Korean J Radiol.  2008 Feb;9(1):45-53. 10.3348/kjr.2008.9.1.45.

Quantitative Assessment of Synovial Vascularity Using Contrast-Enhanced Power Doppler Ultrasonography: Correlation with Histologic Findings and MR Imaging Findings in Arthritic Rabbit Knee Model

Affiliations
  • 1Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
  • 2Department of Radiology, Yonsei University College of Medicine, Seoul, Korea. jss@yumc.yonsei.ac.kr

Abstract


OBJECTIVE
To validate contrast-enhanced power Doppler ultrasonography (PD US) for the evaluation of synovial vascularity in an arthritic rabbit knee model in correlation with MR and histological findings. MATERIALS AND METHODS: Power Doppler ultrasonography was performed for carrageenin-induced arthritic left knee and control right knee of 13 rabbits, first without and then with sonic contrast agent enhancement (Levovist, Schering, Berlin Germany), followed by gadolinium-enhanced MR imaging. Synovial vascularity was quantitatively assessed by calculating the color pixel area in power Doppler sonography using a computer-aided image analysis program and by grading the enhancement on MR images: grade 1, enhancement of knee joint is less than one-third of the area; grade 2, one-third to two-thirds enhancement; and grade 3, more than two-thirds enhancement. Microvessel density (MVD) was measured on slides stained immunohistochemically for CD31 antigen for histological assessment. RESULTS: The mean area of color pixels in PD US changed from 4.37 to 16.42 mm2 in the arthritic knee after enhancement (p < 0.05), whereas it changed from 0.77 to 2.31 mm2 in the control knee (p < 0.05). Arthritic knees had greater power Doppler signal than control knees both before and after contrast administration (p < 0.05). The average MVD was 88 in arthritic knees and 46 in control knees. MVDs correlated with color pixel areas of contrast-enhanced power Doppler imaging in arthritic knees. In MR grading of arthritic knees, five were grade 2 and eight were grade 3. MVD and PD US revealed no significant difference between grade 2 and 3 arthritic knees (p > 0.05). CONCLUSION: Sonic contrast-enhanced PD US improves the visualization of synovial vascularity and allows quantitative measurement in experimentally induced rabbit arthritic knees.

Keyword

Arthritis; Joints, US; Synovitis; Ultrasound (US), Power Doppler studies; Magnetic resonance (MR); Arthrtis, animal studies

MeSH Terms

Animals
Contrast Media
Gadolinium DTPA/diagnostic use
Image Processing, Computer-Assisted
Immunohistochemistry
Magnetic Resonance Imaging
Osteoarthritis, Knee/pathology/*ultrasonography
Polysaccharides/diagnostic use
Rabbits
Statistics, Nonparametric
Synovial Membrane/*blood supply/pathology/ultrasonography
*Ultrasonography, Doppler
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