Mechanical biomarkers by torsional shear ultrasound for medical diagnosis

Abstract

The WHO estimates that 15 million babies yearly (1 in 10) will be born preterm. Worldwide, complications of preterm births have supplanted pneumonia as the primary cause of child mortality [1]. The biology of cervical ripening that leads to birth is poorly understood, and there is no clinical tool to quantitatively evaluate the cervical biomechanical state, which in words of Feltovich [2]“… likely contributes to the reason the singleton spontaneous preterm birth rate has not changed appreciably in more than 100 years.” Towards this problem, we work on enabling new sensor technologies sentient to soft tissue biomechanics, to endow a new class of biomarkers that quantify the mechanical functionality of the cervix, and indeed any soft tissue, ranging pathologies from tumors, atherosclerosis, liver fibrosis to osteoarticular syndromes. Ultrasonic characterization of soft tissue has been developed as a clinical diagnostic tool [3] and evolved through different technologies including our torsional wave principle [4]. Our recent advances covering (a) torsional waves (shear elastic waves that propagate in quasifluids radially and in depth in a curled geometry), (b) sensors (based on a novel arrangement of concentric sandwiches of elements), (c) propagation models and (d) patient testing, are allowing to quantify the mechanical functionality beyond linear parameters: dispersive and nonlinear. [1] WHO, 2012; [2] Feltovich. AJOG207(2012):345–354 [3] Barr. Ultras Quart28(2012):13–20; [4] Melchor. Ultrasonics, 54(2014):1950–1962.

Objective Assessment of Regional Stiffness in Vastus Lateralis with Different Measurement Methods: A Reliability Study

“…The intra- and inter-day reliability of SWE described in this study (ICC = 0.62 to 0.80) was similar to what previous investigations have reported in healthy participants [ 11 , 13 ], although the CV registered in our study (CV = 15.3 to 33.8%) was higher in both measurement time comparisons [ 11 , 13 ]. SWE is based on the interpretation of the propagation of shear waves to estimate shear wave velocity (m/s) and shear modulus (kPa) [ 33 ], so factors such as depth, the anatomical structures evaluated, or the degree of stenosis could affect the results and reliability tasks [ 8 , 9 , 33 , 34 ]. The thickness of superficial connective tissue could provoke the saturation of the elastogram, which occurs when the elasticity of the tissue exceeds the upper limit of the elasticity scale that is used to render the elastogram, and would make the SWE exam of subjacent tissue difficult [ 16 ].…”

“…Elastography ultrasound is widely used to quantify the mechanical properties of tissues [ 5 , 7 , 8 , 9 ]. There are different methods of elastography which have been applied to describe passive muscle stiffness based on the adaptation of the tissue to mechanical stimuli.…”

Shear Wave Elastography in Patients with Primary and Secondary Hyperparathyroidism

“…Labeled as “palpation imaging”, elastography offers qualitative and quantitative information on the tissue anatomical architecture, identifying changes in tissue stiffness [ 20 , 22 , 23 , 24 ]. Elastography has been validated as a marker of pathological states in many clinical fields by facilitating the diagnosis, differential diagnosis, and therapeutic management and establishing its role in endocrinology (thyroid and parathyroid area) [ 25 , 26 ], hepatogastroenterology [ 20 , 27 , 28 , 29 ], senology [ 30 , 31 ], urology [ 32 , 33 , 34 ], and otorhinolaryngology [ 35 ].…”

Shear Wave Elastography in Diagnosing Secondary Hyperparathyroidism

“…By analyzing the particle displacements with an ultrafast ultrasound acquisition sequence, quantitative measurements of tissue elasticity can be obtained [36]. Evaluation of the elasticity characteristics of the tissue can help in identifying special types of tissues [39] Shear wave elastography (Aixplorer Super Sonic) overlays the elastographic image on the B-mode, providing a real-time map of elasticity. The operator should also pay attention not to apply any kind of pressure on the probe [40].…”