The president of the Quebec Association of Radiologists says he agrees with a warning issued by Quebec doctors to multiple sclerosis patients urging them not to seek the "liberation" treatment at clinics outside Canada.

Dr. Frédéric Desjardins says the balloon angioplasty used in the liberation treatment carries known risks that are not insignificant.

The procedure involves inserting a catheter into a vein and then inflating a balloon to unblock the vein. While angioplasty is performed every day on heart patients with blocked coronary arteries, Desjardins warns it is not risk-free.

"We don't know the benefits of this procedure and the procedure has some risks to it. So in medicine, it's always a balance between risk and benefit," he told CTV's Canada AM Wednesday morning from Montreal.

Desjardins explained that there are known complications from angioplasty, including the possibility of thrombosis, which is the formation of a blood clot inside a blood vessel. The procedure can also cause an embolism, which is a clot that travels along a vessel until it clogs the vessel, or a CVA (cerebrovascular accident), also known as a stroke.

Desjardins says it's hard to say how many Canadian MS patients who have undergone the liberation treatment outside of Canada are experiencing these complications.

"Right now, in Quebec, we don't have a registry of complications, because people are doing this on their own," he said.

"What we know so far is that in the small clinical trials already going on, there are some complications."

No medical centres in Canada are performing the liberation treatment outside of a clinical trial. So many MS patients are travelling overseas, spending upwards of $20,000 to travel to clinics in Costa Rica, Poland, and elsewhere, where doctors can offer them the treatment.

While some patients are returning home reporting no benefits from the procedure, many others say the treatment offers them relief of some of their symptoms, such as increased energy and better balance.

But on Tuesday, the Quebec College of Physicians held a news conference to say that much more research is needed on the treatment and warned MS patients not to seek the treatment overseas.

College president and CEO Dr. Charles Bernard noted that while balloon angioplasty has been used for years to widen coronary arteries, the procedure may have poorly documented risks when used in veins, which can have thinner walls and are more vulnerable to damage and blood clots.

He added that it's not clear that there is a link between neck vein blockages and multiple sclerosis. And he advised patients to wait until more research is done on CCSVI, the term coined by Italian surgeon Dr. Paolo Zamboni, and on the treatment.

"The college is saying to them today that we need to wait for the results of studies that are currently underway before generalizing Professor Zamboni's treatments," Bernard said.

"In particular, we are recommending to these individuals that they refrain from consulting any medical tourism clinics offering these treatments prematurely with little regard for their effectiveness and side-effects."

Dr. Zamboni himself has also warned patients to refrain from getting the treatment except in the context of an approved clinical trial.

"Surgery is not recommended at this stage," Zamboni told an MS conference in Sweden last month.