Role of Contrast Enhanced Ultrasound in Radiofrequency Ablation of Metastatic Liver Carcinoma

Objective： To investigate the application of contrast enhanced ultrasound （CEUS） in planning and guiding for radiofrequency ablation （RFA） for metastatic liver carcinoma （MLC）. Methods： One hundred and thirty-five patients with clinically and pathologically diagnosed MLC （from gastrointestinal tumors） were included in the present study, and 104 of them had received CEUS prior to RFA to assess the number, size, shape, infiltration, location and enhancing features of the lesions. Among the 204 patients, 21 （20.1%） were excluded from RFA treatment due to too many lesions or large infiltrative range based on CEUS. The remaining 83 patients with 147 lesions underwent RFA （group A）. During the same period, other 32 patients with 202 lesions serving as control group were treated based on findings of conventional ultrasound without contrast （group B）. The patients underwent follow-up enhanced CT at the 1st month, and then every 3-6 months after RFA. The tumor was considered as early necrosis if no contrast enhancement was detected in the treated area on the CT scan at the 2st month. Results： In group A, 72 of 147 MLC lesions （48.9%） showed increased sizes on CEUS. Among them, 48 lesions （66.6%） appeared enlarged in arterial phase, and 24 （33.3%） showed enlarged hypoechoic area in parenchymal phase. CEUS showed total 61 additional lesions in 35 patients （42.2%） （ranged from 8 to 15 mm） compared with conventional ultrasound （US）, and 42 （68.8%） of them were visualized in parenchymal phase only. There were total 208 lesions in group A underwent RFA with CEUS planning, and the tumor necrosis rate was 94.2% （196/208）. In this group, local recurrence was found in 26 lesions （7.7%） during 3-42 months＇ following up, and new metastases were seen in 30 cases （36.2%）. For group B, the tumor necrosis rate was 86.3% （88/202）, local recurrence in 27 lesions （16.7%）, and new metastases in 13 cases （41.9%）. Tumor early necrosis and recurrence rates were significantly different between the two groups （P=0.018, P=0.016, respectively）. Conclusion： CEUS played an important role in RFA for liver metastases by candidate selecting and therapy planning, which helped to improve the outcome of the treatment.

Clinical diagnosis and treatment of alpha-fetoprotein-negative small hepatic lesions

Objective： We examined 103 cases over the last five years and discussed diagnosis and treatment of alpha- fetoprotein （AFP）-negative small hepatic lesions. Background： Small hepatic lesions （less than 2 cm in diameter） usually have no typical imaging characteristics and therefore are difficult to diagnose, especially when AFP tests provide a negative result. Methods： A total of 103 patients with AFP-negative small hepatic lesions from January 2003 to December 2008 were retrospectively reviewed. Differential diagnosis was performed by digital subtraction angiography （DSA）, dynamic contrast-enhanced magnetic resonance imaging （DCE-MRI）, contrast-enhanced ultrasound （CEUS）, or positron emission tomography-computed tomography （PET-CT） based on the multiplicity of lesions. Ninety-four patients with suspected cancers underwent partial hepatectomy. Clinical data were collected from hospital records and follow-up questionnaires. Results： Hepatocellular carcinoma （HCC） diagnostic sensitivity of DSA, DCE-MRI, CEUS and PET-CT was 88.2%, 93.9%, 88.9% and 88.9%, respectively. The surgery-related complication rate was 6.4%. Prognosis was good, with 1- and 3-year survival rates of 98.8% and 76.1%, respectively. Conclusions： DSA, DCE-MRI, CEUS and PET-CT are valuable for diagnosis of small hepatic lesions. Partial hepatectomy is a preferred surgical procedure. Surgery for small liver cancers usually has little risk and good prognosis, therefore it can be actively applied in suspected HCC cases.

Clinical value of contrast-enhanced ultrasound in improving diagnostic accuracy rate of transthoracic biopsy of anteriormedial mediastinal lesions

Objective： To evaluate the clinical value of contrast-enhanced ultrasound（CEUS） in transthoracic biopsy of anterior-medial mediastinal lesions.Methods： A total of 123 patients with anterior or middle mediastinum lesions required ultrasound guided transthoracic biopsy for pathological diagnosis. Among them, 72 patients received CEUS examinations before biopsy. After CEUS, 8 patients were excluded from biopsy and the rest 64 patients underwent biopsy（CEUS group）. During the same period, 51 patients received biopsy without CEUS examination（US group）. The ultrasonography characteristics, the number of biopsy puncture attempts, diagnostic accuracy rate and the incidence of complications were recorded and compared between the two groups.Results： A large portion of necrosis area or superficial large vessels was found in 8 patients, so the biopsy was cancelled. The internal necrosis was demonstrated in 43.8% of the lesions in CEUS group and in 11.8% of US group（P0.001）. For thymic carcinoma, CEUS increased the detection rate of internal necrosis and pericardial effusion than conventional ultrasound（62.5% vs. 18.8%, P=0.012; 56.3% vs. 12.5%, P=0.023）. The average number of punctures in CEUS group and US group was 2.36±0.70 and 2.21±0.51 times, respectively（P0.05）. The diagnostic accuracy rate of biopsy in CEUS group（96.9%, 62/64） was significantly higher than that in US group（84.3%, 43/51）（P=0.022）. In US group, 2 patients suffered from mediastinal bleeding（3.9%）, while no major complications occurred in CEUS group.Conclusions： CEUS examination provided important information before transthoracic mediastinum biopsy and improved diagnostic accuracy rate in biopsy of anterior and middle mediastinum lesions than conventional ultrasound.

Study on correlation between pathology and the contrast-enhanced ultrasound characteristics of primary liver cancer

Objective:The aim of this study was to evaluate the value of contrast-enhanced ultrasound(CEUS) for blood perfusion of primary liver cancer(PHC) and investigate the correlation between microvascular architecture of PHC and pathological differentiation.Methods:Two hundred and seventy-eight patients with 329 PHC lesions were examined by CEUS and analysised the contrast enhancement pattern and correlation with pathology.Results:1.CEUS patterns of PHC:71.7%(236/329) showed "swift enhancement in the arterial phase and swift expurgation in the portal phase",13.4%(44/329) for as "swift enhancement and slow expurgation",7.3%(24/329) as "swift enhancement and simultaneity expurgation",4.3%(14/329) for the "slow enhancement and swift expurgation",2.1%(7/329) as "slow enhancement and expurgation",1.2%(4/329) as "not fast forward".2.90.3%(297/329) of PHC lesions were hypervascular liver cancer and 9.7%(32/329) were hypovascular.Hepatocellular carcinoma(HCC) were hypervascular lesions and intrahepatic cholangiocarcinoma(ICC) were hypovascular lesions.3.PHC size had a significant difference on the contrast media purfusion pattern(P < 0.05),but not on the contrast media expurgation pattern.4.The accuracy of PHC by CEUS were 97.3% and compared to pathology,9 lesions of PHC were misdiagnosed.Conclusion:CEUS can show the different blood perfusion characteristics of PHC with closely related to pathological differentiation,which be valuable to diagnose liver cancer.

Subcarrier and power allocation algorithm based on inter-cell interference mitigation for OFDMA system

This article proposes a dynamic subcarrier and power allocation algorithm for multicell orthogonal frequency division multiple access （OFDMA） downlink system, based on inter-cell interference （ICI） mitigation. Different from other ICI mitigation schemes, which pay little attention to power allocation in the system, the proposed algorithm assigns channels to each user, based on proportional-fair （PF） scheduling and ICI coordination, whereas allocating power is based on link gain distribution and the loading bit based on adaptive modulation and coding （AMC） in base transceiver station （BTS）. Simulation results show that the algorithm yields better performance for data services under fast fading.