Liao et al. BMC Cancer 2012, 12:236 http://www.biomedcentral.com/1471-2407/12/236 Table 1 Summary of the included studies Author year Journal Modality TP FP FN TN Stevens MH 1985 Arch Otolaryngol Head Neck Surg CT 5 1 1 9 Maremonti P 1997 J Craniomaxillofac Surg CT 6 0 6 12 Righi PD 1997 Head Neck CT 6 0 4 23 Byers RM 1998 Head Neck CT 2 2 9 12 Myers LL 1998 Laryngoscope CT 4 1 3 9 Takes RP 1998 Int J Radiat Oncol Biol Phys CT 14 3 12 35 Akoglu E 2005 J Otolaryngol CT 2 1 1 10 Wilson GR 1994 Br J Plast Surg MRI 11 14 0 13 Braams JW 1995 J Nucl Med MRI 3 2 2 5 Maremonti P 1997 J Craniomaxillofac Surg MRI 4 4 8 8 Yucel T 1997 Acta Radiol MRI 4 1 1 12 Akoglu E 2005 J Otolaryngol MRI 2 1 1 10 Thomsen JB 2005 Acta Radiol MRI 5 4 9 52 Braams JW 1995 J Nucl Med PET 5 2 0 5 Myers LL 1998 J Otolaryngol PET 7 0 0 4 Myers LL 1998 Laryngoscope PET 7 0 2 15 Kau RJ 2002 Arch Otolaryngol Head Neck Surg PET 1 1 4 6 Brouwer J 2004 Eur Arch Otorhinolaryngol PET 2 1 1 11 Akoglu E 2005 J Otolaryngol PET 2 1 1 10 Schoder H 2006 J Nucl Med PET 6 4 3 23 Wensing BM 2006 Laryngoscope PET 3 4 5 16 Iyer NG 2010 Head Neck PET 15 4 14 113 Liao CT 2010 J Nucl Med PET 26 66 33 143 Richard C 2010 Arch Otolaryngol Head Neck Surg PET 7 5 1 8 van den Brekel MW 1993 Eur Arch Otorhinolaryngol US 21 13 15 39 Maremonti P 1997 J Craniomaxillofac Surg US 8 1 4 11 Righi PD 1997 Head Neck US 6 5 4 18 Byers RM 1998 Head Neck US 3 4 8 10 Takes RP 1998 Int J Radiat Oncol Biol Phys US 18 11 8 27 Hodder SC 2000 Br J Oral Maxillofac Surg US 9 4 3 17 Akoglu E 2005 J Otolaryngol US 3 4 0 7 Thomsen JB 2005 Acta Radiol US 13 10 2 55 TP: true positive; FP: false positive; FN: false negative; FP: false positive. QUADAS: Quality Assessment of Diagnostic Accuracy Studies. Sensitivities and specificities with 95% confidence interval (CI) values were reported for individual studies. Page 4 of 7 QUADAS Sensitivity Specificity (95%CI) (95% CI) 83%(54-100%) 90%(71-100%) 9 50%(22-78%) 100% 7 60%(30-90%) 100% 7 18%(0-41%) 86%(67-100%) 5 57%(21-94%) 90%(71-100%) 10 54%(35-73%) 92%(84-100%) 11 67%(13-100%) 91%(74-100%) 10 100% 48%(29-67%) 11 60%(17-100%) 71%(38-100%) 7 33%(7-60%) 67%(40-93%) 7 80%(45%-100%) 92%(78-100%) 10 67%(13-100%) 91%(74-100%) 10 36%(11-61%) 93%(86-100%) 7 100% 71%(38-100%) 7 100% 100% 10 78%(51-100%) 100% 10 20%(0-55%) 86%(60-100%) 13 67%(13-100%) 92%(76-100%) 9 67%(13-100%) 91%(74-100%) 10 67%(36-98%) 85%(72-99%) 10 38%(4-71%) 80%(63-98%) 11 52%(34-70%) 97%(93%-100%) 12 55%(31-57%) 68%(62-75%) 13 88%(65-100%) 62%(35-88%) 11 58%(42-74%) 75%(63-87%) 9 67%(40-93%) 92%(76-100%) 7 60%(30-90%) 78%(61-95%) 7 27%(1-54%) 71%(48-95%) 5 69%(52-87%) 71%(57-86%) 11 75%(51-100%) 81%(64-98%) 7 100% 64%(35-92%) 10 87%(70-100%) 85%(76-93%) 7 MRI and PET. The pooled estimates for specificity were 93% (87% ~ 97%), 81% (64 ~ 91%), 87% (77 ~ 93%) and 78% (71 ~ 83%) for CT, MRI, PET and US, respectively. There was no difference in QUADAS scores between the studied modalities (p > 0.05). Based on Bayesian theory and collected data with dif- ferent pre-examination probabilities, the post examin- ation positive and negative neck nodal probabilities were simulated (Table 3 and Figure 3). With pre-examination nodal metastasis set at 10%, 20% and 30%, the post-exam positive nodal metastasis probabilities were 47%, 66% and 77% for CT; 27%, 46% and 59% for MRI; 36%, 56% and 69% for PET; and 25%, 42% and 56% for US, re- spectively. The negative nodal metastasis probabilities were 95%, 89% and 82% for CT; 95%, 90% and 84% for MRI; 96%, 91% and 86% for PET; and 95%, 90% and 84% for US, respectively. Discussions In the development of treatment paradigms for cN0 neck, it is important to be aware that most patients with a cN0 neck presented no cancer cells in the cervical lymph nodes and that over-treating the neck should be avoided.