angiographic findings were significant. Multivariate analysis showed that tumor size and differentiation were significant.

CONCLUSION

These results indicate that tumor characteristics play an important role in power Doppler signals and that these could be assessed by the presence or absence of power Doppler signals.