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/mm2). The median mean ADC (ADC mean) value and median minimum ADC (ADC min) 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 ADC mean/ADC min was calculated with SPSS 18.0 software.
Results: The mean ADC mean values, ADC min values and median NCR were (1.07 ± 0.12) × 10(-3) mm2/s, (0.86 ± 0.14) × 10(-3) mm2/s, and (14.9 ± 2.6) %, respectively, in adenocarcinoma; (0.88 ± 0.10) × 10(-3) mm2/s, (0.73 ± 0.12) × 10(-3)) mm2/s, and (20.6 ± 4.4) %, respectively, in squamous cell carcinoma; and (0.89 ± 0.13) × 10(-3) mm2/s, (0.67 ± 0.13) × 10(-3) mm2/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 ADC mean/NCR and ADC min/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.