Non-invasive Assessment of in Vivo Auricular Cartilage by Ultra-short Echo Time (UTE) $$T_{2}^{*}$$ Mapping

Abstract

In this paper, Ultra-short Echo Time (UTE) \(T_{2}^{*}\) mapping is proposed to non-invasively evaluate auricular cartilages from volunteers and donated bodies. The mono- and bi-exponential models were used for mono- and bi-component analysis (short component \(T_{2}^{*}\) and long component \(T_{2}^{*}\)) respectively. The external ears were manually segmented from images and then reconstructed into 3D \(T_{2}^{*}\) mappings. In the mono-component analysis, the mean \(T_{2}^{*}\) value for 3 volunteers was 34.987 ± 2.266 ms. As for results from the bi-component analysis, the mean values for 3 volunteers were 8.992 ± 0.466 ms and 53.648 ± 1.961 ms for short component \(T_{2}^{*}\) and long component \(T_{2}^{*}\) respectively, with the ratio of bound water to free water of 0.464 ± 0.020. The bi-exponential fitting model performed better than the mono-exponential fitting model on the curve fitting in volunteers, with \(R^{2}\)[bi] = 0.999 ± 0.131 vs. \(R^{2}\)[mono] = 0.972 ± 0.144. According to the bi-component analysis from donated specimens of auricular cartilage, the ratio of bound water to free water was 0.023 ± 0.018, which was significantly different from that of volunteers (p < 0.01), but the fitting curves of specimens showed similar findings with volunteers, with \(R^{2}\)[bi] = 0.999 ± 0.001 vs. \(R^{2}\)[mono] = 0.903 ± 0.005. Our preliminary results demonstrated that the proposed UTE \(T_{2}^{*}\) mapping is a feasible non-invasive means for evaluating the development of auricular cartilage scaffold with bio-inks in reconstructive surgery using 3D bioprinting technique.