Acoustic Radiation Force Impulse quantitative elastography: a new noninvasive technique for the evaluation of parotid glands. A preliminary study in controls and in patients with irradiated nasopharyngeal carcinoma.

Abstract

Aim: We aim to define the values of the shear wave velocity (SWV) in the normal parotid glands (PG) and to identify the modifications of tissue stiffness in patients with irradiated nasopharyngeal carcinoma. Material and methods: Sixty normal parotid glands pertaining to 30 healthy volunteers and 40 pathological parotid glands pertaining to 20 patients who had had underwent radiation therapy for nasopharyngeal carcinoma were included in this study. The patients underwent a B mode ultrasonography examination and the volume of the parotid gland was determined. A subsequent Acoustic Radiation Forde Impulse Imaging (ARFI) examination was performed and the SWV were determined for the central and the periphery of the glandular parenchyma. Results: The mean volume of the gland in the volunteers' group (12.02±0.6 ml) was significantly higher than in the group of patients who underwent radiation therapy (10.3±0.74 ml) (p<0.0001). The SWV values in the normal group were lower compared to the patients group (1.54±0.6 m/s vs. 1.76±0.73 m/s, p<0.0001). Conclusion: Elastography using the ARFI technique constitutes an objective method used for the evaluation of glandular stiffness in both normal and post radiotherapy glands. The SWV values determined in patients who underwent head and neck radiotherapy are increased, indicating a greater tissue stiffness thereby implying a structural transformation of the glandular parenchyma.

Quantitative measurements of radiation‐induced fibrosis for head and neck cancer: A narrative review

“…The degree and speed of the tissue's response to this deformation are then monitored by ultrasound tracking beams. By analyzing the deformation wavefront at multiple points and correlating the measurements with the time elapsed, the shear wave velocity (SWV, m/s) can be determined 34–36 . The velocity of these waves correlates with the tissue's stiffness; the waves travel faster in stiffer tissues and slower in softer ones.…”

“…43,44 More recently, it has been used to characterize tissue stiffness in the submandibular gland (SMG) and parotid gland (PG) following RT (Figures 4 and 5). 35,36 These articles demonstrated ARFI's ability to detect differences stiffness and time elapsed since RT. 46 Wen etal.…”

“…The figures and caption were adapted with permission. 36 and position of the region of interest on the elastogram can further affect the results, thereby not providing entirely precise elastography indices. 38 Environmental factors, such as room temperature and patient positioning, can influence measurements, albeit to a lesser extent.…”

Ultrasonographic and elastographic biometry in adult major salivary glands: a preliminary case-control report

“…In diseased salivary glands, such as primary Sjögren’s syndrome 17 and post-irradiated glands 18 , the shear wave velocity (SWV) is higher than that in normal glands. However, these results varied as a result of the measurement site 19 and pre-compression level 20 . Therefore, the related factors of the biometry and stiffness of the major salivary glands with US are not clear.…”

Ultrasound Elastography in Diffuse and Focal Parotid Gland Lesions

“…Glandular loss of function and damage begin around 30-40 Gy [33] . In a preliminary study, Badea et al [34] verified variation in shear wave velocities between healthy and irradiated glandular parenchyma. They pointed out that SWE was capable of depicting radiation-induced changes in the elasticity of glandular tissue and implied morphological alterations of the parotid gland.…”