Ultrasound and CT Agreement for Non-Invasive ONSD Measurement: A Systematic Review and Meta-Analysis

Area of Science:

• Neuroimaging
• Ophthalmology
• Critical Care Medicine

Background:

• Optic nerve sheath diameter (ONSD) measurement is a key non-invasive technique for elevated intracranial pressure (ICP) monitoring.
• The concordance between ultrasonography (US) and computed tomography (CT) for ONSD measurement is not well-established.
• This study systematically reviews and meta-analyzes the agreement between US and CT for ONSD measurements in elevated ICP.

Purpose of the Study:

• To evaluate the concordance between US and CT for ONSD measurements in patients with elevated ICP.
• To determine if US and CT ONSD measurements are interchangeable in clinical practice.
• To synthesize pooled estimates of agreement and differences between US and CT ONSD measurements.

Main Methods:

• Systematic literature search of PubMed, Cochrane Library, and Lilacs databases.
• Inclusion of 8 non-randomized studies with 273 patients comparing simultaneous US and CT ONSD measurements.
• Application of a random-effects model for meta-analysis, assessing mean difference and inter-class correlation coefficient (ICC).

Main Results:

• Pooled mean difference between US and CT ONSD measurements was -0.07 mm (p=0.85), indicating no significant difference.
• Inter-class correlation coefficient (ICC) was 0.80, signifying substantial agreement between modalities.
• Bland-Altman analysis showed limits of agreement from -1.52 to 1.38 mm, with high heterogeneity observed.

Conclusions:

• Ultrasonography and computed tomography demonstrate general agreement in ONSD measurements for elevated ICP.
• Despite high heterogeneity, both modalities are comparable for ONSD assessment.
• US offers portability and radiation avoidance; CT is a reliable emergency alternative.