Utility of diffusion-weighted imaging to differentiate benign and malignant solid orbital tumours

Area of Science:

• Ophthalmology
• Radiology
• Oncology

Background:

• Orbital tumors require accurate differentiation between benign and malignant types for appropriate management.
• Diffusion-weighted imaging (DWI) offers a non-invasive method to assess tissue characteristics.
• Apparent diffusion coefficients (ADCs) derived from DWI can potentially distinguish tumor types.

Purpose of the Study:

• To evaluate the utility of apparent diffusion coefficients (ADCs) in differentiating benign from malignant orbital tumors.
• To validate previously observed ADC cut-off values in a clinical setting.
• To assess the reliability and accuracy of ADC measurements by non-radiologists.

Main Methods:

• Retrospective review of biopsy-confirmed orbital tumors.
• Blinded measurement of tumor ADCs by oculoplastic surgeons, a neuroradiologist, and a medical student using the Region of Interest tool.
• Comparison of non-radiologist measurements for reliability and with expert neuroradiologist measurements and pathology for accuracy.

Main Results:

• Twenty-nine orbital tumors (6 benign, 23 malignant) were analyzed.
• Mean ADC values were significantly different between benign (1430.59 ± 254.81) and malignant (798.68 ± 309.12) tumors.
• An optimized ADC cut-off of 1120.84 × 10⁻⁶ mm²/s achieved 100% sensitivity and 90% specificity; inter-rater reliability was excellent (ICC=0.92).

Conclusions:

• Apparent diffusion coefficients (ADCs) can reliably differentiate benign and malignant orbital tumors.
• A validated ADC cut-off value aids in risk stratification of orbital tumors.
• Oculoplastic surgeons can effectively utilize ADC measurements in clinic to guide patient management and further investigations.