RESUMO
Objective: To evaluate the diagnostic value of DWI in assessment of metastatic neck lymph node in a sample of Iranian patients with Head and Neck cancer. Methods: 25 patients with 80 neck lymph nodes were analyzed using 1.5 T MRI. DWI was performed with b values of 0 and 1,000 s/mm2. Short axis diameter and ADC values (min, max and mean) were calculated for metastatic and non-metastatic neck LNs and results were compared with histopathological findings. The optimal ADC thresholds were analyzed using receiver coefficient characteristic (ROC) curves for discriminating between metastatic and benign neck lymph nodes. Result: Histopathological findings revealed that there are 45% (n=36) metastatic and 55% (n=44) non-metastatic neck LNs respectively. There was no statistically significant difference in short axis diameter between the two groups (p = 0.346). However, The ADC values of metastatic neck LNs were significantly lower than those of non-metastatic neck LNs (p < 0.001); 0.90 ± 0.10 × 10-3 mm2/s vs 1.06 ± 0.12 × 10-3 mm2/s ( ADC mean ), 0.78 ± 0.08 × 10-3 mm2/s vs 0.92 ± 0.20× 10-3 mm2/s ( ADC min ) and 1.02 ± 0.12 × 10-3 mm2/s vs 1.24 ± 0.15 × 10-3 mm2/s (ADC max ). The optimal mean ADC threshold value was equal to 0.996 × 10-3 mm2/s for differentiating malignant from benign lymph nodes with sensitivity, specificity and accuracy of 80.56 %, 77.27 % and 71.59 % respectively. Conclusion: MR diffusion imaging and ADC values as a non-invasive technique can assess metastatic neck LNs in head and neck cancer with higher sensitivity, specificity and accuracy.
