Effectiveness of anatomic criteria for predicting parotid tumour location

Abstract

rMasseter and tMasseter were useful as anatomic landmarks to differentiate a parotid deep lobe tumour from a superficial lobe tumour.

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

“…Kurabayashi et al first compared the FNline with the tMasseter and the tRMV in 36 cases, and showed lower accuracy (81%) and sensitivity (13%) . Previous reports showed an accuracy ranging from 63% to 85% and a sensitivity ranging from 13% to 89% . Our results showed a higher accuracy (92%) than previous studies.…”

“…Among these three criteria, the tMasseter had the best performance, with an accuracy of 93% and a sensitivity of 40%. Previously reports of the tMasseter, which was proposed by Kurabayashi et al in 1993, showed an accuracy ranging from 86% to 92% and a sensitivity ranging from 44% to 63% . Despite its high accuracy, the low sensitivity made it a weak diagnostic criterion …”

“…TheConn's arc also had higher accuracy (93%), but had the lowest sensitivity (10%) in our study. The Conn's arc was first proposed by Conn et al in 1983, where reports showed the accuracy to range from 71% to 88% and the sensitivity to range from 11% to 77% . Possible reasons for its low sensitivity may be that large deep lobe tumours with radiuses of more than 8.5 mm would exceed the range of Conn's arc, and would thus be misclassified as a superficial lobe tumour.…”

“…However, visualisation of the parotid duct needs sialography or computerized tomography sialography, which are seldom performed now. In addition to the above criteria, Kim et al added the rMasseter (the straight line from the RMV to the lateral surface of the masseter muscle) and the FTM angle (the angle formed by the line from the tumour to the FN trunk and the line from the tumour to the lateral surface of the masseter muscle) . They compared these eight criteria and results showed superior accuracy for the rMasseter (85.5%) and the tMasseter (86.3%), although sensitivity was low for both (33.3% and 44.4%).…”

“…Some reports have used neck CT for evaluating the location of parotid tumours, [3][4][5][6][7][8][9][10][11][12][13] and many anatomical landmarks were reported. On a neck CT, the location of the facial nerve trunk is on the midpoint between the styloid process and the mastoid process on the upper CT section, and between the digastric muscle and the SCM muscle on the lower CT section.…”