Diagnosis of hilar and mediastinal lymph node metastasis of lung cancer by positron emission tomography using 11C-methionine

In order to evaluate the usefulness of positron emission tomography using 11C-methionine in the diagnosis of lymph node metastasis, 11C-met. PET studies were performed before operation in 29 patients with primary lung cancer. 11C-met. PET studies were assessed quantitatively by the tumor muscle contrast ratio (TMR). A total 101 lymph nodes, including 24 lymph nodes pathologically diagnosed as metastatic, were recognized and assessed by 11C-met. PET. The TMR in metastatic lymph nodes (n=24) was 4.73±1.53 while that of non-metastatic lymph nodes (n=77) was 2.95±0.76, indicating a significant difference (p<0.0001). The most adequate cutoff value for diagnosis of metastasis, based on the ROC curve, was 4.4. The sensitivity, specificity and accuracy of 11C-met. PET were 70.8%, 94.8% and 89.1%, superior to those of computed tomography (50.0%, 93.5% and 83.2%). Metastatic lymph nodes of 5 mm and over could be detectable by 11C-met. PET. (author)