Characterization of diffuse orbital mass using Apparent diffusion coefficient in 3-tesla MRI.

Area of Science:

• Radiology
• Oncology
• Ophthalmology

Background:

• Orbital masses present a diagnostic challenge.
• Accurate characterization is crucial for appropriate management.
• Diffusion-weighted MRI offers potential for improved tissue characterization.

Purpose of the Study:

• To assess the diagnostic accuracy of apparent diffusion coefficient (ADC) values in diffusion-weighted magnetic resonance imaging (DW-MRI) for diffuse orbital masses.
• To determine if ADC improves the differentiation between benign and malignant orbital lesions.

Main Methods:

• Retrospective analysis of 39 diffuse orbital masses evaluated with ADC DW-MRI between 2000 and 2015.
• Lesions were histopathologically classified as benign, pre-malignant, or malignant.
• Lymphoproliferative lesions were further subcategorized into lymphoma and other lymphoproliferative types.
• ADC values were compared between diagnostic groups, and the area under the curve (AUC) was calculated.

Main Results:

• Statistically significant differences in median ADC values were observed between malignant tumors (0.58 × 10^(-3) mm⁽²⁾/s) and benign lesions (1.19 × 10^(-3) mm⁽²⁾/s) (P < 0.001).
• ADC values also differed significantly between lymphomas (0.51 × 10^(-3) mm⁽²⁾/s) and other lymphoproliferative lesions (0.9 × 10^(-3) mm⁽²⁾/s) (P = 0.02).
• An ADC threshold of 0.8 × 10^(-3) mm⁽²⁾/s demonstrated 87% sensitivity, 67% specificity, and 88% accuracy in distinguishing malignant from benign masses.

Conclusions:

• ADC is a valuable imaging biomarker for characterizing diffuse orbital masses.
• It aids in differentiating malignant from benign lesions with high accuracy.
• ADC can also help distinguish lymphomas from other non-lymphoproliferative orbital lesions.