Source: Doctor’s Guide (www.docguide.com)
Author: Arushi Sinha

Use of positron emission tomography (PET) imaging offers modest improvement in positive predictive value, specificity, and accuracy compared with computed tomography (CT) for diagnosing head and neck cancers.

Researchers at the American Head and Neck Society 7th International Conference on Head and Neck Cancer (AHNS) presented new data on the effectiveness of PET scans singly or in combination with CT compared with CT scans alone.

“We used the scans in comparison to the gold standard, which was the pathology findings from neck dissections,” explained study presenter Surjeet Pohar, MD, Department of Radiation Oncology, Eastern Virginia Medical School, Norfolk, Virginia.

The study, presented in a poster session on July 22, used information gathered from 36 patients diagnosed with head and neck squamous cell carcinoma. All the patients underwent neck dissection as well as CT scans, PET scans, or combined PET and CT. In addition, all patients received a full medical examination, endoscopy, and X-ray imaging to help stage their disease. In addition, nodal involvement and information about the side of the neck were also documented.

As a result of the full diagnostic workup, the researchers found that most patients exhibited locally advanced disease: 4 patients had stage II disease; 3 had stage III disease; and 25 had stage IV disease. Four patients had indeterminate staging at the time of the initial workup.

Results showed that several parameters of the different imaging technique were comparable. CT scans exhibited sensitivity to the samples in 72% of the cases, while the sensitivity for PET scans was 69%.

Specificity was 89% for CT and 95% for PET imaging. The positive predictive value was 61% for CT scans and 75% for PET scans. The negative predictive value was 93% for both imaging techniques, and the accuracy was 86% for CT scans and 90% for PET scans.

Based on these findings, the authors concluded that that there was a modest improvement in positive predictive value through the use of PET imaging.

“PET scan was a little better in picking up some things, and CT scans pick up more false positives,” said Dr. Pohar. “PET scans only added a small amount to the accuracy.”

[Presentation title: What Does PET Imaging Add to the Staging of Head And Neck Tumors? Abstract P577]