Optimal region-of-interest settings for tissue characterization based on ultrasonic elasticity imaging

Evaluation of local changes in radio-frequency signal waveform and brightness caused by vessel dilatation for ascertaining reliability of elasticity estimation inside heterogeneous plaque: a preliminary study

PURPOSE

To diagnose plaque characteristics, we previously developed an ultrasonic method to estimate the local elastic modulus from the ratio of the pulse pressure to the strain of the arterial wall due to dilatation in systole by transcutaneously measuring the minute thinning in thickness during one cardiac cycle. For plaques, however, some target regions became thicker as the vessel dilates, resulting in false elasticity. Therefore, a method to identify a reliable target for the elastic modulus estimation is indispensable. As a candidate for an identification index of plaques that become thicker during one cardiac cycle, the correlation of the radio-frequency (RF) signals remains high and it is not sufficient to obtain the elasticity. In this study, we thoroughly observed the target with a high correlation but positive strain in the plaque and characterized it by the property of the surrounding area.

METHODS

For the plaque formed in the right carotid sinus of a patient with hyperlipidemia and the wall of the right common carotid artery of a young healthy male, (1) the correlation value as the similarity between the RF signals, (2) change in brightness obtained from the log-compressed envelope signals, and (3) strain obtained between the time of the R-wave and that of the maximum vessel dilatation were observed to characterize the region in the plaque.

RESULTS

In the plaque, it was found that the region with high correlation and positive strain and its surrounding area could be classified into one of the three typical patterns.

CONCLUSION

As a preliminary study, this study provides a clue to assert the reliability of elasticity estimates for a region with high correlation and positive strain in the plaque based on measurable properties.

Shear wave elastography and pulsed doppler for breast lesions: Similar diagnostic performance and positively correlated stiffness and blood flow resistance

PURPOSE

To compare the diagnostic performance of shear wave elastography (SWE) and pulsed Doppler ultrasound in breast lesions, and to explore whether the quantitative SWE parameters correlated with pulsed Doppler ultrasound parameters.

MATERIALS AND METHODS

Seventy-nine patients with 79 breast lesions who had undergone conventional ultrasound, pulsed Doppler ultrasound and SWE examination were included. All of them underwent core needle biopsy or surgery within one week. Parameters including Emax (the maximum elastic modulus), Emean (mean elastic modulus), Emin (minimum elastic modulus), Esd (elastic modulus standard deviation), and RI (resistive index), PI (pulsatility index), PSV (peak systolic velocity) and EDV (end diastolic velocity) were obtained for statistical analysis.

RESULTS

Almost all SWE parameters were significantly different between benign and malignant breast lesions (P＜0.05). There was no significant difference between Esd and PI (P＞0.05), which had the best AUC among SWE and vascular parameters respectively (0.877 vs. 0.871). Emax showed a moderate correlation with PI (P = 0.000, r = 0.552) and RI (P = 0.000, r = 0.544), and Esd moderately correlated with PI (P = 0.000, r = 0.567) and RI (P = 0.000, r = 0.546). For the benign group, no parameters showed any significant correlation (P＞0.05), while for the malignant group, Emax and Esd also significantly correlated with PI or RI.

CONCLUSIONS

SWE and pulsed Doppler ultrasound had similar diagnostic efficacy for breast lesions. SWE and pulsed Doppler parameters were significantly correlated in breast lesions, especially in malignant ones, indicating the potential association between elastographic and vascular characteristics of breast tumors.

Relationship between upper limb peripheral artery stiffness using the radial artery and atherosclerotic parameters

PURPOSE

A new method has been developed for evaluating arterial stiffness using transcutaneous and high-frequency ultrasound. There may be a difference in the clinical significance of peripheral arteries, such as the radial artery (a muscular property), and other medium/large-sized arteries (an elastic property). The aim of this study was to determine the relationship between upper limb peripheral arterial stiffness (ULPAS) using the new method for the radial artery and atherosclerotic parameters in comparison with carotid intima-media thickness (IMT) and cardio-ankle vascular index (CAVI) in a healthy population and a diseased population with hypertension (HT) and diabetes mellitus (DM).

METHODS

Forty-four apparently healthy individuals (mean age = 26.3 years, men/women = 14/30), 45 patients with drug-treated HT (mean age = 55.3 years, men/women = 17/28), and 37 patients with drug-treated DM (mean age = 55.2 years, men/women = 21/16) were investigated. Body mass index, systolic blood pressure (SBP), diastolic blood pressure (DBP), CAVI, IMT, ultrasonographically measured ULPAS, blood lipid/glucose-related parameters, and C-reactive protein (CRP) were all determined.

RESULTS

Among the healthy subjects, ULPAS showed a significantly positive correlation with SBP and CRP. ULPAS showed a different correlation pattern with atherosclerotic parameters from that of IMT and CAVI. The HT subjects had significantly higher ULPAS levels than those with DM. In this diseased population, ULPAS showed a significant positive correlation with SBP and DBP, as well as a significant negative correlation with glucose.

CONCLUSION

These results suggest that ULPAS may provide new information in association with some atherosclerotic conditions as a unique index different from IMT and CAVI.