In a study to determine the diagnostic value of molecular imaging in nodal staging of patients with thyroid cancer, researchers were able for the first time to accurately distinguish between cancerous cells in regional lymph nodes and normal residual thyroid tissue directly after surgery.
Researchers from the University of Erlangen-Nürnberg, Germany, reported in an article in the January issue of The Journal of Nuclear Medicine on the results of a study using a hybrid single photon emission computed tomography-computed tomography (SPECT-CT) camera to determine and locate the spread of cancer cells to nearby lymph nodes.
According to the researchers, the demonstration or exclusion of cancer spread (metastasis) in regional lymph nodes plays a major role in treating the disease since all patients with lymph node metastases are considered to be at high risk for recurrence.
Currently, patients with differentiated thyroid carcinoma (DTC) who have had their thyroid removed are treated with radioactive iodine, which effectively zeros in on and kills any remaining cancerous thyroid cells. Because one of the functions of the thyroid gland is to absorb iodine from the blood, radioiodine is taken up by any thyroid tissue not removed by surgery, including cancerous cells spreading to other body parts, such as lymph nodes. In addition to emitting electrons that destroy the tissue harboring the radionuclide, radioactive iodine emits photons suitable for imaging.
"Normal thyroid tissue as well as residual cancer cells concentrate radioiodine. Performed after ingestion of radioiodine, SPECT-CT provides three-dimensional images of the distribution of the radionuclide in the human body and is therefore used for staging this type of cancer," said Torsten Kuwert, MD, co-author of the article. "Incorporated at first treatment, SPECT-CT allows us to better stratify patients into treatment groups."
In the study, 57 patients received radioiodine therapy. Afterwards, a SPECT-CT camera was rotated around the patients at a variety of angles to capture where the radioactivity was occurring. SPECT imaging can locate cells in the body that are not behaving normally, but does not provide the detailed, X-ray-like images that CT imaging can. The hybrid camera, however, is able to reveal both the malignant cell activity and the exact anatomical location.