Local ablation has been accepted in many treatment guidelines as a good alternative to curative resection or transplantation for patients with unresectable hepatocellular carcinoma (HCC). The main advantage of local ablative therapy is minimal invasiveness, guaranteeing low morbidity even for the patient with poor hepatic reserve. Furthermore, the therapeutic efficacy of local ablation, especially radiofrequency ablation (RFA), has been shown to be as effective as surgical resection for early-stage (smaller than 3 cm, less than 4 in number) HCC. The long-term outcome after radiofrequency ablation for HCC reported in large series studies were overall survival of 50% to 60% at 5 years and 27 to 32% at 10 years. Major complication rates are 0% to 2.4%. However, controversy remains regarding whether local ablation can replace surgical resection because many retrospective comparative studies have produced conflicting results. Only a well-designed randomized study will be able to clearly answer this long-standing question. During the past decade, many technical advancements in local ablation have been reported, including novel electrodes, thermal protection (i.e., artificial ascites), fusion image guidance, Sonazoid-enhanced ultrasound guidance, and emerging energy sources (i.e., microwaves, High internsity focused ultrasound, Irreversible electroporation). Local ablation is still an evolving technique in the era of minimally invasive treatment for HCC. Many more technical advances are ongoing to enhance the therapeutic efficacy of local ablation. In summary, local ablation will remain a mainstay of non-surgical treatment early stage HCC and play an important role in multidisciplinary approach for HCC management.
Carcinoma, Hepatocellular* ; Electrodes ; Humans ; Microwaves ; Retrospective Studies ; Transplantation ; Transplants ; Ultrasonography

BACKGROUND/AIMS: We experimented with different ablation methods and two types of microwave antennas to determine whether microwave ablation (MWA) increases intrahepatic pressure and to identify an MWA protocol that avoids increasing intrahepatic pressure. METHODS: MWA was performed using either a single-step standard ablation or a stepwise increment ablation paired with either a 16-gauge (G) 2-cm antenna or a 14G 4-cm antenna. We compared the maximum pressures and total ablation volumes. RESULTS: The mean maximum intrahepatic pressures and ablation volumes were as follows: 16G single-step: 37+/-33.4 mm Hg and 4.63 cm3; 16G multistep: 31+/-18.7 mm Hg and 3.75 cm3; 14G single-step: 114+/-45.4 mm Hg and 15.33 cm3; and 14G multistep: 106+/-43.8 mm Hg and 10.98 cm3. The intrahepatic pressure rose during MWA, but there were no statistically significant differences between the single and multistep methods when the same gauge antennae were used. The total ablation volume was different only in the 14G groups (p<0.05). CONCLUSIONS: We demonstrated an increase in intrahepatic pressure during MWA. The multistep method may be used to prevent increased intrahepatic pressure after applying the proper power.
Ablation Techniques/instrumentation/*methods ; Animals ; Cattle ; Liver/*physiology/surgery ; Medical Illustration ; *Microwaves ; Models, Animal ; *Pressure

Sclerosing stromal tumor of the ovary is a rare benign neoplasm, with distinctive clinical and pathologic features. It occurs predominantly in females during the second and third decades of life. Histologically, it is composed of cellular and acellular collagenized areas, and edematous stromal areas, and at ultrasonography and computed tomography is seen as a distinctive mixed solid and cystic mass lesion. We report a case of sclerosing stromal tumor of the ovary in a 15-year-old girl with a history of menorrhagia since menarche. Ultrasonography revealed the tumor as a well-defined, lobulated, heterogenous echogenic pelvic mass, while at CT, a huge pelvic mass 9x9x10 cm in size, was seen. This comprised a well-enhanced internal solid portion, a capsule, septa, and a non-enhanced cystic portion.
Adolescent ; Collagen ; Female ; Humans ; Menarche ; Menorrhagia ; Ovary* ; Ultrasonography

A case of a 36-yr-old woman with retroperitoneal synovial sarcoma is described. Her presenting symptom was epigastric pain that radiating to the back. On radiologic study, bulky retropancreatic soft tissue mass was detected which showed cystic and solid components. At operation, complete resection of the tumor was not possible because of the adhesion to the vena cava and the liver. During the follow-up, extensive tumor recurrence and liver metastasis were revealed. Primary retroperitoneal synovial sarcoma is a very rare malignant tumor with high mortality and recurrence rates. Retroperitoneal synovial sarcoma usually appears as a nonspecific soft tissue mass that do not have specific imaging features differentiating it from other mesenchymal tumors. However general radiologic findings and anatomic location of the tumor may help the diagnosis. In addition, synovial sarcoma should be included in the differential diagnosis of retroperitoneal soft tissue mass detected in young adults.
Adult ; Female ; Humans ; Retroperitoneal Neoplasms/*pathology/radiography/surgery ; Sarcoma, Synovial/*pathology/radiography/surgery ; Tomography, X-Ray Computed

PURPOSE: To determine the factors that are related to local recurrence after Radiofrequency thermal ablation (RFTA) of hepatic tumors. MATERIALS AND METHODS: We selected 30 patients with 51 hepatic nodules less than 5 cm in diameter (HCC, n=33; metastasis, n=18) who underwent RF thermal ablation between May 1999 and April 2000. Ablation was defined as 'complete'if immediately post-procedual CT showed that a nodule's margin was completely covered by ablation. Every three months, follow-up CT scans were examined for signs of local recurrence, and a nodule was assessed in terms of its size, the histologic diagnosis, adjacent vessels, perfect ablation (a safety margin of more than 5mm beyond the tumor margin), and whether hyperemia was observed after ablation. Finally, a group in which there was local recurrence (group A, n=15) and another showing no recurrence (group B, n=36) were compared. RESULTS: Mean nodule size in group A and group B was 3.26 and 2.24 cm, respectively. Local recurrence was noted in 7 of 33 HCC nodules (21.2%), and in 8 of 18 (44.4%) which were metastatic. There was recurrence in 9 of 31 nodules with adjacent vessels (29.0%), and in 6 of 20 (30%) without adjacent vessels. In two of 17 perfectly ablated nodules (11.8%) there was local recurrence, but this was observed in 13 of 34 imperfectly ablated nodules (38.2%). Finally, local recurrence was seen in 14 of 36 nodules showing hyperemia (38.9%) but in one of 15 (6.7%) without hyperemia. Using chi-square analysis, it was thus shown that with regard to local recurrence, tumor size, perfect ablation and peritumoral hyperemia were statistically significant factors (p<0.05). CONCLUSION: Local recurrence after RF thermal ablation of hepatic tumors clearly increases in nodules which are larger. The degree to which ablation is perfect, and the presence of peritumoral hyperemia, may be factors related to the local recurrence observed after RFTA.
Diagnosis ; Follow-Up Studies ; Humans ; Hyperemia ; Neoplasm Metastasis ; Recurrence* ; Tomography, Spiral Computed* ; Tomography, X-Ray Computed

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.
Carcinoma, Hepatocellular ; Gastroenterology ; Humans ; Transplants

PURPOSE: To determine the incidence and pattern of peritumoral hyperemia at CT after radiofrequency thermal ablation of hepatic tumors, as well as its correlation with local marginal recurrence. MATERIALS AND METHODS: Forty-five tumor nodules in 28 patients with hepatocellular carcinoma (n=34) or metastasis (n=11) were treated by RF thermal ablation. Serial follow-up contrast- enhanced CT scans were reviewed by three radiologists for 1) the presence, 2) the morphological characteristics [circumferential, THAD (transient hepatic attenuation difference), nodular form], and 3) the temporal course (acute, persistent, delayed onset pattern) of peritumoral hyperemia after RF thermal ablation. These findings were correlated with the frequency of recurrence at the margin of the treated tumors. RESULTS: The frequency of acute hyperemia observed on immediate follow-up CT scans after RF ablation was 71% (32/45). There was the local recurrence in nine of 32 tumors (28%) with hyperemia and in one of 13 (8%) without hyperemia (p>0.05). Among 32 tumors, the circumferential form was observed in 22 (69%); the THAD form in eight (25%); and the nodular form in two (6%). Marginal recurrence was noted in five of 22 tumors circumferential tumors (23%), in three of eight (38%) with the THAD form, and in one of two (50%) which were nodular. Among 32 nodules, an acute transient pattern was noted in 21 (66%), a persistent pattern in nine (28%), and a nodular pattern in two (6%). There was marginal recurrence in two (10%) of 21 tumors with acute transient hyperemia, in six (67%) of nine with persistent hyperemia, and in both tumors with delayed-onset hyperemia. There was significant correlation between the pattern of persistent/delayed-onset hyperemia and marginal tumor recurrence of (p=0.001). CONCLUSION: Although peritumoral hyperemia after RF thermal ablation therapy is a frequent transient finding at follow-up imaging studies, its temporal pattern may help detect early marginal tumor recurrence.
Carcinoma, Hepatocellular ; Follow-Up Studies ; Humans ; Hyperemia* ; Incidence ; Liver Neoplasms ; Neoplasm Metastasis ; Recurrence ; Tomography, X-Ray Computed

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.
Animals ; *Ascites ; *Body Temperature ; Burns/etiology/prevention & control ; *Catheter Ablation/adverse effects/methods ; Diaphragm/injuries ; Glucose/administration & dosage ; Liver/pathology/*surgery ; Rabbits ; Solutions

Objective: To compare the outcomes of radiofrequency ablation (RFA) using dual switching monopolar (DSM), switching bipolar (SB), and combined DSM + SB modes at two different interelectrode distances (25 and 20 mm) in an ex vivo study, which simulated ablation of a 2.5-cm virtual hepatic tumor. Materials and Methods: A total of 132 ablation zones were created (22 ablation zones for each protocol) using three separable clustered electrodes. The performances of the DSM, SB, and combined DSM + SB ablation modes were compared by evaluating the following parameters of the RFA zones at two interelectrode distances: shape (circularity), size (diameter and volume), peritumoral ablative margins, and percentages of the white zone at the midpoint of the two electrodes (ablative margin at midpoint, AMm) and in the electrode path (ablative margin at electrode path, AMe). Results: At both distances, circularity was the highest in the SB mode, followed by the DSM + SB mode, and was the lowest in the DSM mode. The circularity of the ablation zone showed a significant difference among the three energy groups (p < 0.001 and p = 0.002 for 25-mm and 20-mm, respectively). All size measurements, AMm, and AMe were the greatest in the DSM mode, followed by the DSM + SB mode, and the lowest were with the SB mode (all statistically significant). The white zone proportion in AMm and AMe were the greatest in the SB mode, followed by the DSM + SB mode and DSM in general. Conclusion DSM and SB appear to be complementary in creating an ideal ablation zone. RFA with the SB mode can efficiently eradicate tumors and create a circular ablation zone, while DSM is required to create a sufficient ablative margin and a large ablation zone.