Interventional radiology is a medical specialisation that involves performing a range of imaging procedures to obtain images of the inside of the body. The interventional radiologist carefully interprets these images to diagnose injury and disease, and to perform a range of interventional medical procedures. The images are used to guide the catheters and instruments to the exact area where the procedure or treatment is to be performed.
This procedure reduces the need for traditional (open) or keyhole (endoscopic) surgery as treatment can be given via a small plastic tube about the size of a straw. Examples of interventional procedures used to treat veterinary oncology patients:
Interventional radiologists use imaging techniques such as X-rays, MRIs (magnetic resonance imaging) scans, fluoroscopy (an X-ray procedure that makes it possible to see internal organs in motion), CT (computed tomography) scans and ultrasounds. Interventional radiologists perform a broad range of procedures such as treating tumours, taking organ biopsies or placing stents by inserting tiny instruments and thin plastic tubes (catheters) into the body via an artery or vein. This type of procedure is performed under general anaesthesia, as the respiratory movement can be controlled better when the animal is breathing via a ventilator.
Radiofrequency or microwave ablation for cancer is a minimally invasive procedure that uses heat (via radiowaves or microwaves resp.) to destroy cancer cells. This treatment option only treats tumours in the area where the needle is placed and will have no effect on any other tumours in the body. For this reason, radiofrequency ablation may be used along with other treatments capable of reaching cancer cells in other areas of the body.
The procedure: the dog is put under anesthesia, and the veterinarian will via CT, MRI or ultrasound imaging guide a special needle through the skin or through an incision into the tumour. This specially designed needle is connected to a radiofrequency generator, which can heat the needle tip. Once the probe’s needle is inserted into the center of the tumour, high-frequency energy passes through this needle. This released energy causes the surrounding tissue to heat up, killing the nearby cells. It is possible to have more than one tumour heated during the procedure. It takes approximately 30 minutes per tumour. This procedure damages the tumour only, sparing surrounding healthy tissue.
Radiofrequency ablation is typically considered as a treatment option in case of several small tumours in an organ and/ or delicate organs (adrenal glands, pancreas, bone, kidney, lung, thyroid tumour and metastatic liver lesions) and is less invasive than surgery. It can also be used as a palliative treatment to lessen pain from e.g. bone metastases.
There are few side effects with radiofrequency ablation, and the dog may return home the same day the procedure took place. The dog may feel tired or have soreness or fever for 1-2 days after the procedure. More serious complications are rare but include infection and bleeding. Call your veterinarian if your dog has a fever and/ or presents with redness, warmth, or drainage where the needle was inserted.
Intraarterial chemotherapy is a procedure in which chemotherapeutics are delivered via an artery that feeds the tumour. Chemoembolization is a procedure in which the blood supply to a tumour is blocked after agents that obstruct the artery are delivered via an artery that feeds the tumour. These obstructive agents can be beads coated with anticancer drugs.
Intraarterial chemotherapy has been used to treat osteosarcoma and lower urinary tract neoplasia. Chemoembolization is used to treat liver cancer.
The procedure requires anesthesia of the dog. The interventional radiologist places a catheter in a thigh artery (femoral artery) and directs it towards to artery that feeds the tumour. Then, anticancer drugs (intraarterial chemotherapy) or beads coated with anticancer drugs (chemoembolization) can be administered through the catheter. The beads block blood flow to the tumour as they release the drug. This allows a higher amount of drug to reach the tumour for a longer period of time, which may kill more cancer cells. It also causes fewer side effects because very little of the chemodrug reaches other parts of the body.
