Ultrasound Elastography supplement assessing nodal status of magnetic resonance imaging staged cervical N0 patients with nasopharyngeal carcinoma

BACKGROUND: To determine whether ultrasound elastography can distinguish reactive or metastatic small lymph nodes (sLN) of magnetic resonance imaging (MRI) staged cervical N0 patients with nasopharyngeal carcinoma (NPC). METHODS: A pilot study was performed involving the diagnostic performances of conventional high-frequency ultrasound (CHFU) and/or shear wave elastography (SWE) for predicting metastases in sLN of MRI-staged N0 NPC patients with reference to the histologically-proven ultrasound guided core needle biopsy (US-CNB). The diagnosis of CHFU was based on the superficial lymph node ultrasonic criteria with the five-point-scale (FPS). The mean (Emean), minimum (Emin) and maximum (Emax) of the elasticity indices were measured by SWE at the stiffest part of the sLN in kilopascal. Diagnostic performances were analyzed using a receiver operating curve (ROC) on a per-node basis. The authenticity of this article has been validated by uploading the key raw data onto the Research Data Deposit public platform (http://www.researchdata.org.cn), with the approval RDD number as RDDA2017000447. RESULTS: All 113 cervical sLN of 49 MRI-staged cervical N0 NPC patients underwent evaluation of CHFU and SWE; 38 sLN (FPS < 2) were regarded as benign, which were excluded from subsequent analysis due to none biopsy-proven. And 75 indeterminate sLN (FPS ≥ 2) were referred to US-CNB and revealed 15 (20%) metastases. All SWE elastic indices were significantly higher in malignant sLNs than in benign sLNs (p < 0.05). Moreover, Emax exhibited the highest diagnostic value (AUC:0.733 ± 0.067, p = 0.005) with excellent measurement reproducibility (ICC: 0.786; 95%CI: 0.684, 0.864). CHFU plus SWE was superior to CHFU or SWE alone for predicting metastases in sLN of MRI-staged N0 patients with NPC (p < 0.001). CONCLUSIONS: CHFU plus SWE is an optional non-invasive modality to supplement MRI in assessing cervical nodal status of patients with NPC. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s40644-019-0199-3) contains supplementary material, which is available to authorized users.