Correlation of diffusion MRI with the Ki-67 index in non-small cell lung cancer

BACKGROUND: The primary objective of the study was to evaluate the association between the minimum apparent diffusion coefficient (ADC(min)) and Ki-67, an index for cellular proliferation, in non-small cell lung cancers. Also, we aimed to assess whether ADC(min) values differ between tumour subtypes and tissue sampling method. METHODS: The patients who had diffusion weighted magnetic resonance imaging (DW-MRI) were enrolled retrospectively. The correlation between ADC(min) and the Ki-67 index was evaluated. RESULTS: Ninety three patients, with a mean age 65 ± 11 years, with histopathologically proven adenocarcinoma and squamous cell carcinoma of the lungs and had technically successful DW-MRI were included in the study. The numbers of tumour subtypes were 47 for adenocarcinoma and 46 for squamous cell carcinoma. There was a good negative correlation between ADC(min) values and the Ki-67 proliferation index (r = −0.837, p < 0.001). The mean ADC(min) value was higher and the mean Ki-67 index was lower in adenocarcinomas compared to squamous cell carcinoma (p < 0.0001). There was no statistical difference between tissue sampling methods. CONCLUSIONS: Because ADC(min) shows a good but negative correlation with Ki-67 index, it provides an opportunity to evaluate tumours and their aggressiveness and may be helpful in the differentiation of subtypes non-invasively.