The clinical value of three-dimensional measurement in the diagnosis of thoracic myelopathy caused by ossification of the ligamentum flavum.

BACKGROUND: Thoracic ossification of the ligamentum flavum (OLF) is a major cause of thoracic myelopathy, which is often accompanied by multiple segmental stenosis or other degenerative spinal diseases. However, in the above situations, it is difficult to determine the exact segment responsible. The objective of this study was to analyze three-dimensional (3D) radiological parameters in order to establish a novel diagnostic method for discriminating the responsible segment in OLF-induced thoracic myelopathy, and to evaluate its superiority compared to the conventional diagnostic methods. METHODS: Eighty-one patients who underwent surgery for thoracic myelopathy caused by OLF from 2016 to 2020 were enrolled in this study as the myelopathy group, and 79 patients who had thoracic OLF but displayed no definite neurological signs from 2018 to 2020 were enrolled as the non-myelopathy group. We measured the one-dimensional (1D), two-dimensional (2D), and 3D radiological parameters, calculated their optimal cutoff values, and compared their diagnostic values. RESULTS: Significant differences were observed in the 1D, 2D, and 3D radiological parameters between the myelopathy and non-myelopathy groups (P<0.01). As a 3D radiological parameter, the OLF volume (OLFV) ratio (OLFV ratio = OLFV/normal canal volume × 100%) was the most accurate parameter for diagnosing OLF-induced thoracic myelopathy, with a diagnostic coincidence rate of 88.1%. We also found that an OLFV ratio of 26.3% could be used as the optimal cutoff value, with a sensitivity of 87.7% and a specificity of 88.6%. Moreover, the OLFV ratio [area under the curve (AUC): 0.92, 95% confidence interval (CI): 0.86-0.95] showed a statistically higher diagnostic value than the 1D and 2D parameters (AUC: 0.75, 95% CI: 0.67-0.81; AUC: 0.84, 95% CI: 0.77-0.89, respectively) (P<0.05). Pearson correlation analysis illustrated that the OLFV ratio was significantly negatively correlated with preoperative modified Japanese Orthopedic Association (mJOA) score (r=-0.73, 95% CI: -0.81 to -0.60, P<0.01). CONCLUSIONS: Our results demonstrate the superiority of the OLFV ratio over the conventional 1D and 2D computed tomography (CT)-based radiological parameters for the diagnosis of OLF-induced thoracic myelopathy. The novel diagnostic method based on the OLFV ratio will help to determine the responsible segment in multi-segmental thoracic OLF or when thoracic OLF coexists with other degenerative spinal diseases. The OLFV ratio also accurately reflects the clinical state of symptomatic patients with thoracic OLF.

Synthesis and photoluminescent properties of NaYF4:Eu3+ core and NaYF4:Eu3+/NaYF4 core/shell nanocrystals.

NaYF4:Eu3+ core and NaYF4:Eu3+/NaYF4 core/shell nanocrystals (NCs) were synthesized via a wet chemical method. The transmission electron microscope photographs show that the core and core/shell nanoparticles are monodisperse and uniform NCs with average diameters of 22 and 26 nm respectively. The photoluminescence (PL) properties of the samples, including the PL excitation and emission spectra, and luminescent decay curves, are investigated in detail. The results show that the intensity of 5D2 emission relative to that of 5D0 is stronger in NaYF4:Eu3+/NaYF4 core/shell NCs than that in NaYF4:Eu3+ core NCs, and a longer decay lifetime of 5D2 is observed in core/shell samples. In addition, from the corrected emission spectra of 5D0, the 5D0 radiative lifetimes were calculated. These together with the measured decay lifetime of 5D0 emission give the intrinsic quantum yields of 5D0. The results were well interpreted by considering the surface effects.

[Preparation of Y2O3:Er3+ by coprecipitation method and influence of initial pH on the luminescent properties].

Samples of Y2O3:1%Er were prepared by coprecipitation method and the pH value of precipitant ammonium bicarbonate was adjusted by ammonia. Results of Fourier transform infrared spectra (FTIR) and elemental analysis showed that the chemical construction of precursors at pH range of 8.0-9.5 had little change. By X-ray fluorescence spectrometer (XRF) and scanning electron microscope (SEM) analysis, it was found that the pH value of precipitant had a significant impact on the content of erbium in precursor and it can influence particle size as well as its distribution of the products, both of which had important effects on the luminescent properties of the products.

[Preparation and luminescence of down-conversion material beta--NaYF4 : Tb3+, Yb3+].

NaYF4 : Tb3+, Yb3+ down-conversion (DC) phosphors were synthesized by hydrothermal method. X-ray diffraction (XRD), photoluminescence (PL) and photoluminescence excitation (PLE) spectra were used to characterize the samples. Experiment results revealed that samples of NaYF4 : Tb3+, Yb3+ crystallized in hexagonal shape without cubic shape. When the doping concentration of Tb3+ and Yb3+ was altered, the lattice structure of samples did not change, indicating that the Tb3+ and Yb3+ ions are completely dissolved in the NaYF4 host lattice by substitution for the Y3+. The emission from 5D4 --> 7F6 (489 nm), 5D4 --> 7F5 (542 nm), 5D4 --> F4 (584 nm), and 5D4 --> F3 (619 nm) of Tb3+ ions was observed, in which the dominant emission was at 542 nm. With single Tb3+ doping, no near-infrared (NIR) emission was observed under excitation of 355 nm pulsed laser. However, while with Tb3+ and Yb3+ codoping, the NIR emission at around 950 -1 100 nm from Yb3+ (2F5/2 --> 2F7/2) was observed under the same excitation. The dependence of the visible and NIR-emissions on Yb3+ doping concentration has been investigated. These results show that there is energy transfer process between Tb2+ and Yb3+. Furthermore, it is a possible DC process through cooperative energy transfer from Tb3+ to Yb3+. When the doping concentration is 1% mol Tb3+ and 6% mol Yb3+ respectively, the intensity of NIR emission reaches its strongest.