ce in percutaneous RFA led the researchers to recognize that it has two important limitations. Tumors larger than 3 centimeters are difficult to treat with RFA, with increased rates of technical failures and tumor recurrence. Also, the area being treated cannot be effectively monitored with computed tomography (CT) or ultrasound. The Mayo study findings show that cryoablation can be used for some larger tumors with simultaneous operation of multiple cryoprobes guided by ultrasound. The ablation margin (the edge of the frozen tissue) can be accurately monitored with CT, to ensure that the total tumor mass is treated.
The researchers reviewed the records of the 23 men and 17 women with kidney cancer treated with percutaneous cryoablation at Mayo Clinic between March 12, 2003, and Aug. 4, 2005. They found that this treatment was chosen over RFA for reasons such as larger tumor size, proximity of tumor to ureter or bowel, or a central location on the kidney. Cryoablation was successful in 38 of the 40 patients, with no repeat treatment necessary.
In percutaneous cryoablation, one or more hollow needles are inserted through the skin directly into a tumor. Doctors can observe and guide the insertion by combined use of ultrasound and CT. The needle, or cryoprobe, is filled with argon gas, which results in rapid freezing of the tissue to temperatures of -100° C; and the tissue is then thawed by replacing the argon with helium. The procedure consists of two freezing and thawing cycles, seeking a frozen margin of approximately 5 millimeters beyond the tumor edge to ensure death of the entire tumor. After the cryoprobes are removed, small bandages are placed over the skin puncture sites, and the patient spends one night in the hospital before returning home.
Surgeons continue to seek less invasive methods than the traditional radical nephrectomy (removal of cancerous kidney) for the treatment of small tumors, and percutaneous cryoablatioPage: 1 2 3 Related biology news :1
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