In vivo morphological characterisation of skin by MRI micro-imaging methods.

Background/purpose: Quantitative assessments in skin layers using images obtained with standard magnetic resonance imaging (MRI) sequences are limited, since the stratum corneum and dermis, the layers of most clinical interest, have low signal due to their short spin-spin relaxation, T2.

Methods: In the present work, different methods of MRI contrast, such as magnetisation transfer contrast (MTC), T1-weighting (where T1 is spin-lattice relaxation time), T2*-weighting (where T2* is the combination of T2 and magnetic field in-homogeneity effect) and chemical shift, were used. These techniques were combined with high-resolution MRI.

Results: We found that skin is a very MT active tissue, and MTC provides data enabling the evaluation of how the tissue in skin layers interacts with the interstitial fluids. Details obtained from high-resolution high-quality in vivo skin images with different contrast allowed for differentiation of skin layers, sub-layers and excellent correlation of MR data with known histological features and water constituent of skin layers.

Conclusion: Combining MT and other MRI data employing other contrast mechanisms provides a superior non-invasive in vivo technique for visualisation and also quantitative assessment of the constituents of the stratum corneum, epidermis, papillary dermis, reticular dermis and hypodermis as major structural layers of the skin. This type of study can be extended to cutaneous disease states or skin ageing, where defects in water mobility, concentration and/or macromolecular structural changes are expected.