Microbubble disappearance-time is the appropriate timing for liver-specific imaging after injection of Levovist

Evaluation of hepatic fibrosis: a review from the society of abdominal radiology disease focus panel

Hepatic fibrosis is potentially reversible; however early diagnosis is necessary for treatment in order to halt progression to cirrhosis and development of complications including portal hypertension and hepatocellular carcinoma. Morphologic signs of cirrhosis on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) alone are unreliable and are seen with more advanced disease. Newer imaging techniques to diagnose liver fibrosis are reliable and accurate, and include magnetic resonance elastography and US elastography (one-dimensional transient elastography and point shear wave elastography or acoustic radiation force impulse imaging). Research is ongoing with multiple other techniques for the noninvasive diagnosis of hepatic fibrosis, including MRI with diffusion-weighted imaging, hepatobiliary contrast enhancement, and perfusion; CT using perfusion, fractional extracellular space techniques, and dual-energy, contrast-enhanced US, texture analysis in multiple modalities, quantitative mapping, and direct molecular imaging probes. Efforts to advance the noninvasive imaging assessment of hepatic fibrosis will facilitate earlier diagnosis and improve patient monitoring with the goal of preventing the progression to cirrhosis and its complications.

Effect of signal intensity from the accumulated microbubbles in the liver for differentiation of idiopathic portal hypertension from liver cirrhosis

PURPOSE

To examine the possibility of using contrast material-enhanced ultrasonography (US) to differentiate idiopathic portal hypertension (IPH) from cirrhosis.

MATERIALS AND METHODS

This was an institutional review board-approved prospective study with written informed consent. The study consisted of 23 patients (mean age, 60 years +/- 11; range, 37-85 years) with biopsy-proved cirrhosis, 10 patients (mean age, 65 years +/- 8; range, 51-78 years) with IPH, and 27 control subjects (mean age, 46 years +/- 17; range, 26-82 years) without any focal hepatic lesions or portal vein thrombosis. The patients underwent contrast-enhanced US for the observation of the right liver lobe. The time of the onset of contrast enhancement in the right hepatic artery and right portal vein was examined at vascular phase under continuous low-power emission, and signal intensity differences (in decibels) by using instantaneous high-power emission in the liver parenchyma were analyzed at late phase (15 minutes). Interobserver variability was quantified as coefficients of variation.

RESULTS

Onset time of contrast enhancement in the right portal vein was significantly longer for both IPH (22 sec +/- 3.9, P = .0035) and cirrhosis (19.3 sec +/- 4.7, P = .04) patients than for control subjects (17 sec +/- 3.3), with no significant difference in the onset time in the right hepatic artery. Images obtained in both IPH patients (21.2 dB +/- 1.4) and control subjects (22.1 dB +/- 2.2) had significantly higher signal intensity differences than those obtained in cirrhosis patients (13.8 dB +/- 2.8, P < .0001), with no significant difference between images of IPH patients and control subjects. Signal intensity differences of more than 18 dB had 100% sensitivity and specificity for the diagnosis in IPH patients and control subjects. Interobserver variability for signal intensity differences was 8.7%.

CONCLUSION

Contrast-enhanced US may offer the possibility for a simple, easy, and noninvasive diagnosis of IPH.

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.

Can imaging modalities diagnose and stage hepatic fibrosis and cirrhosis accurately?

The accurate diagnosis and staging of hepatic fibrosis is crucial for prognosis and treatment of liver disease. The current gold standard, liver biopsy, cannot be used for population-based screening, and has well known drawbacks if used for monitoring of disease progression or treatment success. Our objective was to assess performance and promise of radiologic modalities and techniques as alternative, noninvasive assessment of hepatic fibrosis. A systematic review was conducted. Six hundred twenty-eight studies were identified via electronic search. One hundred fifty-three papers were reviewed. Most described techniques that could differentiate between cirrhosis or severe fibrosis and normal liver. Accurate staging of fibrosis or diagnosis of mild fibrosis was often not achievable. Ultrasonography is the most common modality used in the diagnosis and staging of hepatic fibrosis. Elastographic measurements, either ultrasonography-based or magnetic resonance-based, and magnetic resonance diffusion weighted imaging, show the most promise for accurate staging of hepatic fibrosis. Most currently available imaging techniques can detect cirrhosis or significant fibrosis reasonably accurately. However, to date only magnetic resonance elastography has been able to stage fibrosis or diagnose mild disease. Utrasonographic elastography and magnetic resonance diffusion weighted appear next most promising.

How to characterize non-hypervascular hepatic nodules on contrast-enhanced computed tomography in chronic liver disease: feasibility of contrast-enhanced ultrasound with a microbubble contrast agent

BACKGROUND AND AIM

Although hypervascular appearance is characteristic in hepatocellular carcinoma (HCC), hepatic nodules without hypervascular appearance are sometimes found in patients with chronic liver disease (CLD). The aim of the present study was to clarify the efficacy of contrast-enhanced ultrasound (CEUS) with Levovist to characterize small, non-hypervascular hepatic nodules on contrast-enhanced computed tomography (CECT) in patients with CLD.

METHODS

The subject was 41 hepatic nodules (<30 mm, 18.5 +/- 5.6 mm) which showed non-hypervascular appearance on CECT in 35 patients with CLD; their histological results were 31 HCC (15 well, 14 moderate, and two poor) and 10 regenerative nodules (RN). CEUS with Levovist was performed under intermittent scanning (1-s interval) using APLIO at the early phase and the liver-specific phase, and the contrast enhancement of the nodule was assessed in comparison to that of the surrounding liver parenchyma. The contrast-enhanced findings with the time-intensity analysis were compared with the histological results.

RESULTS

Twelve nodules with weak enhancement in the liver-specific phase were HCC, regardless of their early-phase appearances. The other 29 nodules with equivalent or weak enhancement in the early phase and equivalent enhancement in the liver-specific phase were 19 HCC and 10 RN. Among them, the maximum-intensity ratio of tumor to non-tumor in the early phase was significantly higher in HCC than in RN (P < 0.01, n = 16), and the receiver-operating characteristic analysis showed a sensitivity of 1.0 and a specificity of 0.83 for their characterization.

CONCLUSION

CEUS with Levovist may be an alternative to biopsy to characterize small, non-hypervascular hepatic nodules on CECT in patients with CLD.

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

AIM

To evaluate the efficacy of contrast-enhanced ultrasound for the localization of ultrasonically invisible hypervascular lesions in the liver to facilitate percutaneous ultrasound-guided treatment.

MATERIALS AND METHODS

Forty patients with 47 ultrasonically invisible hypervascular lesions (5-20mm) diagnosed on contrast-enhanced computed tomography were enrolled in the retrospective study. Contrast-enhanced ultrasound (CEUS) with Levovist was performed to localize the lesions both in the early phase and liver-specific phase. Diagnosis of was confirmed by percutaneous needle biopsy where feasible, and on the basis of on treatment outcomes or changes in computed tomography findings in those not amenable to biopsy.

RESULTS

Thirty-two lesions were diagnosed as hepatocellular carcinoma (HCC). Contrast-enhanced ultrasound localized hepatocellular carcinoma in 24/32 (75%) lesions, the mean diameter (15.1+/-4.9mm), as measured using computed tomography, being significantly larger than that of the remaining eight lesions (10.5+/-2.1mm). Ultrasound-guided treatment was performed in 19 of the 24 lesions, and transarterial chemoembolization (TACE) was applied for the other five lesions because of difficult percutaneous access. Five of the eight non-visualised lesions were treated by transarterial chemoembolization, and the other three by surgical resection. The beneficial effect of CEUS was significantly greater when the reason for poor initial visualisation was the coarse liver architecture (17/17) than when it was due to adverse location (seven of 15, p<0.005). Fifteen of the CT-detected hypervascular lesions were considered to represent false positives for HCC, based on their behaviour during follow-up.

CONCLUSION

Contrast-enhanced ultrasound with Levovist facilitates the application of percutaneous ultrasound-guided treatment by improving localization of ultrasonically invisible hypervascular hepatocellular carcinomas in the liver.