Quantitative ultrasound biomicroscopy for the analysis of healthy and repair cartilage tissue

Abstract

The increasing spectrum of different cartilage repair strategies requires the introduction of adequate nondestructive methods to analyse their outcome in-vivo, i.e. arthroscopically. The validity of non-destructive quantitative ultrasound biomicroscopy (UBM) was investigated in knee joints of five miniature pigs. After 12 weeks, six 5-mm defects, treated with different cartilage repair approaches, provided tissues with different structural qualities. Healthy articular cartilage from each contralateral unoperated knee joint served as a control. The reflected and backscattered ultrasound signals were processed to estimate the integrated reflection coefficient (IRC) and apparent integrated backscatter (AIB) parameters. The cartilage repair tissues were additionally assessed biomechanically by cyclic indentation, histomorphologically and immunohistochemically. UBM allowed high-resolution visualisation of the structure of the joint surface and subchondral bone plate, as well as determination of the cartilage thickness and demonstrated distinct differences between healthy cartilage and the different repair cartilage tissues with significant higher IRC values and a steeper negative slope of the depth-dependent backscatter amplitude AIB slope for healthy cartilage. Multimodal analyses revealed associations between IRC and the indentation stiffness. Furthermore, AIB slope and AIB at the cartilage-bone boundary (AIB dC ) were associated with the quality of the repair matrices and the subchondral bone plate, respectively. This ex-vivo pilot study confirms that UBM can provide detailed imaging of articular cartilage and the subchondral bone interface also in repaired cartilage defects, and furthermore, contributes in certain aspects to a basal functional characterization of various forms of cartilage repair tissues. UBM could be further established to be applied arthroscopically in-vivo.

Quantitative Ultrasound Assessment of Cartilage Degeneration in Ovariectomized Rats with Low Estrogen Levels

“…Gelse et al (2010) applied highfrequency ultrasound to quantitatively assess healthy and repaired cartilage tissue ex vivo. However, the highfrequency ultrasound system used in the present study is not capable of performing in vivo examinations of the articular cartilage of small animals.…”

“…Saarakkala et al (2004) quantified the integrity of the cartilage surface with an ultrasound reflection coefficient (i.e., the spatial variation of the ultrasound reflection coefficient [SVR]) and an ultrasound roughness index (URI) and reported significant decreases in the SVR and increases in the URI of damaged cartilage tissues Wang et al (2010a) reported that a 4-wk tail suspension rat model induced significant decreases in cartilage thickness in the medial femoral condyle and patella and a significant increase in the URI at the patella. Gelse et al (2010) reported that integrated reflection coefficients of repaired cartilage tissue are significantly greater than those of healthy tissue. Niu et al (2012) observed a strong correlation of acoustic parameters, for example, surface roughness index and reflection coefficient, with pathologic assessments of articular cartilage.…”

Ultrasound Assessment of Boundary Effect on Osmosis-Induced Shrinkage and Swelling of Articular CartilageIn Vitro

“…Ultrasound technique has been regarded as a potential approach for the study on the swelling behavior of articular cartilage. High frequency focused ultrasound with a high resolution has been applied to monitor relatively small specimens [9,10,26] or small animals [27,28]. Most of those studies are still in a fundamental laboratory level.…”

High-frequency backscatter analysis of human articular cartilage

“…Cartilage samples were immersed at 25°C in PBS and measured in C-scan mode (scan increment: 20 μm in x and y direction) using the custom scanning acoustic microscope SAM200Ex [4,6]. The SAM is controlled by custom software (SAMEx, Q-BAM, Halle, Germany) and consists of a 3-axis high precision scanning stage, a 200 MHz pulser/receiver (Panametrics 5900PR, Waltham, USA) and a 500 MSs-1 A/Dcard (Gage CS8500, Gage Applied Technologies Inc., Lachine, Canada).…”

“…3) Depth-dependent backscatter parameters AIB and AFB were calculated as a function of depth using a sliding window technique [6]. The first window was centered at the detected surface position and the maximum depth was set to 2.5 mm.…”