[The value of dual time point 11C-choline PET-CT in differentiating malignant from benign lesion of mediastinum].

ABSTRACT

OBJECTIVE: To evaluate the value of dual time point 11C-choline PET-CT in differentiating malignant from benign lesions of mediastinum. METHODS: Thirty-five patients with mediastinal diseases, including 8 non-small cell lung cancer or highly suspected lung cancer patients with mediastinal lymphadenectasis, were subject to CT, dual time point PET-CT and videomediastinoscopy within four weeks. 11C-choline was used as PET tracers to visualize various masses. The imaging protocol included the first PET scanning 5-10 min after the-injection of 370 MBq 11C-choline and then a second PET scanning 25-30 min later. The PET data were evaluated using the standardized uptake value (SUV) and the difference between the two point (DeltaSUV). Then the results were analyzed in accordance with the pathologic data. RESULTS: Eleven of the 35 patients with mediastinal diseases were diagnosed as with sarcoidosis, 6 with tuberculosis, 5 with lymphoma, 11 with nodal metastasis (8 had their modes from the lung and the primary lesions of the other 3 failed to be identified), and 2 with lung cancer with reactive hyperplasia lymph node. The SUV of the delayed images of the 16 malignant lesions was 6.48 (3.0-11.2), higher than that of the early images [6.17 (3.2-9.8)] with a DeltaSUV of 0.31 (-0.4-1.4). The value of SUV of delayed images of the 19 benign lesions was 4.99 (2.2-9.3), lower than that of early images [5.11 (2.9-8.3)] with a DeltaSUV of -0.12 (-0.9-1.0). The DeltaSUV of the benign lesions was significantly lower than that of the malignant lesions (F = 1.939, P = 0.04). The accuracy rates of diagnosis of mediastinal masses of CT, first-time PET-CT, dual time point PET-CT, and videomediastinoscopy were 54.3% (19/35), 74.3% (26/35), 82.9% (29/35), and 100% (35/35) respectively. Conclusion With a high diagnostic yield, videomediastinoscopy remains the gold standard in differentiation of malignant and benign lesions located in the middle mediastinum. Dual time point PET-CT may improve the accuracy.