日本超音波医学会 第15回関西地方会 特別講演

The Use of US Contrast in the Diagnosis of Neoplastic Diseases

Robert F. Mattrey, M.D. Professor of Radiology University of California, San Diego


第1会場 13:30〜14:30

座長 別府 慎太郎(大阪大学保健学科)


The latest generation agents are bubble-based and hold great promise in solid organ gray-scale imaging. Experience with agents limited to Doppler imaging has shown that these agents increase the ability to visualize previously undetected flow, but do not contribute significant additional data.
The newer agents that can alter tissue echogenicity on gray-scale promise to add not only image contrast to aid in detection but significant perfusion data to aid in characterization. Further, these agents lend themselves to the use of unique ultrasound instrumentation techniques that have been shown to further increase tissue contrast and improve vascular imaging.
The angiographic visualization of tumor microcirculation should aid in tumor characterization. This is possible with the use of robust and elastic microbubble and high resolution harmonic imaging. The tortuous vessels become evident. Liver lesions enhance with a triple phase pattern as bubbles traversed the arterial and portal venous systems and finally accumulate in liver parenchyma. During the arterial phase shimmering enhancement of the tumor's vascular portions occurs relative to the surrounding liver and areas of necrosis. As the blood reaches the portal vein, the liver parenchyma gradually enhances as the tumor vasculature washes out until the parenchymal phase when the entire tumor becomes hypoech oic relative to the enhanced liver. It is not yet clear whether the parenchymal enhancement when vessels are devoid of echoes is due to the entrapment of bubbles in the sinusoids or the RE cells.
Because of the high blood volume of the liver and kidney and the lower blood volume of tumors, it is possible to employ techniques more sensitive to differences in blood volume such as flash-echo, bubble extinction, acoustic stimulation, or transient response imaging. All these techniques are similar in principle, although the latter 2 employ color Doppler techniques.
Tumors outside the liver enhance dramatically in conparison to the less vascularized tissues such as muscle. The arterial phase shows the most dramatic contrast effect. With high resolution harmonic imaging, the microvasculature and the blood supply to the lesion become apparent.
In summary, ultrasound contrast agents, particularly when combined with contrast specific instrumentation have the potential to significantly expand the role of sonography in cancer detection and characterization.