Utility of MRI with morphologic and diffusion weighted imaging in the detection of post-treatment nodal disease in head and neck squamous cell carcinoma.

PURPOSE

To determine the diagnostic performance of morphologic MRI with diffusion weighted imaging (DWIMRI) for the detection of post-treatment lymph node (LN) recurrence of head and neck squamous cell carcinoma (HNSCC).

METHODS

This retrospective study is based on 33 HNSCC patients who underwent DWIMRI with apparent diffusion coefficient (ADC) measurements for suspected post-treatment loco-regional failure. Two radiologists, blinded to clinical/histopathological data, analyzed MR images according to established morphologic criteria and measured ADC values by drawing regions of interest on each normal/abnormal looking lymph node (LN). Histopathological findings in 40 neck dissections, 133 LN-levels and 755 LNs served as gold standard.

RESULTS

Malignant LNs had lower ADCmean values than benign LNs (1.15 ± 0.35 × 10 mm/s versus 1.28 ± 0.28 × 10 mm/s, p = .028). The optimal ADCmean threshold to differentiate malignant from benign LNs was 1.1695 × 10 mm/s. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values (95%CI in parentheses) of DWIMRI with morphologic criteria and ADCmean <1.1695 × 10 mm/s were: (a) 100%(86.2;100), 44.4%(15.3;77.3), 86.1%(69.7;94.7), and 100%(39.5;100) per neck dissection; (b) 83.6%(69.7;92.2), 91.6%(83.0;96.2), 85.4%(71.6;93.4), and 90.5%(81.7;95.5) per LN-level; (c) 53.1%(43.5;62.4), 95.5%(93.5;96.9), 67.4%(56.6;76.7), and 92.0%(89.6;93.9) per LN, respectively.

CONCLUSION

The high NPV of DWIMRI irrespective of analysis type (per neck dissection/per neck level/per lymph node) make it a useful follow-up tool after treatment.