Quantitative assessment of synovial vascularity using contrast-enhanced power Doppler ultrasonography: correlation with histologic findings and mr imaging findings in arthritic rabbit knee model.
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.


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 mm(2) in the arthritic knee after enhancement (p < 0.05), whereas it changed from 0.77 to 2.31 mm(2) 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).


CONCLUSIONS
Sonic contrast-enhanced PD US improves the visualization of synovial vascularity and allows quantitative measurement in experimentally induced rabbit arthritic knees.
Lee
Sang Hoon
SH
Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Suh
Jin Suck
JS
Shin
Myung Jin
MJ
Kim
Seong Moon
SM
Kim
Namkug
N
Suh
Sang Hyun
SH
D000818:Animals; D003287:Contrast Media; D019786:Gadolinium DTPA; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000473:pathology; D011134:Polysaccharides; D011817:Rabbits; D018709:Statistics, Nonparametric; D013583:Synovial Membrane / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000473:pathology; D018608:Ultrasonography, Doppler
D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508; D019786:Gadolinium DTPA