Ultrasound Backscattering Is Anisotropic in Bovine Articular Cartilage.
Collagen, proteoglycans and chondrocytes can contribute to ultrasound scattering in articular cartilage. However, anisotropy of ultrasound scattering in cartilage is not fully characterized. We investigate this using a clinical intravascular ultrasound device with ultrasound frequencies of 9 and 40 MHz. Osteochondral samples were obtained from intact bovine patellas, and cartilage was imaged in two perpendicular directions: through articular and lateral surfaces. At both frequencies, ultrasound backscattering was higher (p < 0.05) when measured through the lateral surface of cartilage. In addition, the composition and structure of articular cartilage were investigated with multiple reference methods involving light microscopy, digital densitometry, polarized light microscopy and Fourier infrared imaging. Reference methods indicated that acoustic anisotropy of ultrasound scattering arises mainly from non-uniform distribution of chondrocytes and anisotropic orientation of collagen fibers. To conclude, ultrasound backscattering in articular cartilage was found to be anisotropic and dependent on the frequency in use.
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Cancer Center, Kuopio University Hospital, Kuopio, Finland. Electronic address: satu.inkinen@uef.fi.
Satu I
SI
Inkinen
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
Jukka
J
Liukkonen
School of Medicine, Institute of Biomedicine, Anatomy, University of Eastern Finland, Kuopio, Finland.
Virpi
V
Tiitu
Cancer Center, Kuopio University Hospital, Kuopio, Finland.
Tuomas
T
Virén
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
Jukka S
JS
Jurvelin
Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, Kuopio, Finland.
Juha
J
Töyräs
D000818:Animals; D016880:Anisotropy; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000502:physiology*; D002417:Cattle; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D066298:In Vitro Techniques; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D000069453:Ultrasonic Waves; D014463:Ultrasonography / Q000379:methods*
Articular cartilage; Chondrocyte; Collagen; Imaging; Scattering; Ultrasound