title: Correlation of diffusion MRI with the Ki-67 index in non-small cell lung cancer.
abstract: BACKGROUND
  The primary objective of the study was to evaluate the association between the minimum apparent diffusion coefficient (ADCmin) and Ki-67, an index for cellular proliferation, in non-small cell lung cancers. Also, we aimed to assess whether ADCmin 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 ADCmin 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 ADCmin values and the Ki-67 proliferation index (r = -0.837, p < 0.001). The mean ADCmin 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 ADCmin 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.
authors.affiliation: Department of Radiology, Ataturk University, Medical Faculty, Erzurum, Turkey.
authors.forename: Adem
authors.initials: A
authors.lastname: Karaman
authors.affiliation: Department of Radiology, Ataturk University, Medical Faculty, Erzurum, Turkey.
authors.forename: Irmak
authors.initials: I
authors.lastname: Durur-Subasi
authors.affiliation: Department of Radiology, Ataturk University, Medical Faculty, Erzurum, Turkey.
authors.forename: Fatih
authors.initials: F
authors.lastname: Alper
authors.affiliation: Department of Pulmonary Diseases, Ataturk University, Medical Faculty, Erzurum, Turkey.
authors.forename: Omer
authors.initials: O
authors.lastname: Araz
authors.affiliation: Department of Thoracic Surgery, Erzurum Regional Training and Research Hospital, Erzurum, Turkey.
authors.forename: Mahmut
authors.initials: M
authors.lastname: Subasi
authors.affiliation: Department of Pathology, Ataturk University, Medical Faculty, Erzurum, Turkey.
authors.forename: Elif
authors.initials: E
authors.lastname: Demirci
authors.affiliation: Department of Pathology, Ataturk University, Medical Faculty, Erzurum, Turkey.
authors.forename: Mevlut
authors.initials: M
authors.lastname: Albayrak
authors.affiliation: Department of Radiology, Ataturk University, Medical Faculty, Erzurum, Turkey.
authors.forename: Gökhan
authors.initials: G
authors.lastname: Polat
authors.affiliation: Department of Pulmonary Diseases, Ataturk University, Medical Faculty, Erzurum, Turkey.
authors.forename: Metin
authors.initials: M
authors.lastname: Akgun
authors.affiliation: Department of Radiology, Pamukkale University, Medical Faculty, Denizli, Turkey.
authors.forename: Nevzat
authors.initials: N
authors.lastname: Karabulut
keywords: Ki-67 index; adenocarcinoma; apparent diffusion coefficient; diffusion weighted-magnetic resonance imaging; squamous cell carcinoma