Percutaneous Microwave versus Radiofrequency Ablation of Colorectal Liver Metastases: Ablation with Clear Margins (A0) Provides the Best Local Tumor Control

Purpose

To identify and compare predictors of local tumor progression (LTP)-free survival (LTPFS) after radiofrequency (RF) ablation and microwave (MW) ablation of colorectal liver metastases (CLMs).

Evaluation of the In Vivo Efficiency and Safety of Hepatic Radiofrequency Ablation Using a 15-G Octopus? in Pig Liver

Objective

To determine in vivo efficacy of radiofrequency ablation (RFA) in porcine liver by using 15-gauge Octopus® (15-G Octopus®) electrodes to create a large coagulation.

Materials and Methods

A total of 18 coagulations were created by using a 180-W generator and 15-G Octopus® electrodes during laparotomy, performed in 14 pigs. Coagulation necrosis was created in the pig livers by the use of one of three RFA protocols: 1) group A, monopolar RFA using a 15-G Octopus® electrode with a 5-mm inter-electrode distance (n = 4); 2) group B, monopolar RFA using a 15-G Octopus® electrode with a 10-mm inter-electrode distance (n = 6); and 3) group C, switching monopolar RFA using two 15-G Octopus® electrodes (n = 8). The energy efficiency, shape, maximum and minimum diameters (Dmx and Dmi), and the volume of the coagulation volume were measured in each group. The Summary statistics were obtained and Mann-Whitney test was were performed.

Results

The mean ablated volume of each group was 49.23 cm³ in A, 64.11 cm³ in B, and 72.35 cm³ in C. The mean Dmx and Dmi values were 5.68 cm and 4.58 cm in A and 5.97 cm and 4.97 cm in B, respectively. In group C, the mean diameters of Dmx and Dmi were 6.80 cm and 5.11 cm, respectively. The mean ratios of Dmi/Dmx were 1.25, 1.20, and 1.35 in groups A, B, and C, respectively. There was one animal death during the RFA procedure, the cause of which could not be subsequently determined. However, there were no other significant, procedure-related complications during the seven-hour-delayed CT scans.

Conclusion

RFA procedures using 15-G Octopus® electrodes are useful and safe for creating a large ablation in a single electrode model as well as in the multiple electrodes model.     

Colloid Cysts of the Third Ventricle: Are MR Imaging Patterns Predictive of Difficulty with Percutaneous Treatment?

BACKGROUND AND PURPOSE: Colloid cysts of the third ventricle are rare benign brain tumors. The purpose of this study was to correlate their patterns on MR images with the probability of success of percutaneous treatment. METHODS: Nineteen patients underwent endoscopic treatment for colloid cysts of the third ventricle. The cases were divided into two groups based on difficulty of the aspiration procedure. We reviewed CT scans and MR images and divided cysts into groups based on their signal intensity on the MR images and their density on CT scans. Intensity and density were correlated with difficulty of aspiration during the endoscopic procedure. RESULTS: The aspiration procedure was difficult in 63% of the cases. Eighty-nine percent of hyperdense cysts on unenhanced axial CT scans were categorized as difficult, and 75% of hypodense cysts were categorized as easy. On T2-weighted MR sequences, 100% of low-signal cyst contents were difficult and nearly 63% of high-signal lesions were easy. There was a significant correlation between the T2-weighted sequences and the CT scans regarding the difficulty of the aspiration procedure. CONCLUSION: T2-weighted MR sequences are useful for predicting difficulty of aspiration during stereotactic or endoscopic procedures. A T2-weighted low-signal cyst is correlated with high-viscosity intracystic contents.