Principles and clinical application of ultrasound elastography for diffuse liver disease

Accurate assessment of the degree of liver fibrosis is important for estimating prognosis and deciding on an appropriate course of treatment for cases of chronic liver disease (CLD) with various etiologies. Because of the inherent limitations of liver biopsy, there is a great need for non-invasive and reliable tests that accurately estimate the degree of liver fibrosis. Ultrasound (US) elastography is considered a non-invasive, convenient, and precise technique to grade the degree of liver fibrosis by measuring liver stiffness. There are several commercial types of US elastography currently in use, namely, transient elastography, acoustic radiation force impulse imaging, supersonic shear-wave imaging, and real-time tissue elastography. Although the low reproducibility of measurements derived from operator-dependent performance remains a significant limitation of US elastography, this technique is nevertheless useful for diagnosing hepatic fibrosis in patients with CLD. Likewise, US elastography may also be used as a convenient surveillance method that can be performed by physicians at the patients' bedside to enable the estimation of the prognosis of patients with fatal complications related to CLD in a non-invasive manner.

Therapeutic Efficacy and Safety of Percutaneous Ethanol Injection with or without Combined Radiofrequency Ablation for Hepatocellular Carcinomas in High Risk Locations

OBJECTIVE: To evaluate the therapeutic efficacy and safety of percutaneous ethanol injection (PEI) alone and combined with radiofrequency ablation (RFA) for hepatocellular carcinomas (HCCs) in high risk locations. MATERIALS AND METHODS: We performed PEI for HCCs in RFA-high risk locations, either alone or in combination with RFA. There were 20 HCCs (1.7 +/- 0.9 cm) in 20 patients (PEI group: n = 12; PEI + RFA group: n = 8). We evaluated technical success, local tumor progression and complications in both groups. RESULTS: Technical success was achieved in all HCCs in both groups. During follow-up, local tumor progression was found in 41.7% (5/12) in the PEI group, whereas 12.5% (1/8) for the PEI + RFA group (p = 0.32). Bile duct dilatation was the most common complication, especially when the tumors were in periportal locations; 55% (5/9) in the PEI group and 50% (2/4) in the PEI + RFA group (p = 1.00). One patient in the PEI group developed severe biliary stricture and upstream dilatation that resulted in atrophy of the left hepatic lobe. One patient treated with PEI + RFA developed cholangitis and an abscess. CONCLUSION: Combined PEI and RFA treatment has a tendency to be more effective than PEI alone for managing HCCs in high risk locations, although the difference is not statistically significant. Even though PEI is generally accepted as a safe procedure, it may cause major biliary complications for managing HCCs adjacent to the portal vein.

Radiofrequency Ablation Combined with Chemoembolization for Intermediate-Sized (3-5 cm) Hepatocellular Carcinomas Under Dual Guidance of Biplane Fluoroscopy and Ultrasonography

OBJECTIVE: To assess the technical feasibility and local efficacy of percutaneous radiofrequency ablation (RFA) combined with transcatheter arterial chemoembolization (TACE) for an intermediate-sized (3-5 cm in diameter) hepatocellular carcinoma (HCC) under the dual guidance of biplane fluoroscopy and ultrasonography (US). MATERIALS AND METHODS: Patients with intermediate-sized HCCs were treated with percutaneous RFA combined with TACE. RFA was performed under the dual guidance of biplane fluoroscopy and US within 14 days after TACE. We evaluated the rate of major complications on immediate post-RFA CT images. Primary technique effectiveness rate was determined on one month follow-up CT images. The cumulative rate of local tumor progression was estimated with the use of Kaplan-Meier method. RESULTS: Twenty-one consecutive patients with 21 HCCs (mean size: 3.6 cm; range: 3-4.5 cm) were included. After TACE (mean: 6.7 d; range: 1-14 d), 20 (95.2%) of 21 HCCs were visible on fluoroscopy and were ablated under dual guidance of biplane fluoroscopy and US. The other HCC that was poorly visible by fluoroscopy was ablated under US guidance alone. Major complications were observed in only one patient (pneumothorax). Primary technique effectiveness was achieved for all 21 HCCs in a single RFA session. Cumulative rates of local tumor progression were estimated as 9.5% and 19.0% at one and three years, respectively. CONCLUSION: RFA combined with TACE under dual guidance of biplane fluoroscopy and US is technically feasible and effective for intermediate-sized HCC treatment.

Radiofrequency Ablation for Viable Hepatocellular Carcinoma around Retained Iodized Oil after Transcatheter Arterial Chemoembolization: Usefulness of Biplane Fluoroscopy Plus Ultrasound Guidance

OBJECTIVE: To assess the technical feasibility and local efficacy of biplane fluoroscopy plus US-guided percutaneous radiofrequency ablation (RFA) for viable hepatocellular carcinoma (HCC) around retained iodized oil after transcatheter arterial chemoembolization (TACE). MATERIALS AND METHODS: Our prospective study was approved by our institutional review board and informed consent was obtained from all participating patients. For patients with viable HCC around retained iodized oil after TACE, biplane fluoroscopy plus US-guided RFA was performed. We evaluated the rate of technical success and major complications on a post-RFA CT examination and local tumor progression with a follow-up CT. RESULTS: Among 40 consecutive patients, 19 were excluded due to one of the following reasons: poorly visible HCC on fluoroscopy (n = 13), high risk location (n = 2), RFA performed under monoplane fluoroscopy and US guidance (n = 2), and poorly identifiable new HCCs on US (n = 2). The remaining 21 patients with 21 viable HCCs were included. The size of total tumors ranged from 1.4 to 5.0 cm (mean: 3.2 cm) in the longest diameter. Technical success was achieved for all 21 HCCs, and major complications were observed in none of the patients. During the follow-up period (mean, 20.3 months; range, 6.5-29.9 months), local tumor progression was found in two patients (2/21, 9.5%). Distant intrahepatic metastasis developed in 76.2% (16/21) of patients. CONCLUSION: When retained iodized oil around the tumor after TACE hampers the targeting of the viable tumor for RFA, biplane fluoroscopy plus US-guided RFA may be performed owing to its technical feasibility and effective treatment for viable HCCs.

Radiofrequency Ablation of Hepatocellular Carcinoma: Pros and Cons

Among locoregional treatments for hepatocellular carcinoma (HCC), radiofrequency ablation (RFA) has been accepted as the most popular alternative to curative transplantation or resection, and it shows an excellent local tumor control rate and acceptable morbidity. The benefits of RFA have been universally validated by the practice guidelines of international societies of hepatology. The main advantages of RFA include 1) it is minimally invasive with acceptable morbidity, 2) it enables excellent local tumor control, 3) it has promising long-term survival, and 4) it is a multimodal approach. Based on these pros, RFA will play an important role in managing the patient with early HCC (smaller than 3 cm with fewer than four tumors). The main limitations of current RFA technology in hepatic ablation include 1) limitation of ablation volume, 2) technically infeasible in some tumors due to conspicuity and dangerous location, and 3) the heat-sink effect. Many technical approaches have been introduced to overcome those limitations, including a novel guiding modality, use of artificial fluid or air, and combined treatment strategies. RFA will continue to play a role as a representative ablative modality in the management of HCC, even in the era of targeted agents.

The Accuracy of Axillary Ultrasonography for Patients with T1-2 Breast Cancers

PURPOSE: We wanted to investigate the accuracy of axillary ultrasonography for detecting axillary nodal metastasis in patients with T1-2 breast cancer and we also wanted to determine the factors affecting the sensitivity. MATERIALS AND METHODS: Two radiologists performed axillary ultrasonography in 119 consecutive patients with T1-2 breast cancer and clinically uninvolved axillae. We analyzed the accuracy of ultrasonography for detecting axillary nodal metastasis with the histologic results being used as a reference standard. We evaluated the number of involved lymph nodes, T staging and the histologic grade of the tumors. RESULTS: Axillary nodes were involved in 39% of total patients (46/119); 30% of the patients with T1 cancer and 55% of the patients with T2 cancer. The sensitivity, specificity, positive predictive value and negative predictive value were for 52%, 92%, 80% and 75%, respectively. The sensitivity was significantly lower for the cases with one to two lymph nodes metastasis and T1 cancer than in those cases with 3 or more lymph nodes metastasis and T2 cancer (35% and 75% in the cases with 1-2 cancer and the cases with > 3 lymph nodes metastasis, respectively, p = 0.009; 38% and 68% in the cases with T1 and the cases with T2 cancer, respectively, p = 0.045). CONCLUSIONS: The ultrasonographic sensitivity for detecting axillary lymph node metastasis is low, especially in the cases with one to two lymph nodes metastasis and the cases with T1 cancer. Detailed analysis and adoption of cytologic examination of the axillary lymph nodes are necessary to improue the accuracy of ultrasonography.

Percutaneous Radiofrequency Ablation of Hepatocellular Carcinomas Adjacent to the Gallbladder with Internally Cooled Electrodes: Assessment of Safety and Therapeutic Efficacy

OBJECTIVE: The objective of this study was to evaluate the safety and therapeutic efficacy of percutaneous radiofrequency (RF) ablation for the treatment of hepatocellular carcinomas (HCCs) adjacent to the gallbladder with the use of internally cooled electrodes. MATERIALS AND METHODS:We retrospectively assessed 45 patients with 46 HCCs (mean size, 2.2 cm) adjacent to the gallbladder ( or =3 cm) and tumor location (a tumor that abutted the gallbladder) were associated with an increased risk of early incomplete treatment. No variable was significantly associated with local tumor progression. CONCLUSION: Percutaneous RF ablation of HCCs adjacent to the gallbladder using an internally cooled electrode is a safe and effective treatment. Significant risk factors that lead to early incomplete treatment include tumor size, tumor location and electrode direction.

Percutaneous Radiofrequency Ablation for the Hepatocellular Carcinoma Abutting the Diaphragm: Assessment of Safety and Therapeutic Efficacy

OBJECTIVE: To assess the safety and therapeutic efficacy of a percutaneous radiofrequency (RF) ablation for the hepatocellular carcinoma (HCC) abutting the diaphragm. MATERIALS AND METHODS: We retrospectively assessed 80 patients who underwent a percutaneous RF ablation for a single nodular (< 4 cm) HCC over the last four years. Each patient underwent an ultrasound-guided RF ablation using internally cooled electrodes for the first-line treatment. We divided patients into two subgroups based on whether the index tumor was abutting (less than 5 mm) the diaphragm or not: group A (abutting; n = 31) versus group B (non-abutting; n = 49). We compared the two subgroups for complications and therapeutic efficacy using image and the review of medical records. The statistical assessment included an independent t-test, Fisher's exact test, and chi-square test. RESULTS: The assessment of the diaphragmatic swelling at CT immediately following the procedure was more severe in group A than group B (mean thickness change:1.44 vs. 0.46 mm, p = 0.00). Further, right shoulder pain was more common in group A than B (p = 0.01). Although minor complications (hemothorax 1 case, pleural effusion 1 case) were noted only in group A, no major thoracic complication occurred in either group. The technical success rate was lower in group A than group B (84% vs. 98%, p = 0.03). As well, the primary and secondary technique effectiveness rates in group A and group B were 90% versus 98% (p = 0.29) and 79% versus 91% (p = 0.25), respectively. The local tumor progression rate was higher in group A than in group B (29% vs. 6%, p = 0.02). CONCLUSION: We found that the percutaneous RF ablation for the HCC abutting the diaphragm is a safe procedure without major complications. However, it is less effective with regard to technical success and local tumor control.

Does Artificial Ascites Induce the Heat-Sink Phenomenon during Percutaneous Radiofrequency Ablation of the Hepatic Subcapsular Area?: an in vivo Experimental Study Using a Rabbit Model

OBJECTIVE: To evaluate the effect of the heat-sink phenomenon induced by artificial ascites on the size of the ablation zone during percutaneous radiofrequency (RF) ablation of the hepatic subcapsular area in an in vivo rabbit model. MATERIALS AND METHODS: A total of 21 percutaneous rabbit liver RF ablations were performed with and without artificial ascites (5% dextrose aqueous solution). The rabbits were divided into three groups: a) control group (C, n = 7); b) room temperature ascites group (R, n = 7); and c) warmed ascites group (W, n = 7). The tip of a 1 cm, internally cooled electrode was placed on the subcapsular region of the hepatic dome via ultrasound guidance, and ablation was continued for 6 min. Changes in temperature of the ascites were monitored during the ablation. The size of the ablation zones of the excised livers and immediate complications rates were compared statistically between the groups (Mann-Whitney U test, Kruskal-Wallis test, linear-by-linear association, p = 0.05). RESULTS: One rabbit from the "W" group expired during the procedure. In all groups, the ascites temperatures approached their respective body temperatures as the ablations continued; however, a significant difference in ascites temperature was found between groups "W" and "R" throughout the procedures (39.2 +/- 0.4 degrees C in group W and 33.4 +/- 4.3 degrees C in group R at 6 min, p = 0.003). No significant difference was found between the size of the ablation zones (782.4 +/- 237.3 mL in group C, 1,172.0 +/- 468.9 mL in group R, and 1,030.6 +/- 665.1 mL in group W, p = 0.170) for the excised liver specimens. Diaphragmatic injury was identified in three of seven cases (42.9%) upon visual inspection of group "C" rabbits (p = 0.030). CONCLUSION: Artificial ascites are not likely to cause a significant heat-sink phenomenon in the percutaneous RF ablation of the hepatic subcapsular region.

SPIO-Enhanced MRI Findings of Well-Differentiated Hepatocellular Carcinomas: Correlation with MDCT Findings

OBJECTIVE: This study was designed to assess superparamagnetic iron oxide (SPIO)-enhanced MRI findings of well-differentiated hepatocellular carcinomas (HCCs) correlated with their multidetector-row CT (MDCT) findings. MATERIALS AND METHODS: Seventy-two patients with 84 pathologically proven well-differentiated HCCs underwent triple-phase MDCT and SPIO-enhanced MRI at a magnetic field strength of 1.5 Tesla (n = 49) and 3.0 Tesla (n = 23). Two radiologists in consensus retrospectively reviewed the CT and MR images for attenuation value and the signal intensity of each tumor. The proportion of hyperintense HCCs as depicted on SPIO-enhanced T2- or T2*-weighted images were compared in terms of tumor size ( 1 cm), five CT attenuation patterns based on arterial and equilibrium phases and magnetic field strength, by the use of univariate and multivariate analyses. RESULTS: Seventy-eight (93%) and 71 (85%) HCCs were identified by CT and on SPIO-enhanced T2- and T2*-weighted images, respectively. For the CT attenuation pattern, one (14%) of seven isodense-isodense, four (67%) of six hypodense-hypodense, four (80%) of five isodense-hypodense, 14 (88%) of 16 hyperdense-isodense and 48 (96%) of 50 hyperdense-hypodense HCCs were hyperintense (Cochran-Armitage test for trend, p 0.05). CONCLUSION: Most well-differentiated HCCs show hyperintensity on SPIO-enhanced MRI, although the lesions show various CT attenuation patterns. The CT attenuation pattern is the main factor that affects the proportion of hyperintense well-differentiated HCCs as depicted on SPIO-enhanced MRI.

Hypointense Hepatic Lesions Depicted on Gadobenate Dimeglumine-Enhanced Three-Hour Delayed Hepatobiliary-Phase MR Imaging: Differentiation between Benignancy and Malignancy

Gadobenate dimeglumine-enhanced magnetic resonance (MR) imaging simultaneously provides both morphological and functional information by the acquisition of dynamic and hepatobiliary-phase imaging. Focal lesions with no functioning hepatocytes, where hepatobiliary metabolism is blocked or inhibited, are generally unable to uptake and excrete gadobenate dimeglumine into the bile. Such lesions are typically malignant and usually appear hypointense as compared to the normal liver parenchyma as seen on hepatobiliary-phase imaging. However, various benign hepatic lesions may also be hypointense due to (a) the presence of no functioning hepatocytes, (b) damage to the functioning hepatocytes or (c) impairment of biliary function as depicted on hepatobiliary-phase imaging. All of these imaging features may result in recognition of the benign hepatic lesions as hepatic malignancies. As depicted on three-hour delayed hepatobiliary-phase imaging, peripheral iso/hyperintensity due to fibrotic tissue compared to the hypointense center with a fuzzy margin may be a clue for the presence of a benign hepatic lesion. In contrast, peripheral hypointensity due to rich tumoral cellularity compared to the center with a clear margin may favor an indication of the presence of a malignant hepatic lesion.

Chondrolipoma in the Pelvic Cavity: a Case Report

A chondrolipoma is an extremely rare form of a benign mesenchymal tumor containing mature cartilage and fatty tissue. Chondrolipomas may be found in almost any part of the body, particularly in the connective tissue of the breast, head and neck area, as well as in the skeletal muscle. However, to the best of our knowledge, chondrolipomas located in the pelvic cavity have not been reported. In this case report, we describe a case of a chondrolipoma in the pelvis, and show that it has its own characteristic imaging findings, which included the composition of fatty tissue and calcification in most parts, as well as some focal areas of chondroid tissue based on the CT and MR findings.

Needle Tract Implantation after Percutaneous Interventional Procedures in Hepatocellular Carcinomas: Lessons Learned from a 10-year Experience

Percutaneous interventional procedures under image guidance, such as biopsy, ethanol injection therapy, and radiofrequency ablation play important roles in the management of hepatocellular carcinomas. Although uncommon, the procedures may result in tumor implantation along the needle tract, which is a major delayed complication. Implanted tumors usually appear as one or a few, round or oval-shaped, enhancing nodules along the needle tract on CT, from the intraperitoneum through the intercostal or abdominal muscles to the subcutaneous or cutaneous tissues. Radiologists should understand the mechanisms and risk factors of needle tract implantation, minimize this complication, and also pay attention to the presence of implanted tumors along the needle tract during follow-up.

Sonography Guided Percutaneous Radiofrequency Ablation of Hepatocellular Carcinoma: Effect of Cooperative Training on the Pretreatment Assessment of the Operation's Feasibility

OBJECTIVE: The aim of this study is to investigate the effects of cooperative training on the pretreatment assessment of the feasibility to perform Ultrasonography (US) guided percutaneous radiofrequency ablation for patients afflicted with hepatocellular carcinoma. MATERIALS AND METHODS: In our prospective study, 146 patients with 200 hepatocellular carcinomas were referred for radiofrequency ablation after triage by hepatologists. Three radiologists with different levels of experience performed the planning US before (group I) and after (group II) cooperative training, to evaluate whether radiofrequency ablation was feasible. The feasibility rates considered eligible according to our criteria were evaluated. In addition, we analyzed the reasons for the lack of feasibility were analyzed. The interobserver agreement for the assessment of feasibility before and after training was also calculated. RESULTS: The overall feasibility rates for both groups was 73%. No significant difference in the feasibility rates was observed. The feasibility rates of each observer for group I were 71% (observer 1), 77% (observer 2) and 70% (observer 3) and those for group II were 73%, 76% and 69%, respectively. In the tumors (n = 164) considered ineligible, the two most common causes for refraining from performing radiofrequency ablation included non-visualization of the tumor (62%) and the absence of a safe route for the percutaneous approach (38%). We found moderate interobserver agreement for all observers before cooperative training and a good agreement after training. CONCLUSION: Although the cooperative training did not affect the feasibility rate of each observer, it improved the interobserver agreement for assessing the feasibility of performing US guided radiofrequency ablation, which may reduce unnecessary admission or delayed treatment.

Complications Following Radiofrequency Ablation of the Porcine Liver through Portal Vein Penetration: Radiological Findings

PURPOSE: To evaluate complications after radiofrequency ablation (RFA) of the porcine liver through portal vein penetration. MATERIALS AND METHODS: Twelve pigs were divided into two groups. In group I (n=11) animals, the portal veins were directly penetrated with an electrode, and in the group II (n=16) animals, the portal veins were located within the expected ablation area. For the group I pigs, RFA were performed for seven minutes after complete portal vein passing of the exposed tip. Gray-scale and Doppler ultrasonography, and CT were performed before and after RFA on the procedure day, and on day two. If any complications were found, the same studies were performed at day seven. We analyzed the presence and extent of thrombotic occlusion, the vascular stricture, the arterioportal shunt, and the presence of an intra-abdominal hemorrhage. We applied Fisher's exact test to compare the complication rate between the two groups;, a value was considered statistically significant if the p-value was less than 0.05. RESULTS: In the group I animals (n=11), three had complete thrombotic occlusion of the portal vein. Among these three animals,, one had a segmental infarction, and one animal showed a partial occlusion. In the group II animals (n=16), complications were not identified. Statistical analysis revealed the complication rate of group I was significantly higher than that of group II (p=.019). CONCLUSION: The portal vein occlusion rate was significantly higher in the portal vein penetrating group than in the non-penetrating group.

Long-term Results of Percutaneous Ethanol Injection for the Treatment of Hepatocellular Carcinoma in Korea

OBJECTIVE: To evaluate the long-term follow-up results of percutaneous ethanol injection (PEI) for the treatment of hepatocellular carcinoma (HCC) in Korea. MATERIALS AND METHODS: Sixty-eight nodular HCCs initially detected in 64 patients, were subjected to US-guided PEI as a first-line treatment. Long-term survival rates, local tumor progression rates, and complications were evaluated, as were the influences of tumor size and Child-Pugh class on these variables. RESULTS: No major complications occurred. The overall survival rates of the 64 patients at three and five years were 71% and 39%, and their cancer-free survival rates were 22% and 15%, respectively. The overall survival rate of patients with a small HCC (< or = 2 cm) was significantly higher (p = 0.014) than that of patients with a medium-sized HCC (< or = 2 cm). The overall survival rate of patients with Child-Pugh class A was significantly higher (p = 0.049) than that of patients with Child-Pugh class B. Of 59 cases with no residual tumor, local tumor progression was observed in ablation zones in 18, and this was not found to be significantly influenced by tumor size or Child-Pugh class. CONCLUSION: The results of our investigation of the long-term survival rates of PEI in HCC patients in Korea (a hepatitis B virus-endemic area) were consistent with those reported previously in hepatitis C endemic areas. Patients with a smaller tumor or a better liver function exhibited superior survival rates.

Depiction of Viable Tumor in Hepatocellular Carcinoma Treated with Transarterial Chemoembolization: Multiphasic Helical CT with Review of the Previous Serial CT Images

OBJECTIVE: The purpose of our study was to assess whether a review of multiphasic helical CT combined with the previous serial CT images could be helpful to depict a viable tumor in hepatocellular carcinoma treated with transarterial chemoembolization. MATERIALS AND METHODS: Twenty-four consecutive patients with 35 hepatocellular carcinomas underwent transarterial chemoembolization followed by hepatic resection. First, three radiologists independently analyzed the last CT images taken before resection for the presence of viable tumor. A second analysis was then performed using the last CT combined with the previous serial CT images. The CT analyses were then compared with the pathologic results. The added value of the review of the previous serial CT images was evaluated by performing a receiver operating characteristic analysis. The sensitivity, specificity and diagnostic accuracy for the depiction of viable tumor were also assessed, and the characteristics of the false-negative lesions were pathologically evaluated. RESULTS: The mean diagnostic accuracies (Az values) for the depiction of viable tumor with using the last CT alone and with the review of the previous serial CT images for all observers were 0.885 and 0.901, respectively, which were not significantly difference (p> 0.05). However, the additional review of the previous serial CT images allowed the observers to render a correct diagnosis for three lesions that had been incorrectly diagnosed with the review of last CT alone. The sensitivity, specificity and diagnostic accuracy of the last CT along with the review of the previous serial CT images were 78%, 97% and 84%, respectively. All of the 16 false-negative lesions diagnosed by each observer showed 90% or greater necrosis on the pathologic examination. CONCLUSION: For the depiction of viable tumor in hepatocellular carcinoma treated with transarterial chemoembolization, although the difference in the diagnostic accuracies was not statistically significant, a review of the multiphasic helical CT combined with the previous serial CT images could help reach a correct diagnosis for those lesions incorrectly diagnosed with the review of the last CT alone.

Radiofrequency Ablation of Rabbit Liver In Vivo: Effect of the Pringle Maneuver on Pathologic Changes in Liver Surrounding the Ablation Zone

OBJECTIVE: We wished to evaluate the effect of the Pringle maneuver (occlusion of both the hepatic artery and portal vein) on the pathologic changes in the hepatic vessels, bile ducts and liver parenchyma surrounding the ablation zone in rabbit livers. MATERIALS AND METHODS: Radiofrequency (RF) ablation zones were created in the livers of 24 rabbits in vivo by using a 50-W, 480-kHz monopolar RF generator and a 15-gauge expandable electrode with four sharp prongs for 7 mins. The tips of the electrodes were placed in the liver parenchyma near the porta hepatis with the distal 1 cm of their prongs deployed. Radiofrequency ablation was performed in the groups with (n=12 rabbits) and without (n=12 rabbits) the Pringle maneuver. Three animals of each group were sacrificed immediately, three days (the acute phase), seven days (the early subacute phase) and two weeks (the late subacute phase) after RF ablation. The ablation zones were excised and serial pathologic changes in the hepatic vessels, bile ducts and liver parenchyma surrounding the ablation zone were evaluated. RESULTS: With the Pringle maneuver, portal vein thrombosis was found in three cases (in the immediate [n=2] and acute phase [n=1]), bile duct dilatation adjacent to the ablation zone was found in one case (in the late subacute phase [n=1]), infarction adjacent to the ablation zone was found in three cases (in the early subacute [n=2] and late subacute [n=1] phases). None of the above changes was found in the livers ablated without the Pringle maneuver. On the microscopic findings, centrilobular congestion, sinusoidal congestion, sinusoidal platelet and neutrophilic adhesion, and hepatocyte vacuolar and ballooning changes in liver ablated with Pringle maneuver showed more significant changes than in those livers ablated without the Pringle maneuver (p < 0.05) CONCLUSION: Radiofrequency ablation with the Pringle maneuver created more severe pathologic changes in the portal vein, bile ducts and liver parenchyma surrounding the ablation zone compared with RF ablation without the Pringle maneuver. Therefore, we suggest that RF ablation with the Pringle maneuver should be performed with great caution in order to avoid unwanted thermal injury.

Radiofrequency Ablation of Liver Cancer: Early Evaluation of Therapeutic Response with Contrast-Enhanced Ultrasonography

The early assessment of the therapeutic response after percutaneous radiofrequency (RF) ablation is important, in order to correctly decide whether further treatment is necessary. The residual unablated tumor is usually depicted on contrast-enhanced multiphase helical computed tomography (CT) as a focal enhancing structure during the arterial and portal venous phases. Contrast-enhanced color Doppler and power Doppler ultrasonography (US) have also been used to detect residual tumors. Contrast-enhanced gray-scale US, using a harmonic technology which has recently been introduced, allows for the detection of residual tumors after ablation, without any of the blooming or motion artifacts usually seen on contrast-enhanced color or power Doppler US. Based on our experience and reports in the literature, we consider that contrast-enhanced gray-scale harmonic US constitutes a reliable alternative to contrast-enhanced multiphase CT for the early evaluation of the therapeutic response to RF ablation for liver cancer. This technique was also useful in targeting any residual unablated tumors encountered during additional ablation.

Focal Nodular Hyperplasia of the Liver: Triphasic Helical CT Findings

PURPOSE: To analyze the morphologic and enhancement patterns of focal nodular hyperplasia (FNH) of the liver observed at triphasic helical CT. MATERIALS AND METHODS: The triphasic helical CT findings of 15 pathologically-proven FNHs in 15 patients (male: female = 7:8; mean age, 40 years) were retrospectively analyzed. Triphasic helical CT images were obtained at 30 secs (arterial phase), 70 secs (portal phase), and 3 mins (equilibrium phase) after the initiation of contrast injection of a total of 120 mL nonionic contrast material at a rate of 3 mL/sec. Image analysis focused on the morphologic and enhancement patterns of the FNHs. Morphologically, their size and margin conspicuity were determined, as well as the presence or absence of a capsule, central scar, malformed arterial vessel, calcification, and mosaic pattern. As for the enhancement pattern, the degree of tumor enhancement (hyper-, iso-, or hypoattenuation) was compared with the surrounding hepatic parenchyma at each phase. All hyperattenuating FNHs were further analyzed after dividing them into two groups, strongly and weakly enhanced. RESULTS: Ten of the 15 tumors were less than 3 cm in diameter. With regard to the other morphologic parameters, a central scar, malformed arterial vessel, and capsule were found in four, four, and five FNHs, respectively. Eleven FNHs showed hyperattenuation, with strong enhancement at the arterial phase. During the portal and equilibrium phases, the enhancement pattern changed to iso- or hypoattenuation in nine and 13 FNHs, respectively. Of six hyperattenuating FNHs at the portal phase, five were weakly enhanced. CONCLUSION: Though our sample was small, we found that FNHs were hyperattenuating lesions, strongly enhanced at the arterial phase but iso- or hypoattenuating during the portal and equilibrium phases. A central scar, malformed arterial vessel, and capsule were observed fairly frequently. Thus, for the differentiation of FNH from other hypervascular hepatic tumors, precise recognition of their CT findings is important.