Is Contrast-Enhanced Computed Tomography Redundant for Suspected Intracranial Infection in the Emergency Setting?

Area of Science:

• Neuroradiology
• Infectious Disease Imaging
• Medical Imaging Analysis

Background:

• Guidelines for contrast use in head CT for acute intracranial infection are lacking.
• Contrast-enhanced CT is often used despite its limitations in certain scenarios.
• Magnetic resonance imaging (MRI) is the gold standard for central nervous system pathology.

Purpose of the Study:

• To determine the frequency of conspicuous noncontrast CT findings correlating with contrast-enhanced CT abnormalities in acute intracranial infections.
• To assess the diagnostic utility of noncontrast CT in identifying potential infections requiring further MRI.

Main Methods:

• Retrospective review of head CT scans (noncontrast and contrast-enhanced) from 2004-2021.
• Exclusion of patients with prior head surgery or cancer history.
• Analysis of noncontrast CT for vasogenic edema or mass effect, and contrast CT for enhancing abnormalities, with chart review for diagnosis confirmation.

Main Results:

• 11.3% (39/343) of patients had acute infections with enhancing CT findings.
• 32 of these 39 patients had correlative noncontrast CT findings (vasogenic edema or mass effect).
• Noncontrast CT demonstrated high accuracy (98.0%) for detecting infection markers, with sensitivity of 82.1% and specificity of 100%.

Conclusions:

• Contrast-enhanced head CT is largely redundant for suspected acute intracranial infections, as noncontrast CT often reveals sufficient findings.
• Noncontrast CT findings can independently indicate the need for further MRI evaluation in most cases.
• Contrast-enhanced CT offers primary benefit when confluent white matter changes obscure noncontrast findings.