UNASSIGNED: To investigate the feasibility and evaluate the safety and effectiveness of Computed Tomography (CT) guided125I radioactive particle implantation for treating lymph node metastases in radioiodine-refractory differentiated thyroid cancer (RAIR-DTC). To verify the accuracy of the computerized three-dimensional treatment planning system (TPS) in treating lymph node metastasis using125I particle implantation at the dosimetric level.
UNASSIGNED: A retrospective analysis was conducted on 42 patients with RAIR-DTC and lymph node metastases who were admitted to the General Hospital of the Northern Theater Command between December 2016 and January 2019. During this analysis, physicians utilized preoperative CT images to design an intraoperative plan using TPS. The dosimetric parameters of the postoperative plan were then compared to the preoperative plan. Additionally, this study examined the changes in tumor size and tumor-related marker Thyroglobulin (Tg) values in patients at 2, 6, and 12 months after the operation.
UNASSIGNED: The number of125I radioactive particles implanted in 42 patients was 226, with an average of 14.5 (range 2.0-30.0) particles implanted per lesion. The local remission rates were 97.62% (41/42), 88.10% (37/42), and 85.71% (36/42) at 2, 6, and 12 months postoperatively, respectively. The volume of the lesions was (4.44 ± 1.57) cm3, (4.20 ± 1.70) cm3, and (4.23 ± 1.77) cm3at 2, 6, and 12 months after treatment, respectively, which significantly decreased from the preoperative baseline level of (6.87 ± 1.67) cm3(t-values: 9.466, 9.923, 7.566, all P<0.05). The Tg levels were 15.95 (5.45, 73.93) μg/L, 8.90 (2.20, 39.21) μg/L, and 6.00 (1.93, 14.18) μg/L at 2, 6, and 12 months after treatment, respectively, which were significantly lower than the preoperative baseline levels of 53.50 (20.94, 222.92) μg/L (Z values: -5.258, -5.009, -4.987, all P < 0.001). Postoperatively, Delivered to 90% of the GTV(D90) was slightly lower than the prescribed dose in 95.23% (40/42) of patients, but the difference was not statistically significant [(12,378.8 ± 3,182.0), (12,497.8 ± 1,686.4) cGy; t=0.251, P>0.05], and postoperative dose parameters delivered to 100% of the gross tumor volume (GTV)(D100) (6,881.5 ± 1,381.8) cGy, the volume percentages of GTV receiving 150% of the prescribed dose(V150) (58.5 ± 18.40)%) were lower than the preoperative plan D100 (8,085.8 ± 2,330.0) cGy, V150 (66.5 ± 17.70)%; t-value=8.913 and 3.032, both P<0.05; the remaining indicators were not significantly different from the preoperative plan (the differences in the number of implanted particles, Planning Target Volume(PTV), the volume percentages of GTV receiving 100% of the prescribed dose(V100), Homogeneity Index(HI)were not statistically significant (t/Z = -0.593, -1.604, 1.493, -0.663, all P>0.05).
UNASSIGNED: Referring to the TPS preoperative plan, the125I particle implantation therapy for RAIR-DTC lymph node metastasis can achieve the expected dose distribution, ensuring precise short-term local tumor control efficacy.

OBJECTIVE: To evaluate the clinical value of 1251 seed implantation in the treatment of lymph node metastasis of 111 cases of refractory differentiated thyroid cancer (RAIR-DTC).
METHODS: From January 2015 to June 2016, 42 patients with RAIR-DTC with lymph node metastasis (14 males and 28 females, median age 49 years) were analyzed retrospectively. After CT-guided 1251 seed implantation, CT was reexamined 2,4,6 months after operation, and the changes of metastatic lymph node size, serum thyroglobulin (Tg) level and complications were compared before or after treatment. Paired-Samples T Test, Methods repetitive measure analysis of variance, Spearman correlation coefficient analysis were used to analyze the data.
RESULTS: Among the 42 patients, 2 had complete remission (4.76%), 9 had partial remission (21.43%), 29 had no change (69.05%), and 2 had disease progression (4.76%), with an overall effective rate of 95.24% (40/42). The diameter of lymph node metastasis was (1.39 ± 0.75) cm after treatment and (1.99 ± 0.38) cm before treatment; the diameter of lymph node metastasis was significantly reduced after treatment compared with that before metastasis (t = 5.557, P< 0.01); the serum Tg at 2, 4 and 6 months after treatment were (53.34 ± 14.05) ug/L, (33.17 + 7.61)ug/L and (25.93 ± 10.91)ug/L, respectively, compared with (57.72 ± 15.23)ug/L before treatment, and the differences between serum Tg after treatment and before treatment were all statistically significant (F = 23.612,P<0.05). Except for the diameter of lymph node metastasis (χ2 = 4.524, P<0.05), the patients\' age, gender, metastasis site and the number of implanted particles per lesion were not influential factors in the efficacy (χ2 = 0.569-15.884, rs = 0.277, all P>0.05).
CONCLUSIONS: 125I RSIT can significantly alleviate the clinical symptoms of RAIR-DTC patients with LNM, and the LNM lesions size has relevance for the treatment effect. The clinical follow-up time of serum Tg level can be extended to 6 months or even longer.

The aim of the present study was to investigate the factors influencing the short-term response to the initial radioiodine therapy (RT) course in patients with intermediate- and high-risk papillary thyroid carcinoma (PTC). A total of 182 patients with intermediate- and high-risk PTC who underwent RT in our hospital from March 2018 to October 2020 were retrospectively enrolled. The patients were divided into incomplete response (IR) and nonincomplete response (Non-IR) groups according to the response observed in clinical follow-up within 6-12 months after RT. Univariate and multivariate logistic regression analyses were used to investigate the effects of 15 observed factors on the response to RT. Receiver operating characteristic (ROC) curve analysis was used to determine the value of factors found to be significant in multivariate analyses for predicting an IR. A total of 182 patients with intermediate- and high-risk PTC were analyzed; the percentage of patients with a Non-IR was 61.54% (112/182), and the percentage of patients with an IR was 38.46% (70/182). The CD4+ T-cell percentage (t = 4.757, P = 0.000), CD4/CD8 (z = - 2.632, P = 0.008), stimulated thyroglobulin (sTg) level (z = - 8.273, P = 0.000) and M stage (χ2 = 17.823, P = 0.000) of the two groups were significantly different. Multivariate analysis showed that only the sTg level (OR: 1.116, 95% CI 1.068-1.165, P < 0.001) and CD4+ T-cell percentage (OR: 0.909, 95% CI 0.854-0.968, P = 0.003) were independent factors associated with the therapeutic response to RT. The cutoff sTg level and CD4+ T-cell percentage for predicting an IR were 7.62 μg/L and 40.95%, respectively. The sTg level and CD4+ T-cell percentage were verified to be independent predictive factors of RT response. Higher sTg levels and lower CD4+ T-cell percentages were related to an IR in patients with intermediate- and high-risk PTC.

Serum thyroglobulin (Tg) serves as a sensitive and easily available tumor marker for patients with metastatic differentiated thyroid carcinoma (m-DTC). The aim of the present study was to evaluate the predictive value of suppressed Tg changes (Δsup-Tg) and/or stimulated Tg changes (Δsti-Tg) to evaluate the efficacy of radioiodine therapy (RT).
We studied 117 patients with m-DTC who received RT. Δsup-Tg and Δsti-Tg were compared after the first RT in different therapeutic response groups and a receiver-operating characteristic (ROC) curve was used to determine the cut-off values to predict non-remission. Univariate and multivariate analyses were used to investigate the effects of 17 observed factors on the efficacy of RT.
A total of 218 RT events in 117 patients with m-DTC were analyzed. After the last RT, the remission rate was 70.94% (83/117), and the proportion of remission events accounted for 74.77% (163/218). ROC curve analysis showed that the cut-off values for Δsup-Tg and Δsti-Tg after the first RT to predict the non-remission of RT were 21.54% and 27.63%, respectively. Age, the size of the metastasis, the maximum count of target metastatic lesions and the average count of contralateral non-target tissue on tomographic imaging (Tmax/NTmean) of the first RT, and Δsup-Tg after the first RT were identified as independent factors associated with RT efficacy.
Tg response was valuable to predict RT efficacy for patients with m-DTC. Age, the size of the metastasis, Tmax/NTmean, and Δsup-Tg after the first RT were verified as independent predictive factors of RT efficacy.

BACKGROUND: To explore the value of gemstone spectral imaging (GSI) and metal artefact reduction sequence (MARs) to reduce the artefacts of metal seeds.
METHODS: Thirty-five patients with 125 I seed implantation in their abdomens underwent GSI CT. Six types of monochromatic images and the corresponding MARs images at 60-110 keV (interval of 10 keV) were reconstructed. The differences in the quality of the images of three imaging methods were subjectively assessed by three radiologists. Length of artefacts, the CT value and noise value of tissue adjacent to 125 I seeds, contrast-to-noise ratio (CNR), and artefact index (AI) were recorded.
RESULTS: The differences in subjective scoring were statistically significant (t = 10.87, P < 0.001). Images at 70 keV showed the best CNR (0.84 ± 0.17) of tissues adjacent to 125 I seeds, and received the highest subjective score (2.82 ± 0.18). Images at 80 keV had the lowest AI (70.67 ± 19.17). Images at 110 keV had the shortest artefact lengths. High-density metal artefacts in the MARs spectral images were reduced. The length of metal artefacts in images at 110 keV was shorter than that of the polychromatic images and MARs spectral images (t = 3.35, 3.89, P < 0.05). The difference in CNR between MARs spectral images and polychromatic images, and images at 70 keV was statistically significant (t = 3.57, 4.16, P < 0.01).
CONCLUSIONS: Gemstone spectral imaging technique can reduce metal artefacts of 125 I seeds effectively in CT images, and improve the quality of images, and improve the display of tissues adjacent to 125 I seeds after implantation. MARs technique cannot reduce the artefacts caused by radioactive seeds effectively.

Herein we report the radiosynthesis of a pyridine derived azide prosthetic group for iodine radioisotope labeling of dibenzocyclooctyne (DBCO) conjugated molecules. The radiolabeling of the stannylated precursor 2 was conducted using [(125)I]NaI and chloramine-T to give (125)I-labeled azide ([(125)I]1) with high radiochemical yield (72±8%, n=4) and radiochemical purity (>99%). Using (125)I-labeled azide ([(125)I]1), cyclic RGD peptide and near infrared fluorescent molecule were efficiently labeled with modest to good radiochemical yields. The biodistribution study and SPECT/CT images showed that [(125)I]1 underwent rapid renal clearance. These results clearly demonstrated that [(125)I]1 could be used as an useful radiotracer for in vivo pre-targeted imaging as well as efficient in vitro radiolabeling of DBCO containing molecules.

Herein we report an efficient method for iodine radioisotope labeling of cyclooctyne-containing molecules using copper-free click reaction. For this study, radioiodination using the tin precursor 2 was carried out at room temperature to give (125)I-labeled azide ([(125)I]1) with high radiochemical yield (85%) and excellent radiochemical purity. Dibenzocyclooctyne (DBCO) containing cRGD peptide and gold nanoparticle were labeled with [(125)I]1 at 37°C for 30min to give triazoles with good radiochemical yields (67-95%). We next carried out tissue biodistribution study of [(125)I]1 in normal ICR mice to investigate the level of organ accumulation which needs to be considered for pre-targeted in vivo imaging. Large amount of [(125)I]1 distributed rapidly in liver and kidney from bloodstream and underwent rapid renal and hepatobiliary clearance. Moreover [(125)I]1 was found to be highly stable (>92%) in mouse serum for 24h. Therefore [(125)I]1 could be used as a potentially useful radiotracer for pre-targeted imaging. Those results clearly indicated that the present radiolabeling method using copper free click reaction would be quite useful for both in vitro and in vivo labeling of DBCO group containing molecules with iodine radioisotopes.