Non-Invasive Measurement of Auricular Cartilage in vivo by UTE T2* Mapping
Li Xue, Zhang Weiwei*
State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
Abstract:This paper proposed to utilize MRI ultra-short echo time (UTE) imaging in conjunction with T2* mapping for image-based analysis ofin vivo auricular cartilage, exploring the technical feasibility of not only non-invasive imaging but also quantitative measurement of the biological components of auricular cartilage and providing innovative ideas for standardization and evaluation of advanced biotechnology-based microtia reconstruction and surgery. Firstly, in the presented method, 30 volunteers were imaged for the right-sided ear using the sequence of multiple echo times (TE) containing one UTE and five short TEs. Secondly, these multiple images for each volunteer were preprocessed with intra-rigid registration and then manual segmentation of auricular cartilage and the external ear (containing not only auricular cartilage but also surrounding tissues, e.g. skin, fat, and other soft tissues). Next, for each volunteer, the component analysis was carried out to calculate the T2* values in ROIs of auricular cartilage and external ear respectively, using both the mono- and bi-exponential models (short component T2* and long component T2*). Finally, both exponential models were used to fit the curves of the auricular cartilage intensityversus echo time. In the experiment of mono-component analysis of the 30 right-sided ears, the mean T2* value of external ear was(49.269±16.979) ms and the mean T2* value of segmented auricular cartilage was (23.799±9.629) ms. In the bi-component analysis, the mean short component T2* was (11.713±3.111) ms and the mean long component T2* was (65.128±13.132) ms for the external ear, while for the segmented auricular cartilage, the mean short component T2* was(5.577±1.830) ms and the mean long component T2* was(30.628±8.413) ms. There was a significant difference of T2*values calculated by both component analyses between the external ear and the auricular cartilage (P<0.05). The model with bi-exponential fitting outperformed the one with mono-exponential fitting with a better fitted curve and a calculated value of R2 [bi]=0.999 ± 0.001 vs R2 [mono]=0.905±0.014 (P <0.05). Our preliminary results demonstrated that the proposed UTE T2* mapping has shown to be a feasible non-invasive means for quantifying the auricular cartilage in vivo and a potential tool used to image and evaluate the complex of auricular cartilage with biomaterials in reconstructive surgery for microtia using tissue engineering or 3D bioprinting technique in the future.
李雪, 张唯唯. MRI超短回波时间成像序列结合T2*映射技术用于在体耳软骨无创检测[J]. 中国生物医学工程学报, 2020, 39(3): 271-279.
Li Xue, Zhang Weiwei. Non-Invasive Measurement of Auricular Cartilage in vivo by UTE T2* Mapping. Chinese Journal of Biomedical Engineering, 2020, 39(3): 271-279.
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