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Shear wave elastography is emerging as a clinically valuable diagnostic tool to differentiate between benign and malignant breast masses. Elastography techniques assume that soft tissue can be modelled as a purely elastic medium. However, this assumption is often violated as soft tissue exhibits viscoelastic properties. In order to explore the role of viscoelastic parameters in suspicious breast masses, a study was conducted on a group of patients using shear wave dispersion ultrasound vibrometry in the frequency range of 50–400 Hz. A total of 43 female patients with suspicious breast masses were recruited before their scheduled biopsy. Of those, 15 patients did not meet the data selection criteria. Voigt model based shear elasticity showed a significantly (p = 7.88x10-6) higher median value for the 13 malignant masses (16.76±13.10 kPa) compared to 15 benign masses (1.40±1.12 kPa). Voigt model based shear viscosity was significantly different (p = 4.13x10-5) between malignant (8.22±3.36 Pa-s) and benign masses (2.83±1.47 Pa-s). Moreover, the estimated time constant from the Voigt model, which is dependent on both shear elasticity and viscosity, differed significantly (p = 6.13x10-5) between malignant (0.68±0.33 ms) and benign masses (3.05±1.95 ms). Results suggest that besides elasticity, viscosity based parameters like shear viscosity and time constant can also be used to differentiate between malignant and benign breast masses. [ABSTRACT FROM AUTHOR]

Introduction: Osteoarthritis (OA) is the most common musculoskeletal disease. Current treatments for OA are mainly symptomatic and inadequate since none results in restoration of fully functional cartilage. Hyaluronic Acid (HA) intra-articular injections are widely accepted for the treatment of pain associated to OA. The goal of HA viscosupplementation is to reduce pain and improve viscoelasticity of synovial fluid. Platelet-rich plasma (PRP) has been also employed to treat OA to possibly induce cartilage regeneration. The combination of HA and PRP could supply many advantages for tissue repair. Indeed, it conjugates HA viscosupplementation with PRP regenerative properties. The aim of this study was to evaluate the rheological and biological properties of different HA compositions in combination with PRP in order to identify (i) the viscoelastic features of the HA-PRP blends, (ii) their biological effect on osteoarthritic chondrocytes and (iii) HA formulations suitable for use in combination with PRP. Materials and Methods: HA/PRP blends have been obtained mixing human PRP and three different HA at different concentrations: 1) Sinovial, 0.8% (SN); 2) Sinovial Forte 1.6% (SF); 3) Sinovial HL 3.2% (HL); 4) Hyalubrix 1.5% (HX). Combinations of phosphate buffered saline (PBS) and the four HA types were used as control. Rheological measurements were performed on an Anton PaarMCR-302 rheometer. Amplitude sweep, frequency sweep and rotational measurements were performed and viscoelastic properties were evaluated. The rheological data were validated performing the tests in presence of Bovine Serum Albumin (BSA) up to ultra-physiological concentration (7%). Primary osteoarthritic chondrocytes were cultured in vitro with the HA and PRP blends in the culture medium for one week. Cell viability, proliferation and glycosaminoglycan (GAG) content were assessed. Results: PRP addition to HA leads to a decrease of viscoelastic shear moduli and increase of the crossover point, due to a pure dilution effect. For viscosupplements with HA concentration below 1% the viscoelasticity is mostly lost. Results were validated also in presence of proteins, which in synovial fluid are more abundant than HA. Chondrocytes proliferated overtime in all different culture conditions. The proliferation rate was higher in chondrocytes cultured in the media containing PRP compared to the cultures with different HA alone. GAG content was significantly higher in chondrocytes cultured in PRP and HL blend. Discussion: We investigated the rheological and biological properties of four different HA concentrations when combined with PRP giving insights on viscoelastic and biological properties of a promising approach for future OA therapy. Our data demonstrate that PRP addition is not detrimental to the viscosupplementation effect of HA. Viscosupplements containing low HA concentration are not indicated for combination with PRP, as the viscoelastic properties are lost. Although having the same rheological behavior of SF and HX, HL was superior in stimulating extracellular matrix production in vitro. [ABSTRACT FROM AUTHOR]