| The purpose of this study was to directly compare dynamic enhanced CT with (18)~F-FDG PET in the diagnosis of mediastinal enlarged lymph nodes with lung cancer.Materials and MethodsEighty lung cancer patients with mediastinal enlarged lymph nodes were selected to undergo dynamic enhanced CT scanning. The time points of enhanced scanning were: 30s, 60s, 90s, and 120s after contrasted. 59 patients in 80 matched condition, and there were 158 mediastinal enlarged lymph nodes (120 were metastasis, 38 were not metastasis). After scanning, the images were post-processed. The density of lymph nodes and primary focus were measured, and were drawn to Time-Density Curve. Curves were grouped into 4 types. The comparison was progressing by pathology results and clinical follow-up. Correlation between mediastinal metastasis lymph nodes and primary focus were analyzed. The diagnostic valuation of dynamic enhanced CT for mediastinal enlarged lymph nodes with lung cancer was appreciated by some statistics index. Another eighty lung cancer patients with mediastinal enlarged lymph nodes were selected to undergo PET/CT scanning. 61 patients in 80 matched condition, and there were 166 mediastinal enlarged lymph nodes. The patients'limosis sugar was tested and controlled below the level of 6.4mmol/L. CT and PET dissectional scan were performed after intravenous injection of the (18)~F-FDG (5.55~7.40MBq/Kg). The mean SUV of lymph nodes were calculated blindly by two experienced nuclear physicians. SUVmax≥2.5 was taken as the positive criteria. Results1. No statistical difference was noted between the density of metastasis lymph nodes(43.95±10.44HU) and non-metastasis lymph nodes(41.23±8.77HU) on plain scanning images. (P=0.052>0.05)2. The mediastinal metastasis lymph nodes'plain densities of non-small cell carcinoma of lung, SqCa of lung, adenocarcinoma of lung, adenosquamous carcinoma of lung of lung were 34.73±5.90HU, 43.79±5.08HU, 53.81±8.77HU, 41.56±8.41HU. No statistical difference(P=0.344>0.05) was noted between the plain densities of SqCa of lung and adenosquamous carcinoma of lung. There were statistical differences (all P<0.05) between plain densities of other groups.3. The net enhancement value of mediastinal metastasis lymph nodes (29.05±15.21HU) was lower than that of non-metastasis lymph nodes in mediastinum. (P<0.001)4. The net enhancement values of non-small cell carcinoma of lung, SqCa of lung, adenocarcinoma of lung, adenosquamous carcinoma of lung of lung were 21.76±9.15HU, 31.25±7.01HU, 27.28±6.12HU, 42.79±7.27HU. Different patho-categoris of lung carcinoma had the different net enhancement values of mediastinal metastasis lymph nodes.(all P<0.05)5. 97.5% TDCs of mediastinal metastasis lymph nodes with lung carcinoma were type I(28.33%), type II(36.67%), type III(32.5%), and only 2.5% TDCs were type IV. 86.84% TDCs of non-metastatic lymph nodes were type IV, and other TDCs were type I(5.26%), type II(7.9%).6. Different patho-categoris of lung carcinoma had the different TDC shapes'constituent ratio of mediastinal metastasis lymph nodes. 58.0%TDCs of non-small cell carcinoma of lung were type III, 59.26% TDCs of SqCa of lung were type I, 54.84% TDCs of adenocarcinoma of lung were type II. The statistical differences were noted in the three categories above. (P<0.01)7. 94.17% of mediastinal metastasis lymph nodes TDCs matched the corresponding primary lung carcinoma focus TDCs. The TDCs shapes of non-small cell carcinoma of lung(96% ), SqCa of lung (92.59%), adenocarcinoma of lung (90.32%) all matched respective primary focus.8. Using the coincidence of TDCs shapes as the diagnostic criteria, the sensibility, specificity, positive predictive value and negative predictive value of diagnosing mediastinal enlarged lymph nodes with lung carcinoma were 94.17%, 86.84%, 95.76%, 82.5%.9. Using SUVmax≥2.5 as the diagnostic criteria in (18)~F-FDG PET scanning, the sensibility, specificity, positive predictive value and negative predictive value of diagnosing mediastinal enlarged lymph nodes with lung carcinoma were 90.68%, 75%, 89.92%, 76.6%.ConclusionsDynamic enhanced CT scanning could show the time-density curve shapes, and progress correlation analysis with primary focuses. Compared with (18)~F-FDG PET, dynamic enhanced CT has higher sensibility, specificity, positive predictive value and negative predictive value. Dynamic enhanced CT scanning has some clinical value in diagnosis of mediastinal lymph nodes. |
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