For detecting malignant tumors, diffusion-weighted magnetic resonance imaging (DWI) as well as fluoro-2-deoxy-glucose positron emission tomography/computed tomography (FDG-PET/CT) are available. It is not definitive how DWI correlates the pathological findings of lung cancer. The aim of this study is to evaluate the relationships between DWI findings and pathologic findings. In this study, 226 patients with resected lung cancers were enrolled. DWI was performed on each patient before surgery. There were 167 patients with adenocarcinoma, 44 patients with squamous cell carcinoma, and 15 patients with other cell types. Relationships between the apparent diffusion coefficient (ADC) of DWI and the pathology were analyzed. When the optimal cutoff value (OCV) of ADC for diagnosing malignancy was 1.70 × 10-3 mm2/s, the sensitivity of DWI was 92.0% (208/226). The sensitivity was 33.3% (3/9) in mucinous adenocarcinoma. The ADC value (1.31 ± 0.32 × 10-3 mm2/s) of adenocarcinoma was significantly higher than that (1.17 ± 0.29 × 10-3 mm2/s) of squamous cell carcinoma (p = 0.012), or (0.93 ± 0.14 × 10-3 mm2/s) of small cell carcinoma (p = 0.0095). The ADC value (1.91 ± 0.36 × 10-3 mm2/s) of mucinous adenocarcinoma was significantly higher than that (1.25 ± 0.25 × 10-3 mm2/s) of adenocarcinoma with mucin and that (1.24 ± 0.30 × 10-3 mm2/s) of other cell types. The ADC (1.11 ± 0.26 × 10-3 mm2/s) of lung cancer with necrosis was significantly lower than that (1.32 ± 0.33 × 10-3 mm2/s) of lung cancer without necrosis. The ADC of mucinous adenocarcinoma was significantly higher than those of adenocarcinoma of other cell types. The ADC of lung cancer was likely to decrease according to cell differentiation decreasing. The sensitivity of DWI for lung cancer was 92% and this result shows that DWI is valuable for the evaluation of lung cancer. Lung cancer could be evaluated qualitatively using DWI.
Keywords: apparent diffusion coefficient (ADC); diffusion-weighted magnetic resonance imaging (DWI); lung cancer; magnetic resonance imaging (MRI); pathology.