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Diagnostic Imaging of Diseases of the Skull
Shannon P. Holmes

Animal Cross-Sectional Imaging Specialists, Athens, GA, USA

Diagnostic imaging of the feline skull can be challenging The necessary additional radiographs will depend on the
partly because of its small size. Additionally, the paired disease process being investigated. For example, an oblique
bones of the skull have a complex organization into differ- rostroventral‐caudodorsal open‐mouth radiograph centered
ent anatomic systems, such as the nasal and oral cavities, on the nasal cavity allows evaluation of this region without
calvarial vault, and pharyngeal‐laryngeal region. A large superimposition of the mandible. The most common use of
number of soft tissue systems are condensed into and radiography of the skull in general veterinary practice is
around the osseous anatomy, which further adds to the dental radiography. The teeth are a good example of more
anatomic complexity of the skull. A system‐based approach peripherally located anatomy that can be evaluated with
to diagnostic imaging of the feline skull for evaluation of radiography because the superimposition of structures can
nonneurologic diseases is presented in this chapter, such as be omitted or diminished. In canine patients, similar accu-
diseases specific to the dentition, oral and nasal cavities, racy in diagnosing otitis media has been demonstrated with
and ears. Imaging of the skull typically implements radiog- the use of radiography and CT [4]. The tympanic bullae are
raphy and, increasingly, computed tomography (CT) and also a ventral and peripheral structure that can be highlighted
magnetic resonance imaging (MRI). in radiographs. Superimposition is the major limitation of
Radiography is more economical than cross‐sectional this modality in evaluating the skull, which is eliminated
imaging. It may be diagnostic for diseases of the skull, but with cross‐sectional imaging modalities.
only if care is taken to position the skull with symmetry of The increased availability of CT and MRI has reduced
the anatomy that is critical for the interpretation. A mini- the number of radiographic examinations of the skull per-
mal examination of the feline skull should consist of ven- formed in veterinary medicine. However, the superior
trodorsal (VD)/dorsoventral (DV), lateral and opposite accuracy of these modalities is the main reason radiogra-
oblique lateral radiographs (Figure 5.1) [1, 2]. General phy is infrequently used in the evaluation of the skull in
anesthesia or heavy sedation is recommended for optimal veterinary medicine [5, 6]. They have proven to be more
radiographic imaging of the skull to obtain symmetric sensitive than radiography for the assessment of nasal dis-
positioning and make minor adjustments without the ease, abnormalities in the caudal maxillary and mandibu-
patient moving between radiographic exposures. lar regions and in cases of head trauma (Figure 5.4) [7–10].
Additionally, the skull can be manipulated to remove or CT can be performed on awake or lightly sedated patients,
diminish superimposition of structures, allowing for evalu- especially with the technologic development of multidetec-
ation of specific anatomy (i.e., open‐mouth radiography for tor CT units [11–13]. It has also been suggested as a supe-
dental evaluation or oblique head positioning to evaluate a rior first‐line diagnostic for nasal disease [14]. MRI requires
specific area like the tympanic bullae) (Figure 5.2) [3]. general anesthesia to prevent patient motion and takes
Subtle asymmetry can lead to misdiagnosis through the longer than CT. With the advent of three‐dimensional
artifactual generation of increased opacity in normally printing, CT has the added benefit of providing printed
aerated regions (Figure 5.3). models of the feline skull for surgical planning in complex
Because of the complexity of the skull and the need to min- cases of oral and maxillofacial surgery, as well as depicting
imize superimposition or highlight anatomic regions, a large abnormalities in a manner that is more understandable for
number of radiographic projections have been developed. clients [15].

Feline Diagnostic Imaging, First Edition. Edited by Merrilee Holland and Judith Hudson.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.