Spectral virtual histology of thyroid specimens with a compact laboratory X-ray system.

Iodine plays a central role in thyroid physiology, and knowledge of its spatial distribution may aid diagnostic framing and follow-up of neoplastic thyroid pathologies. Conventional histology is the gold standard for thyroid assessment but consumes biological material, limiting volumetric context and further analyses, and offers limited specificity for iodine. We present a virtual histology (VH) workflow using a compact microtomography X-ray system with a small-pixel spectral detector, combining phase-contrast and spectral imaging to produce volumetric iodine maps together with morphological images. Four formalin-fixed, paraffin-embedded human thyroid specimens (benign and malignant neoplasms and Hashimoto's thyroiditis) were imaged with this system and benchmarked against a synchrotron reference. The voxel-wise comparison showed strong agreement between laboratory and synchrotron iodine maps (mean correlation r = 0.89, range from 0.75 to 0.96). Average iodine content varied among samples (about 0.25 to 1.15 mg/ml), while discrepancies between laboratory and synchrotron quantification were always below 20%. Comparison with conventional histology indicates that pathologically relevant features, such as distinction between lesion and normal parenchyma, macrofollicles, thyroid capsule, capsular invasion, are visible in spectral VH. This work shows that laboratory spectral VH non-destructively provides volumetric morphology and iodine quantification with fidelity close to synchrotron measurements, and holds promise as an adjunct to histopathology for thyroid lesion characterization.