On the Importance of Proper Window and Level Settings in Temporal Bone CT Imaging

During a discussion on temporal bone imaging, a group of resident trainees in otolaryngology were asked to corroborate the finding of a fracture in set of images that were supposed to be representative of a fracture involving the otic capsule.1 (Figure 1) Their comments included the following statements:“The image still does not clearly identify the fracture. It would have been better if the images were set to the optimal bone window configuration...” “The windowing must be of concern as well. The exposure setting for the non-magnified view is different from the magnified ones. One must observe consistent windowing in order to assess the fractures more accurately.” “...the images which demonstrate a closer look on the otic capsule areas are not rendered in the temporal bone window which makes it difficult to assess.”“...aside from lack of standard windowing...”

Imaging anatomy of the retrotympanum: variants and their surgical implications

The retrotympanic anatomy is complex and variable but has received little attention in the radiological literature. With advances in CT technology and the application of cone beam CT to temporal bone imaging, there is now a detailed depiction of the retrotympanic bony structures. With the increasing use of endoscopes in middle ear surgery, it is important for the radiologist to appreciate the nomenclature of the retrotympanic compartments in order to aid communication with the surgeon. For instance, in the context of cholesteatoma, clear imaging descriptions of retrotympanic variability and pathological involvement are valuable in pre-operative planning. The endoscopic anatomy has recently been described and the variants classified. The retrotympanum is divided into medial and lateral compartments with multiple described potential sinuses separated by bony crests. This pictorial review will describe the complex anatomy and variants of the retrotympanum. We will describe optimum reformatting techniques to demonstrate the structures of the retrotympanum and illustrate the associated anatomical landmarks and variants with CT. The implications of anatomical variants with regards to otologic surgery will be discussed.