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Impact of acoustic radiation force impulse imaging in clinical practice of patients after orthotopic liver transplantation.

ABSTRACT: Acoustic radiation force impulse (ARFI) elastography is a reliable diagnostic device for quantitative non-invasive assessment of liver fibrosis in patients with chronic liver disease. The aim of our prospective study was to evaluate the impact of ARFI in patients after orthotopic liver transplantation (OLT). Therefore, we compared ARFI shear wave velocities with clinical features, non-invasive markers, and the histology of patients following OLT.Post-transplant patients underwent a clinical examination and blood samples were taken. B-mode and Doppler ultrasound (US) of the portal vein and the hepatic artery were performed. Subsequently, a minimum of 10 valid ARFI values were measured in the left and right liver lobe. Liver biopsy was performed if indicated.Between May 2012 and May 2014, 58 Patients after OLT were included in the prospective study. Laboratory markers and aspartate aminotransferase-to-platelet ratio index (APRI) correlated with ARFI values (r=0.44, p<0.001). The histological (n=22) fibrosis score (Ludwig) was significantly correlated with the ARFI of the biopsy site (r=0.55, p=0.008). The mean shear-wave velocities were significantly increased in advanced fibrosis (F?2 1.57±0.57 m/s; F?3 2.85±0.66 m/s; p<0.001), obstructive cholestasis and active viral hepatitis. The area under the receiver operating characteristic (AUROC) curves for the accuracy of ARFI were 74% (F?1), 73% (F?2), 93% (F?3), and 80% (=F4).ARFI elastography correlates well with laboratory values and with noninvasive and invasive markers of fibrosis in patients after OLT. In this regard, elevated ARFI-velocities should be interpreted with caution in the context of obstructive cholestasis and active viral disease.

SUBMITTER: Wildner D

PROVIDER: S-EPMC4218901 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Impact of acoustic radiation force impulse imaging in clinical practice of patients after orthotopic liver transplantation.

Wildner Dane D Strobel Deike D Konturek Peter C PC Görtz Rüdiger S RS Croner Roland S RS Neurath Markus F MF Zopf Steffen S

Medical science monitor : international medical journal of experimental and clinical research 20141024

<h4>Background</h4>Acoustic radiation force impulse (ARFI) elastography is a reliable diagnostic device for quantitative non-invasive assessment of liver fibrosis in patients with chronic liver disease. The aim of our prospective study was to evaluate the impact of ARFI in patients after orthotopic liver transplantation (OLT). Therefore, we compared ARFI shear wave velocities with clinical features, non-invasive markers, and the histology of patients following OLT.<h4>Material and methods</h4>Po ...[more]

PMID: 25342166

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Project description:Chronic viral hepatitis is associated with substantial morbidity and mortality worldwide. The aim of our study was to assess the ability of point shear-wave elastography (pSWE) using acoustic radiation force impulse imaging for the prediction of the following liver-related events (LREs): new diagnosis of HCC, liver transplantation, or liver-related death (hepatic decompensation was not included as an LRE). pSWE was performed at study inclusion and compared with liver histology, transient elastography (TE), and serologic biomarkers (aspartate aminotransferase to platelet ratio index, Fibrosis-4, FibroTest). The performance of pSWE and TE to predict LREs was assessed by calculating the area under the receiver operating characteristic curve and a Cox proportional-hazards regression model. A total of 254 patients with a median follow-up of 78 months were included in the study. LRE occurred in 28 patients (11%) during follow-up. In both patients with hepatitis B virus and hepatitis C virus (HCV), pSWE showed significant correlations with noninvasive tests and TE, and median pSWE and TE values were significantly different between patients with LREs and patients without LREs (both P < 0.0001). In patients with HCV, the area under the receiver operating characteristic curve for pSWE and TE to predict LREs were comparable: 0.859 (95% confidence interval [CI], 0.747-0.969) and 0.852 (95% CI, 0.737-0.967) (P = 0.93). In Cox regression analysis, pSWE independently predicted LREs in all patients with HCV (hazard ratio, 17.9; 95% CI, 5.21-61-17; P < 0.0001) and those who later received direct-acting antiviral therapy (hazard ratio, 17.11; 95% CI, 3.88-75.55; P = 0.0002). Conclusion: Our study shows good comparability between pSWE and TE. pSWE is a promising tool for the prediction of LREs in patients with viral hepatitis, particularly those with chronic HCV. Further studies are needed to confirm our data and assess their prognostic value in other liver diseases.

Project description:High intensity focused ultrasound (HIFU) in the abdomen can be sensitive to acoustic aberrations that can exist in the beam path of a single sonication. Having an accurate method to quickly visualize the transducer focus without damaging tissue could assist with executing the treatment plan accurately and predicting these changes and obstacles. By identifying these obstacles, MR acoustic radiation force imaging (MR-ARFI) provides a reliable method for visualizing the transducer focus quickly without damaging tissue and allows accurate execution of the treatment plan.MR-ARFI was used to view the HIFU focus, using a gated spin echo flyback readout-segmented echo-planar imaging sequence. HIFU spots in a phantom and in the livers of five live pigs under general anesthesia were created with a 550 kHz extracorporeal phased array transducer initially localized with a phase-dithered MR-tracking sequence to locate microcoils embedded in the transducer. MR-ARFI spots were visualized, observing the change of focal displacement and ease of steering. Finally, MR-ARFI was implemented as the principle liver HIFU calibration system, and MR-ARFI measurements of the focal location relative to the thermal ablation location in breath-hold and breathing experiments were performed.Measuring focal displacement with MR-ARFI was achieved in the phantom and in vivo liver. In one in vivo experiment, where MR-ARFI images were acquired repeatedly at the same location with different powers, the displacement had a linear relationship with power [y = 0.04x + 0.83 μm (R(2) = 0.96)]. In another experiment, the displacement images depicted the electronic steering of the focus inside the liver. With the new calibration system, the target focal location before thermal ablation was successfully verified. The entire calibration protocol delivered 20.2 J of energy to the animal (compared to greater than 800 J for a test thermal ablation). ARFI displacement maps were compared with thermal ablations during seven breath-hold ablations. The error was 0.83 ± 0.38 mm in the S/I direction and 0.99 ± 0.45 mm in the L/R direction. For six spots in breathing ablations, the mean error in the nonrespiration direction was 1.02 ± 0.89 mm.MR-ARFI has the potential to improve free-breathing plan execution accuracy compared to current calibration and acoustic beam adjustment practices. Gating the acquisition allows for visualization of the focal spot over the course of respiratory motion, while also being insensitive to motion effects that can complicate a thermal test spot. That MR-ARFI measures a mechanical property at the focus also makes it insensitive to high perfusion, of particular importance to highly perfused organs such as the liver.

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Impact of acoustic radiation force impulse imaging in clinical practice of patients after orthotopic liver transplantation.

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Impact of acoustic radiation force impulse imaging in clinical practice of patients after orthotopic liver transplantation.

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