Contrast-enhanced 3D sonography shows promise for liver tumor imaging
Contrast-enhanced 3D sonography is an alternative method for visualization of the characteristic vascularity of focal liver tumors and may significantly contribute to the diagnosis, monitoring and evaluation of therapeutic effectiveness and to follow-up after treatment, according to a multinational team of researchers. Their work, published this month in the American Journal of Roentgenology, suggests that 3D sonography can contribute to the visualization of tumor vascularity.
“In this study, we performed contrast-enhanced 3D sonography using the automatic scan capability of a volume transducer and the static 3D functionality of a sonographic imaging system to evaluate the vascular patterns of focal liver tumors with various visualization methods,” the authors wrote.
The team, from the Yokohama City University Medical Center in Japan and Xijing Hospital in China, also utilized a perflubutane-based contrast agent, Sonazoid by Daiichi Sankyo, which is commercially available in Japan for imaging of patients with liver tumors and has been used in phase-inversion harmonic grayscale sonography.
“This substance is a second-generation sonographic contrast agent that consists of microbubbles of perfluorobutane gas stabilized by phospholipid monolayer shells,” they wrote.
The scientists enrolled 100 patients with at least one focal liver tumor detected at conventional grayscale sonography over a period of seven months last year. The group reported that enrollment criteria for tumor evaluation were contrast-enhanced 3D sonographic images clearly depicted the tumor without artifact interference; the final diagnosis was confirmed with a reference standard of histopathologic or typical radiologic findings; and the patient had not been previously treated for the tumor.
The clinicians utilized a Logiq 7 (GE Healthcare) system for the acquisition of their contrast-enhanced 3D sonographic images, which were acquired 30 to 60 seconds after Sonazoid injection. Images in three orthogonal planes were presented as tomographic sonographic images, such as those acquired at CT and MRI, for interpretation by two experienced readers.
“Because of the flexible operation of ultrasound transducers, in most cases the three orthogonal planes of 3D sonographic images are not parallel to the transverse, sagittal and longitudinal axes of the human body, as are the planes of 3D CT scans,” the authors noted.
In addition to tomographic sonographic images, sonographic angiographic images simulating radiographic angiograms were reconstructed to illuminate tumors and vessels, according to the scientists.
The confirmed final diagnoses were 50 hepatocellular carcinomas, 20 metastatic lesions, nine hemangiomas and five cases of focal nodular hyperplasia. The main pattern, intratumoral vessels with early homogeneous or heterogeneous tumor enhancement, had a sensitivity of 97 percent (average of both readers), a specificity of 94 percent and a positive predictive value of 96 percent for hepatocellular carcinomas, the team reported.
The authors noted that a combined review of tomographic sonographic images and sonographic angiographic images is important for acquiring precise information.
“Tomographic sonographic images have high resolution for the display of tumor vessels and early tumor enhancement, they wrote. “Sonographic angiographic images show complex anatomic structures in a spatial volume, allowing convenient reading of integral information in the reconstructed volume.”
The preliminary study successfully demonstrated that 3D sonography facilitates the integral observation of anatomic structures, shows the spatial location of tumors and also allows for the visualization of the distribution and morphologic features of vessels within and around tumors. The authors reported that they plan to continue their research and examine other functions of contrast-enhanced 3D sonography to visualize characteristics of the middle and late phases of contrast enhancement.
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| A 40-year-old man with intrahepatic cholangiocellular carcinoma (diameter, 75 mm) of segment VIII of liver. A and B, Sonographic angiographic images rendered with transparent maximum mode mixed with surface smooth mode show intratumoral vessels (arrows) and early heterogeneous enhancement within tumor. Arrowheads indicate margins of tumor. Image and caption courtesy of the American Roentgen Ray Society. |
The team, from the Yokohama City University Medical Center in Japan and Xijing Hospital in China, also utilized a perflubutane-based contrast agent, Sonazoid by Daiichi Sankyo, which is commercially available in Japan for imaging of patients with liver tumors and has been used in phase-inversion harmonic grayscale sonography.
“This substance is a second-generation sonographic contrast agent that consists of microbubbles of perfluorobutane gas stabilized by phospholipid monolayer shells,” they wrote.
The scientists enrolled 100 patients with at least one focal liver tumor detected at conventional grayscale sonography over a period of seven months last year. The group reported that enrollment criteria for tumor evaluation were contrast-enhanced 3D sonographic images clearly depicted the tumor without artifact interference; the final diagnosis was confirmed with a reference standard of histopathologic or typical radiologic findings; and the patient had not been previously treated for the tumor.
The clinicians utilized a Logiq 7 (GE Healthcare) system for the acquisition of their contrast-enhanced 3D sonographic images, which were acquired 30 to 60 seconds after Sonazoid injection. Images in three orthogonal planes were presented as tomographic sonographic images, such as those acquired at CT and MRI, for interpretation by two experienced readers.
“Because of the flexible operation of ultrasound transducers, in most cases the three orthogonal planes of 3D sonographic images are not parallel to the transverse, sagittal and longitudinal axes of the human body, as are the planes of 3D CT scans,” the authors noted.
In addition to tomographic sonographic images, sonographic angiographic images simulating radiographic angiograms were reconstructed to illuminate tumors and vessels, according to the scientists.
The confirmed final diagnoses were 50 hepatocellular carcinomas, 20 metastatic lesions, nine hemangiomas and five cases of focal nodular hyperplasia. The main pattern, intratumoral vessels with early homogeneous or heterogeneous tumor enhancement, had a sensitivity of 97 percent (average of both readers), a specificity of 94 percent and a positive predictive value of 96 percent for hepatocellular carcinomas, the team reported.
The authors noted that a combined review of tomographic sonographic images and sonographic angiographic images is important for acquiring precise information.
“Tomographic sonographic images have high resolution for the display of tumor vessels and early tumor enhancement, they wrote. “Sonographic angiographic images show complex anatomic structures in a spatial volume, allowing convenient reading of integral information in the reconstructed volume.”
The preliminary study successfully demonstrated that 3D sonography facilitates the integral observation of anatomic structures, shows the spatial location of tumors and also allows for the visualization of the distribution and morphologic features of vessels within and around tumors. The authors reported that they plan to continue their research and examine other functions of contrast-enhanced 3D sonography to visualize characteristics of the middle and late phases of contrast enhancement.