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/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.