Stress Test of Contrast-Enhanced US with Phenylephrine in a Rabbit VX2 Liver Tumor Model: Differentiating Benign Periablational Enhancement from Residual Tumor after Radiofrequency Ablation.
OBJECTIVE
To differentiate benign periablational enhancement (BPE) from residual tumor after radiofrequency (RF) ablation by using a stress contrast-enhanced ultrasonography (US) test with phenylephrine in a rabbit VX2 liver tumor model.


METHODS
VX2 tumors were implanted in the livers of 40 rabbits for two experiments. In experiment one, liver tumors from 32 animals were completely ablated. On days 2, 7, 14, and 21 after RF ablation, eight animals were randomly chosen for contrast-enhanced US before and after phenylephrine administration, and the microvessel density (MVD) of BPE at these four time points was assessed. In experiment two, liver tumors from eight animals were partly ablated, and each animal underwent contrast-enhanced US before and after phenylephrine administration on day 7 after RF ablation. Perfusion parameters were observed, including maximum intensity (IMAX), rise time (ie, time between 10% and 90% of IMAX), time to peak, mean transit time, and area under the curve (AUC), along with the profile of time-intensity curves (TICs) in BPE and residual tumor in response to phenylephrine.


RESULTS
Among the four time points after ablation, the IMAX and AUC before phenylephrine administration and the MVD of BPE were greatest on day 7 (P < .05). The profile of TICs and the corresponding perfusion parameters in residual tumor did not change significantly in response to phenylephrine. However, those from BPE changed significantly (P < .05).


CONCLUSIONS
Contrast-enhanced US with phenylephrine stress may be helpful in differentiating BPE from residual tumor after RF ablation in hepatocellular carcinoma.
Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 JieFang Rd., Wuhan, Hubei 430022, China.
Xuefeng
X
Kan
Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 JieFang Rd., Wuhan, Hubei 430022, China.
Yanrong
Y
Zhang
Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 JieFang Rd., Wuhan, Hubei 430022, China.
Chuansheng
C
Zheng
Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 JieFang Rd., Wuhan, Hubei 430022, China.
Lin
L
Li
Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 JieFang Rd., Wuhan, Hubei 430022, China.
Juan
J
Chen
Department of Ultrasound, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 JieFang Rd., Wuhan, Hubei 430022, China.
Yihua
Y
Wu
Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 JieFang Rd., Wuhan, Hubei 430022, China.
Tao
T
Guo
Department of Radiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 JieFang Rd., Wuhan, Hubei 430022, China. Electronic address: herrxiong@126.com.
Bin
B
Xiong
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D017115:Catheter Ablation / Q000009:adverse effects; D003287:Contrast Media / Q000008:administration & dosage*; D003937:Diagnosis, Differential; D008114:Liver Neoplasms, Experimental / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D008297:Male; D045423:Microbubbles; D008833:Microcirculation / Q000187:drug effects*; D018365:Neoplasm, Residual; D055420:Perfusion Imaging / Q000379:methods; D010656:Phenylephrine / Q000008:administration & dosage*; D010743:Phospholipids / Q000008:administration & dosage*; D011237:Predictive Value of Tests; D011817:Rabbits; D012039:Regional Blood Flow; D013459:Sulfur Hexafluoride / Q000008:administration & dosage*; D013997:Time Factors; D014463:Ultrasonography / Q000379:methods*; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*
D003287:Contrast Media; D010743:Phospholipids; D014662:Vasoconstrictor Agents; C420843:contrast agent BR1; D010656:Phenylephrine; D013459:Sulfur Hexafluoride