The Propagation Display Method Improves the Reproducibility of Pancreatic Shear Wave Elastography

Protocol for acquisition of images and measurement of transabdominal ultrasound pancreatic two-dimensional shear wave elastography (2D-SWE)

INTRODUCTION

Transabdominal ultrasound (TU) pancreatic 2D-SWE elastography is a developing technique that needs to be protocolized.

OBJECTIVES

Establish a protocol for image acquisition and measurement of TU pancreatic - 2D-SWE elastography and estimate the minimum number of measurements to be performed.

MATERIALS AND METHODS

Ten measurements of pancreatic elasticity were taken in healthy volunteers using TU-2D-SWE, following a strict protocol for image acquisition and measurement.

RESULTS

The 70% of the participants were women, with an average age, weight, and BMI of 49.5±15.7 years, 65.9±11.9kg, and 24.5±4.2kg/m2, respectively. Measurements were taken from the body (70%), tail (16.7%), and pancreatic head (13.3%). The median mean velocity and elasticity were 1.46±0.25cm/sec and 6.46±2.87KPa, respectively. The ROI depth was 4.12±1cm and the SP-ROI distance was 5.2mm on average. There were no statistically significant differences between the 10 measurements. The reliability analysis of the measurements showed high internal consistency and repeatability. Taking 5-6 measurements ensured high concordance with the ten reference measurements. The measurements were significantly lower when the SP-ROI values were intermediate (0.3-0.6cm). The measurement accuracy was higher when performed at a depth less than 4.8cm.

CONCLUSION

To measure pancreatic elasticity using TU-2D-SWE, we propose a strict protocol for image acquisition and measurement, taking a minimum of 5 measurements in the best visualized and accessible pancreatic portion, and preferably at a depth of less than 4.8cm.

Evaluation of ulcerative colitis activity using transabdominal ultrasound shear wave elastography

BACKGROUND

Transabdominal ultrasound (US) has been reported to be effective in the evaluation of ulcerative colitis (UC). US can measure shear wave elastography (SWE) and shear wave dispersion (SWD), which may be correlated with inflammation and necrosis. We aimed to investigate the relationship between UC activity and SWE and SWD.

METHODS

Patients with UC who underwent US within 2 days before or after a colonoscopy between April 2019 and March 2020 were included. SWE and SWD were measured in the sigmoid colon; the correlations of SWE and SWD with the Lichtiger index and the Ulcerative Colitis Endoscopic Index of Severity (UCEIS) were investigated. We also compared SWE and SWD between patients with mucosal healing and those in the active phase according to the UCEIS.

RESULTS

Twenty-six UC patients were enrolled. The median Lichtiger index, UCEIS, SWE values, and SWD values were 8 [interquartile range (IQR), 5.3-10.8], 4 (IQR, 3.3-5), 1.69 (IQR, 1.49-2.16) m/s, and 11.9 (IQR, 10.9-13.3) (m/s)/kHz, respectively. The Lichtiger index and UCEIS were negatively correlated with the SWE values (rs=-0.404 and rs=-0.506) but not with the SWD values (rs=0.004 and rs=0.002). The SWE values differed significantly between the mucosal healing and active phase groups [2.40 (IQR, 2.18-3.38) vs. 1.62 (IQR, 1.44-1.95) m/s, P=0.007], whereas the SWD values did not [13.1 (IQR, 7.05-21.6) vs. 11.9 (IQR, 11.1-13.2) (m/s)/kHz, P=0.918].

CONCLUSIONS

SWE may be useful for the evaluation of UC activity and could be a noninvasive method of assessing disease severity.

Variability measurements provide additional value to shear wave elastography in the diagnosis of pancreatic cancer

Shear wave elastography (SWE) is a technique to non-invasively and quantitatively evaluate tissue stiffness. We aimed to investigate whether we can differentiate pancreatic cancer (PC) from normal pancreatic parenchyma (NPP) by SWE using transabdominal ultrasound. We investigated a total of 106 patients (84 with NPP and 22 with PC) whose pancreatic elastic modulus was measured by two-dimensional SWE (2D-SWE). Intra-rater reliability in this study was examined, and three measurements were sufficiently reliable. There were no differences between the two groups in factors that could affect SWE measurements. The median value of the elastic modulus was 5.70 kPa in the PC patients and 5.66 kPa in the NPP group, which was not significantly different (P = 0.785). On the contrary, the range was 8.64 kPa and 4.72 kPa, with a significantly greater range in the PC patients (P = 0.001). In conclusion, the median elastic modulus measured by 2D-SWE was not significantly different between PC and NPP, and evaluating the obtained elastic modulus itself is not useful in differentiation. However, the variability was significantly greater in PC than in NPP. Evaluating the range of elasticities will provide additional information in SWE, which may be useful in the diagnosis of PC.

Percutaneous Two-Dimensional Shear Wave Elastography for Diagnosis of Pancreatic Tumor

BACKGROUND

To investigate the efficacy of two-dimensional shear wave elastography (2D-SWE) for the diagnosis of pancreatic mass lesions.

METHODS

This ethics committee-approved cross-sectional study included 52 patients with histologically-proven pancreatic tumors (pancreatic ductal adenocarcinoma (PDAC), 36; tumor-forming pancreatitis (TFP), 15; neuroendocrine tumor, 1) and 33 control subjects. The 2D-SWE was performed for the tumor/non-tumor tissues, and SWE-mapping patterns and propagation quality were assessed.

RESULTS

Three mapping patterns were detected based on the size and distribution of the coloring areas. Pattern A (whole coloring) was detected in all non-tumor tissues and TFP, whereas pattern C (multiple small coloring spots) was detected in PDAC only. Pattern B (partial coloring with smaller spots) was detected in other lesions. The specificity and positive predictive value of pattern A for non-PDAC and those of pattern C for PDAC were 100%. The SWE value was higher in tumor lesions than in the non-tumor tissues (38.1 vs. 9.8 kPa; p < 0.001) in patients with PDAC. The SWE value in the non-tumor lesion was higher in patients with PDAC than in control (9.8 vs. 7.5 kPa; p < 0.001).

CONCLUSIONS

2D-SWE may play a role as a novel diagnostic tool for PDAC to detect a specific mapping pattern with quantitative assessment.