Ultrasound shear wave elastography imaging of common carotid arteries in patients with Spontaneous Coronary Artery Dissection (SCAD)

Effects of acute cervical stretching on arterial wall elastic properties

Purpose: Acute (immediate) or regular (mid- or long-term) stretching increases arterial compliance and reduces arterial stiffness. Stretching is widely known to induce arterial functional factor changes, but it is unclear whether stretching alters arterial structural factors. Ultrasound shear wave elastography can quantify the distribution of tissue elastic properties as an index of arterial structural factors. This study thus aimed to examine the effects of acute cervical stretching on arterial wall tissue elastic properties. Methods: Seventeen healthy young adults participated in two different trials for 15 min in random order on separate days: a resting and sitting trial (CON) and a supervised cervical stretching trial (CS). In CS, subjects performed 10 different stretches. At each site, the stretch was held for 30 s followed by a 10-s relaxation period. In CON, subjects rested on a chair for 15 min. Results: After the experiment, carotid arterial compliance, assessed by combined ultrasound imaging and applanation tonometry, was significantly increased in CS, but not in CON. However, there was no significant change in tissue elasticity properties of the arterial wall in either trial, as assessed by ultrasound shear wave elastography. Conclusion: Acute cervical stretching significantly increased carotid artery compliance in young participants, but did not reduce elastic tissue properties (i.e., arterial structural factors) of the carotid artery wall. These results strongly suggest that changes in structural factors have little relation to stretching-induced acute increases in arterial compliance.

Ultrasound Elastography to Differentiate the Thrombus and Plaque in Peripheral Arterial Diseases

Purpose

Arterial stiffness and steno-occlusion of the lower-extremity can result from many vascular lesions, including acute thromboembolisms, soft plaques, calcified plaques, or inflammatory disease. Ultrasound (US) elastography measures the tissue deformation response to compression and displays tissue stiffness. This study aimed to evaluate the characteristics of arterial lesions in the lower extremities using US elastography.

Materials and Methods

We retrospectively analyzed the data of 20 patients who visited our institute for arterial disease treatment between May 2016 and November 2017. An US examination with B-mode and strain elastography (SE) was performed of four different lesion types at 45 sites: acute and subacute thromboembolisms, soft plaques, calcified plaques, and thromboangiitis obliterans lesions (TAOs). During SE, stress was externally applied by the operator using the transducer. Strain ratio (SR) was calculated as the fraction of the average strain in the reference area divided by the average strain in the lesion. The SR was compared among different lesion types, with the accompanying vein as the reference region of interest.

Results

The strain was highest in the soft plaques (0.63%±0.23%), followed by the TAOs (0.45%±0.11%), calcified plaques (0.44%±0.13%), and acute thromboembolisms (0.34%±0.23%), which were statistically significant (P=0.026). However, the mean SR was highest for the calcified plaques (2.33%±0.80%), followed by the TAOs (1.63%±0.40%), acute thromboembolisms (1.60%±0.48%), and soft plaques (1.51±0.39), and which were statistically significant (P=0.013).

Conclusion

Despite several limitations, vascular elastography may be useful for differentiating between lesion types in peripheral arterial disease.