Objective: To assess the diagnostic utility of various radiologic criteria such as the lateral margin or dislocation of the retromandibular vein (RMV), Utrecht line, facial nerve line, Conn's arc, lines passing from the lateral margin of the masseter muscle to the facial nerve trunk or RMV, minimum distance from the fascia to the tumor (MDFT), and direct tracing of the intraparotid facial nerve (DT) for differentiating a parotid deep lobe tumor from a superficial lobe tumor.
Methods: Twenty-one studies with 2225 participants from PubMed, Embase, Web of Science, Cochrane Library, SCOPUS, and Google Scholar up to March 2022 were analyzed. Sensitivity, specificity, and negative and positive predictive values of the methods were extracted.
Results: The diagnostic odds ratio (DOR) of radiologic criteria compared to surgical findings was 18.9109. The area under the summary receiver operating characteristic curve was 0.879. The sensitivity and specificity were 0.6663 and 0.9190. MDFT (DOR 61.2917) and DT (DOR 91.9883) showed superior results as diagnostic landmarks. For tumors crossing the anatomical criteria line, strict way (any tumor crossing the line) could help differentiate a deep lobe tumor more accurately than conventional way (> 50% of the tumor volume located medial to the line).
Conclusion: Various radiologic criteria, especially MDFT and DT, showed good diagnostic accuracy for differentiating a parotid deep lobe tumor.
Keywords: CT; Deep lobe parotidectomy; Facial nerve; MRI; Parotid gland; US.
© 2022. Italian Society of Medical Radiology.