Proton magnetic resonance and human thyroid neoplasia III. Ex vivo chemical-shift microimaging.

Magnetic-resonance chemical-shift microimaging, with a spatial resolution of 40 x 40 microns, is a modality which can detect alterations to cellular chemistry and hence markers of pathological processes in human tissue ex vivo. This technique was used as a chemical microscope to assess follicular thyroid neoplasms, lesions which are unsatisfactorily investigated using standard histopathological techniques or water-based magnetic-resonance imaging. The chemical-shift images at the methyl frequency (0.9 ppm) identify chemical heterogeneity in follicular tumors which are histologically homogeneous. The observed changes to cellular chemistry, detectable in foci of approximately 100 cells or less, support the existence of a preinvasive state hitherto unidentified by current pathological techniques.