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\u2019s 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 (median correlation r = 0.9). 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 confirmed that many pathologically relevant features 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 accessible adjunct to histopathology for thyroid lesion characterization.