A systematic review on volumetric analysis in orbital MRI

Area of Science:

• Ophthalmology
• Radiology
• Medical Imaging

Background:

• Volumetric analysis of orbital soft tissues via MRI provides critical insights into various orbital conditions.
• Optimal MRI protocols and post-processing techniques for orbital volumetry are not yet clearly defined.
• Understanding these technical variables is crucial for accurate interpretation of orbital MRI data.

Purpose of the Study:

• To systematically review MRI acquisition parameters and post-processing volumetry techniques for orbital soft tissues.
• To identify commonly analyzed orbital regions and assess the validation of volumetric methods.
• To provide a framework for future research and standardization in orbital MRI volumetry.

Main Methods:

• Systematic literature search conducted in PubMed/MEDLINE, Web of Science, and Cochrane Library up to November 2024.
• Adherence to PRISMA guidelines and prospective registration of the review.
• Analysis of primary outcomes including MRI acquisition parameters, volumetry techniques, and regions of interest (ROI), alongside secondary outcomes on clinical relevance and validation.

Main Results:

• Thirty-five articles were included from 4323 records, revealing significant heterogeneity in MRI acquisition and post-processing methods.
• Extraocular muscles and orbital fat were the most frequent targets for volumetry, with considerable variation in ROI definitions.
• Validation of volumetric methods was infrequent, and analysis of other orbital structures like the globe and optic nerve was less common.

Conclusions:

• Heterogeneity in MRI acquisition and processing complicates the interpretation of orbital soft tissue volumetry.
• Standardization of MRI protocols, validated segmentation techniques, and automated volumetry are necessary for improved reproducibility.
• This systematic review offers a foundational understanding to guide future advancements in orbital MRI volumetry for clinical practice.