IMAGE-GUIDED
CRYOABLATION
LIVER METASTASIS —
Cryosurgery Procedures
Open Surgical Cryosurgery
(freezing) of Liver Metastases
Image-guided cryotherapy is considered an acceptable treatment for select patients with metastatic tumors of the liver. Cryotherapy is a well-established technology for the treatment of various benign and malignant conditions. Combining Galil Medical’s patented freezing technology and ultra-thin cryoablation needles with advanced imaging capabilities has created the opportunity to perform precisely targeted tumor destruction for certain secondary liver cancers considered unresectable.
Because the cryoablation needles are only 1.47 mm in diameter, it is now possible to perform these procedures using minimally invasive techniques such as laparoscopy and image guidance. Minimally invasive techniques have been shown to result in the benefit of a shorter hospital stay and a quicker recovery, and currently most liver cryoablations are performed as minimally invasively as is possible while ensuring the most effective destruction of the liver tumor. In some cases, open surgery may still be the method preferred by the operating physician.
Image guidance refers to the use of imaging techniques (e.g., fluoroscopy, ultrasound, CT and MRI) during a procedure. Intraprocedurally, imaging is used to target and place the cryoablation needles into the tumor, to monitor the double freeze-thaw process, and to control the treatment, as necessary. Imaging is also used before the procedure to plan the treatment and after the procedure to assess the treatment response.
To perform liver cryosurgical ablation during an open surgical procedure, the patient is placed in the supine position on the operating table and general anesthesia is administered. An incision is made in the right side, dividing the obliques from the rectus abdominus. Any adhesions from previous colon resection must be dissected away from the midline wound to allow access to the liver and gall bladder. The liver and surrounding tissue will then be assessed to make sure that there is no extrahepatic spread of disease that was not visible on pre-operative imaging, as this may be a contraindication to proceed. The incision may then be extended as necessary in order to better access the metastatic site. The lower flap of abdominal wall will be reflected and sutured back, while hemostasis of the incision and adhesion dissection is obtained. The liver is fully mobilized to allow complete assessment of the hepatic disease, and to allow full access to the liver in case of excessive bleeding during the procedure.
Intraoperative ultrasound is then used to systematically examine the liver and note all masses and their exact location in the liver, including the relationship of the tumor to the major vascular structures. The cryoablation needles and thermal sensors are then placed into the tumor(s) under direct vision as well as ultrasound guidance, and a double freeze-thaw cycle is initiated. The iceball growth is usually monitored with ultrasound, although another imaging technique may be used. This intraoperative imaging allows the surgeon to observe the ablation process closely, and to adjust the treatment parameters as necessary to obtain optimal tissue destruction.
At the end of the second freeze cycle, a short active thaw is initiated. The cryoablation needles are then twisted lightly between the thumb and forefinger, and if there is no resistance, the needles and thermal sensors are removed. A thorough check is made to assure hemostasis, and drains may be placed above and below the liver.
Because of the precision of Galil
Medical’s third generation 17
gauge cryoablation needles, real time temperature
monitoring, and the ability to place and control
several groups of cryoablation needles during
a procedure, it is now possible to completely
ablate several lesions in a single session. One
of the advantages of cryosurgical
ablation is that the procedure is repeatable
in the event that there is residual or recurrent
tumor after the initial treatment session.
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