Ultrasound imaging for the differential diagnosis of periapical lesions of endodontic origin in comparison with histopathology - a systematic review and meta-analysis

Background Differentiating periapical lesions is important for treatment planning and subsequent treatment outcome. Objective To assess the diagnostic accuracy of ultrasound imaging for the differentiation of periapical lesions in comparison with histopathology. Methods PubMed, Scopus, Embase, Web of Science and ProQuest databases were searched for clinical studies published until June 2020 that evaluated the use of ultrasound (US) imaging for differential diagnosis of periapical lesions and used histopathology as the reference standard. Animal studies, laboratory-based studies, reviews and clinical studies not using a reference standard were excluded. Risk of bias (RoB) assessment was performed using a modified Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. The random effects model was used for quantitative analysis of the data, and the Deeks test was used for calculating publication bias. Quality of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE). Results Twelve articles were included in the systematic review, out of which ten articles were quantitatively assessed. All the articles had a high RoB and concerns regarding applicability in the patient selection domain. For the index test domain, seven articles had low and the remaining five had unclear RoB and concerns regarding applicability. In the reference standard domain, low RoB and concerns regarding applicability were observed for all the articles. The RoB was low in flow and timing domains in all the articles except for one, where it was high. Summary estimates of sensitivity and specificity of US to diagnose periapical granulomas were 0.94 and 0.98, whereas for periapical cysts it was 0.98 and 0.99, respectively. Area under the curve for diagnosis of both periapical granulomas and periapical cysts was 0.99. All the included articles had inherent publication bias. Quality of evidence using GRADE, for sensitivity, was moderate for periapical granulomas and high for periapical cysts, whereas for specificity, it was high for periapical granulomas and low for periapical cysts. Discussion The available evidence is considered to be of low quality due to the observational nature of the studies and inherent publication bias. Conclusion Although the sensitivity and specificity for differentiating periapical cysts and periapical granulomas using US were high, taking the quality of evidence into consideration, it can serve as an additional tool in differential diagnosis of periapical lesions.