In the Waters method for parietoacanthial projection of the paranasal sinuses, where should the petrous ridges be projected?

In the Waters method for imaging the paranasal sinuses, the positioning is crucial to ensure an accurate representation of the anatomy. The petrous ridges should be projected just below the maxillary sinuses when the patient is positioned correctly according to this technique. This positioning allows for optimal visualization of the maxillary sinuses, which lie directly below the petrous ridges.

By projecting the petrous ridges just below the maxillary sinuses, the radiologist can achieve a clear view of the sinuses while minimizing distortion and superimposition from other structures. This is important for diagnostic accuracy, as it directly impacts the assessment of sinus diseases or abnormalities such as infections or polyps.

The other options would not provide the necessary clarity or alignment. If the petrous ridges were at the level of the maxillary sinuses or above them, the maxillary sinuses would be obscured, complicating the interpretation of the radiographic image. Hence, positioning the petrous ridges just below the maxillary sinuses is essential for effective imaging in the Waters method.