Influencing Factors of 2D Shear Wave Elastography of the Muscle - An Ex Vivo Animal Study.

OBJECTIVE: To evaluate measurement confounders on 2D shear wave elastography (2D-SWE) elastography of muscle. MATERIALS AND METHODS: Ex vivo , porcine muscle was examined with a GE LOGIQ E9 ultrasound machine with a 9 L linear (9 MHz) and C1-6 convex probe (operating at 2.5 or 6 MHz). The influence of different confounders on mean shear wave velocity (SWVmean) was analyzed: probes, pressure applied by probe, muscle orientation, together with the impact of different machine settings such as frequency, placement depth and size of region of interest (ROI). The mean of twelve repeated SWVmean measurements (m/s) and coefficient of variation (CV; standard deviation/mean in %) were assessed for each test configuration. RESULTS: Reproducibility (CV) and maximum possible tissue depth of the linear probe were inferior to the convex probe. With the linear probe, there was a linear decrease of SWVmean with placement depth from 4.56 m/s to 1.81 m/s. A significant increase of SWVmean (p<0.001) was observed for larger ROI widths (range 3.96 m/s to 6.8 m/s). A change in the machine operation mode ('penetration' instead of 'general') led to a significant increase of SWVmean (p=0.04). SWVmean in the longitudinal direction of muscle was significantly higher than in cross section (p<0.001) (e. g. 4.56 m/s versus 3.42 m/s). An increase of linear probe pressure significantly increased muscle SWVmean from 5.29 m/s to 7.21 m/s (p<0.001). CONCLUSIONS: 2D-SWE of muscle is influenced by a wealth of parameters. Therefore, standardization of measurement is advisable before application in clinical research studies and routine patient assessment.

Quantification of aortic valve calcification on contrast-enhanced CT of patients prior to transcatheter aortic valve implantation.

AIMS: The aim of the study was to develop a formula enabling the quantification of aortic valve calcification (AVC) on contrast-enhanced CT of patients undergoing transcatheter aortic valve implantation (TAVI). METHODS AND RESULTS: Two hundred and seventeen (217) consecutive patients with severe aortic valve stenosis undergoing non-enhanced electrocardiography-gated CT angiography (NECT) and contrast-enhanced electrocardiography-gated CT angiography (CECT) prior to TAVI were subdivided into a training cohort (n=145) and a validation cohort (n=72). Aortic valve calcification (AVC) was semi-automatically segmented on CECT (AVC.

Value of CT signs and measurements as a predictor of pulmonary hypertension and mortality in symptomatic severe aortic valve stenosis.

To assess the value of computed tomography (CT) for non-invasive detection of pulmonary hypertension (PH) in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI) and to correlate CT measurements and signs with mortality after TAVI. 257 TAVI patients (median 84 years; 134 females) with both right heart catheterisation (RHC) and CT within 3 days were retrospectively analyzed. According to guidelines PH was defined as mean pulmonary artery pressure ≥25 mmHg in RHC. CT-signs for PH assessment were evaluated. Clinical data was recorded before and at 30 days, 1 year and 2 years after TAVI. 161 patients exhibited PH (median 83 years; 90 females). In patients with PH, main pulmonary artery diameter (MPA; p < 0.001) and anterior pericardial recess (PR; p = 0.003) were significantly larger. Furthermore, pleural effusion (p < 0.001) was significantly more common. Sensitivity and specificity for predicting PH were calculated for MPA diameter ≥29 mm (56 and 61%), PR diameter ≥10 mm (37 and 82%), and presence of pleural effusion (42 and 91%). Patients with PH showed significantly higher 2 years mortality after TAVI (30 vs. 17%; p = 0.01) with a Hazard ratio (HR) of 2.5 (95% CI 1.1-5.8; p = 0.027). Pleural effusion was a predictor of higher 2-year-all-cause mortality after TAVI (42 vs. 20%; p = 0.022) with a HR of 2.0 (95% CI 1.0-3.8; p = 0.042). Patients with symptomatic AS and PH at baseline display higher 2 year-all-cause mortality after TAVI. Several CT-signs suggest the presence of PH in TAVI patients with moderate to high specificity, but low sensitivity. Pleural effusion in CT is a predictor of higher 2 year-all-cause mortality.