Focal fatty sparing as an indicator of higher-grade fatty liver assessed by attenuation imaging: a prospective clinical study in NAFLD population

Background As part of a prospective clinical study, the degree of hepatic fatty degeneration was quantified in a patient population with nonalcoholic fatty liver disease and sonographically diagnosed with hepatic steatosis using attenuation imaging. Methods A total of 113 patients with hepatic steatosis were examined, of whom 35 showed focal fatty sparing. Patients with the condition after right nephrectomy, other known liver diseases, and relevant alcohol consumption were excluded from the evaluation. B-scan sonography and sonographic quantification of steatosis content using attenuation imaging (Aplio i800 Canon Medical Systems) were performed. Attenuation imaging is a new ultrasound-based measurement technique that allows objective detection and quantification of hepatic steatosis. Results The prevalence of focal fatty sparing was 31.0% in the patient population examined. Patients with focal fatty sparing showed a statistically significantly higher attenuation coefficient in contrast to patients without focal fatty sparing (0.79 ± 0.10 vs. 0.66 ± 0.09 dB/cm/MHz, p < 0.0001). Conclusion Detection of focal fatty sparing is associated with an increased attenuation coefficient and is thus an expression of higher-grade hepatic fatty degeneration. Patients with focal fatty sparing are more often male and have a higher BMI and a larger liver than patients with nonalcoholic fatty liver disease without focal fatty sparing.

Shear Wave Elastography and Shear Wave Dispersion Imaging in the Assessment of Liver Disease in Alpha1-Antitrypsin Deficiency

Liver affection of Alpha1-antitrypsin deficiency (AATD) can lead to cirrhosis and hepatocellular carcinoma (HCC). A noninvasive severity assessment of liver disease in AATD is urgently needed since laboratory parameters may not accurately reflect the extent of liver involvement. Preliminary data exist on two-dimensional shear wave elastography (2D-SWE) being a suitable method for liver fibrosis measurement in AATD. AATD patients without HCC were examined using 2D-SWE, shear wave dispersion imaging (SWD) and transient elastography (TE). Furthermore, liver steatosis was assessed using the controlled attenuation parameter (CAP) and compared to the new method of attenuation imaging (ATI). 29 AATD patients were enrolled, of which 18 had the PiZZ genotype, eight had PiMZ, two had PiSZ and one had a PiZP-Lowell genotype. 2D-SWE (median 1.42 m/S, range 1.14–1.83 m/S) and TE (median 4.8 kPa, range 2.8–24.6 kPa) values displayed a significant correlation (R = 0.475, p < 0.05). 2D-SWE, ATI (median 0.56 dB/cm/MHz, range 0.43–0.96 dB/cm/MHz) and CAP (median 249.5 dB/m, range 156–347 dB/m) values were higher in PiZZ when compared to other AATD genotypes. This study provides evidence that 2D-SWE is a suitable method for the assessment of liver disease in AATD. The newer methods of SWD and ATI require further evaluation in the context of AATD.

Coda-attenuation imaging of the North Anatolian Fault Zone, northern Turkey

&lt;p&gt;The North Anatolian Fault (NAF), a right-lateral strike-slip fault spanning 1500 km in length, stretches across northern Turkey and it marks the boundary between the Eurasian and Anatolian plates. Nucleating in the east, at the Karliova triple junction and reaching the Aegean Sea at the west, it is a particularly active fault zone with a series of migrating high-magnitude earthquakes. Using 6445 Z-component waveforms from a temporary seismic network in the area (Dense Array for North Anatolia &amp;#8211; DANA), this study aims to investigate the western part of the NAF, which splays into a northern and southern branch. Coda attenuation imaging is utilised for imaging the absorption characteristics of the area, as it can be used as a marker for source and dynamic Earth processes due to its higher sensitivity to small variations of lithospheric properties compared to seismic velocity. The absorption structure is recovered by inverting for the coda attenuation quality factor, Q&lt;sub&gt;c&lt;/sub&gt;, at frequencies between 3-18 Hz, using sensitivity kernels. The extensive seismicity in the area, as well as the density of the seismic stations, provide high-resolution models of 0.04-0.05 degrees in spacing. The scattering structure of the region is imaged using peak-delay time, which is used as a direct measure for multiple forward scattering. Preliminary results show a clear change in scattering between the Istanbul and Sakarya zones, north and south of the fault respectively, with the scattering increasing from north to south at lower frequencies and decreasing at higher frequencies. At a smaller scale, absorption and scattering anomalies appear to outline contrasting geological units beneath the DANA network.&lt;/p&gt;