Preoperative diagnosis of N-factor by MR in primary lung cancer

We compared the accuracies of preoperative diagnosis of N-factor by CT and MR in 71 cases of primary lung cancer. Lymph nodes larger than 10 mm in diameter were defined as positive. As a result, CT and MR both achieved an accuracy of more than 80%. MR was inefficient in detecting calcification and showed lower spatial resolution than CT; however, MR was useful in detecting hilar lymph nodes because of the signal loss of blood vessels. MR should be used to detect the contralateral hilar lymph nodes swelling because the sensitivity in the hilus is 20% higher in MR than in CT and the information about the contralateral hilar lymph nodes is more important than ipsilateral hilar lymph nodes for operation. (author)