FDG PET Appears to Be Highly Specific In Detecting Malignant Breast Lesions

MINNEAPOLIS--Breast imaging with FDG PET can identify breast cancerwith a high specificity, a German study has shown. This techniquevisualizes malignant tumor tissue by increased FDG (fluorine-18-fluorodeoxyglucose)uptake (see image on " FDG PET Imaging Visualizes MalignantBreast Lesions"), said Norbert Avril, MD, of the Departmentof Nuclear Medicine, Technical University, Munich.

The study, presented at the Society of Nuclear Medicine meeting,included 71 patients scheduled for breast biopsy. Two observersclassified lesions seen on PET imaging as definitely malignant(37 of 95 lesions), probably malignant (16 lesions), or unlikelyto be malignant (42 lesions). Biopsy results showed that 49 ofthe 95 tumors were malignant and 46 were benign, Dr. Avril said.

When the 16 lesions that were classified as "probably malignant"on PET imaging were considered as negative, sensitivity was 74%and specificity, 98%. If "probably malignant" resultswere regarded as positive, sensitivity was 88% and specificity,78%.

There was a significant difference between FDG uptake of benignlesions (SUV, or standardized uptake value, of 1.4 ± 0.4)and malignant tumors (SUV of 3.6 ± 2.5), Dr. Avril said.A SUV of 2.3 represented the highest value for benign breast lesions,and all tumors with higher SUV values were found to be malignant.However, there was an overlap between benign and malignant tumorsfor SUV values lower than 2.3.

Although most of the research with FDG PET in breast lesions isbeing conducted to gain a better understanding of breast tumorphysiology, the technique does have potential clinical benefits,Dr. Avril said.

"This imaging procedure can provide more accurate preoperativestaging of disease," he said. "PET can show metastaticspread to the lymph nodes in the axilla, which cannot be detectedby mammog-raphy." This means that the results could influencethe type of surgery performed and enable physicians to decidewhich patients are appropriate for breast conservation therapy,he added.