A Novel Indicator for Quantitative Assessment of Articular Cartilage Degeneration Using Ultrasound

Abstract

Abstract. Assessment of articular cartilage degeneration induced by degenerative diseases using quantitative ultrasound method is promising but challenging. Currently, in literature, proposed methods have limited diagnostic abilities, and some quantitative ultrasound cartilage evaluation results are inconsistent or hard to compare with each other. Thus it is desirable to find a parameter which is easier to compare and can sensitively reflect changes due to cartilage degeneration. In the present study, a new parameter "averaged magnitude ratio" (AMR) was defined as an indicator to detect articular cartilage degeneration. In vitro experiments were conducted on 12 cartilage-bone samples from porcine knee joints. Six of the samples were digested using 0.25% trypsin solution. Ultrasound V (z, t) signal was collected from the samples using a broadband ultrasound transducer with center frequency of 15MHz. Integrated reflection coefficient (IRC), apparent integrated backscattering coefficient (AIB) and AMR were computed from ultrasound signal. Young's modulus of the samples was measured using atomic force microscopy (AFM). With Mann-Whitney U test, statistically significant decrease in IRC and increase in AMR were observed after digestion. With Pearson's correlation analysis, Young's modulus was significantly correlated with AMR, IRC, and AIB. Our results demonstrate that AMR is sensitive to enzymatically induced cartilage changes. AMR is easier to compute, needs no reference material and can achieve equivalent or even better performance than IRC and AIB in detecting cartilage degeneration.