Ultrasonographic Optic Nerve Sheath Diameter Technical Pitfalls and Imaging Artifacts.

Area of Science:

• Neuroscience
• Medical Imaging
• Critical Care Medicine

Background:

• Ultrasonographic optic nerve sheath diameter (ONSD) is a valuable non-invasive surrogate for intracranial pressure (ICP) monitoring.
• Accurate ONSD assessment is crucial for timely clinical decision-making in various neurological conditions.

Purpose of the Study:

• To comprehensively review the impact of ultrasound settings on ONSD measurements.
• To identify and explain common imaging artifacts affecting ONSD assessment.
• To discuss intrinsic optic nerve sheath (ONS) properties influencing ultrasonographic evaluation.

Main Methods:

• Review of existing literature on ultrasound physics and ONSD assessment.
• Analysis of how specific ultrasound parameters (gain, dynamic range, frequency, harmonic imaging, focal zones) influence ONSD measurements.
• Categorization and description of imaging artifacts (e.g., shadowing, enhancement, comet tail, speckle, partial volume, refraction).

Main Results:

• Ultrasound settings like gain and frequency can significantly alter ONSD values.
• Acoustic shadowing, enhancement, and beam property artifacts can lead to inaccurate ONSD readings.
• Changes in ONS echogenicity and ONS kinking due to ICP variations present challenges in ONSD assessment.

Conclusions:

• Understanding the influence of ultrasound settings and artifacts is essential for reliable ONSD measurements.
• Careful technique and artifact recognition are critical for accurate non-invasive ICP assessment using ONSD.
• Further standardization of ONSD measurement protocols may improve its clinical utility.