Differences in the dielectric properties of various benign and malignant thyroid nodules.

PURPOSE: This experiment was conducted to investigate the dielectric properties of different types of thyroid nodules. Our goal was to find a simple and fast method to detect thyroid diseases at different stages from the dielectric properties of thyroid nodules. METHODS: We used the open-ended coaxial line method to measure the dielectric permittivities of thyroid tissues from 155 patients at frequencies ranging from 1 to 4000 MHz. Tissues that were investigated included normal thyroid tissue and benign and malignant thyroid nodules (nodular goiter, follicular adenoma, papillary carcinoma, and follicular carcinoma), as determined from pathological reports. Differences in dielectric properties were measured between each nodule and the surrounding 1 cm of tissue. RESULTS: The analysis results revealed that the dielectric permittivity and conductivity values were positively correlated with the degree of malignancy of the nodule (normal < benign < malignant; all differences P < 0.05). This was more obvious at frequencies within 20~70 MHz, following the order normal tissue < nodular goiter < follicular adenoma < papillary carcinoma < follicular carcinoma. A significant difference (P < 0.05) in dielectric permittivity and conductivity was found when comparing these nodules with the surrounding 1 cm of tissue. CONCLUSIONS: Normal, benign, and malignant nodules were successfully distinguished from one another, and dielectric permittivity was found to be a more sensitive parameter than conductivity. In particular, different disease types can be distinguished at a stimulation frequency of 20~70 MHz, which shows that dielectric properties have application prospects for the detection and diagnosis of cancer. At the same time, the dielectric parameter differences between the surrounding 1 cm of tissue and the diseased nodule can distinguish the tumor and its surrounding tissues in real time during surgery to determine the tumor boundary.

Prognostic impact of preoperative prognostic nutritional index in resected advanced gastric cancer: A multicenter propensity score analysis.

BACKGROUND: Advanced gastric cancer (AGC) causes debilitating malnutrition and leads to deterioration of the immune response. However, the concept of the prognostic nutritional index (PNI) is controversial when applied to patients with AGC. The aim of the present study was to evaluate the effect of the PNI after gastrectomy in patients with AGC. MATERIALS AND METHODS: A multicenter retrospective study was conducted using propensity score matching (PSM) in gastric adenocarcinoma patients who underwent resection via laparoscopic or open surgery between 2014 and 2017. To overcome selection bias, we performed 1:1 matching using 5 covariates. RESULTS: The resection margins (P < 0.001) and LNM (P = 0.004) were significantly different between the two groups. In univariate analysis, poor tumor differentiation (P = 0.038) (R1+R2, P = 0.004), vascular and neural invasion (P < 0.001), and a PNI<50 (P < 0.001) were associated with poor recurrence-free survival (RFS). In multivariate analysis, a PNI<50 (hazard ratio (HR), 12.993; P < 0.001) was a risk factor for RFS. Univariate analysis for overall survival (OS) revealed that a PNI<50 (P < 0.001) (R1+R2,P = 0.006) and vascular and neural invasion (P < 0.001) were risk factors. In subsequent multivariate analysis, a PNI<50 (HR, 24.501; P < 0.001) was a significant risk factor for OS. Clinical assessments performed during a 12.34 (±5.050) month follow-up revealed that OS (P < 0.001) and RFS (P < 0.001) were worse in patients with a low PNI (<50) than in matched patients with a high PNI. CONCLUSION: A low PNI is a strong predictor of unfavorable RFS and OS in patients with AGC.