Characteristics of liver on magnetic resonance diffusion-weighted imaging: dynamic and image pathological investigation in rabbit liver VX-2 tumor model.
OBJECTIVE
To investigate dynamical and image pathological characteristics of the liver on magnetic resonance (MR) diffusion-weighted imaging (DWI) in the rabbit VX-2 tumor model.


METHODS
Forty New Zealand rabbits were included in the study and VX-2 tumor piece was implanted intrahepatically. Fifteen animals received two intrahepatic implantations while 25 had one intrahepatical implantation. DWI, T1- and T2-weighted of magnetic resonance imaging (MRI) were carried out on the 7th and the 14th d after implantation and DWI was conducted, respectively on the 21st d. Ten VX-2 tumor samples were studied pathologically.


RESULTS
The rate of lump detected by DWI, T1WI and T2WI was 78.7%, 10.7% and 53.5% (c2=32.61, P<0.001) on the 7th d after implantation and 95.8%, 54.3% and 82.9% (c2=21.50, P<0.001) on the 14th d. The signal of most VX-2 tumors on DWI was uniform and it was equal on the map of apparent diffusion coefficient (ADC). The signal of VX tumors did not decrease on the 7th d after implantation, most of them slowly growing during the week following implantation without significant cell dying within the tumor. VX-2 tumors grew increasingly within 14 d after implantation but the signal of most VX-2 tumors on DWI or on the map of ADC was uniform or uneven and ADC of VX tumors decreased obscurely or slightly because tumor necrosis was still not obvious. On the 21st d after implantation, the signal of most VX-2 tumors on DWI or on the map of ADC was uneven because tumor necrosis was evident and ADC of VX-2 tumor necrotic areas decreased. The areas of viable cells in VX-2 tumors manifested a high signal on DWI and a low signal on the map of ADC. The areas of dead cells or necrosis in VX-2 tumors manifested low signals on DWI and low, equal or high signals on the map of ADC but they manifested high signals on DWI and on the map of ADC at the same time when the areas of necrotic tumor became liquefied or cystic. The border of tumors on DWI appeared gradually distinct and internal signals of tumor became progressively uneven.


CONCLUSIONS
The manifestations of viable, necrotic and liquefied or cystic areas in VX-2 tumors on DWI are typical and DWI is of significant and potential values in clinical application in both the early detection and diagnosis of liver tumors.
Yuan
You-Hong
YH
Department of Radiology, Hunan Province People's Hospital, Changsha 410005, Hunan Province, China. heyuanyouhong@yahoo.com.cn
Xiao
En-Hua
EH
Liu
Jian-Bin
JB
He
Zhong
Z
Jin
Ke
K
Ma
Cong
C
Xiang
Jun
J
Xiao
Jian-Hua
JH
Chen
Wei-Jian
WJ
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D045744:Cell Line, Tumor; D002470:Cell Survival; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D008099:Liver / Q000473:pathology*; D008114:Liver Neoplasms, Experimental / Q000473:pathology*; D008297:Male; D009336:Necrosis; D011817:Rabbits; D015203:Reproducibility of Results; D013997:Time Factors