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At the Cleveland Clinic Foundation, radiofrequency ablation of liver tumors is performed via a laparoscopic surgical technique under the direction of Allan E. Siperstein, MD, Staff Surgeon at the Cleveland Clinic Foundation. Dr. Siperstein, who established the Liver Tumor Ablation Program at UCSF/Mount Zion Medical Center, has specialized training in laparoscopic surgery and the use of intraoperative laparoscopic ultrasonography. Our first patient was treated in 1996, and we have treated and collected data on patients with both primary and metastatic tumors of the liver under a university approved protocol since that time.
Details about laparoscopic thermal liver tumor ablation
In the operating room under general anesthesia, a diagnostic laparoscopy is performed and suspicious lesions outside the liver are biopsied for staging. Laparoscopic ultrasound is then performed, and all lesions within the liver are located and mapped. Blood supply to these lesions is evaluated by Doppler (color-flow) analysis, and a biopsy of at least one lesion is obtained to confirm tumor histology, also using ultrasound guidance. The radiofrequency thermal ablation catheter is placed through the skin and into the liver, using ultrasound to guide the tip of the probe into the center of the tumor. The prongs are deployed into the tumor, and an ablation cycle is initiated. Dynamic monitoring is afforded by thermocouples in the tips of the prongs which provide temperature feedback. The radiofrequency generator is run at an average temperature mode. The target temperature is set to 105 degrees Celcius and the generator maintains the average temperature by regulating the power delivered (maximum of 150 W). The ablation catheter can deploy out to a maximum diameter of 5 cm. Deployment sizes and ablation parameters vary according to tumor size. When the ablation is finished, the power is turned off, and tissue temperature is obtained by allowing to cool down with the catheter in its original ablation position. Doppler US of the tumor after ablation also documents the lack of blood flow in the tumor. Microbubble formation in the ablated tissue due to the decreased solubility of nitrogen gas also provides feedback about the formation of the ablation zone.
Documentation during the procedure
Meticulous documentation in the operation room eases the later follow-up process dramatically. We designed databases and sheets to document ablation parameters. The Tumor Registry data sheets track the most important parameters. If you are interested in more or different ablation parameters, please contact us. Temperature curves during the ablation or ultrasound appearance are some of the parameters we document additionally.
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Localization of treated lesion is much easier with the use of a liver diagram. Ablated areas are marked as in this example. With the assigned number and the diameters measured in ultrasound, lesions can be better found in CT scans. |
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Immediate postoperative Follow-up
Patients are followed for their short hospital stay and as outpatients. The suggested method of follow up for patients is spiral CT scan with images of the liver without contrast, and during the hepatic arterial, and portal venous phase after contrast administration. For patients with renal failure MRI can be used to follow the lesions in the liver. An initial CT scan should be done within 1 week of the ablation to insure that there has not been rapid progression of disease from the time when the patient was referred for treatment. We do a follow up scan on post operative day #7 to insure complete ablation and to measure the size of the ablated lesions (they should be larger than the pre-ablation lesions).
After that, scans should be obtained every 3 months. Liver function tests are monitored as well as specific tumor markers if applicable.
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