The diagnostic performance of ultrasonography and computerized tomography in differentiating superficial from deep lobe parotid tumours

Abstract

Objectives To validate and compare ultrasound (US) versus computerized tomography (CT) criteria in the localisation of superficial/deep lobe tumours of the parotid gland. Design and setting This was a retrospective study of diagnostic tests performed from January 2008 to June 2017. Participants We included adult patients who were referred for a neck ultrasonography examination due to parotid tumours, and who subsequently underwent parotid surgery. Main outcome measures We assessed the location of parotid tumours, comparing the minimum fascia‐tumour distance (MFTD) criterion on an US with eight CT criteria. We analysed receiver operating characteristic (ROC) curves of the MFTD for malignant, benign, and all parotid tumours, and compared the accuracy, sensitivity, and specificity of the optimal MFTD with those of CT anatomical criteria. Results A total of 166 parotid tumours were included. The mean (SD) MFTD in superficial lobe tumours was significantly shorter than that of deep lobe tumours (1.2 [0.7] vs 2.8 [1.9] mm, effect size: 1.84; 95% CI, 1.27‐2.41). The areas under the ROC curve were 0.63 for malignant tumours and 0.88 for benign tumours. The optimal MFTD cut point was 2.4 mm for the 154 benign parotid tumours, and the accuracy, sensitivity and specificity were 90%, 80% and 91%, respectively. For the 136 benign parotid tumours that underwent CT examination, three criteria had an accuracy of over 90% (FNline, tMasseter and Conn's arc), but the sensitivities were all below 50%. Conclusions Minimum fascia‐tumour distance is more feasible for benign tumours than for malignant tumours for the localisation of parotid tumours. For benign parotid tumours, US is enough to guide operations.

Ultrasonography techniques in the preoperative diagnosis of parotid gland tumors – an updated review of the literature

“…Cheng et al (2019) showed that the US assessment of the minimum distance between the parotid fascia and the parotid tumor (MFTD) with a cutoff value of 2.4 mm can be used to differentiate the location of benign tumors in the parotid gland; distance of less than 2.4 mm correlates with the tumor localization in the superficial lobe of the parotid gland [22]. On the other hand, for a more precise and objective localization of tumors in the parotid glands with the help of the US, a schematic diagram based on marking the tumor location in relation to the external ear structures was proposed.…”

Ultrasound can help to indirectly predict contact of parotid tumors to the facial nerve, correct intraglandular localization, and appropriate surgical technique

“…The diagnostic accuracy of our procedure is superior compared to the existing studies . Lesion contact with the FN and localizing the lesion in the correct lobe were correctly predicted in 96% of the patients.…”

“…The diagnostic accuracy of our procedure is superior compared to the existing studies. [11][12][13][14]24 Lesion contact with the FN and localizing the lesion in the correct lobe were correctly predicted in 96% of the patients. As the FN is the boundary between the superficial lobe and the DL of the parotid gland, accurately localizing the nerve is crucial for predicting the correct lobe.…”

“…Furthermore, tumors more than 3 mm from the surface of the parotid gland have an increased probability of being in the DL. 23,24 This multifactorial assessment based on US examination improves the diagnostic accuracy but is sometimes time consuming and requires an experienced investigator. The diagnostic accuracy of our procedure is superior compared to the existing studies.…”

A Novel Sonographic Scoring Model in the Prediction of Major Salivary Gland Tumors

“…US, which has the advantage of being safe, widely available, easily performed, and low cost, is usually the first tool used to evaluate major salivary gland tumors in Taiwan. 14,15 Furthermore, in-office US operated by the surgeon, who is familiar with the patient's history and physical exam findings, has become more and more common. After the real-time imaging and evaluating the characteristics of the tumor, the surgeon can make an immediate assessment for the patient.…”