The contribution of shear wave elastography and t2* mapping to the diagnosis of early stage troclear cartilage damage

Objective: To examine femoral trochlear cartilage in patients with early knee osteoarthritis using MRI T2 * Mapping and Ultrasound Shear wave elastography methods and to evaluate the contribution of these two techniques to diagnosis. Materials and Methods: Technical evaluations were carried out prospectively by using Siemens brand 3T MRI device in the Department of Radiology over knee MRI examinations requested by clinical branches for any reason. By evaluating the trochlear cartilage structure in MRI, 41 cases with normal findings and 41 cases with early osteoarthritis findings were performed MRI T2 * Mapping, gray scale Ultrasound and Shear wave elastography with VTQ / ARFI method. T2 * in trochlear cartilage, relaxation time measurements were measured from 3 regions, medial condyle (MC), lateral condyle (LK) and intercondylar (IC) area in the axial plane, using 5 mm2 ROIs from the same cross-sectional area and their averages were recorded. In the Shear wave elastography method, trochlear cartilage Shear wave velocity measurements were measured from 3 regions, including MK, LK and IC area in the axial plane, using pre-determined 5x5 mm ROIs and 3 values were measured from the same cross-sectional area and their averages were recorded. For both examinations, thicknesses of the trochlear cartilage from the MC, LK and IC region were measured. Results: A statistically significant difference was observed between the groups in terms of cartilage thickness on ultrasound. It was observed that the cartilage thicknesses were significantly higher in the study group compared to the normal group in MK (p=0.002), IC (p=0.002) and LK (p=0.001). A statistically significant difference was observed between the groups in terms of cartilage thickness in MRI. It was observed that the cartilage thicknesses were significantly higher in the study group compared to the normal group in MK (p=0.003), HR (p=0.001) and LK (p=0.001). A statistically significant difference was observed between the groups in terms of shear wave velocity values. It was observed that the shear wave velocity values were significantly lower in MK (p=0.023), IC (p=0.001) and LK (p=0.753) in the study group compared to the normal group. A statistically significant difference was observed between the groups in terms of T2 * mapping value. It was observed that T2 * mapping value was significantly higher in MK (p=0.001), HR (p=0.001) and LK (p= 0.001) in the study group compared to the normal group. Conclusion: In our study, an increase in cartilage thickness was observed in both ultrasound and MRI in the group with early findings of osteoarthritis. In the pathological group, a decrease in Shear wave velocity values secondary to softening in the cartilage and prolongation in T2 * mapping were observed. It has been concluded that shear wave elastography and MRI T2 * mapping techniques are reliable methods in evaluating the changes in the trochlear cartilage, especially in the early stages of knee OA patients. Keywords: Osteoarthritis, Shear wave elastography, Trochlear cartilage, T2 * mapping, MRI