REAL DOUBLE IMAGES VS REAL DOUBLE OBJECTS: OBJECTS NEAR THE PANORAMIC CENTER OF ROTATION PATH PRESENT CONFUSING IMAGING RESULTS

Abstract

<h3>Background</h3> A 57-year-old male presented for routine dental care without symptoms. Panoramic imaging depicted a large, laminated radiopacity inferior to the right posterior mandible. A similar image was noted on the contralateral side with a blurred, mirrored orientation. A smaller radiopacity was seen medial to the left larger radiopacity; however, no similar radiopacity was seen on the right. A firm, palpable mass was detected along the right lateral neck clinically, with nothing noted on the left side. <h3>Objective</h3> The aim of this study was to explain the potentially confusing imaging results of a sialolith on the panoramic center of rotation path by reviewing panoramic imaging acquisition principles and comparison with cone beam computed tomography (CBCT) results. <h3>Materials and Methods</h3> Panoramic images and a CBCT volume were acquired for implant planning purposes and for definitive assessment of the initial differential diagnosis based on the panoramic images. <h3>Results</h3> Multiple unilateral vs bilateral sialoliths, tonsilloliths, and calcified lymph nodes were considered after initial panoramic acquisition. CBCT confirmed a large sialolith on the right, with an additional, smaller sialolith in a slightly more anterior location on the left. Because of lack of symptoms, no treatment was recommended, and only periodic follow-up was suggested. <h3>Discussion</h3> Although the formation of real single, real double, and ghost images may be easy to understand, distinguishing among these entities sometimes may be challenging. The double-image area is not confined solely to the midline, and the area expands laterally, depending on the diverging path of the center of rotation. A large sialolith on the right side positioned in the lateroposterior aspect of the double-image area yielded a double image on the contralateral side with a mirrored orientation and similar proportions. The left sialolith yielded only a real single image due to the small difference of the anterior position. Objects just anterior to the double image area, but outside the focal trough, may have a similar blurred appearance to a real double image projected from the contralateral side. Recognizing the wider region of the double-image area, as well as proper patient positioning, is important for accurate diagnosis of real double images vs real double objects.