BackgroundThe aim of this study is to build a risk assessment system for central lymph node metastasis (CLNM) in papillary thyroid microcarcinoma (PTMC) of stage cN0 and to explore its application value in clinical practice.MethodsA total of 500 patients with PTMC who underwent thyroid operation from 2013 to 2015 in Ningbo First Hospital were selected as the model group. Independent risk factors related to CLNM in PTMC were analyzed and determined, and a risk assessment system for CLNM was preliminarily established. Furthermore, the clinicopathological data from 328 PTMC patients with the same conditions as the model group from 2016 to 2017 were further collected as the validation group to verify the diagnostic value of the risk assessment system.ResultsThe risk assessment system was based on the score rating (score ≤ 5 was classified as low risk, 6–8 was classified as medium risk, and ≥9 was classified as high-risk). The area under the receiver operating characteristic curve (ROC) was 0.687 (95% CI: 0.635–0.783). According to the risk assessment system, 328 PTMC patients in the validation group were scored. Among the low-risk group, the moderate-risk group, and the high-group, 96.8%, 58.1%, and 43.2% were the CLNM (-) patients, and 3.1%, 41.9%, and 65.8% were CLNM (+) patients, respectively. The area under ROC was 0.837 (95% CI: 0.778–0.869).ConclusionsThe risk assessment system in this study is of diagnostic value and can provide a theoretical foundation for intraoperative decision-making of prophylactic central neck dissection (pCND).

We report a single-frequency linearly polarized Q-switched fiber laser based on a Nb2GeTe4 saturable absorber (SA). The Nb2GeTe4 SA triggers passive Q-switching of the laser, and an un-pumped Yb-doped fiber together with a 0.08-nm-bandwidth polarization-maintaining fiber Bragg grating act as an ultra-narrow bandwidth filter to realize single-longitudinal-mode (SLM) oscillation. The devices used in the laser are all polarization-maintaining to ensure linearly polarized laser output. Stable SLM linearly polarized Q-switching operation at 1064.6 nm is successfully achieved with a shortest pulse width of 1.36 μs, a linewidth of 28.4 MHz, a repetition rate of 28.3-95.9 kHz, and a polarization extinction ratio of about 30 dB. It is believed that the single-frequency linearly polarized pulsed fiber laser studied in this paper has great application value in gravitational wave detection, beam combining, nonlinear frequency conversion, and other fields.

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