IMAGE-GUIDED
CRYOABLATION
RENAL TUMOR — Cryosurgery
Procedures
Image-Guided Cryoablation of Renal Tumors
Image-guided cryoablation is indicated as a treatment for cortical or peripheral kidney tumors, for solid lesions less than 4cm, and for patients with a single kidney or poor kidney function. Kidney cancer ablation eradicates the cancerous tissue by freezing it. Very precise targeting and control of the energy allows for efficient destruction of tumor cells while leaving healthy kidney tissue intact and functional.
To freeze the cancer, special 1.47mm cryoablation needles are placed percutaneously (through the skin, with no surgical incision) into the tumor. Argon gas is delivered under pressure into a small chamber inside the tip of the needle where it expands and cools, reaching a temperature well below -100o Celsius. This produces an iceball of predictable size and shape around the needle. This iceball engulfs the tumor, killing the cancerous cells as well as a small margin of surrounding tissue while sparing healthy kidney structures. A double freeze-thaw cycle is favored, since studies suggest that consistently larger areas of cell death are achieved with a double rather than single freeze-thaw cycle. Ultra-thin thermal sensors may also be placed at the margin of the tumor to monitor tissue temperature and help ensure that the entire tumor is destroyed.
Interventional radiologists are specially trained in non-surgical, minimally invasive procedures to treat a variety of medical conditions, including many cancers. They use sophisticated imaging techniques to guide the application of a treatment to a specific targeted area of tissue. In the case of kidney cryoablation, image guidance refers to the use of intraprocedural ultrasound, fluoroscopy, CT, or MRI to guide the percutaneous placement of the cryoablation needles into the tumor, and to monitor the double freeze-thaw cycle. This gives the physician precise control of the lethal freeze zone and the ability to adjust the ablation parameters during the procedure to further optimize treatment.
The patient is positioned in the CT or MRI scanner. The cryoablation needles and thermal sensors are inserted through the skin and positioned in the tumor under the guidance of real-time ultrasound or CT fluoroscopy and the entire procedure is monitored using CT or MRI. Image-guided percutaneous cryoablation may be performed under general anesthesia, or light sedation with local or regional anesthesia.
The benefits of image-guided percutaneous renal tumor ablation are compelling. The percutaneous nature of the procedure means that it can be performed with little or no blood loss and without a surgical incision. After the procedure, a percutaneous approach translates into significantly less pain, a shorter hospital stay, and a more rapid recovery when compared with more invasive techniques. This can mean that effective kidney cancer treatment can be achieved with minimal disruption to patients’ lives. Patients usually are able to return to family, work, and routine activity in well less than half the time that it takes to recover from open surgery.
Kidney cancer treatment that allows for the maintenance of adequate renal function is of the utmost importance to the patient’s ongoing quality of life. Because only the cancer is destroyed during image-guided cryoablation therapy and normal kidney tissue is spared, remaining renal function is maximized. This means that the kidneys can continue to perform their many jobs more efficiently than if the entire kidney, or a significant part of it, had been removed. In addition, sparing a portion of the affected kidney creates more options if a new tumor develops in the patient's second kidney, a risk confronting a small number of people with kidney cancer.
In most cases, image-guided targeted ablation and real time temperature monitoring assure that only one session of cryotherapy ablation is necessary. Should the patient’s cancer recur, or if residual tumor is found on follow-up visits, renal cryosurgery can be repeated at the physician’s discretion with minimal trauma to the patient. |
