Abstract:

Objective  To investigate the difference of PET/CT between non-specific high uptake of the aged mediastinal lymph nodes and mediastinal lymph nodes metastases caused by malignant tumors especially lung cancer. Methods  110 patients with detailed clinical data were retrospectively studied, including 55 with non-specific high uptake of the aged mediastinal lymph nodes (group1), 53 with mediastinal lymph nodes metastases(group2), and 2 with both non-specific high uptake of the aged mediastinal lymph nodes and mediastinal lymph nodes metastases. The  SUVmax, SUVmean, length diameter, short diameter, mean CT value and maximum CT value of the lymph nodes were measured with a  blind method. Results  Obvious differences between  group 1 and the group 2 were found in SUVmax(3.98±1.48 vs 7.41±3.69), SUVmean(3.37±1.16 vs 5.88±2.64), length diameter［(10.32±3.01)mm vs (16.0±5.97mm)］,short diameter［(7.48±2.29)mm vs (11.95±4.78)mm］, mean CT value［（64.16±21.73)Hu vs (33.84±8.80)Hu］ and maximum CT value ［(111.02±149.41)Hu vs (67.93±32.45Hu)］ (P＜0.01). Conclusions  The non-specific high uptake of the aged mediastinal lymph nodes  usually accompanied with symmetrical distribution, SUV value lower than 5 and CT value higher than 50Hu. The SUV value and CT value (particularly the increased CT value) could be used as references in the differential diagnosis of benign and malignant lymph nodes caused by malignant  tumors especially lung cancer.

Key words: lymph nodes;non-specific uptake;Tomography;Emission-computed