Interventional Radiology

 By Michelle Fabiani, DVM, Diplomate ACVR

Interventional radiology involves the use of imaging modalities such as fluoroscopy (moving x-rays) or ultrasonography to gain access to different structures in order to deliver materials for therapeutic purposes.  The use of interventional techniques in veterinary patients offers a number of advantages compared to more traditional (surgical) therapies.  These procedures are minimally invasive and can therefore lead to shorter anesthesia times, shorter hospital stays, and improved survival compared to more invasive surgical procedures.  Some techniques such as chemoembolization (administration of chemotherapy directly into the blood supply of a tumor) or stenting for obstructions caused by cancer offer alternative treatment options for patients with conditions that may not be otherwise treatable.  In the Houston area, Gulf Coast Veterinary Specialists is the only facility to offer these procedures.  GCVS has the necessary equipment, board certified radiologists and internists with the advanced training needed to gain expertise in these procedures, and finally board certified critical care specialists to manage the patient during and after the procedure,

The most common use of interventional radiology is in small and toy breed dogs, which are predisposed to tracheal collapse.  In affected patients, the trachea (windpipe) collapses or narrows with breathing.  These patients can present with just a mild “honking” cough or can be in respiratory distress due to complete airway obstruction.  Initially, the cough is managed with a combination of drugs which may include anti-inflammatories, cough suppressants, sedatives, bronchodilators, and antibiotics.  Additionally, weight loss, restricted exercise, and removal of inhaled allergens (such as smoke) can help to improve clinical signs. Patients that fail this aggressive management can be candidates for interventional treatments.  Intraluminal metallic stents can now be placed inside the trachea to treat tracheal collapse using a minimally invasive procedure. Tracheal stent placement can be performed quickly, requiring shorter anesthesia time than surgery, which is beneficial in older patients or patients with concurrent cardiac or pulmonary disease.   With careful patient selection, significantly improved quality of life can be achieved. 

Urinary abnormalities in geriatric patients can be caused by cancer of the bladder and in male patients (as in humans), cancer of the prostate.  Clinical signs include difficulty urinating and complete urinary tract obstruction (inability to pass urine).  Previously, there were few treatment options for these tumors that alleviated the presenting urinary signs.  Now combinations of minimally invasive techniques such as ultrasound guided laser ablation and/ or placement of metallic urethral stents can provide relief in these patients.  Stents can be placed in the urethra under fluoroscopic guidance rapidly, safely, and effectively relieve urethral obstructions.  Similar intraluminal stents can also be used when cancer of the colon causes obstruction and inability to defecate.

In cats, the ureters (the tube connecting the kidneys to the bladder) are usually 1mm in diameter and can easily become obstructed by stones or can stricture after passage of a stone.  Surgery on the ureters is difficult without special microsurgical techniques.  Now we have the option of placing a temporary ureteral stent rapidly and minimally invasively (without surgery) to relieve kidney obstruction.  This lifesaving technique requires specially sized stents, fluoroscopy, ultrasound, and requires special training.  A specialist that has the expertise and equipment and are able to perform these procedures is critical when the emergency situation arises.

Other diseases in which interventional techniques can be utilized include portosystemic shunts, parathyroid adenomas, hepatic (liver) tumors, and epistaxsis (nasal bleeding).  The use of interventional and minimally invasive radiology techniques in veterinary medicine are increasingly being studied and continue to evolve.

NOTE: This article is copyrighted and originally published in Houston PetTalk Magazine. Used with permission. All rights reserved.