To preserve pulmonary function in lung cancer patients, the video assistant thoracic surgery and conformal radiotherapy are developing. The accurate nodal staging is essential in these treatments. Although FDG-PET is the most accurate diagnostic procedure, there are some false-positive and false–negative diagnoses. We hypothesized that some pathological features of lymphatics are revealed on HRCT in patients with mediastinal metastases to normal-size lymph nodes. The purpose of this study is to evaluate whether it is useful to assess CT appearances of the primary site of lung cancer in the nodal staging.
Two chest radiologists reviewed thoracic CT images of 91 non-small-cell lung cancer patients diagnosed as clinical T1N0 by nodal size criterion. The nodal staging of all patients was pathologically proven by thoracotomy within four weeks after CT examinations (pN0=72, pN1=7, pN2=12). Radiologists assessed HRCT findings of the primary site including the size, density, and marginal characteristics of the nodule and the appearances around the nodule. These HRCT findings were compared between patients with and without nodal metastases.
The patients with the primary lesion of ground-glass attenuation alone had no nodal metastasis. Irregular and long pleural tags (more than 1 cm in length) were seen in all patients with N2 and 10 patients with N0 (p<0.01). Irregular thickening of proximal vessels running toward primary tumor were seen in eight patients with N2 and one with N0 (p<0.01). This CT feature was pathologically correlated with the dilatation of lymph channels accompanied by the vessels. Areas of GGA around the primary lesion were present in eight patients with N2 and one with N0 (p<0.01).
Some HRCT features of primary sites indicated mediastinal nodal metastasis in T1 lung cancer. The assessment of HRCT appearances of the primary site may be useful in the nodal staging of lung cancer.
HRCT may be useful in the nodal staging of the lung cancer as well as the differnetial diagnosis of the small nodule.
T. Matsumoto, None.