Liao et al. BMC Cancer 2012, 12:236 http://www.biomedcentral.com/1471-2407/12/236 Table 2 The pooled estimates of different imaging modalities in cN0 neck evaluation Modalities Sensitivity Specificity LR + LR- QUADAS (95%CI) (95%CI) (95%CI) (95%CI) score* (95%CI) CT 0.52 0.93 7.9 0.51 8.1 (0.39 ~ 0.65) (0.87 ~ 0.97) (3.6 ~ 17.4) (0.38 ~ 0.68) (3.8 ~ 12.4) MRI 0.65 0.81 3.4 0.44 7.6 (0.34 ~ 0.87) (0.64 ~ 0.91) (1.8 ~ 6.2) (0.21 ~ 0.93) (4.1 ~ 11.1) PET 0.66 0.87 5.2 0.39 10 (0.47 ~ 0.80) (0.77 ~ 0.93) (2.6 ~ 10.4) (0.24 ~ 0.65) (6.9 ~ 13.1) US 0.66 0.78 3.0 0.44 7.5 (0.54 ~ 0.77) (0.71 ~ 0.83) (2.1 ~ 4.2) (0.3 ~ 0.64) (3.6 ~ 11.4) *Yes: 1; No/unclear: 0. LR+: likelihood ratio positive; LR-: likelihood ratio negative. Systematic review and meta-analysis of the accuracy of diagnostic tests can answer some clinically relevant ques- tions, highlight important gaps in the evidence and aid in the design of further studies. Our results are the first to use meta-analytic data in neck metastasis rate esti- mation on different pre-test probabilities among differ- ent diagnostic imaging techniques. Because most individual studies have a limited number of cases, meta-analysis uses more data and provides more reli- able results. The optimal method for managing cN0 neck in SCC of the head and neck remains controversial. In 1994, Weiss et al. [3] recommended with decision analysis that when the probability of occult cervical metastases is more than 20% (with a positive predictive rate above 20%), the neck should be electively treated. Based on Bayesian theory, the predictive probability of neck nodal metastasis given Table 3 The positive and negative predictive value of nodal metastasis following imaging exams among various baseline possibilities of neck nodal metastasis Imaging Modalities CT MRI PET US Baseline possibility of neck nodal metastasis 10% 20% 30% 10% 20% 30% 10% 20% 30% 10% 20% 30% Page 5 of 7 95% 89% 82% 95% 90% 84% 96% 91% 86% 95% 90% 84% Positive predictive value* Negative predictive value& 47% 66% 77% 27% 46% 59% 36% 56% 69% 25% 42% 56% *: Possibility of neck nodal metastasis following a “positive” imaging result. &: Possibility of “absent” neck nodal metastasis following a “negative” imaging result. that a test is negative or positive depends on the pre-test probability (baseline possibility), and the sensitivity and specificity of the test. According to our results, if the pretest prevalence (baseline possibility) of clinical occult neck metastases was set at 30%, the post-test negative Figure 2 The positive predictive value generated based on Bayesian theory and the collected data. Figure 3 The performance of different imaging modalities shown with summary receiver operating characteristic curves. The pooled estimates for sensitivity were 52%, 65%, 66% and 66%, on a per-neck basis for CT, MRI, PET and US. The pooled estimates for specificity were 93%, 81%, 87%, and 78% for CT, MRI, PET and US, respectively.