MR study of N2 disease in lung cancer: contrast-enhanced method using gadolinium-DTPA.

OBJECTIVE: In several previous studies, including one of our own, CT and MRI provided similar information on N2 detection in the staging of lung cancer. Both imaging techniques can be considered effective in detecting enlarged mediastinal lymph nodes but the results are often inaccurate when confronted with pathological findings. The purpose of this study was to assess the diagnostic accuracy of gadolinium-DTPA enhanced MRI in the detection of mediastinal lymph nodes in lung cancer.

METHODS: A prospective study to compare standard unenhanced MRI and Gd-DTPA enhanced MRI was carried out in patients with diagnosed lung cancer. The study focused on the status of mediastinal lymph nodes. Gd-DTPA was administered at a dosage of 0.2 mmol2/KG before T1 weighted sequences. Qualitative visual analyses of both standard and contrast enhanced MRI images were performed on each patient by 2 independent radiologists. The imaging results were then compared to pathological findings obtained after surgical operation.

RESULTS: In the identification of mediastinal lymph node metastases standard MRI was 62% sensitive, 100% specific and 74% accurate whereas Gd-DTPA enhanced MRI was 100% sensitive, 91% specific and 97% accurate.

CONCLUSIONS: Gd-DPTA enhanced MRI was more accurate than standard MRI in the detection of metastatic lymph nodes in patients with lung cancer. These initial results can be considered encouraging especially with regards to the reduction of false negative findings although further confirmation is, understandably, required.