Nasopharyngeal carcinoma: correlation of apparent diffusion coefficient value with prognostic parameters

The aim of this study was to correlate the apparent diffusion coefficient (ADC) value with the prognostic parameters of nasopharyngeal carcinoma (NPC). This was a prospective study conducted on 30 consecutive patients (19 men, 11 women; mean age 61 years) with NPC. Patients underwent diffusion-weighted magnetic resonance (DW-MR) singleshot echoplanar imaging at 1.5 Tesla. NPC ADC value was correlated with pathological tumour type, pathological tumour grade, tumour volume and nodal status. Mean NPC ADC value was 0.99 +/- 0.11x10(-3)mm(2)/s. ADC values of well-differentiated and moderately differentiated tumours differed significantly (p=0.005) from those of poorly differentiated and undifferentiated NPC. There was also a significant difference in ADC value among small, medium and large tumour volume (p=0.03). ADC value was also significantly lower (p=0.003) when metastatic cervical lymph nodes were present. ADC value correlated inversely with tumour volume (r=-0.799, p=0.03). ADC value can be considered a noninvasive prognostic parameter that correlates well with prognostic parameters of NPC.