Discriminating orbital lymphoma from inflammation and correlating with histopathology using microstructure-based...

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Preoperative differentiation between orbital B-cell lymphoma and inflammatory lesions is challenging with conventional imaging.
• Diffusion MRI (dMRI) shows promise, but advanced techniques are needed for improved diagnostic accuracy.

Purpose of the Study:

• To evaluate the potential of time-dependent diffusion MRI (td-dMRI) to enhance the differential diagnosis of orbital lesions.
• To correlate td-dMRI derived microstructural parameters with histopathological findings.

Main Methods:

• Prospective enrollment of 48 patients with suspected orbital tumors.
• Acquisition of td-dMRI data using oscillating and pulsed gradient spin-echo sequences on a 3T scanner.
• Derivation of microstructural parameters (cell diameter, cellularity, extracellular diffusivity, intracellular volume fraction) and correlation with histopathology.

Main Results:

• td-dMRI parameters demonstrated excellent interobserver agreement and strong correlations with histological metrics.
• Orbital lymphomas showed significantly lower ADC, cell diameter, and extracellular diffusivity, with higher intracellular volume fraction and cellularity compared to inflammatory lesions.
• Cellularity (AUC=0.87) and intracellular volume fraction (AUC=0.82) showed the highest diagnostic performance for differentiating lymphomas.

Conclusions:

• td-dMRI provides reproducible, histologically correlated biomarkers for differentiating orbital lymphoma from inflammatory lesions.
• This technique offers valuable non-invasive characterization for preoperative diagnosis and risk stratification of orbital lesions.
• td-dMRI complements conventional ADC-based assessments, improving diagnostic confidence.