Duke Inventional Radiology: Safe and Effective
What is Percutaneous Ablation?
Percutaneous ablation is a relatively new procedure whereby small probes are passed through the skin into tumors which are then either heated or cooled. When the tissue around the probe tip reaches the appropriate heated or cooled temperature, the cells will then break apart and die.
Currently there are three percutaneous techniques available at Duke University Medical Center:
- Radiofrequency (RF) Ablation
- Microwave (MW) Ablation
Diagram showing the probe inserted into a tumor (gray) in the liver (red) and the corresponding thermal zone (white) cause by heating the tissue with RF energy resulting in cellular death.
Radiofrequency and Microwave Ablation use heat therapy to destroy the tumor while Cryoablation uses ice therapy. The choice of RF, MW, or Cryoablation is determined by several different factors, including the size and location of the tumor. These procedures are particularly advantageous for treating tumors localized to the kidney, liver, lung, and adrenal glands. Since RF, MW, and Cryoablation kill both the tumor and the non-tumor cells, the goal is to place the probe(s) so that all of the tumor plus the adequate “rim” of non-tumorous tissue around it is destroyed, thereby minimizing local tumor recurrence.
These procedures are usually performed by placing one or more probes through small incisions in the skin using an ultrasound (US) and/or CT scanner to guide the tip into the tumor.
76 year old man with a throat cancer. He has previously undergone surgery for removing a tumor from his liver. This image is a CT scan which reveals a small but new tumor nodule in the liver (arrow).
What Type of Tumors can be Treated?
Radiofrequency, Microwave, and Cryoablation have been mainly used to treat liver tumors. This includes tumors that originate in the liver, such as hepatocellular carcinoma and tumors that originate in another organ but then spread or metastasize to the liver. These procedures have also been proven to be effective in treating tumors of the kidneys and lungs, when surgery is not appropriate. There is also some limited experience in treating tumors in the adrenal gland, certain lymph nodes and painful bone lesions.
How Effective is this Form of Treatment?
This image demonstrates what the liver looks like after the RF ablation. The much larger dark area represents dead tumor and a small amount of normal liver.
With ablation therapy being a relatively new procedure, most of the long-term data comes from the treatment of liver tumors. For example, in patients with tumor(s) isolated to their liver (i.e. there are no other tumors outside the liver such as in the lungs, lymph nodes, colon, etc.), improvements in survival have been noted. About a third of tumors demonstrate local recurrence at the prior ablation site but these areas can usually be ablated again. Tumors that are adjacent to a major blood vessel often recur locally since the blood vessel itself draws heat away from the area during the treatment, the so-called “heat sink phenomenon.” As a result tumor cells that are next to the blood vessel cannot get hot or cold enough to achieve cell death. The heat-sink phenomenon is less of a problem with Microwave ablation compared to Radiofrequency ablation.
The lesion to be treated is first localized by either CT or ultrasound. At times, both CT and ultrasound are used. A corresponding mark is made with a felt tip pen on the skin which is then cleansed with a cold soap (Betadine) and a large plastic drape is placed over the cleansed area to maintain a sterile field.
Example of probes inserted into a tumor for deposition of RF energy. The top devise is a single probe which is used for small lesions. The bottom device is a triple or “cluster” probe which is used for larger lesions. These probes have “Cool-tip” stenciled on the handle because cold water is circulated inside the probes to increase the amount of tissue destroyed.
For pain control, both local and intravenous medications will be administered and is addressed in detail below. One or more tiny incisions are then made to the skin, each measuring less than 1/4 inch in length. The Radiofrequency, Microwave, or Cryoablation probes are then advanced into the lesion using CT, ultrasound, or both to guide placement of the probe. Once in place, the probe is hooked up to a special machine which controls and monitors the production of heat in the case of RF and MW and the production of an ice ball in the case of Cryoablation. This process requires several minutes (up to 30 minutes per ablative session), depending upon the size of the lesion being treated.
Larger lesions can take longer or require multiple treatment sessions. Since it is our goal to destroy both the tumor and a cuff of normal tissue around the tumor, we often treat each lesion more than once within a single session.
When the procedure is complete and the probe(s) removed, a Band-Air or gauze dressing will be placed over the incision(s). The patient will be moved to the Radiology recovery room for 2 – 4 hours of observation and released at the point when all of the following conditions are met:
- Vital signs stable: lying down, sitting up, and standing
- Adequate pain control
- Able to tolerate liquids and solids by mouth
- Able to empty the bladder
- No signs of complications
Anytime a needle is placed under the skin there is always the risk of bleeding and/or infection. Prior to the procedure, blood work will be done to check for a bleeding tendency. Bleeding complications are further minimized by “coagulating” the tract with Radiofrequency or Microwave energy upon withdrawal of the probe.
Infectious complications are minimized by administering antibiotics both intravenously during the procedure and by mouth for several days after the procedure.
Other less common complications vary depending upon the site of treatment. Diaphragmatic injury may occur with kidney, liver, or lung ablation and often manifests as right shoulder pain.
The lung may collapse during the treatment of lung tumors, or lesions within the liver that are adjacent to the diaphragm. Lung collapse may require placement of a small tube between the lung and chest wall to re-inflate the lung.
A leak of bile or urine can occur when treating kidney or liver lesions, respectively.
On rare occasions, significant damage to the liver or kidney may occur as a results of the ablation. If the severity of organ damage is significant, the injury may be life-threatening.
Injury to other structures such as blood vessels or the bowel is unlikely when CT or US are used to guide probe placement. Experience has shown that all of these complications are uncommon, occurring in approximately 5% or less of the patients.
To Schedule an Appointment
If you interested in a consultation concerning whether or not you are a candidate—
For a Radiofrequency, Microwave, or Cryoablation in the bone, kidney, or liver, please contact
Alicia Baity Blount, Interventional Nurse Coordinator at (919) 684-7373.
For lung ablations, please contact Brenda Baker at (919) 684-7443.
Our mailing address is:
Duke University Medical Center
Department of Radiology
2301 Erwin Road
Durham, NC 27710
Is It Performed on an In-patient or Out-patient basis?
Ideally, we would like to perform the procedure early in the day so that there is adequate time for the patient to be monitored and observed in the Radiology Recovery Room. If the patient is feeling well, he/she will then be discharged from the hospital on the day of the procedure. However, if the patient lives far away we recommend that he/she stay in town and make overnight accommodations. If there are no problems overnight, the patient may return home the next morning.
If the procedure is not performed until the afternoon, there may not be adequate time for recovery in Radiology, in which case an overnight hospital stay (referred to as a 23 hour admission) may be necessary. If there are no overnight complications, the patient will be discharged the next morning.
All patients must have a driver with them who is required to stay at the hospital during the procedure; patients are not permitted to drive less than 24 hours following the procedure.
Is It Painful?
Radiofrequency, Microwave, and Cryoablation can be painful procedures. In the majority of cases,“moderate sedation” is the best choice for the control of both anxiety and pain. With this technique, a combination of sedative and pain medications, typically Versed, Fentanyl and occasionally Dilaudid, are used and are administered intravenously. With moderate sedation, patients are usually very drowsy
but not entirely asleep. For example, during the procedure you will be able to respond to basic commands such as “take in a deep breath and hold it” but you may not remember the procedure afterwards. Some patients may have allergies to the medications given during the procedure, so remember to describe all known drug allergies and any prior adverse reactions to the doctor and nurse before the procedure.
How Will You Feel Afterwards?
For the first 12 hours after the procedure many patients experience only mild pain requiring an occasional pain tablet by mouth. Percocet is a common medication used for pain control following ablation. A few patients may also experience nausea or vomiting as a result of the medications used during the procedure, which can be controlled with an antinausea medication.
Patients with larger tumors may experience a “post infarction syndrome” which is associated with a low grade fever (less than 101°F), nausea, and/or achy flu-like symptoms. These symptoms are not associated with an infection and are treated with Tylenol, and they usually subside within 12 to 24 hours. Also, in rare instances, a patient may experience prolonged pain greater than one week, in which they should contact their doctor.
What Kind of Follow-up Will You Have?
Imaging follow up protocols can vary based upon the type of tumor. In general, we would like you to have a follow-up CT scan 1-3 months after the procedure with and without contrast. What we find during that scan will determine how often a follow-up CT will be needed thereafter. In some patients, an MRI with intravenous contrast material is an acceptable alternative. Occasionally, a PET scan is performed to help interpret the CT or MRI findings. We would prefer that you have your imaging at Duke University Medical Center primarily because techniques vary widely from institution-to-institution.
Can You be Treated More Than Once?
Some lesions, particularly those that are larger, will require more than one treatment session to destroy the entire tumor. In some patients, additional lesions will arise at a later date and these may also be treated. In general, as long as we can see the lesion with CT or US and are able to navigate the probe into the lesion, we can treat you as many times as necessary.