PET-scan imagery (Courtesy Dr. Dave Webster)

PET-scan imagery (Courtesy Dr. Dave Webster)

It's almost like a scene from Star Trek.

A patient is injected with radioactive material. Then, in exactly one hour, he enters a tube-shaped device for full-body scanning.

Doctors soon examine pictures showing lit up areas of disease in the patient's body.

Dr. Dave Webster was doing just that in his office — reading positron emission tomography (PET) imagery that helps him detect, diagnose and better treat cancer — but only for a very select number of patients.

"Ontario is now quite literally the last medical jurisdiction in the world [not adopting PET]" Webster said. "I think in light of this, we need to have some clarification."

PETs are widely available in Canada, with the best access in Quebec. That province will conduct an estimated 21,000 scans this year. PET scanning is also extensively accessible in British Columbia, Alberta, Manitoba and New Brunswick. (Nova Scotia will be added to the list later this year.)

During his off time in nuclear medicine at Sudbury Regional Hospital, Webster reads PET scans two days a week for a private clinic. Those scans aren't covered by OHIP. His patients at the Mississauga clinic, CareImaging, pay $2,350 out-of-pocket for the procedure.

Webster said he runs a deficit to perform his job there. He has read over 500 PET scans for free, and working for the clinic has actually cost him money when he factors in travelling.

Not a PET project in Ontario

Webster also claimed Ontario patients have among the worst access to PET: "I have had my own technologists travelling through Argentina who have run into PET cameras in towns smaller than Sudbury."

In Ontario, getting one means having a specific kind of cancer, then being referred by your doctor to a registry of clinical PET trials.

Dr. Bill Evans, head of the PET Ontario steering committee, wasn't available to comment on why the province was conducting such restricted trials with the super tool.

Instead, Andrew Morrison, an Ontario health ministry spokesperson, spoke to the issue.

"We've elected to generate evidence and then embark on a study to determine if, when and how PET would be incorporated," said Morrison.

As of March 31, 2007, there were 1,154 Ontario patients enrolled in the three-year-old registry, which accepted patients with certain types of head, neck, lung, breast and colorectal cancers.

Eight Ontario health centres, including Ottawa Hospital, Hamilton Health Sciences Centre and Toronto's Princess Margaret Hospital are testing patients using nine scanners.

With demand lacking because of the registry restrictions, scanners are underused. And that frees them up for animal research.

For safety, multiple tests are conducted on animals rather than people. However, the amount of radiation emitted from one PET scan is small. It's less than with a computed tomography (CT) scan, which can be the equivalent to 200 chest X-rays.

A tool for medical tools

According to Webster, using a PET scanner allows doctors to better use the tools they already have in place. He says that in his experience, 50 per cent of lymphoma cancer cases diagnosed with a CT scanner have been inaccurate.

A CT scanner is an anatomical technique that defines the location of cancer masses within the body. But it has no ability to determine whether a lump is scar tissue, a benign tumour or cancer.

To do the same thing, PET uses "radioactive sugar" or fluorodeoxyglucose. Cancer cells have a particularly voracious appetite for sugar, so when injected into the body, they suck it up more than regular cells. These sugar areas then light up on scanner photographs, allowing doctors to determine where the cancer is, and how far it has spread.

This is vital in knowing how serious a cancer is, for example, whether it has moved into the lymph nodes. It can also prevent one of the most painful operations — lung surgery — when a doctor can determine from a PET scan that it's inoperable.

PET case study

In Sault Ste. Marie, doctors told a cancer patient who underwent four CT scans "not to worry," and to enjoy a planned family vacation. The scans had detected stabilized cancer in his spleen and other places.

The patient then underwent PET. The test found his cancerous sites to be active, and also found new sites undetected by the CT. "So now he had to be treated with the most aggressive treatment we have for lymphoma," Webster explained.

The best detection (aside from a biopsy absolutely confirming cancerous tissue) comes when CT and PET are both used. This is because CT detects location better — within a millimetre — while PET is superior at locating overall cancer regions.

CT scans are usually part of the diagnosis, but when used with PET, they are set in low radiation mode.

Health care funding waste?

Ontario is reluctant to adopt PET before completing its own tests into whether the tool actually helps patients.

"It's a promising health technology," Morrison said. "But there is insufficient quality evidence of clinical utility to justify what could potentially be multimillion-dollar funding."

The scans are expensive because cost of producing the radioactive material is high. It's made in a pricey particle generator called a cyclotron. The scanners themselves are also top dollar, setting hospitals back up to $5 million.

Webster believes the near-$2,500 fee for a scan could be reduced to $950 if private money was able to initially fund the scanners. Private sources could easily have cyclotrons and PET/CT scanners in the province in the next six months to a year, he said.

"We have no trouble accepting people can own nuclear medicine machines in private health-care facilities," explained Webster. "We've gotten by the fact people can own and bill OHIP for an X-ray. Does it really matter whether that equipment is sitting in a building across from the hospital?"

Assessment tool misleading

Webster is not alone in supporting PET for better patient care. According to Dr. Alexander McEwan of Oncologic Imaging at the University of Alberta, the Ontario health ministry's decision to use clinical trials investigating whether PET is worth its high cost was misinformed.

The decision was made by a steering committee of oncologists and other specialists based on a review performed in 2001.

In an article McEwan wrote for the Journal of Nuclear Medicine, he said the study used a "health technology assessment" (HTA) to examine the effectiveness of PET. The technology, he explained, is known to be a policy-funding tool, which in the past has justified negative funding choices.

It assessed sentinel lymph nodes in breast cancer cases. But PET isn't good at detecting this early cancer as it can miss lesions up to two centimetres.

"In the case of sentinel lymph nodes, literally microscopic disease makes a difference," Webster said. "The trial was deliberately designed to get a negative result, in other words, make PET look bad."

The scans are best at diagnosing and detecting the stages of at least 13 cancers: lung, lymphoma, ovarian, oesophageal, sarcomas, melanoma, gastric, pancreatic, prostate, kidney, recurring prostate, non-aggressive lymphoma and breast when it's located behind the sternum.

Lighting up the brain 'light years' ahead

Besides reducing surgeries and helping doctors determine whether followup chemotherapy is necessary, PET is also helping doctors study the brain.

Amyloid proteins in Alzheimer's patients are much more detectable using PET.

The scans also detected lit up areas of opioid brain activity in smokers' brains. They were similar to patterns set off with heroin use.

PET would have seemed science fiction to the first generation of Star Trek viewers in the 1960s.

In 2000, the technology was named Time Magazine's "Invention of the Year."

Today, said Webster, "there's no question this is now the gold standard."