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 hepatic tumors: postablation syndrome.

OBJECTIVE: Our objective was to define the spectrum and possible predictors of symptoms that occur in patients after percutaneous radiofrequency ablation of hepatic tumors. SUBJECTS AND METHODS: We performed 50 consecutive percutaneous radiofrequency ablation sessions on 39 patients with a total of 89 liver tumors. All patients had pre- and postablation laboratory studies and CT or MRI scans. After treatment, patients were followed for 3 weeks with a standardized questionnaire to assess for postablation symptoms. Comparisons of the presence or absence of symptoms were made for the laboratory test values, liver volumes, and pre- and postablation tumor volumes. RESULTS: Postablation symptoms occurred in 14 of 39 (36%) patients after 17 of 50 (34%) ablation sessions. Symptoms consisted of fever (16/17), malaise (12/17), chills (6/17), delayed pain (5/17), and nausea (2/17). On average, the symptoms presented 3 days after ablation and lasted 5 days. Statistically significant (p < 0.01) predictors of symptoms were tumor volumes > 50 cm3 (4.5 cm diameter), ablated tissue volumes > 150 cm3 (6.5 cm diameter), a difference between preablation tumor volume and the volume of tissue ablated > 125 cm3, or postablation aspartate aminotransferase levels > 350 IU/L. CONCLUSION: Approximately one third of patients undergoing percutaneous radiofrequency ablation of hepatic tumors develop delayed, transient flulike symptoms that can be treated conservatively and are significantly related to the volume of tissue ablated. Familiarity with this postablation syndrome should facilitate appropriate management of affected patients.

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.

Radiofrequency tissue ablation: effect of hepatic blood flow occlusion on thermal injuries produced in cirrhotic livers.

BACKGROUND: Radiofrequency thermal ablation has been used as a treatment for several types of hepatic malignancies. Many of these lesions exist in the presence of cirrhosis. Limitations exist to the size of the ablations and, subsequently, the efficacy of treatment. Hepatic vascular inflow occlusion has been advocated as an adjunctive measure to increase the efficacy of the ablation. We present a model in the human cirrhotic liver that demonstrates the advantage of blood flow occlusion during radiofrequency ablation. METHODS: Five patients with advanced endstage liver disease scheduled to have orthotopic liver transplantation were enrolled in this study. After laparotomy and before hepatectomy, radiofrequency ablation was performed without and with hepatic blood flow occlusion. After hepatectomy, the liver was sectioned, the area of ablation was measured in three dimensions, and the volume of ablation calculated. RESULTS: Three of the patients had had previously placed transjugular intrahepatic portosystemic shunt. The mean volume of the ablation without blood flow occlusion was 22.5 +/- 7.4 cm(3) and that with blood flow occlusion was 48.4 +/- 24.0 cm(3) (P =.05). CONCLUSIONS: Ablation area is increased significantly with hepatic blood flow occlusion in the human cirrhotic liver. This result may have application in the treatment of larger (>3 cm) hepatic malignancies.

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.