Non-thermal ablation of rabbit liver VX2 tumor by pulsed high intensity focused ultrasound with ultrasound contrast agent: Pathological characteristics.
OBJECTIVE
To investigate the pathological characteristics of non-thermal damage induced by pulsed high intensity focused ultrasound (PHIFU) combined with ultrasound contrast agent (UCA), SonoVue (Bracco SpA, Milan, Italy) in rabbit liver VX2 tumor.


METHODS
Liver VX2 tumor models were established in 20 rabbits, which were divided randomly into PHIFU combined with ultrasound contrast agent group (PHIFU + UCA group) and sham group. In the PHIFU + UCA group, 0.2 mL of SonoVue was injected intravenously into the tumor, followed by ultrasound exposure of I(SP) 5900 W/cm(2). The rabbits were sacrificed one day after ultrasound exposure. Specimens of the exposed tumor tissues were obtained and observed pathologically under light microscope and transmission electron microscope. The remaining tumor tissues were sent for 2,3,5-Triphenyltetrazolium chloride (TTC) staining.


RESULTS
Before TTC staining, tumor tissues in both the sham and the PHIFU + UCA groups resembled gray fish meat. After TTC staining, the tumor tissues were uniformly stained red, with a clear boundary between tumor tissue and normal tissue. Histological examination showed signs of tumor cell injury in PHIFU + UCA group, with cytoplasmic vacuoles of various sizes, chromatin margination and karyopyknosis. Electron microscopic examination revealed tumor cell volume reduction, karyopyknosis, chromatin margination, intercellular space widening, the presence of high electron-density apoptotic bodies and vacuoles in cytoplasm.


CONCLUSIONS
The non-thermal effects of PHIFU combined with UCA can be used to ablate rabbit liver VX2 tumors.
Zhou
Cheng-Wen
CW
Bioengineering College, Chongqing University, 174 Shazhengjie St, Shapingba District, Chongqing 400044, China. lifaqi70@163.com
Li
Fa-Qi
FQ
Qin
Yan
Y
Liu
Chun-Mei
CM
Zheng
Xiao-Lin
XL
Wang
Zhi-Biao
ZB
D055011:Ablation Techniques / Q000379:methods*; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000601:surgery* / Q000648:ultrastructure; D002843:Chromatin / Q000648:ultrastructure; D003287:Contrast Media; D005260:Female; D008113:Liver Neoplasms / Q000473:pathology* / Q000601:surgery* / Q000648:ultrastructure; D008297:Male; D011817:Rabbits; D014464:Ultrasonic Therapy / Q000379:methods*; D014617:Vacuoles / Q000648:ultrastructure
D002843:Chromatin; D003287:Contrast Media