Utility of contrast-enhanced ultrasonography for qualitative imaging of atherosclerosis in Watanabe heritable hyperlipidemic rabbits: initial experimental study.
OBJECTIVE
Using Watanabe heritable hyperlipidemic (WHHL) rabbits, we investigated the ability of ultrasonography (US) to detect contrast enhancement of atherosclerotic lesions after intravenous injection of a microbubble contrast agent (MB) and confirmed the localization of MB in the lesion by transmission electron microscopy (TEM).


METHODS
The abdominal aortic wall of six WHHL rabbits was observed for 20 min after MB delivery. To evaluate contrast enhancement, a region of interest (ROI) was set in the intima-media complex (IMC) and the aortic lumen. The average image brightness of the ROI was recorded as the echogenicity at each time point. Differences at each time point were analyzed by analysis of variance and the t-test. Histological analysis was performed after US observation.


RESULTS
The echogenicity of the IMC was 8.48 ± 3.01 before and 10.96 ± 7.88, 32.42 ± 12.79, 79, 17.73 ± 9.118, and 31.18 ± 13.35, respectively, at 0.5, 2, 5, 10, and 20 min after MB injection. The echogenicity of the vessel lumen was 1.16 ± 1.57, 64.21 ± 11.52, 53.55 9.81, 13.32 ± 9.78, 2.63 ± 1.45, and 3.66 ± 3.01 at the corresponding time points. At 20 min after injection, the echogenicity of the IMC was significantly higher than before or 0.5 min after injection. The distribution of MB inside macrophages in atherosclerotic plaques could not be confirmed by TEM.


CONCLUSIONS
Ultrasonography was able to detect contrast enhancement of the IMC at 10 and 20 min after injection of MB.
Department of Radiology, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Japan. sekoayumi@yahoo.co.jp
Ayumi
A
Nitta-Seko
Norihisa
N
Nitta
Masashi
M
Shiomi
Akinaga
A
Sonoda
Shinichi
S
Ota
Keiko
K
Tsuchiya
Masashi
M
Takahashi
Mineko
M
Fujimiya
Murata
M
Kiyoshi
D000704:Analysis of Variance; D000818:Animals; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging; D050197:Atherosclerosis / Q000000981:diagnostic imaging* / Q000209:etiology; D003287:Contrast Media; D004195:Disease Models, Animal; D005290:Ferric Compounds; D006801:Humans; D006950:Hyperlipidemia, Familial Combined / Q000150:complications; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D007501:Iron; D008297:Male; D045423:Microbubbles; D010087:Oxides; D011817:Rabbits; D015203:Reproducibility of Results; D014463:Ultrasonography
D003287:Contrast Media; D005290:Ferric Compounds; D010087:Oxides; C069727:Sonazoid; D007501:Iron