Objectives
This study aimed to clarify the anatomical and CT imaging features of the parotid duct at the anterior portion near the orifice together with its surrounding structures and to determine appropriate CT slice thicknesses for depicting the duct.
Methods
Initially, two cadavers were dissected to clarify the relationship between the duct and its surrounding structures. Next, original urethane phantoms with 2- and 3-mm diameters were scanned. The resultant images were constructed at 0.5-, 2-, and 3-mm slice thicknesses and evaluated, taking the partial volume effect into account. Finally, axial CT images of 190 adult subjects (107 men; 83 women) were analyzed for the relationship between the duct and other structures, together with the types of duct curvature on the axial plane and the slice ranges for the duct’s run in the body axis direction.
Results
The facial vein, which could always be observed anteriorly to the parotid duct, appeared to be an effective anatomical landmark for identifying the duct. The zygomaticus major muscle and buccal fat pad capsule should be carefully differentiated from the duct. The phantom study revealed that 2-mm slice thickness was appropriate, and this was confirmed in the actual CT images with a high detection rate (98 %). The run of the parotid duct showed three types of curvature within ranges of four slices at 2-mm thickness.
Conclusions
On axial CT images constructed at ≤2-mm slice thicknesses, the parotid duct was sufficiently depicted and could be well identified from other structures by reference to the facial vein.