Diagnostic accuracy of elastography and magnetic resonance imaging in patients with NAFLD: A systematic review and meta-analysis.

BACKGROUND AND AIMS: Vibration-controlled transient elastography (VCTE), point shear wave elastography (pSWE), 2-dimensional shear wave elastography (2DSWE), magnetic resonance elastography (MRE), and magnetic resonance imaging (MRI) have been proposed as non-invasive tests for patients with non-alcoholic fatty liver disease (NAFLD). This study evaluated their diagnostic accuracy for liver fibrosis and non-alcoholic steatohepatitis (NASH). METHODS: PubMED/MEDLINE, EMBASE and the Cochrane Library were searched for studies examining the diagnostic accuracy of these index tests, against histology as the reference standard, in adult patients with NAFLD. Two authors independently screened and assessed methodological quality of studies and extracted data. Summary estimates of sensitivity, specificity and area under the curve (sAUC) were calculated for fibrosis stages and NASH, using a random effects bivariate logit-normal model. RESULTS: We included 82 studies (14,609 patients). Meta-analysis for diagnosing fibrosis stages was possible in 53 VCTE, 11 MRE, 12 pSWE and 4 2DSWE studies, and for diagnosing NASH in 4 MRE studies. sAUC for diagnosis of significant fibrosis were: 0.83 for VCTE, 0.91 for MRE, 0.86 for pSWE and 0.75 for 2DSWE. sAUC for diagnosis of advanced fibrosis were: 0.85 for VCTE, 0.92 for MRE, 0.89 for pSWE and 0.72 for 2DSWE. sAUC for diagnosis of cirrhosis were: 0.89 for VCTE, 0.90 for MRE, 0.90 for pSWE and 0.88 for 2DSWE. MRE had sAUC of 0.83 for diagnosis of NASH. Three (4%) studies reported intention-to-diagnose analyses and 15 (18%) studies reported diagnostic accuracy against pre-specified cut-offs. CONCLUSIONS: When elastography index tests are acquired successfully, they have acceptable diagnostic accuracy for advanced fibrosis and cirrhosis. The potential clinical impact of these index tests cannot be assessed fully as intention-to-diagnose analyses and validation of pre-specified thresholds are lacking. LAY SUMMARY: Non-invasive tests that measure liver stiffness or use magnetic resonance imaging (MRI) have been suggested as alternatives to liver biopsy for assessing the severity of liver scarring (fibrosis) and fatty inflammation (steatohepatitis) in patients with non-alcoholic fatty liver disease (NAFLD). In this study, we summarise the results of previously published studies on how accurately these non-invasive tests can diagnose liver fibrosis and inflammation, using liver biopsy as the reference. We found that some techniques that measure liver stiffness had a good performance for the diagnosis of severe liver scarring.

ACC inhibitor alone or co-administered with a DGAT2 inhibitor in patients with non-alcoholic fatty liver disease: two parallel, placebo-controlled, randomized phase 2a trials.

Alterations in lipid metabolism might contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, no pharmacological agents are currently approved in the United States or the European Union for the treatment of NAFLD. Two parallel phase 2a studies investigated the effects of liver-directed ACC1/2 inhibition in adults with NAFLD. The first study ( NCT03248882 ) examined the effects of monotherapy with a novel ACC1/2 inhibitor, PF-05221304 (2, 10, 25 and 50 mg once daily (QD)), versus placebo at 16 weeks of treatment; the second study ( NCT03776175 ) investigated the effects of PF-05221304 (15 mg twice daily (BID)) co-administered with a DGAT2 inhibitor, PF-06865571 (300 mg BID), versus placebo after 6 weeks of treatment. The primary endpoint in both studies was percent change from baseline in liver fat assessed by magnetic resonance imaging-proton density fat fraction. Dose-dependent reductions in liver fat reached 50-65% with PF-05221304 monotherapy doses ≥10 mg QD; least squares mean (LSM) 80% confidence interval (CI) was -7.2 (-13.9, 0.0), -17.1 (-22.7, -11.1), -49.9 (-53.3, -46.2), -55.9 (-59.0, -52.4) and -64.8 (-67.5, -62.0) with 16 weeks placebo and PF-05221304 2, 10, 25 and 50 mg QD, respectively. The overall incidence of adverse events (AEs) did not increase with increasing PF-05221304 dose, except for a dose-dependent elevation in serum triglycerides (a known consequence of hepatic acetyl-coenzyme A carboxylase (ACC) inhibition) in 23/305 (8%) patients, leading to withdrawal in 13/305 (4%), and a dose-dependent elevation in other serum lipids. Co-administration of PF-05221304 and PF-06865571 lowered liver fat compared to placebo (placebo-adjusted LSM (90% CI) -44.6% (-54.8, -32.2)). Placebo-adjusted LSM (90% CI) reduction in liver fat was -44.5% (-55.0, -31.7) and -35.4% (-47.4, -20.7) after 6 weeks with PF-05221304 or PF-06865571 alone. AEs were reported for 10/28 (36%) patients after co-administered PF-05221304 and PF-06865571, with no discontinuations due to AEs, and the ACC inhibitor-mediated effect on serum triglycerides was mitigated, suggesting that PF-05221304 and PF-06865571 co-administration has the potential to address some of the limitations of ACC inhibition alone.

Pixel compounding: resolution-enhanced ultrasound imaging for quantitative analysis.

Accurate measurement of structural features represented in medical images is important in clinical trials and patient diagnosis. A key factor for precision is spatial resolution, which in ultrasonic imaging is limited by transducer array arrangements, transmitting frequency, and data acquisition firmware. In this paper, a variation of pixel compounding is proposed to enhance ultrasound resolution using acquired cine loops. The technique operates on a sequence of ultrasound B-scan images acquired with random motion. Subpixel registration is estimated and a maximum a posteriori (MAP) approach with the shift information is used to reconstruct a high-resolution single image. A nonhomogeneous anisotropic diffusion algorithm follows from the estimation process and is implemented to enhance the high-resolution edges. Preliminary tests using simulations and phantom studies show promising results. Pixel compounding can be a powerful preprocessing tool to assure accurate segmentation, measurement, and analysis of ultrasound images.

Novel ultrasound and DCE-MRI analyses after antiangiogenic treatment with a selective VEGF receptor inhibitor.

We report a comparison between tumor perfusion estimates acquired using contrast-enhanced MRI and motion-corrected contrast-enhanced ultrasound before and after treatment with AG-028262, a potent vascular endothelial growth factor receptor tyrosine kinase inhibitor. Antiangiogenic activity was determined by assessing weekly ultrasound and MRI images of rats with bilateral hind flank mammary adenocarcinomas before and after treatment with AG-028262. Images were acquired with a spoiled gradient, 1.5 T magnetic resonance sequence and a destruction-replenishment ultrasound protocol. For ultrasound, a time to 80% contrast replenishment was calculated for each tumor voxel; for MR imaging, a measure of local flow rate was estimated from a linear fit of minimum to maximum intensities. AG-028262 significantly decreased tumor growth and increased the time required to replenish tumor voxels with an ultrasound contrast agent from 2.66 to 4.54 s and to fill with an MR contrast agent from 29.5 to 50.8 s. Measures of flow rate derived from MRI and ultrasound demonstrated a positive linear correlation of r2 = 0.86.