They've been doing PET scans here for over a decade so I can't begin to fathom why Health Canada is still doing clinical trials (not to mention they have recomended there use for H&N cancer since 2005 in BC). Whereas The entire country of Canada has 1 cancer center, we have 3 in California alone. For what it's worth, many Canadians come here for health care.

The NCCN member institutions are a collaboration of the top 21 comprehensive cancer centers in the US. They define the standards of care for cancer diagnosis and treatment and most of the world uses their guidelines. PET (or PET/CT) is definitely on the list of scans to perform as part of the pre-treatment diagnostic workup. Most of the false positives revolve around post Tx issues.

From Don's link:

"Positron Emission Tomography
The use of positron emission tomography (PET) is becoming more widespread worldwide in the management of patients with cancer. Numerous studies have demonstrated that squamous cell carcinomas of the head and neck region are well imaged by PET and there is accumulating evidence supporting its use for a number of indications in head and neck cancers.

Effective August 16, 2005, the Functional Imaging Department has expanded the clinical indications for referral within the framework of the evidence-based BCCA guidelines for FDG-PET. PET/CT scan referrals will now be accepted at our facility for certain indications in adult oncology patients. To view the referral guideline, please go to the Functional Imaging page.

There is support in the literature for the use of PET in three main areas:

1. In the initial staging of head and neck tumours where there is some uncertainty as to how extensive initial surgery or radiotherapy should be.

2. As an additional procedure in the diagnosis of carcinoma of unknown primary presenting as a nodal neck mass.

3. In the detection of recurrent disease post therapy where standard investigations are equivocal and further salvage therapy is feasible."

Contrast agents are typically used with MRI. I am unaware of contrast agents being used with PET scans. See:

http://radiology.rsna.org/content/227/3/817.full