Skull radiography remains a relatively common procedure in veterinary practice. In the past, radiographs were the imaging modality of choice by default. However, advances in imaging have resulted in skull radiography being replaced by CT examination of the skull. While skull radiographs are difficult to obtain and rarely yield a definitive diagnosis for disorders of the nasal cavity and ear canal, CT examination has improved early disease diagnosis particularly for nasal disease.

The reason CT is superior to radiographic evaluation is because axial imaging (CT) can demonstrate bone and soft tissue change earlier than radiographs. Previous studies have shown that a 30-50% change in bone density is required before it is visible radiographically. This number is significantly lower for CT. Conversely, if a radiographic skull series is normal significant disease may be present.

Skull radiography is also difficult and time consuming. General anesthesia is an absolute requirement. A 5 view study is necessary to begin to evaluate the nasal cavity and inner ear. These advanced radiographic views are rarely performed in most veterinary practices so numerous repeats are necessary to obtain diagnostic images of the skull.

Interpreting skull radiographs is also difficult. Artifacts created by oblique projections will mimic pathology so it is often impossible to draw meaningful conclusions from suboptimal skull radiographs.

In short, skull radiography is an expensive radiographic study that often results in frustration and the need to perform a skull CT for a definitive diagnosis.

CT imaging of the skull is far superior to skull radiographs. Technically, skull CT is simple to perform. With newer helical CT scanners, a CT examination of the skull can be performed in a fraction of the time it takes to obtain proper skull radiographs which significantly reduces anesthesia time. The most important consideration when recommending a CT is knowing that the study will be diagnostic. A partial list of cases that may benefit from a skull CT are:

• Nasal discharge
• Facial deformity
• Facial trauma
• Exophthalmia
• Epistaxis

Fortunately, outpatient CT imaging of the skull is becoming more available. Outpatient imaging centers are becoming more common in veterinary medicine. Additionally, many referral hospitals offer CT imaging of the skull. If CT is available in your area you might decide to think twice before you spend your clients money on skull radiographs that may not be diagnostic.