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E2376. Digging Around Dorello's Canal: A Pictorial Review of Petrous Apex Pathology
Authors
  1. Gianna DiGrazia; Loyola University Medical Center
  2. Mariah Bashir; Loyola University Medical Center
Background
The importance of the petrous apex and surrounding structures dates back to the early 1800s when first described by the anatomist Wenzel Gruber and eventually in the early 1900s by Primo Dorello. This anatomically dense region remains relevant today to radiologists as a variety of anatomic variants and pathologic entities can arise from this region. The contents of the petrous apex can be considered a blind spot on CT imaging, however MRI has revealed some of the very important structures traversing this area and is useful in evaluating pathology. A pictorial review of the normal anatomy, anatomic variants, and imaging characteristics of various common petrous apex lesions will make identifying lesions in this area an easier, more predictable task.

Educational Goals / Teaching Points
-Review the history and discovery of the petrous apex, including Dorello's Canal. -Review the anatomy of the petrous apex including important bony landmarks, traversing vascular structures and cranial nerves. -Discuss normal anatomic variants of the petrous apex. -Review potential clinical features of petrous apex lesions. -Discuss the high yield differential diagnosis of lesions in the petrous apex including a pictorial review using CT and MR imaging.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Petrous apex anatomy. Petrous apex anatomic variations on CT and MR. Imaging appearance on CT and MR of common lesions arising from the petrous apex, including cholesterol granulomas, cholesteatomas, mucoceles, cehaloceles, endolymphatic sac tumor, petrous apicitis, meningioma, schwannoma, paraganglioma, chondroma, chordoma, chondrosarcoma, petrous carotid aneurysm.

Conclusion
This educational exhibit reviews the anatomically dense petrous apex. Understanding of the basic anatomy and key imaging features of petrous apex lesions will aid in detecting subtle findings needed to diagnosis pathology in this difficult to image region. A variety of pathologic processes were discussed in order to help formulate broad differential diagnoses when faced with lesions in the petrous apex. On completion of this exhibit, the reader should feel confident in making diagnoses of common lesions in the petrous apex.