Thyroid cancer neck lymph nodes metastasis: Meta-analysis of US and CT diagnosis

Ultrasound (US) is the first imaging technique in the assessment of cervical lymph nodes metastasis (LNM) of papillary thyroid cancer (PTC) patients preoperatively. Computed tomography (CT) exerts an influence on surgical strategy especially for patients with lateral cervical LNM. This meta-analysis aimed at assessing the diagnostic values of US and CT in detecting the cervical LNM in thyroid cancer patients.

Medline, Embase and Cochrane Library (CENTRAL) were retrieved up to 16^th Sep, 2019 for studies about comparison of the diagnostic performance between US and CT. The pooled sensitivity, specificity, positive likelihood ratio (LR), negative LR and diagnostic odds ratio (DOR), with each's 95 % CI were calculated.

A total of 5656 thyroid cancer patients in 10 studies were included. CT had a higher sensitivity in central (0.400 [0.385, 0.416] vs 0.284 [0.270, 0.298], P < 0.001), lateral (0.811 [0.778, 0.416] vs 0.758 [0.722, 0.792], P = 0.029) and the whole (0.664 [0.633, 0.694] vs 0.593 [0.561, 0.625], P = 0.002) compartments regions. US had a higher specificity in central (0.895 [0.885,0.903] vs 0.950 [0.944, 0.956], P < 0.001), lateral (0.84 [0.813,0.864] vs 0.88 [0.856, 0.901], P = 0.012) and the whole (0.834 [0.804,0.862] vs 0.911 [0.887, 0.932], P < 0.001) compartments regions.

US and CT performed poorly when trying to identify the presence of central LNM. CT has a higher sensitivity while US has a higher specificity for the assessment of central, lateral and the whole cervical LNM. Performing CT to detect the lateral cervical LNM will effectively reduce the rate of missed diagnosis and improve surgical planning. Both US and CT are needed for neck lymph nodes staging preoperatively owning to low sensitivities.