Chapter 22. Portable Computerized Axial Tomography Scanning

Introduction

While not widely accessible, portable computerized axial tomography (CT) scanning (Figure 22-1) has become available commercially and is ideal for the intensive care unit (ICU) patient, who may be at risk during transportation to and from the remotely located CT scanner.

Definitions and Terms

• ▪  Neurological emergency: Unexplained change in mental status, obtundation, or neurological deficit

Techniques

• ▪  CT scan with or without contrast is the standard approach to the radiographic determination of intracranial anatomy and pathology.
• ▪  Noncontrast CT can be used to reveal intracranial hemorrhage, large cerebrovascular events, skull trauma and evaluate ventricular size.
• ▪  Contrast enhancement is used to evaluate specific lesions which will become more apparent to the presence of contrast in the blood flowing through the lesion, that is, infection or tumor.

Clinical Pearls and Pitfalls

• ▪  Contrast dye may be unnecessary for certain patients and contraindicated for other (ie, renal insufficiency, contrast dye allergy).
• ▪  Contrast dye can cause afferent arteriolar vasospasm in the kidney, and patients with certain conditions (ie, diabetes, myeloma, renal insufficiency, dehydration, and congestive heart failure) are at increased risk.
• ▪  Prophylactic hydration reduces the risk of contrast nephropathy, as may prophylactic administration of N-acetylcysteine.

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