Detection accuracy of maxillary sinus floor septa in panoramic radiographs using CBCT as gold standard: a multi-observer receiver operating characteristic (ROC) study.

OBJECTIVES: To investigate diagnostic accuracy of panoramic radiography in detecting maxillary sinus floor septa by means of a multi-observer receiver operating characteristic (ROC) analysis and a standardized protocol for reporting (STARD protocol; Clin Chem 49(1):1-6, 2003). MATERIAL AND METHODS: From our database, 25 cone beam computed tomographies (CBCTs) were selected with one maxillary sinus floor septum (height ≥ 2.5 mm). For the same patient, a recent panoramic radiograph (PAN) had to be available in the database. As controls, 28 CBCTs plus corresponding PANs without evidence of a sinus septum were selected. Using the CBCTs as ground truth, 17 observers from our dental school on a five-point confidence scale rated both sinuses in all 53 PANs with respect to presence/absence of a sinus septum. Areas beneath ROC curves (Az-values), sensitivity/specificity (SNT/SPF), positive/negative predictive values (PPV, NPV), and positive/negative likelihood ratios (LR+, LR-) were computed for each observer and pooled over all observers. Inter-rater reproducibility was assessed by means of the intraclass coefficient (ICC) using a two-way random effects model. RESULTS: A pooled Az-value of 0.839 was observed (SNT 84.6%, SPF 73.5%). PPV ranged between 0.492 and 0.824 (median 0.627) and NPV between 0.838 and 0.976 (median 0.917). A median LR+ of 3.567 was computed (LR- median 0.193). Inter-rater reliability revealed an ICC of 0.55 (95% confidence interval 0.48 to 0.62). CONCLUSIONS: Our results indicate that PAN is a moderately accurate method for sinus elevation planning for the purpose of septum detection. Ruling out a septum by PAN seems to work more accurately than ruling in. CLINICAL RELEVANCE: For the purpose of maxillary sinus floor septa detection, panoramic radiography can be relatively safely advocated, particularly for judgment of a septum-free sinus.