Percutaneous radiofrequency ablation of renal tumors: midterm results in 16 patients

PURPOSE: To evaluate the outcome of 16 patients after percutaneous radiofrequency ablation of renal tumors. MATERIALS AND METHODS: Sixteen patients (nine women, seven men; mean age, 61+/-9 years) with 24 unresectable renal tumors (mean volume, 4.3+/-4.3 cm3) underwent CT-guided (n=20) or MR imaging-guided (n=4) percutaneous radiofrequency ablation using an expandable electrode (Starburst XL, RITA Medical Systems, Mountain View, CA) with a 150-W generator. The initial follow-up imaging was performed within 1-30 days after RF ablation, then at 3-6 month intervals using either CT or MRI. Residual tumor volume and coagulation necrosis was assessed, and statistical correlation tests were obtained to determine the strength of the relationship between necrosis volume and number of ablations. RESULTS: Overall, 97 overlapping RF ablations were performed (mean, 3.5+/-1.5 ablations per tumor) during 24 sessions. Five or more RF ablations per tumor created significant larger necrosis volumes than 1-2 (p=.034) or 3-4 ablations (p=.020). A complete ablation was achieved in 20/24 tumors (primary technical success, 83%; mean volume of coagulation necrosis: 10.2+/-7.2 cm3). Three of four residual tumors were retreated and showed complete necrosis thereafter. Three major complications (one percuatneous urinary fistula and two ureteral strictures) were observed after RF ablation. No further clinically relevant complications were observed and renal function remained stable. During a mean follow-up of 11.2 months (range, 0.2-31.5), 15/16 patients (94%) were alive. Only one patient had evidence of local recurrent tumor. CONCLUSION: The midterm results of percutaneous RF ablation for renal tumors are promising and show that RF ablation is well-suited to preserve renal function.     

Percutaneous sonographically guided saline-enhanced radiofrequency ablation of hepatocellular carcinoma

OBJECTIVE: The purpose of our study was to analyze the efficacy, side effects, and short-term complications of saline-enhanced percutaneous radiofrequency ablation performed under sonographic guidance in a series of cirrhotic patients with hepatocellular carcinoma. SUBJECTS AND METHODS. Between September 2000 and June 2002, 84 patients (55 men and 29 women) with cirrhosis who ranged in age from 48 to 74 years (mean age, 64 years) and who had 95 hepatocellular carcinomas (seven patients had two tumors and two patients had three tumors) were treated with high frequency-induced thermotherapy. The diameters of the tumors ranged from 1.5 to 8.5 cm (mean, 3.6 cm). The efficacy of radiofrequency ablation was evaluated with triphasic contrast-enhanced CT performed 4 weeks after the procedure. RESULTS: Posttreatment CT showed complete necrosis in 73 (77%) of 95 hepatocellular carcinomas in 62 patients. Complete necrosis based on tumor size was seen in 40 (95%) of 42 tumors with diameters equal to or smaller than 3 cm, 32 (71%) of 45 tumors with diameters between 3.1 and 5.0 cm, and one (12%) of eight tumors with diameters larger than 5.0 cm. Twenty-two hepatocellular carcinomas showed incomplete necrosis. None of the patients experienced major complications. Four patients were lost to follow-up. The length of the follow-up period ranged from 4 to 22 months (mean, 10 months). One patient died 8 months after the radiofrequency ablation treatment. All the remaining patients are still alive. During the follow-up period, eight (10%) of 80 patients showed a local recurrence on sonography and CT. CONCLUSION: Our experience suggests that percutaneous radiofrequency ablation of hepatocellular carcinoma with high frequency-induced thermotherapy is safe and effective in the treatment of hepatocellular carcinomas equal to or smaller than 3 cm, fairly effective for hepatocellular carcinomas between 3 and 5 cm, and ineffective for tumors larger than 5 cm.     

Combined radiofrequency and alcohol injection for percutaneous hepatic tumor ablation

OBJECTIVE: We sought to determine if alcohol potentiates radiofrequency energy by obtaining larger ablative volumes in 30 liver tumors in human patients. SUBJECTS AND METHODS: We compared two groups of patients: one group treated with radiofrequency ablation alone (radiofrequency-alone group), and a second group treated with radiofrequency ablation and immediate prior injection of alcohol (combined group). The radiofrequency-alone group comprised 20 ablations (mean diameter, 8.4 cm; colorectal cancer metastases [n = 15]; other metastases [n = 5]). The combined group consisted of 30 radiofrequency ablations (mean diameter, 8.8 cm; metastatic colorectal cancer [n = 17]; other metastases [n = 8]; and hepatocellular carcinoma [n = 5]) treated with alcohol injection immediately before radiofrequency ablation. The amount of alcohol injected was determined by the size and location of tumors. Preprocedural laboratory tests (complete blood cell count with differential, liver function tests, and coagulation parameters) were performed in all patients, along with pre- and postprocedural CT, MRI, and PET. Measurements of tissue necrosis were obtained on the postprocedural CT scans and MR images. Volumes of necrosis calculated in each group were corrected for the number of radiofrequency applications and were statistically compared using the Student's t test. In addition, tissue impedances obtained during the radiofrequency ablation procedure were compared between the two groups. RESULTS: The mean ablation volumes for the radiofrequency-alone group were 32.3 cm(2) (median, 28.6 cm(2); range, 14.4-61.8 cm(2)) and for the combined group, 84.6 cm(2) (median, 78.3 cm(2); range, 34.6-149 cm(2)). The difference in the necrosis volumes was significantly larger (p < 0.0001) in the combined group. Overall, the combined treatment group underwent fewer radiofrequency applications per session. Tissue impedance during radiofrequency ablation was higher in the combined group (mean, 62.7 vs 57.3 Omega in the radiofrequency alone group; p = 0.0005) at comparable times during the ablations. No major complications were seen in either group. CONCLUSION: Percutaneous radiofrequency ablation appears to be potentiated by immediate prior alcohol injection into the tumor. Consistently larger lesions are obtainable in fewer sessions, without any increase of complications, using the combined method.     

Radiofrequency ablation of small renal cell carcinomas using multitined expandable electrodes: preliminary experience

PURPOSE: Radiofrequency ablation is a minimally invasive, nephron-sparing option for renal cell carcinoma (RCC) in poor surgical candidates. We report our contemporary experience with RCC radiofrequency ablation using multitined expandable electrodes along with an aggressive treatment strategy to displace adjacent viscera away from probe tines. Involution of the treatment zone was assessed over time. MATERIALS AND METHODS: Over a 36-month period, a quality-assurance database identified 22 patients with 26 sporadic RCC who underwent 43 ablations during 27 radiofrequency ablation sessions. The mean age of the cohort was 71 years (range, 47-89 y). Mean RCC diameter was 2.2 cm (range, 1-4 cm). Twenty-six of radiofrequency ablation sessions were performed using multitined expandable electrodes. All ablations used CT guidance with moderate sedation. Adjunctive techniques used during ablation were recorded, as were instances in which ablation mandated penetration of tines beyond the kidney margin. Post-treatment ablation zones were measured from CT/MR images to evaluate serial involution and treatment response. RESULTS: Technical success in targeting and ablation was 100%. Follow-up periods ranged from 1 to 31 months (mean, 11.2). During this period, one patient presented with marginal local recurrence and underwent repeat radiofrequency ablation. Adjunctive techniques in four patients included water injection for displacement of the tail of the pancreas (n = 1) or descending colon (n = 3). Deliberate penetration of tines beyond the margins of the kidney was performed in 41% of cases; no hemorrhage occurred in these cases. No major complications occurred. Minor complications occurred in 17% of patients, including asymptomatic pneumothorax, perirenal hematomas, subcutaneous hematoma, and subcutaneous abscess. After 6 months, mean involution of the ablation zone was 15% from baseline volume per year. CONCLUSION: Multitined expandable radiofrequency electrodes produce a high rate of local control for small RCCs with a low complication rate, even when tine penetration of the kidney is required for an adequate tumor treatment margin. Adjacent organs can be protected with adjunctive percutaneous maneuvers.     

Imaging-guided radiofrequency ablation of solid renal tumors

OBJECTIVE: We performed a retrospective review of imaging-guided radiofrequency ablation of solid renal tumors. MATERIALS AND METHODS: Since May 2000, 35 tumors in 20 patients have been treated with radiofrequency ablation. The size range of treated tumors was 0.9-3.6 cm (mean, 1.7 cm). Reasons for patient referrals were a prior partial or total nephrectomy (nine patients), a comorbidity excluding nephrectomy or partial nephrectomy (10 patients), or a treatment alterative to nephron-sparing surgery (one patient who refused surgery). Tumors were classified as exophytic, intraparenchymal, or central. Sixteen patients had 31 lesions that showed serial growth on CT or MR imaging. Of these 16 patients, four patients with 10 lesions had a history of renal cell carcinoma, and two patients with 11 lesions had a history of von Hippel-Lindau disease. Four patients had incidental solid masses, two of which were biopsied and shown to represent renal cell carcinoma, and the remaining two masses were presumed malignant on the basis of imaging features. Successful ablation was regarded as any lesion showing less than 10 H of contrast enhancement on CT or no qualitative evidence of enhancement after IV gadolinium contrast-enhanced MR imaging. RESULTS: Of the 35 tumors, 22 were exophytic and 13 were intraparenchymal. Twenty-seven of the 35 were treated percutaneously using either sonography (n = 22) or CT (n = 5). Two patients had eight tumors treated intraoperatively using sonography. Patients were followed up with contrast-enhanced CT (n = 18), MR imaging (n = 5), or both (n = 5) with a follow-up range of 1-23 months (mean, 9 months). No residual or recurrent tumor and no major side effects were seen. CONCLUSION: Preliminary results with radiofrequency ablation of exophytic and intraparenchymal renal tumors are promising. Radiofrequency ablation is not associated with significant side effects. Further follow-up is necessary to determine the long-term efficacy of radiofrequency ablation.     

Radiofrequency ablation of hepatic tumors: variability of lesion size using a single ablation device

OBJECTIVE: In this study, we examined the variability of lesion sizes produced by a single radiofrequency ablation using the same device and algorithm in patients with small malignant hepatic tumors. MATERIALS AND METHODS: A review of the clinical records of 208 patients who underwent radiofrequency ablation of malignant hepatic tumors during a 6-year period revealed 31 patients with small tumors that were treated with a single ablation. Clinical data were recorded using standardized work sheets. Tumor and lesion sizes after ablation were measured from CT scans. The influences of tumor size, tumor type, presence or absence of cirrhosis, and tissue temperature on the ablation size were analyzed. RESULTS: The size of tumor before treatment ranged from 0.8 to 4.0 cm (mean diameter [+/- SD] = 1.8 +/- 0.9 cm) with corresponding volumes of 0.27-30.24 mL (mean volume = 27.1 +/- 15.9 mL). The lesion sizes after ablation ranged from 1.7 to 5.3 cm (mean diameter = 3.6 +/- 0.7 cm) with corresponding volumes of 2.29-75.87 mL (mean volume = 4.9 +/- 7.1 mL). Tumor type (p > 0.25), presence or absence of cirrhosis (p > 0.45), and tissue temperature (p = 0.055) had no relationship to ablation size. Tumor size had a statistically significant influence on ablation lesion size (p < 0.04). Ablation of small tumors (diameter < or = 2.25 cm, n = 32) produced random lesion sizes whereas ablation of large tumors (diameter > 2.25 cm, n = 11) produced larger lesions (mean diameter = 4.0 +/- 0.8 cm). CONCLUSION: Significant variation occurs in the lesion size produced using the same ablation device and algorithm. These findings must be considered when planning ablation strategies.     

Recurrent hepatocellular carcinoma: percutaneous radiofrequency ablation after hepatectomy

PURPOSE: To evaluate the therapeutic efficacy and safety of percutaneous radiofrequency (RF) ablation for recurrent hepatocellular carcinoma (HCC) in the liver after hepatectomy. MATERIALS AND METHODS: Forty-five patients with 53 recurrent HCC tumors in the liver underwent percutaneous RF ablation with ultrasonographic guidance. All patients had a history of hepatic resection for HCC. The mean diameter of recurrent tumors was 2.1 cm (range, 0.8-4.0 cm). All patients were followed up for at least 10 months after ablation (range, 10-40 months; mean, 23 months). Therapeutic efficacy and complications were evaluated with multiphase helical computed tomography (CT) at regular follow-up visits. Overall and disease-free survival rates were calculated. RESULTS: At follow-up CT after initial RF ablation, 11 (21%) of 53 ablated HCC tumor sites showed residual tumor or local tumor progression. After additional RF ablation, complete ablation of 46 (87%) of 53 tumors was attained. Also at initial follow-up CT, before either additional RF ablation or other treatment was performed, 21 (47%) of 45 patients were found to have 41 new HCC tumors at other liver sites. Of these, nine tumors in eight patients were treatable with a second application of RF ablation. Overall survival rates at 1, 2, and 3 years were 82%, 72%, and 54%, respectively. No deaths or complications requiring further treatment occurred as a result of RF ablation. CONCLUSION: Percutaneous RF ablation is an effective and safe method for treating recurrent HCC in the liver after hepatectomy, with a good overall patient survival rate.     

Percutaneous radiofrequency ablation of hepatic tumors against the diaphragm: frequency of diaphragmatic injury

PURPOSE: To retrospectively determine the frequency of diaphragmatic injury when percutaneous hepatic radiofrequency (RF) ablation is performed adjacent to the diaphragm. MATERIALS AND METHODS: Institutional Review Board approval was obtained for our HIPAA-compliant study. Informed consent for the ablation procedure and for use of related data for future research was obtained from each patient. A retrospective review was conducted of 215 patients undergoing percutaneous RF ablation of hepatic tumors. Twenty-nine patients (21 men and eight women; age, 41-89 years) were identified with tumors abutting the diaphragm. Episodes of right shoulder pain were recorded. A panel of radiologists blinded to the patients' clinical histories reviewed their imaging for evidence of diaphragmatic injury and ablation success. A generalized estimating equation model and the Fisher exact test were used for statistical analysis. RESULTS: The 29 patients had a total of 33 tumors abutting the diaphragm. Tumor size was 1.3-5.5 cm (mean, 3.2 cm +/- 1.1). After ablation, five (17%) patients reported right shoulder pain. In four, pain was mild or moderate, with symptoms lasting 2-14 days (median, 5.5 days). Three of these showed diaphragmatic thickening on postablation computed tomographic (CT) scans. One patient had severe pain lasting 2 weeks, followed by milder pain for 2 months. This patient's postablation CT images showed focal nodular diaphragmatic thickening. This patient was treated with a multitined device; the other four, with straight-needle devices. Local tumor progression was seen in 14 tumors (42.4%). Tumors 3 cm or smaller had a much lower local progression rate than tumors larger than 3 cm (12.5% vs 70.6%). CONCLUSION: Of 29 patients who had ablation of hepatic tumors adjacent to the diaphragm, five (17%) had diaphragmatic injury, which was clinically apparent with right shoulder pain.     

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 (≤1.0 cm) treated with RF ablation using an internally cooled electrode system. An electrode was inserted into the tumor either parallel (n = 38) or perpendicular (n = 8) to the gallbladder wall. The safety and therapeutic efficacy of the procedures were assessed with clinical and imaging follow-up examinations. Follow-up with the use of CT ranged from four to 45 months (mean, 19 months). The association between variables (electrode direction, electrode type, tumor size, tumor location, lobar location) and the presence of a residual tumor or local tumor progression was also analyzed.

Results

There were no major complications and minor complications were noted in three patients (7%) including one case of vasovagal syncope and two cases of bilomas. Wall thickening of the gallbladder adjacent to the RF ablation zone was noted in 14 patients (41%) as determined on immediate follow-up CT imaging. Wall thickening showed complete disappearance on subsequent follow-up CT imaging. The primary technique effectiveness rate was 96% (44/46) based on one-month follow-up CT imaging. Local tumor progression was noted in six (14%) of 44 completely ablated tumors during the follow-up period. The direction of electrode insertion (perpendicular), tumor size (≥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.     

Radiofrequency ablation of thoracic lesions: part 2, initial clinical experience--technical and multidisciplinary considerations in 30 patients

OBJECTIVE: The purpose of our study was to report our initial experience with patients who underwent percutaneous imaging-guided radiofrequency ablation of thoracic lesions, and to emphasize technical and multidisciplinary issues and adjunctive procedures specific to thoracic tumor ablation. MATERIALS AND METHODS: Our cohort consisted of 30 patients with a spectrum of primary (n=18) and secondary (n=11) lung tumors, mesothelioma (n=1), and five secondarily eroded, painful ribs who underwent ablation of 36 total lesions (one patient had two ablations). Patients either were nonsurgical candidates because of medical comorbidities or extent of disease, or had exhausted chemotherapy and radiation therapy options, or had refused surgery or undergone unsuccessful surgery. Patients were treated with radiofrequency ablation after agreement among oncologists, thoracic surgeons, and interventional radiologists. An array-style electrode under impedance control was used to treat 29 thoracic tumors and the adjacent rib metastases (n=5). A cool-tip radiofrequency probe was used for two patients. CT guidance and general anesthetic were used for all but one patient. Sonographic guidance and IV conscious sedation were used in one patient. Pain (n=11) and tumor cure or control (n=19) were the primary indications for the procedures. Adjunctive procedures to the radiofrequency ablations included the creation of saline or water windows (n=3); establishment of transosseous and transchondral routes (n=4); use of intercostal and paravertebral nerve blocks (n=15); and use of an intraprocedural catheter (n=1), needle (n=1), or sheath (n=3) for treatment of pneumothoraces. Follow-up was from 2 to 26 months. RESULTS: All ablations were technically successful. No periprocedural mortality occurred. Necrosis of tumor was greater than 90% in 26 of 30 lesions based on short-term follow-up imaging (CT, PET, MRI). In the 11 patients who underwent ablation for pain, relief was complete in four and partial in the other seven. One patient developed a local skin burn, four patients had self-limited hemoptysis up to 4 days after ablation, one had transient atrial fibrillation, one developed hoarseness, and two patients were transiently reintubated after extubation. Eight pneumothoraces developed; one patient underwent placement of a chest tube. Four patients died within 1 year of ablation from extrathoracic spread of tumor. CONCLUSION: Radiofrequency ablation for a variety of thoracic tumors can be performed safely and with a high degree of efficacy for pain control and tumor killing. The effect of ablation can be assessed with CT, MRI, or PET. Various technical issues differentiate thoracic tumor ablation from standard abdominal ablations. Numerous other thoracic interventional radiology procedures are beneficial to assist the radiofrequency ablation. A multidisciplinary approach offers valuable expertise for patient care.     

Changes in bile ducts after radiofrequency ablation of hepatocellular carcinoma: frequency and clinical significance

OBJECTIVE: The purpose of our study was to determine the frequency of bile duct changes after radiofrequency ablation for hepatocellular carcinoma and to evaluate their clinical significance. MATERIALS AND METHODS: Between April 1999 and August 2003, 389 patients with 521 hepatocellular carcinomas underwent a total of 571 sessions of radiofrequency ablation. The maximum dimension of the tumors measured on sonography was 2.4 +/- 0.9 cm (mean +/- SD) (range, 0.5-5.0 cm). The frequency and type of bile duct changes resulting from radiofrequency ablation, the time interval between radiofrequency ablation and the first appearance of bile duct changes, and the serial changes at follow-up CT were analyzed. Complications related to bile duct changes were also evaluated by reviewing medical records and CT scans. RESULTS: Bile duct changes occurred in 69 (12%) of 571 sessions and 66 (17%) of 389 patients. Bile duct changes seen on CT included mild dilatation of upstream bile ducts surrounding the ablation zone in 57 patients (82.6%), biloma in the ablation zone in four patients (5.8%), and both in eight patients (11.6%). The mean time interval between radiofrequency ablation and the initial appearance of bile duct change was 1.6 months (range, immediate-9 months). Most (87%) of the 69 patients with bile duct changes showed no progression on follow-up CT, and only nine (13%) had slight progression. All patients but one, in whom cholangitis developed, had no major complications requiring specific treatment during the follow-up period. CONCLUSION: Although bile duct changes were frequent after the radiofrequency ablation of hepatocellular carcinoma, most were of no clinical significance, and major complications requiring additional treatment were rare.     

Radiofrequency ablation of hepatic tumors: increased tumor destruction with adjuvant liposomal doxorubicin therapy

OBJECTIVE: The purpose of this study was to determine whether the administration of liposomal doxorubicin before radiofrequency ablation increases coagulation more than radiofrequency alone in focal hepatic tumors. SUBJECTS AND METHODS: Fourteen focal hepatic tumors (diameter: mean +/- SD, 4.0+/-1.8 cm) in 10 patients (colorectal cancer, n = 3 patients; hepatocellular carcinoma, n = 4; neuroendocrine tumor, n = 2; breast cancer, n = 1) were treated with internally cooled radiofrequency ablation. In addition to undergoing radiofrequency, five patients (n = 7 lesions) were randomly assigned to receive 20 mg of IV doxorubicin in a long-circulating stealth liposome carrier (Doxil) 24 hr before ablation. Contrast-enhanced helical CT was performed immediately (within 30 min) after radiofrequency ablation (baseline) and 2-4 weeks after ablation. The volume of induced coagulation was measured by three-dimensional reconstruction techniques, and the measurements were compared. RESULTS: For tumors treated with radiofrequency alone, the volume of the thermal lesion had decreased 12-24% (mean +/- SD, 82.5% +/- 4.4% of initial volume) at 2-4 weeks after ablation. By comparison, increased tumor destruction at 2-4 weeks after ablation was observed for all lesions treated with combined Doxil and radiofrequency (p<0.001). Six lesions increased 24-36% in volume, and coagulation surrounding a small colorectal metastasis increased 342%. No coagulation was identified in four unablated control lesions in the two patients receiving Doxil alone. CONCLUSION: Our pilot clinical study suggests that adjuvant Doxil chemotherapy increases tumor destruction compared with radiofrequency ablation therapy alone in a variety of focal hepatic tumors. Optimization of this synergistic strategy may ultimately allow improved clinical efficacy and outcome.     

Efficacy and Safety of Radiofrequency Ablation for Focal Hepatic Lesions Adjacent to Gallbladder: Reconfiguration of the Ablation Zone through Probe Relocation and Ablation Time Reduction

PurposeTo evaluate the safety and efficacy of radiofrequency (RF) ablation for treatment of focal hepatic lesions adjacent to the gallbladder with electrode relocation and ablation time reduction.Materials and MethodsThirty-nine patients who underwent RF ablation for focal hepatic lesions adjacent to the gallbladder (≤ 10 mm) were evaluated retrospectively from January 2011 to December 2014 (30 men and 9 women; age range, 51–85 y; mean age, 65 y). Of 36 patients with hepatocellular carcinoma, 3 had a second treatment for recurrence (mean tumor size, 15 mm ± 6). Patients were divided into 2 subgroups based on lesion distance from the gallbladder: nonabutting (> 5 mm; n = 19) and abutting (≤ 5 mm; n = 20). Electrodes were inserted parallel to the gallbladder through the center of a tumor in the nonabutting group and through the center of the expected ablation zone between a 5-mm safety zone on the liver side and the gallbladder in the abutting group. Ablation time was decreased in proportion to the transverse diameter of the expected ablation zone.ResultsTechnical success and technical effectiveness rates were 89.7% and 97.4%, respectively, with no significant differences between groups (P = 1.00). Local tumor progression was observed in 3 patients (1 in the nonabutting group and 2 in the abutting group; P = 1.00). There were no major complications. The gallbladder was thickened in 10 patients, with no significant difference between groups (P = .72). Biloma occurred in 1 patient in the nonabutting group.ConclusionsRF ablation with electrode relocation and reduction of ablation time can be a safe and effective treatment for focal hepatic lesions adjacent to the gallbladder.     

Treatment strategy to optimize radiofrequency ablation for liver malignancies

PURPOSE: The purposes of this study were to investigate a treatment strategy to increase liver tumor necrosis and minimize complications with ultrasound-guided percutaneous radiofrequency (RF) ablation and to evaluate its therapeutic efficacy. MATERIALS AND METHODS: A total of 332 patients with 503 liver malignancies underwent RF ablation according to a mathematical protocol with adjunctive measures. In the 332 patients, 205 had 308 hepatocellular carcinomas (HCCs) with a mean largest diameter of 4.1 cm and 127 had 195 metastatic liver carcinomas (MLCs) with a mean largest diameter of 3.9 cm. In patients with HCC, 60 (29.3%) had stage I/II disease and 145 (70.7%) had stage III/IV disease. Depending on tumor size, shape, and location, a defined treatment strategy was adopted that consisted of a mathematical protocol, an individualized protocol, and adjunctive measures. The mathematical protocol was followed for tumors larger than 3.5 cm. The individualized protocol was used for tumors located adjacent to the diaphragm, gastrointestinal tract, or gallbladder. Some adjunctive measures such as supplementary fine needle localization, local saline solution injection, and feeding vessel ablation were used to deal with different features of these liver tumors. Patients were followed regularly to assess treatment efficiency, and the tumor was considered to have early complete necrosis if no viability was found on enhanced computed tomography 1 month after RF ablation. RESULTS: In this series, the early necrosis rates were 95.8% for HCC (295 of 308 tumors), 94.9% for MLC (185 of 195 tumors), 91.3% for tumors larger than 3.5 cm (189 of 207 tumors), 90.7% for tumors near the gastrointestinal tract (49 of 54 tumors), 91.5% for tumors near the diaphragm (86 of 94 tumors), and 90.6% for tumors near the gallbladder (48 of 53 tumors). The local recurrence rates were 10.7% for HCC (33 of 308 tumors) and 14.9% for MLC (29 of 195 tumors). The 1-, 2-, and 3-year overall survival rates were 89.6%, 69.4%, and 59.6%, respectively, for HCC and 80.3%, 52.8%, and 30.9%, respectively, for MLC. The 1-, 2-, and 3-year survival rates in 60 patients with stage I/II HCC were 93.7%, 87.1%, and 76.2%, respectively. The incidence of major complications was 1.4% (eight of 574 sessions), which included of three hemorrhages, four injuries to adjacent structures, and one case of needle tract seeding. CONCLUSION: In RF ablation of hepatic tumors, application of a proper protocol and adjunctive measures play important roles in improving tumor necrosis rate and minimizing potential complications.     

Radiofrequency thermal ablation of hepatocellular carcinoma: using contrast-enhanced harmonic power doppler sonography to assess treatment outcome

OBJECTIVE: We evaluated the accuracy of contrast-enhanced harmonic power Doppler sonography in assessing the outcome of radiofrequency thermal ablation of hepatocellular carcinoma. SUBJECTS AND METHODS: Fifty patients with 65 hepatocellular carcinoma nodules (1-5 cm in diameter; mean diameter, 2.5 cm) were studied using unenhanced and contrast-enhanced harmonic power Doppler sonography before and after IV administration of a microbubble contrast agent. The examinations were repeated after treatment of the tumors with radiofrequency ablation. Findings of the Doppler studies were compared with those of dual-phase helical CT, which were used as points of reference for assessing treatment outcome. RESULTS: Before radiofrequency treatment, intratumoral blood flow was revealed by unenhanced power Doppler sonography in 48 (74%) of 65 hepatocellular carcinoma nodules. After injection of the contrast agent, intratumoral enhancement was observed in 61 (94%) of 65 hepatocellular carcinomas (p < 0.01). After radiofrequency treatment, all 51 (84%) of the 61 hepatocellular carcinomas found to be necrotic on helical CT scans failed to show enhancement on power Doppler sonograms. In nine of the 10 lesions that showed a residual viable tumor on helical CT scans, persistent intratumoral enhancement-matching the enhancing areas on helical CT images-was revealed by power Doppler sonography. These nine hepatocellular carcinomas were subjected to repeated radiofrequency thermal ablation with the guidance of contrast-enhanced power Doppler sonography. Complete necrosis was seen after the second treatment session in six of the nine lesions. CONCLUSION: Contrast-enhanced harmonic power Doppler sonography is an accurate technique for assessing the outcome of radiofrequency thermal ablation of hepatocellular carcinoma and may be useful in guiding additional treatment in patients with incomplete response to initial efforts.     

Histopathologic evaluation of tissue extracted on the radiofrequency probe after ablation of liver tumors: preliminary findings

OBJECTIVE: Our aim was to evaluate the histologic characteristics of tissue extracted on the probe immediately after radiofrequency ablation of malignant tumors in the liver. MATERIALS AND METHODS: From April to December 2001, 20 radiofrequency ablations were performed in 19 patients with primary (n = 17) and metastatic (n = 2) liver masses. Track ablation according to device protocol was performed after each ablation. Tissue was adherent to the probe after all radiofrequency probe passes. All pieces of tissue found on the probe were collected and preserved in formalin. RESULTS: Tissue was examined by the study pathologist. In eight (40%) of 20 specimens, coagulation necrosis was present. In five (25%) of 20 specimens, possibly nonviable tissue was extracted, although some cell characteristics were identified. In seven (35%) of 20 specimens with hepatocellular carcinoma, possibly viable tissue was found. Five specimens were identified as hepatocellular carcinoma, and two, as cirrhotic nodules. CONCLUSION: Histopathologic evaluation of the tissue extracted on the radiofrequency probe after ablation is feasible. This study showed that coagulation necrosis was clearly present in at least 40% of the patients, which proves that nonviable tissue can be seen immediately after ablation. Whether this pathologic finding has prognostic value is not known.     

CT-gesteuerte Brachytherapie

PURPOSE: To assess safety and efficacy of CT-guided brachytherapy of liver malignancies. PATIENTS AND METHODS: 21 patients with 21 liver malignancies (19 metastases, two primary liver tumors) were treated with interstitial CT-guided brachytherapy applying a (192)Ir source. In all patients, the use of image-guided thermal tumor ablation such as by radiofrequency or laser-induced thermotherapy (LITT) was impeded either by tumor size > or = 5 cm in seven, adjacent portal or hepatic vein in ten, or adjacent bile duct bifurcation in four patients. Dosimetry was performed using three-dimensional CT data sets acquired after CT-guided positioning of the brachytherapy catheters. RESULTS: The mean tumor diameter was 4.6 cm (2.5-11 cm). The mean minimal tumor dose inside the tumor margin amounted to 17 Gy (12-20 Gy). The proportion of the liver parenchyma exposed to > 5 Gy was 18% (5-39%) of total liver parenchyma minus tumor volume. Nausea and vomiting were observed in six patients after brachytherapy (28%). One patient demonstrated obstructive jaundice due to tumor edema after irradiation of a metastasis adjacent to the bile duct bifurcation. We commonly encountered asymptomatic increases of liver enzymes. Local control rates after 6 and 12 months were 87% and 70%, respectively. CONCLUSION: CT-guided brachytherapy is safe and effective. This technique displays broader indications compared to image-guided thermal ablation by radiofrequency or LITT with respect to tumor size or localization.     

Percutaneous saline-enhanced radiofrequency ablation of unresectable hepatic tumors: initial experience in 26 patients

OBJECTIVE: The purpose of our study was to evaluate the safety and efficacy of percutaneous saline-enhanced radiofrequency ablation for unresectable primary or metastatic hepatic tumors. SUBJECTS AND METHODS: Twenty-six patients with 15 hepatocellular carcinomas and 33 hepatic metastases (maximum diameter < or = 8.6 cm) were treated; of these, seven tumors in five patients were treated twice. Thus, 44 radiofrequency treatments were performed. Saline-enhanced and impedance-controlled radiofrequency ablation (0.5-1.1 mL/min of saline, 15-mm conductive portion of the electrode tip, 25-60 W, 5-43 min) was performed using MR imaging guidance. Coagulation necrosis, volume indexes, morbidity, and complications were assessed. RESULTS: The volume of coagulation necrosis 1-7 days after radiofrequency ablation was 1.6-126.6 cm(3) (median, 18.9 cm(3)), corresponding to coagulation diameters of 1.5-6.2 cm (median, 3.2 cm). The coagulation volume was significantly larger if there were more than four radiofrequency applications (p = 0.006). Tumors of 3 cm or less in diameter were eight times as likely to be successfully completely ablated (p = 0.01) and volume indexes of lesions treated with the patient under general anesthesia were significantly larger than those treated with the patient under conscious sedation (p < 0.001). Major complications occurred in four patients (15%). Incomplete ablation in 19 (35%) of 54 radiofrequency lesions was due to cooling by a large vessel nearby (n = 2) or to low power applied in painful (n = 11) or critical (n = 6) locations. Residual tumor was observed in 14 (58%) of 24 tumors evaluated 6-8 months after radiofrequency ablation. CONCLUSION: Percutaneous saline-enhanced and impedance-controlled radiofrequency ablation can be effective in the treatment of unresectable hepatic tumors and minimizes potential carbonization. A greater number of radiofrequency applications, general anesthesia, and increasing experience provide significantly better results.     

Sonographically observed echogenic response during intraoperative radiofrequency ablation of cirrhotic livers: pathologic correlation

OBJECTIVE: We performed a study to determine the correlation between the diameter of the echogenic response observed with intraoperative sonography during radiofrequency ablation of the cirrhotic liver and the mean diameter of tissue necrosis. SUBJECTS AND METHODS: A total of 22 intraoperative radiofrequency ablations were created in 11 cirrhotic livers. The largest diameter of the sonographically observed echogenic response surrounding and perpendicular to the radiofrequency probe was measured. The subsequent zone of necrosis observed at pathology in the hepatectomy specimens after liver transplantation was measured in three planes and compared with the measured diameter of the echogenic response. RESULTS: During all except three ablations, a hyperechoic region was visualized surrounding the radiofrequency probe. The diameter of the echogenic response correlated significantly with the mean diameter of necrosis (correlation coefficient, 0.84). However, the echogenic response overestimated the minimal diameter of necrosis (mean difference, 0.8 +/- 0.4 cm) in 18 of 22 ablations and underestimated the maximum diameter of necrosis (mean difference, 0.9 +/- 0.8 cm) in 16 of 22 ablations. CONCLUSION: The diameter of the echogenic response observed with intraoperative sonography during radiofrequency ablation of the cirrhotic liver correlates closely with the mean diameter of the subsequent area of tissue necrosis. However, the solitary diameter of the echogenic response as measured in our study was often greater than the smallest diameter and less than the largest diameter of the area of tissue necrosis. Therefore, the echogenic response associated with radiofrequency ablation of the cirrhotic liver should be viewed only as a rough approximation of the area of induced tissue necrosis; the final assessment of the adequacy of ablation should be deferred to an alternative imaging technique.     

Percutaneous radiofrequency ablation of renal tumors: technique, complications, and outcomes

PURPOSE: To report the safety, technical success, and effectiveness of percutaneous radiofrequency (RF) ablation for renal tumors. MATERIALS AND METHODS: The authors retrospectively reviewed the medical records and imaging studies of 29 consecutive patients (18 men, 11 women; mean age, 65 +/- 2.62 years) with 30 renal tumors (mean diameter, 3.5 +/- 0.24 cm) who underwent percutaneous RF ablation at their institution from September 2001 to March 2004. All procedures were performed with computed tomography guidance with general anesthesia, and all patients were admitted to the hospital for overnight observation. Technical success, complications, and their management were recorded. Technique effectiveness was assessed by imaging and clinical follow up. RESULTS: Overall, 88 overlapping ablations were performed (mean, 2.6 +/- 0.16 ablations per tumor per session) in 34 sessions. There were four major complications (12%). Three patients had gross hematuria and urinary obstruction, all were successfully treated. One patient had persistent anterior abdominal wall weakness. There were also two minor complications (6%) without significant clinical sequelae. One patient had gross hematuria which resolved spontaneously, another patient had transient paresthesia of the anterior abdominal wall. There were no significant changes in renal function after RF ablation. The intent of RF ablation was eradication of the primary tumor in 27 patients and treatment of gross hematuria in the other two. Technical success was achieved in all cases. Follow-up images were available for 26 patients. The primary tumor was completely ablated in 23 of 24 patients (96%) in whom eradication of the primary tumor was attempted (follow up period: mean, 10 months, median 7 months). The two patients treated for hematuria remained asymptomatic for 6 and 27 months each. CONCLUSION: Percutaneous RF ablation for renal tumors is safe and well tolerated. High technical success rates are expected. Early reports of the technique's effectiveness are promising.