Topics:

FDG-PET Detects Thyroid Cancer Better Than Conventional Imaging

FDG-PET Detects Thyroid Cancer Better Than Conventional Imaging

Fluorodeoxyglucose positron-emission tomography (FDG-PET) detected recurrent cancer 50% more often than did conventional imaging in people with thyroid cancer who had indications that their cancer had recurred, according to results of a study published in the October 2001 issue of the Journal of Nuclear Medicine. Indeed, use of the FDG-PET scan led to changes in clinical management in almost 80% of patients.

The study evaluated 37 persons with differentiated thyroid carcinoma, who had elevated levels of thyroglobulin and negative iodine-131 (I-131) whole-body scan results after a thyroidectomy and radioactive iodine treatment. An elevated human thyroglobulin (hTg) level is a strong indicator that the cancer persists or has recurred.

Some patients with metastases do not concentrate I-131, and there are indications that they are more likely to have aggressive disease. Finding a way to locate tumors when evidence suggests recurrence but I-131 scan results are negative is, therefore, particularly important.

PET Uncovers Additional Sites of Disease

Of the 37 patients who underwent FDG-PET scanning, 28 (76%) had positive findings. Conventional imaging of the same patients (ultrasound, magnetic resonance imaging [MRI], computed tomography [CT], and x-ray) produced positive results in only 10 cases (27%). Among the 10 patients in whom conventional imaging did not detect a tumor, FDG-PET detected an additional 11 sites of disease, including distant metastases in 5 patients. Among those whose cancer was only detected by the PET scan, 44 different tumor sites were detected.

Overall, the FDG-PET scan findings changed the management of 29 patients; 23 underwent surgery, and disease was confirmed in 20. In three patients, pathology determined that the high FDG uptake was the result of inflammatory disease, for an overall true-positive rate of 70%.

"Our study shows that PET detects significantly more disease than conventional images for these cancer patients. We believe that a PET scan should be added as a first-line investigative tool to look for disease when there is a negative I-131 posttherapy scan yet the patient’s thyroglobulin levels are high," said study coauthor Dr. Badia O. Helal, Hôpital Antoine Béclère, Clamart, France.

 
Loading comments...

By clicking Accept, you agree to become a member of the UBM Medica Community.