Ultrasonographic (US) angiography enhanced with intraarterial CO2 microbubbles, a contrast material used in US imaging, was performed of 103 histologically proved hepatocellular carcinomas (HCCs) smaller than 3 cm in diameter in 95 patients. The detection rate for hypervascular HCC with US angiography was compared with the rate of detection with conventional angiography, digital subtraction angiography (DSA), and computed tomography (CT) after intraarterial injection of iodized oil. Sensitivity in detection of hypervascular HCCs with US angiography was 86% (89 of 103 HCCs), compared with 63% (44 of 70 HCCs) detected with conventional angiography, 70% (23 of 33 HCCs) with DSA, and 82% (75 of 91 HCCs) with CT with iodized oil. US angiography depicted small hypervascular HCCs, especially those less than 1 cm in diameter, and helped clarify vascularity as isovascular or hypovascular in angiographically undetectable HCCs. Findings at US angiography assisted the choice of a therapeutic strategy for treatment of HCC, such as transarterial therapy, percutaneous ethanol injection therapy, or resection.

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Dynamic contrast material-enhanced ultrasonography (US) with intraarterial infusion of carbon dioxide microbubbles was performed for four cases of histologically proved focal nodular hyperplasia (FNH) in four patients and for 167 cases of various hepatic nodules in 144 patients. No complications due to dynamic US were observed in any of the 148 patients. All FNH nodules were less than 3 cm in diameter. Consistent specific findings of FNH were not obtained with US, computed tomography, magnetic resonance imaging, radiocolloid scanning, or angiography in the four cases of FNH. In contrast, the characteristic vascular pattern (ie, early central hypervascular supply with centrifugal filling to the periphery at the arterial phase and a uniform or lobulated dense stain at the capillary phase) was observed in all four cases of FNH with dynamic US. This vascular pattern demonstrated in FNH with dynamic US was not seen in any of the 167 hepatic nodules, including 44 small hepatocellular carcinomas less than 3 cm in diameter. Therefore, the newly developed, dynamic contrast-enhanced US technique seems to be extremely sensitive and specific for diagnosing FNH and is useful in the differentiation of FNH from other hepatic tumors, especially hepatocellular carcinoma.

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Afferent and efferent vessels of premalignant and overt hepatocellular carcinoma (HCC) were analyzed using color Doppler imaging. With afferent blood flow, constant waveform signals reflecting portal inflow are a characteristic finding in dysplastic nodules and early well-differentiated HCC. Among advanced HCCs lacking portal blood flow, inflow of arterial pulsatile blood flow signals is characteristic for advanced HCC with increased arterial vascularity. Efferent blood flow enters the hepatic vein of the lowest pressure system in dysplastic nodules and early well-differentiated HCC with afferent portal blood flow. Analysis of waveforms of efferent blood flow signals in advanced HCC detects in the opposite direction adjacent to an accompanying afferent arterial pulsatile blood flow signal. In conclusion, during multistep human hepatocarcinogenesis hemodynamics show characteristic changes; the state of afferent portal blood with low arterial vascularity loses the portal blood flow, and arterial vascularity gradually increases. The efferent blood flow pathway also changes with the pathological multistep developement process.