Point quantification elastography in the evaluation of liver elasticity in healthy volunteers: a reliability study based on operator expertise

Shear wave elastography and transient elastography in HCV patients after direct-acting antivirals

PURPOSE

To compare the ultrasound (US) and pulse shear wave elastography (pSWE, Elast PQ^®) methods with transient elastography (TE), clinical scores and laboratory tests, during the follow-up of HCV patients receiving direct-acting antiviral drugs (DAA).

METHODS

Our prospective study from June 2016 to December 2017 included 22 consecutively enrolled HCV-positive patients (59.7 ± 12.3 years, 11 male) which were subjected to antiviral therapy. All patients underwent B-mode ultrasound, color-Doppler, pSWE and TE five times: before therapy (T0), at the end of therapy (post-Tx), and at 12, 24, 48 weeks post-therapy. The liver stiffness (LS) values obtained with pSWE and TE and the data coming from US assessment and clinical evaluation were compared.

RESULTS

We obtained a statistically significant reduction of LS values (kPa) measured by pSWE, between T0 (14.3 ± 9.3), post-Tx (11.8 ± 10.5), 12 weeks (7.5 ± 3.3), 24 weeks (8 ± 3.8) and 48 weeks (8.5 ± 4.6) (p = 0.02). The reduction of kPa measured by TE was not significant between T0 (14.7 ± 9.3), post-Tx (12 ± 9.5), 12 weeks (11.6 ± 7.7), 24 weeks (10.3 ± 6) and 48 weeks (10.8 ± 7.5) (p > 0.05). Multivariate baseline analysis showed significant independent association among measurement of TE stiffness with cirrhosis, type of vein hepatic flow and showed significant independent association between delta-pSWE measurement (difference between stiffness measurements at the baseline and 12 months after treatment) with staging of fibrosis (p = 0.006) and sustained virologic response after 12 weeks of treatment (SVR12, p = 0.017).

CONCLUSION

The pSWE method has shown better ability than TE to identify a reduction in LS. Therefore, pSWE allow to evaluate stiffness reduction in HCV patient during DAA treatment follow-up, which is related to SVR12.

Comparison of Supersonic Shear Wave Imaging-Derived Renal Parenchyma Stiffness Between Diabetes Mellitus Patients With and Without Diabetic Kidney Disease

This study aims to evaluate the difference in renal parenchyma stiffness assessed by measuring Young's modulus (YM) using a supersonic shear wave imaging (SSI) technique among healthy patients and patients with type 2 diabetes mellitus (DM) with and without diabetic kidney disease (DKD). We analyzed the correlations of YM with clinical information and conventional ultrasound parameters. All patients (N = 124) were divided into three groups: (i) healthy patients (patients without kidney disease or type 2 DM, N = 31); (ii) patients with type 2 DM without kidney disease (N = 38); and (iii) patients with DKD (N = 55). Conventional and SSI ultrasound examinations were performed in all individuals for both kidneys. Then, we recorded renal length, width, parenchyma thickness, interlobar arterial resistive index (RI) and values of mean, mininum and maximum YM. The mean values of these parameters for the left and right kidneys were calculated for statistical analysis. Statistical significance was considered at p < 0.05. Among all ultrasound parameters, the mean YM demonstrated the largest area under the receiver operating characteristic (ROC) curve (0.860). The areas under the ROC curve (AUCs) for renal length, width, parenchyma thickness, interlobar arterial RI, minimum YM and maximum YM were 0.493, 0.616, 0.507, 0.733, 0.848 and 0.794, respectively. The corresponding cutoff value of mean YM was 31.73 kPa, with a sensitivity of 85.5% and a specificity of 71.0%. The mean YM in patients with type 2 DM without kidney disease (31.44 ± 3.83 kPa) was significantly higher than that in the healthy group (26.45 ± 4.32 kPa) and lower than that in the DKD group (37.60 ± 6.56 kPa). Patients with type 2 DM without kidney disease were considered as stage 0 of DKD. Thus, the mean YM in the control group was significantly lower than that in the stage 0, 2, 3, 4 and 5 subgroups. The mean YM in the stage 0-2 subgroups was lower than that in the stage 5 group, and the mean YM in the stage 0 group was lower than that in the stage 4 group. In the DKD group, the mean YM had a positive correlation with cystine-c (r = 0.634), urea (r = 0.596), creatine (r = 0.690), uric acid (r = 0.263), albumin/creatinine ratio (r = 0.428) and the presence or absence of diabetic retinopathy (r = 0.354). The mean YM also had a negative correlation with the estimated glomerular filtration rate (r = -0.657). SSI is a non-invasive method with which to diagnose DKD and has a performance superior to that of conventional ultrasound. In addition, SSI may provide a secondary index for the staging of DKD and the monitoring of renal damage in type 2 DM patients.

Preliminary analysis of ultrasound elastography imaging-based thermometry on non-perfused ex vivo swine liver

AIMS

Real-time monitoring of tissue temperature during percutaneous tumor ablation improves treatment efficacy, leading clinicians in adjustment of treatment settings. This study aims at assessing feasibility of ultrasound thermometry during laser ablation of biological tissue using a specific ultrasound imaging techniques based on elastography acoustic radiation force impulse (ARFI).

METHODS

ARFI uses high-intensity focused ultrasound pulses to generate 'radiation force' in tissue; this provokes tissue displacements trackable using correlation-based ultrasound methods: the sensitivity of shear waves velocity is able to detect temperature changes. Experiments were carried out using a Nd:YAG laser (power: 5 W) in three non-perfused ex vivo pig livers. In each organ, a thermocouple was placed close to the applicator tip (distance range 1.5-2.5 cm) used to record a reference temperature. Positioning of laser applicator and thermocouple was eco-guided. The organ was scanned by an echography system equipped with ARFI; propagation velocity was measured in a region of interest of 1 × 0.5 cm located close to thermocouple, to investigate influence of tissue temperature on shear waves velocity.

RESULTS

Shear wave velocity has a very low sensitivity to temperature up to 55-60 °C, and in all cases, velocity is < 5 m s^-1; for temperature > 55-60 °C, velocity shows a steep increment. The system measures a value "over limit", meaning a velocity > 5 m s^-1.

CONCLUSIONS

Ultrasound thermometry during laser ablation of biological tissue based on elastography shows an abrupt output change at temperatures > 55-60 °C. This issue can have a relevant clinical impact, considering tumor necrosis when temperature crosses 55 °C to define the boundary of damaged volume.

Current Imaging Techniques for Noninvasive Staging of Hepatic Fibrosis

OBJECTIVE. The purpose of this article is to discuss quantitative methods of CT, MRI, and ultrasound (US) for noninvasive staging of hepatic fibrosis. Hepatic fibrosis is the hallmark of chronic liver disease (CLD), and staging by random liver biopsy is invasive and prone to sampling errors and subjectivity. Several noninvasive quantitative imaging methods are under development or in clinical use. The accuracy, precision, technical aspects, advantages, and disadvantages of each method are discussed. CONCLUSION. The most promising methods are the liver surface nodularity score using CT and measurement of liver stiffness using MR elastography or US elastography.