Application of percutaneous ultrasound-guided treatment for ultrasonically invisible hypervascular hepatocellular carcinoma using microbubble contrast agent

Use of Ultrasound Contrast Agents in Relation to Percutaneous Interventional Procedures: A Systematic Review and Pictorial Essay

The aim of this article is to provide an inventory of the use of contrast-enhanced ultrasound (CEUS) in relation to percutaneous interventional procedures. The article is structured into a systematic literature review followed by a clinical part relating to percutaneous CEUS-guided procedures. A literature search identified 3109 records. After abstract screening, 55 articles were analyzed and supplemented with pictorial material to explain the techniques. In conclusion, the best-evidenced indications for CEUS-guided interventions are biopsy and ablation of inconspicuous or B-mode-invisible tumors, intraprocedural ablation control and follow-up, as well as percutaneous transhepatic cholangiography and drainage procedures.

[Contrast-enhanced sonography. Therapy control of radiofrequency ablation and transarterial chemoembolization of hepatocellular carcinoma]

Due to the imaging of dynamic perfusion, hepatocellular carcinoma can be detected with a sensitivity of >90% using contrast-enhanced sonography. The characterization of liver tumors with contrast-enhanced sonography is comparable to the diagnostic accuracy of contrast-enhanced computed tomography. The dynamic detection of microvascularization with contrast-enhanced sonography allows the differentiation between vascularized tumors and non-vascularized necrotic lesions before, during and after transarterial chemoembolization or percutaneous radiofrequency ablation. Image fusion with volume navigation can be useful in the followup control.

[Ultrasound-guided percutaneous biopsies in 2010]

Ultrasound-guidance is frequently used at the time of biopsy. Its numerous advantages include: lack of ionizing radiation, real-time visualization of the needle tip, flexibility to approach lesions from variable and complex angles, wide availability of ultrasound units. A certain level of experience is nonetheless required to ensure adequate and successful lesion targeting. New software are available to assist the operators. "Electromagnetic navigation" can assist in locating the needle tip and predicting its trajectory. Image fusion with previous cross-sectional imaging studies can assist in detecting lesions that are less conspicuous on routine ultrasound images.

[Radiological diagnosis of hepatocellular carcinoma in 2010]

The aim of diagnosis imaging is to detect hepatocellular carcinoma at an early stage, when a curative treatment is available. Biopsy is no longer required prior to treatment, and diagnosis of hepatocellular carcinoma is heavily dependent of imaging characteristics. Therefore, the purpose of this article is to describe the typical features of small (<20mm) and larger hepatocellular carcinomas with noninvasive diagnostic criteria, including ultrasound, computed tomography and MRI. Advances in these imaging modalities have greatly improved the detection of small hepatic nodules on liver cirrhosis, including the different steps of carcinogenesis, from regenerative to dysplastic nodules, and we emphasize the difficulties of radiological differentiation of precancerous lesions and small hepatocellular carcinomas.

Contrast-enhanced sonography-guided radiofrequency ablation for the local recurrence of previously treated hepatocellular carcinoma undetected by B-mode sonography

BACKGROUND.: The purpose of this study was to assess the usefulness of contrast-enhanced sonography (CEUS) with Sonazoid to demonstrate local recurrence of hepatocellular carcinoma previously treated with radiofrequency ablation (RFA) and not seen on conventional sonography, prior to repeat RFA. METHODS.: This study included 16 cirrhotic patients with 17 cases of hypervascular locally recurrent hepatocellular carcinoma found by contrast-enhanced multidetector row CT (MDCT) but not seen on noncontrast sonography. We used Kupffer-phase imaging and vascular-phase imaging after re-injection. The morphologic patterns of local recurrence detected on CEUS were compared with those on MDCT. We performed repeat RFA guided by CEUS using Kupffer-phase imaging after re-injection. RESULTS.: We were able to detect on CEUS the location of all local recurrences with positive enhancement after re-injection. The morphologic patterns of local recurrence on CEUS were in concordance with those found on MDCT in all lesions. Repeat percutaneous RFA was successfully performed in all lesions. CONCLUSIONS.: The CEUS appearance of local recurrences correlated well with those on MDCT. A wider use of CEUS to guide repeat of percutaneous RFA may be possible with Sonazoid.

Contrast enhanced ultrasound of hepatocellular carcinoma

Sonazoid (Daiichi Sankyo, Tokyo, Japan), a second-generation of a lipid-stabilized suspension of a perfluorobutane gas microbubble contrast agent, has been used clinically in patients with liver tumors and for harmonic gray-scale ultrasonography (US) in Japan since January 2007. Sonazoid-enhanced US has two phases of contrast enhancement: vascular and late. In the late phase of Sonazoid-enhanced US, we scanned the whole liver using this modality at a low mechanical index (MI) without destroying the microbubbles, and this method allows detection of small viable hepatocellular carcinoma (HCC) lesions which cannot be detected by conventional US as perfusion defects in the late phase. Re-injection of Sonazoid into an HCC lesion which previously showed a perfusion defect in the late phase is useful for confirming blood flow into the defects. High MI intermittent imaging at 2 frames per second in the late phase is also helpful in differentiation between necrosis and viable hypervascular HCC lesions. Sonazoid-enhanced US by the coded harmonic angio mode at a high MI not only allows clear observation of tumor vessels and tumor enhancement, but also permits automatic scanning with Sonazoid-enhanced three dimensional (3D) US. Fusion images combining US with contrast-enhanced CT or contrast-enhanced MRI have made it easy to detect typical or atypical HCC lesions. By these methods, Sonazoid-enhanced US can characterize liver tumors, grade HCC lesions histologically, recognize HCC dedifferentiation, evaluate the efficacy of ablation therapy or transcatheter arterial embolization, and guide ablation therapy for unresectable HCC. This article reviews the current developments and applications of Sonazoid-enhanced US and Sonazoid-enhanced 3D US for diagnosing and treating hepatic lesions, especially HCC.

Ultrasound-guided treatments under low acoustic power contrast harmonic imaging for hepatocellular carcinomas undetected by B-mode ultrasonography

BACKGROUND/AIMS

The aim was to examine the efficacy of contrast-enhanced ultrasound (US) with Sonazoid to demonstrate ultrasonically unrecognizable hypervascular hepatocellular carcinoma (HCC) and apply percutaneous US-guided treatments.

METHODS

The subjects of this prospective study were 44 cirrhotic patients with 55 hypervascular lesions (12.7+/-4.5 mm) found by contrast-enhanced computed tomography but unrecognized by non-contrast US. Contrast-enhanced US was performed to demonstrate these hepatic lesions after an intravenous injection of Sonazoid (0.0075 ml/kg). The sonograms in both the early phase (for 1 min after injection) and the late phase (5-10 min after) were taken in the harmonic imaging mode under a low mechanical index (0.24-0.3).

RESULTS

Fifty-three lesions were demonstrated by contrast-enhanced US, 52 with positive enhancement in the early phase and 44 with negative enhancement in the late phase. Percutaneous US-guided treatments were successfully performed for 42 lesions (ethanol injection in 20 and radiofrequency ablation in 22) in 32 patients with reference to contrast-enhanced US findings. Six patients were treated by transarterial chemoembolization alone because they had more than three lesions in the liver. In the remaining seven lesions in six patients, six were diagnosed as non-HCC lesions: five with vascular abnormalities such as arterioportal or arteriovenous communication and the other one with benign lesion in alcoholic liver disease. These six lesions and one HCC lesion with severe liver damage were followed up without any treatment.

CONCLUSIONS

As the detectability of ultrasonically unrecognizable hypervascular HCC improved by contrast-enhanced US with Sonazoid, a wider application of percutaneous US-guided treatments may be possible.

Current role of ultrasound for the management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has a decisive influence on the prognosis of cirrhotic patients. Although α-fetoprotein (AFP) is a known and specific tumor maker for HCC, it is not suitable for the screening and surveillance of HCC because of its poor predictive value and low sensitivity. The use of imaging modalities is essential for the screening, diagnosis and treatment of HCC. Ultrasound (US) plays a major role among them, because it provides real-time and non-invasive observation by a simple and easy technique. In addition, US-guided needle puncture methods are frequently required for the diagnosis and/or treatment process of HCC. The development of digital technology has led to the detection of blood flow by color Doppler US, and the sensitivity for detecting tumor vascularity has shown remarkable improvement with the introduction of microbubble contrast agents. Moreover, near real-time 3-dimensional US images are now available. As for the treatment of HCC, high intensity focused ultrasound (HIFU) was developed as a novel technology that provides a transcutaneous ablation effect without needle puncture. These advancements in the US field have led to rapid progress in HCC management, and continuing advances are expected. This article reviews the current application of US for HCC in clinical practice.

Ablation therapy guided by contrast-enhanced sonography with Sonazoid for hepatocellular carcinoma lesions not detected by conventional sonography

OBJECTIVE

We evaluated the usefulness of contrast-enhanced harmonic gray scale sonography with a newly developed sonographic contrast medium as a means of guidance for percutaneous ablation therapy of hepatocellular carcinoma lesions not detected by conventional sonography.

METHODS

We examined 85 patients with 108 hepatocellular carcinoma lesions that were identified as hypervascular by multidetector-row computed tomography by using contrast-enhanced harmonic gray scale sonography after injection of Sonazoid (GE Healthcare, Oslo, Norway), a lipid-stabilized suspension of a perfluorobutane gas microbubble contrast agent. We scanned the whole liver by this modality at a low mechanical index in the late phase to detect lesions not detected by conventional sonography and then scanned the lesions again by this modality at a high mechanical index to visualize tumor vessels and enhancement. We also performed percutaneous ablation therapy guided by this modality to treat viable hepatocellular carcinoma lesions that could not be detected by conventional sonography.

RESULTS

Conventional sonography identified 90 (83%) of 108 hepatocellular carcinoma lesions; 15 (14%) additional viable lesions not detected by conventional sonography were detected in the late phase of contrast-enhanced harmonic gray scale sonography at a low mechanical index, and tumor vessels and enhancement were observed in the late phase at a high mechanical index. Contrast-enhanced harmonic gray scale sonography diagnosed 105 (97%) of the 108 viable hepatocellular carcinoma lesions, and 14 (93%) of the 15 lesions not detected by conventional sonography were successfully treated by percutaneous ablation therapy guided by this modality.

CONCLUSIONS

Contrast-enhanced harmonic gray scale sonography is useful for guidance of percutaneous ablation therapy of hepatocellular carcinoma lesions not detected by conventional sonography.

Radiological diagnosis of hepatocellular carcinoma

Treatment of hepatocellular carcinomas (HCC) is often complicated by the fact that early HCCs are mostly asymptomatic and the carcinoma is often discovered at an advanced stage. The aim of diagnostic imaging is to detect HCC at an early stage, when curative options are available. In recent years, there have been many efforts to improve early detection of small HCC. The purpose of this article is to describe the pertinent findings of HCCs in non-invasive, diagnostic imaging, including ultrasound, computed tomography, as well as modern magnetic resonance imaging techniques. Special emphasis is given to the frequently addressed difficulties of differentiation of precancerous lesions and small HCCs. A non-invasive diagnostic approach is considered with a review of the literature.