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

Abstract

Objectives: 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(NSLC). Also, we aimed to assess whether ADC_min values differ between tumour subtypes and tissue sampling method.

Methods: Patients with NSLC, 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 non-small cell lung cancer 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(SCC). 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 SCC(p<0.0001). The correlation between ADC_min values and the Ki-67 proliferation index was slightly better in surgical specimens than in biopsy samples (r=-0.870 vs -0.617, respectively).

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.