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.
 陈佳鹏, 张蕾, 陈功, 等. 中国1993—1998年出生缺陷监测能力分析[J]. 中华流行病学杂志, 2006, 27(5):392-395.  Patel RS, Katzen BT. Autologous costochondral microtia reconstruction [J]. Facial Plastic Surgery, 2016, 32(02):188-198.  Mussi E, Furferi R, Volpe Y, et al. Ear reconstruction simulation: From handcrafting to 3D printing[J]. Bioengineering, 2019, 6(1):14-33.  Zhou Guangdong, Jiang Haiyue, Yin Zongqi, et al. In vitro regeneration of patient-specific ear-shaped cartilage and its first clinical application for auricular reconstruction[J]. EBioMedicine, 2018, 28(C):287-302.  Chen Zelong, Yan Chenggong, Yan Shina, et al. Non-invasive monitoring of in vivo hydrogel degradation and cartilage regeneration by multiparametric MR imaging[J]. Theranostics, 2018, 8(4):1146-1158.  Siriwanarangsun P, Statum S, Biswas R, et al. Ultrashort time to echo magnetic resonance techniques for the musculoskeletal system [J]. Quantitative Imaging in Medicine & Surgery, 2016, 6(6):731-743.  Chang EY, Du J, Chung C. UTE imaging in the musculoskeletal system [J]. Journal of Magnetic Resonance Imaging, 2015, 41(4):870-883.  万丽娣, 邵泓达, 汤光宇. MRI超短回波时间序列评价关节软骨的研究进展[J]. 国际医学放射学杂志, 2017, 40(4):424-427.  Mosher TJ, Smith HE, Collins C, et al. Change in knee cartilage T2 at MR imaging after running: A feasibility study[J]. Radiology, 2005, 234(1):245-249.  Hesper T, Hosalkar HS, Bittersohl D, et al. T2* mapping for articular cartilage assessment: Principles, current applications, and future prospects[J]. Skeletal Radiology, 2014, 43(10):1429-1445.  Williams A, Qian Y, Chu CR. UTE-T2* mapping of human articular cartilage in vivo: A repeatability assessment[J]. Osteoarthritis Cartilage, 2011, 19(1):84-88.  Shao H, Chang EY, Pauli C, et al. UTE bi-component analysis of T2* relaxation in articular cartilage[J]. Osteoarthritis & Cartilage, 2016, 24(2):364-373.  刘晓芳, 赵成.基于多模态MRI图像的耳软骨模型构建[J].中国生物医学工程学报, 2019, 38(6):711-718.  Tao H, Qiao Y, Hu Y, et al. Quantitative T2-mapping and T2-mapping evaluation of changes in cartilage matrix after acute anterior cruciate ligament rupture and the correlation between the results of both methods [J]. Biomed Res Int, 2018, 2018:7985672.  Bydder GM. The Agfa Mayneord lecture: MRI of short and ultrashort T2 and T*2 components of tissues, fluids and materials using clinical systems[J]. The British Journal of Radiology, 2011, 84(1008):1067-1082.  Juras V, Apprich S, Szomolanyi P, et al. Bi-exponential T2* analysis of healthy and diseased Achilles tendons: an in vivo preliminary magnetic resonance study and correlation with clinical score[J]. European Radiology, 2013, 23(10):2814-2822.  Weiger M, Pruessmann KP. Short-T2 MRI: Principles and recent advances[J]. Prog Nucl Magn Reson Spectrosc, 2019, 114-115:237-270.  Du J, Diaz E, Carl M, et al. Ultrashort echo time imaging with bicomponent analysis[J]. Magnetic Resonance in Medicine, 2012, 67(3):645-649.  Diaz E, Chung CB, Bae WC, et al. Ultrashort echo time spectroscopic imaging (UTESI): An efficient method for quantifying bound and free water[J]. NMR in Biomedicine, 2012, 25(1):161-168.  Zopf DA, Flanagan CL, Nasser HB, et al. Biomechanical evaluation of human and porcine Auricular cartilage[J]. The Laryngoscope, 2015, 125(8):E262-E268.  Kijowski R, Wilson JJ, Liu F. Bicomponent ultrashort echo time T2* analysis for assessment of patients with patellar tendinopathy[J]. Journal of Magnetic Resonance Imaging, 2017, 46(5):1441-1447.  Dula AN, Gochberg DF, Does MD. Optimal echo spacing for multi-echo imaging measurements of bi-exponential T2 relaxation [J]. Journal of Magnetic Resonance, 2009, 196(2):149-156.