Verification of the Efficacy of New Diagnostic Criteria for Retropharyngeal Nodes in a Cohort of Nasopharyngeal Carcinoma Patients

Abstract

Purpose: A multistage approach to diagnose lateral retropharyngeal nodes (LRPNs) of nasopharyngeal carcinoma (NPC) had been proposed and warranted for validation. Methods: Between 2012 and 2017, the patients with newly diagnosed NPC were enrolled. The responsive nodes or those that progressed during follow-up were positive. The criteria for the multistage approach delimited LRPNs with a minimal axial diameter (MIAD) ≥ 6.1 mm were assessed as positive and if the mean standard uptake value ≥ 2.6, or if the maximal coronal diameter ≥ 25 mm and maximal axial diameter ≥ 8 mm with nodes MIAD < 6.1 mm were also considered as positive. The outcomes were compared with the MIAD cutoff value ≥ 6 mm (traditional method). A chi-squared test was used to compare two areas under the curve of the receiver operating characteristic curves. Results: A total of 67 eligible NPC cases and 155 LRPNs (72 positive and 83 negative) were analyzed. The accuracy, specificity, and sensitivity of the traditional method were 0.91, 0.93, and 0.89, respectively. The values for the multistage approach all reached 0.94. The area under the curve was significantly greater for the multistage approach compared with the traditional method (p = 0.023). Conclusion:The results support the advantage of the multistage approach.

Normal size of benign upper neck nodes on MRI: parotid, submandibular, occipital, facial, retroauricular and level IIb nodal groups

“…Recently Elsholtz et al [ 28 ], proposed using a threshold of < 5 mm to denote normal nodes in the facial, parotid, retroauricular, occipital groups for a Node-RADS system that categorises the likelihood of a metastatic node from 1 to 5. Our findings support lowering the threshold from 10 mm to one that is similar to that already applied to retropharyngeal nodes, i.e., 5 mm or 6 mm [ 9 , 13 , 20 ]. Our current results suggest that 6 mm, rather than 5 mm, would reduce the number of false positive nodes and improve specificity in the parotid, occipital, Level IIb nodes, as well as the retropharyngeal group.…”

“…As malignant nodes tend to be round and reactive nodes oval in shape, the short axis diameter (SAD) on axial images is frequently the measurement of choice [ 8 , 13 – 15 ]. The size threshold chosen to detect a malignant node is of course always a trade-off between sensitivity and specificity [ 8 , 16 – 20 ] and may vary between centers and may be influenced by the clinical scenario [ 21 ]. However, commonly used thresholds in practice and research are SAD thresholds ≥ 11 mm for the jugulodigastric nodes and ≥ 10 mm for other nodes in the head and neck [ 8 , 22 , 23 ].…”

“…However, commonly used thresholds in practice and research are SAD thresholds ≥ 11 mm for the jugulodigastric nodes and ≥ 10 mm for other nodes in the head and neck [ 8 , 22 , 23 ]. The exception is the retropharyngeal nodes where a lower threshold of ≥ 5 or 6 mm is used to reflect the smaller size of normal and reactive nodes in this group [ 9 , 13 , 20 ]. However, benign nodes in the parotid, submandibular, occipital groups and Level IIb of the upper internal jugular group (posterior and separate to the vein) are also usually much smaller than nodes in Level IIa of the upper internal jugular group (adjacent to the vein), but the normal size range of these nodal groups is poorly documented in the literature.…”