It is sometimes difficult to determine whether lymph nodes are metastatic in lung cancer. We present two cases of a resected lung cancer where diffusion-weighted magnetic resonance imaging (DWI) was more accurate in nodal assessment than 18-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (FDG-PET/CT).
Case 1: A 71-year-old man had lung cancer in his right lower lobe. FDG-PET/CT showed little FDG uptake in the hilar and mediastinal lymph nodes and the lung cancer was diagnosed as cN0 lung cancer. DWI revealed decreased diffusion of the lymph nodes and the lung cancer was diagnosed as cN2 lung cancer, with a pathological stage of pN2.
Case 2: A 71-year-old man had lung cancer in his right upper lobe. FDG-PET/CT showed an FDG accumulation (SUVmax 4.18) in the lung cancer and an FDG accumulation (SUVmax 7.57) in the #4R and #4L lymph nodes. DWI showed decreased diffusion of ADC (1.45×10^－3mm²/sec) in the lung cancer, but not in the aforementioned lymph nodes. Pathologically, anthracosilicosis was revealed in the #4R lymph node.
Conclusions: Assessment of pulmonary hilar and mediastinal lymph nodes by DWI might be more effective than by FDG-PET/CT in some lung cancer cases.