ARFI quantitative elastography of the submandibular glands. Normal measurements and the diagnosis value of the method in radiation submaxillitis

Objectives: Evaluation of Acoustic Radiation Force Impulse Imaging (ARFI) elastography performance in predicting the elasticity of the submandibular glands in normal situations and after radiation therapy. Material and method: A number of 54 normal submandibular glands from 27 voluntary subjects and 33 pathological submandibular glands (radiation submaxillities) from 18 patients who had undergone radiation therapy for various cervical and facial oncological conditions were included in study. All the patients had undergone a B mode ultrasonography (Tissue Harmonic Imaging, 8-14 MHz) while the submandibular volume was determined and subsequently an ARFI examination while the shear wave velocity (SWV) was measured (in the central, peripheral and subcapsular areas, with the results expressed in m/s). Results: In the volunteers' group the mean value of the SWV of the left submandibular gland was 1.68 +/- 0.46 m/s, determined in the centre of the gland, 1.88 +/- 0.4 m/s in the periphery (corresponding to the subcapsular parenchyma) and the SWV of the right submandibular gland was 1.74 +/- 0.35 m/s (centrally) and 1.84 +/- 0.43 m/s in the periphery. The mean value of all measurements was 1.82 +/- 0.41 m/s. The mean volume of the glands was 7.97 +/- 2.63 cm(3). In the group of patients who had underwent radiation therapy (at least 35Gy), the mean value of the SWV was 2.24 +/- 0.49 m/s centrally and 2.1 +/- 0.58 m/s in the periphery on the left and 1.99 +/- 0.5 m/s centrally and 2.21 +/- 0.52 m/s in the periphery on the right. The mean value of all the measurements was 2.13 +/- 0.52 m/s and the mean volume of the gland was 5.95 +/- 4.16 cm(3). Conclusions: Elastography using ARFI technique is a valid examination in the evaluation of the normal and pathological submandibular gland stiffness. The values of the shear wave velocities that correspond to a normal stiffness, determined through the ARFI technique, are similar in the two glands. After cervical and facial radiation therapy the values of the SWV are increased, indicating a change in the consistency of the gland thus implying a structural transformation. The ARFI technique can be used in the evaluation of the salivary glands pathology.