Microimaging of hairless rat skin by magnetic resonance at 900 MHz

Abstract

Purpose: Quantitative imaging of the rat skin was performed using magnetic resonance imaging (MRI) at 900 MHz. Materials and methods: A number of imaging techniques utilized for multiple contrast included magnetization transfer contrast, spin-lattice relaxation constant (T1-weighting), combination of T2-weighting with magnetic field inhomogeneity (T2*-weighting), magnetization transfer weighting and diffusion tensor weighting. These were used to obtain 2D slices and 3D multislice-multiecho images with high magnetic resonance contrast. These 2D and 3D imaging techniques were combined to achieve high-resolution MRI. Results: Oil-water phantom showed distinct fat-water contrast. The dermis and epidermis, including the stratum corneum remnants, of nude rat skin were distinct due to their proton magnetic resonance as a result of proton interactions with the skin interstitial tissue. Combined details obtained from high-resolution, high-quality ex vivo skin images with different multicontrast characteristics generated better differentiation of skin layers, sublayers and significant correlation (r 2 =0.4927 for MRI area, r 2 =0.3068 for histology area; Pb.0148) of MR data with co-registered histological areas of the epidermis as well as the hair follicle. Conclusion: The multiple contrast approach provided a noninvasive ex vivo MRI visualization with semi-quantitative assessment of the major skin structures including the stratum corneum remnants, epidermis, hair, papillary dermis, reticular dermis and hypodermis.

Perspectivas de futuro en láseres, nuevas tecnologías y nanotecnología en dermatología

“…El uso de la RMN en dermatología pertenece aún al campo de la experimentación, a pesar de que ya en los años noventa del siglo pasado multitud de publicaciones indicaban su uso potencial. Sin embargo, la capacidad de producción de campos magnéticos no superaba los 3 tesla (T), lo cual se traducía en una pobre definición de las imágenes, dada la baja señal generada por las células de la capa córnea y de la dermis en la resonancia convencional 21 . Parte de la investigación actual se ha centrado en el empleo de diversos contrastes, como, por ejemplo, el contraste de transferencia de magnetización (MT).…”

Robust optimal design of diffusion-weighted magnetic resonance experiments for skin microcirculation

“…At each step of the algorithm, the change from t to t + 1 along each coordinate in K h  S M is done by introducing: (18) stops when h i (t + 1) À h i (t) % 0 for i = 1,. . ., p and q m (t + 1) À q m (t) % 0 for m = 1,. .…”

“…Recent advances in hardware can help overcome low SNR limitations, such as dedicated surface receiver coil [8], hightemperature superconducting (HTS) receiver surface coils [15,16], high-field spectrometers [17,18] and single-sided NMR probes [19,20]. Recent in vivo MR skin studies have made significant progress in increasing the spatial resolution for imaging as well as localized spectroscopy.…”

“…From a pulse sequence programming point-of-view, stimulated-echo pulse sequences [34,33] or single-shot techniques with time-efficient interleaved multi-slice acquisition [18] may be used for DWMR to avoid an excessive drop of signal due to T Ã 2 relaxation. While apparent diffusion coefficients have been measured at a voxel size of 95 Â 95 Â 1000 lm 3 via DWMR in in vitro animal skin tissues in a 2 T clinical whole-body MRI system [35], microimaging at 21 T has been performed on hairless rat skin with spatial resolutions down to 19.5 Â 19.5 Â 300 lm 3 [17] and 15 Â 15 Â 40 lm 3 [18], and several NMR modalities-including DWMR imaging-were evaluated for their usefulness in distinguishing between different skin appendages (stratum corneum, epidermis, reticular dermis, papillary dermis, hair follicle and sebaceous gland).…”

Nanotoxicity Assessment toward the Applications of Carbon Nanotubes as a Small Biomolecule Carrier in Drug Delivery Systems

“…The MRI microimaging was performed before and after placing 10 nm CNT in glass capillaries at different intervals of 2, 4, 6 hours using scan parameters: TR/TE/flip angle = 750ms/ 4.18ms/25°, FOV/matrix size/spatial resolution = 2.6×3.4 cm/ 256×256/0.015 mm, and the inversion time (TI approximately 250 ms) set to null normal skin. Epidermis and hair follicle were measured [2].…”