Relationship between Apparent Diffusion Coefficient and Tumour Cellularity in Lung Cancer

Background and objective: To prospectively investigate the relationship between the apparent diffusion coefficient (ADC) and cellularity in lung cancer. Methods: Sixty patients histopathologically confirmed with lung cancer (41 men, 19 women) underwent diffusion-weighted magnetic resonance imaging of the chest (with b values of 50 and 1000 s/mm(2)). The median mean ADC (ADCmean) value and median minimum ADC (ADCmin) value within each primary tumour were calculated and compared with the median nucleo-cytoplasmic ratio (NCR), which was selected to represent the cellularity. The correlation between the NCR and ADCmean/ADCmin was calculated with SPSS 18.0 software. Results: The mean ADCmean values, ADCmin values and median NCR were (1.07 +/- 0.12) x 10(-3) mm(2)/s, (0.86 +/- 0.14) x 10(-3) mm(2)/s, and (14.9 +/- 2.6) %, respectively, in adenocarcinoma; (0.88 +/- 0.10) x 10(-3) mm(2)/s, (0.73 +/- 0.12) x 10(-3) mm(2)/s, nd (20.6 +/- 4.4) %, respectively, in squamous cell carcinoma; and (0.89 +/- 0.13) x 10(-3) mm(2)/s, (0.67 +/- 0.13) x 10(-3) mm(2)/s, and (18.3 +/- 3.5) %, respectively in small cell lung cancer. The NCR of squamous cell carcinoma and small cell lung cancer is greater than that of adenocarcinoma (P<0.01 and P = 0.002, respectively). There was an inverse relationship between ADCmean/NCR and ADCmin/NCR (r = -0.60, P = 0.001 and r = -0.47, P<0.001, respectively). Conclusion: There is a significant inverse relationship between tumour cellularity and ADC in lung cancer. However, tumour cellularity most likely is not the sole determinant of the ADC.