[Monitoring of 131-Iodine Contamination in Saliva and Perspiration of Patients with Differentiated Thyroid Cancer Treated by 131-Iodine].

Objective To investigate the radioactivity of 131-iodine (131I) in saliva and perspiration of patients with differentiated thyroid cancer after treatment with 131I,and thereby to provide evidence for the control of radioactive contamination.Methods Fifteen patients with differentiated thyroid cancer who would be treated with 131I were enrolled.Samples of saliva and perspiration of them were collected 2-48 h after the oral administration of 3.70-5.55 GBq (100-150 mCi) 131I,and radioactivity was measured with a multichannel detector.Results In the 15 patients treated with 131I,the average specific activity in the saliva collected 2 h,4 h,8 h,24 h,and 48 h after administration was (553.58±478.94)×104 Bq/g,(484.72±431.76)×104 Bq/g,(389.78±254.63)×104 Bq/g,(141.15±104.83)×104 Bq/g,and (53.23±49.8)×104 Bq/g,respectively.The radioactivity in the perspiration from hand was higher than that from the forehead,left-side neck,chest,and left axilla,and 131I in perspiration gradually decreased over time.Conclusion There is radioactive 131I in saliva and perspiration of patients with differentiated thyroid cancer after the administration of 131I,which may cause potential radioactive contamination to the environment.

Performance of PET imaging for the localization of epileptogenic zone in patients with epilepsy: a meta-analysis.

OBJECTIVES: The aim of this meta-analysis was to estimate the clinical use value of 11C-FMZ and 18F-FDG in PET for the localization of epileptogenic zone and to provide evidence for practitioners' clinical decision-making. METHODS: We searched PubMed and Embase in a time frame from inception to May 31, 2020. Studies utilizing FMZ or FDG-PET or FDG-PET/MRI used in patients with epilepsy, with EEG or surgical outcomes as the gold standard and corresponding outcomes such as concordance rates of PET or PET/MRI scan compared with reference standard, absolute numbers of participants with true-positive (TP), false-positive (FP), true-negative (TN), and false-negative (FN) results in FDG or FMZ PET. Pooled concordance rates, overall sensitivity, and specificity of 11C-FMZ-PET and 18F-FDG-PET were calculated. RESULTS: In total, 44 studies met the inclusion criteria. The pooled concordance rates of FDG-PET, FMZ-PET, and FDG-PET/MRI coregistration compared with reference standard were 0.67 (95% CI: 0.60-0.73), 0.75 (95% CI: 0.57-0.93), and 0.93 (95% CI: 0.89-0.97), respectively. The concordance rate of 18F-FDG-PET in patients with temporal lobe epilepsy (TLE) was 0.79 (0.63; 0.92). The overall sensitivity and specificity of 18F-FDG-PET were 0.66 (95% CI: 0.58-0.73) and 0.71 (95% CI: 0.63-0.78), respectively. 11C-FMZ-PET displayed an overall sensitivity of 0.62 (95% CI: 0.49-0.73) and specificity of 0.73 (95% CI: 0.59-0.84). CONCLUSIONS: Both 11C-FMZ PET and 18F-FDG PET are the choice of modalities for the localization of epileptogenic zone, especially when coregistered with MRI. KEY POINTS: • 11C-FMZ-PET may be more helpful than 18F-FDG-PET in the localization of epilepsy foci. • Coregistration of FDG-PET and MRI is recommended in the localization of epileptogenic zone.

[Design and Test of Automatic Dispensing and Injecting System for Positron Radiopharmaceuticals].

Objective To design a novel automatic dispensing and injecting system of positron radiopharmaceuticals,for precise dose dispensing,simplified operation,and reduction of occupational radiation exposure. Methods The automatic dispensing and injecting system was fabricated with tungsten alloy as the shielding material.The performance and radiation protection of the device were assessed. Results The total time of injection using the automatic dispensing and injecting system was about 60 s.The ratio of successful injection in stability test was 100%.The deviation of the dispensing dose with the system was ≤3%.With the tungsten alloy shield(40 mmPb of the cabinet,60 mmPb of the countertop,15 mmPb of the protective shield,and 50 mmPb of the inbuilt jar for radiopharmaceuticals),the average dose rate at 30 cm from the device was 1.44 µSv/h,and the radiation dose at the operator's extremity was reduced by 99%. Conclusions This automatic dispensing and injecting system of positron radiopharmaceuticals is easy to operate with precise dispensing dose.It is safe and meets the requirements of radiation protection.

Using Dynamic 99mT c-GSA SPECT/CT fusion images for hepatectomy planning and postoperative liver failure prediction.

BACKGROUND: Available tools in liver surgery planning rely on the future remnant liver (FRL) volume. Inappropriate decision might be made since the same FRL volume might represent different liver functions depending on the severity of underlying liver damage. This study developed an alternative system to estimate FRL function and to predict the risk of postoperative liver failure. METHODS: Current study recruited 71 prehepatectomy patients and 71 healthy volunteers. A technetium-99-labelled asialoglycoproteins was given to participants and SPECT was used to capture the intensity of the signal, represented by uptake index (UI). The agreement between preoperative UI values, liver function tests, and Child scores were evaluated. Linear regression was used to evaluate the agreement between predicted UI for FRL and postoperative UI values. Area under the receiver operating characteristic (AUC) curve was used to evaluate the discriminative performance of UI in differentiating patient with high risk of liver failure. RESULTS: Preoperative UIs are highly correlated with Child score (P < 0.0001), especially to identify patients with ascites and elevated bilirubin. The predicted UIs were in close agreement with the actual postoperative UI values (r = 0.95 P < 0.001). The AUC analysis indicated that UI values had a high accuracy in predicting the risk of liver failure (AUC = 0.95, P < 0.0001). The best cut-off point was 0.9 and the corresponding sensitivity was 100 % and specificity was 92 %. CONCLUSIONS: The new methodology reliably estimates FRL function and predicts the risk of liver failure. It provides a visual aid for liver surgeon in surgery planning and risk assessment.

Direct attenuation correction for 99mTc-3PRGD2 chest SPECT lung cancer images using deep learning.

Introduction: The attenuation correction technique of single photon emission computed tomography (SPECT) images is essential for early diagnosis, therapeutic evaluation, and pharmacokinetic studies of lung cancer. 99mTc-3PRGD2 is a novel radiotracer for the early diagnosis and evaluation of treatment effects of lung cancer. This study preliminary discusses the deep learning method to directly correct the attenuation of 99mTc-3PRGD2 chest SPECT images. Methods: Retrospective analysis was performed on 53 patients with pathological diagnosis of lung cancer who received 99mTc-3PRGD2 chest SPECT/CT. All patients' SPECT/CT images were reconstructed with CT attenuation correction (CT-AC) and without attenuation correction (NAC). The CT-AC image was used as the reference standard (Ground Truth) to train the attenuation correction (DL-AC) SPECT image model using deep learning. A total of 48 of 53 cases were divided randomly into the training set, the remaining 5 were divided into the testing set. Using 3D Unet neural network, the mean square error loss function (MSELoss) of 0.0001 was selected. A testing set is used to evaluate the model quality, using the SPECT image quality evaluation and quantitative analysis of lung lesions tumor-to-background (T/B). Results: SPECT imaging quality metrics between DL-AC and CT-AC including mean absolute error (MAE), mean-square error (MSE), peak signal-to-noise ratio (PSNR), structural similarity (SSIM), normalized root mean square error (NRMSE), and normalized Mutual Information (NMI) of the testing set are 2.62 ± 0.45, 58.5 ± 14.85, 45.67 ± 2.80, 0.82 ± 0.02, 0.07 ± 0.04, and 1.58 ± 0.06, respectively. These results indicate PSNR > 42, SSIM > 0.8, and NRMSE < 0.11. Lung lesions T/B (maximum) of CT-AC and DL-AC groups are 4.36 ± 3.52 and 4.33 ± 3.09, respectively (p = 0.81). There are no significant differences between two attenuation correction methods. Conclusion: Our preliminary research results indicate that using the DL-AC method to directly correct 99mTc-3PRGD2 chest SPECT images is highly accurate and feasible for SPECT without configuration with CT or treatment effect evaluation using multiple SPECT/CT scans.

Comparative [18F]FDG and [18F]DPA714 PET imaging and time-dependent changes of brown adipose tissue in tumour-bearing mice.

Brown adipose tissue (BAT) is important in monitoring energy homeostasis and cancer cachexia. Different from white adipose tissue, BAT is characterized by the presence of a large number of mitochondria in adipocytes. Translocator protein 18 kDa (TSPO), a critical transporter, is expressed in the outer membrane of mitochondria. We speculated that [18F]DPA714, a specific TSPO tracer, may monitor BAT activity in tumor-bearing mice in vivo. We first analyzed the radioactive uptake of positron emission tomography (PET) tracers in BAT of CT26 xenograft mice with 18F-fluorodeoxyglucose ([18F]FDG) and [18F]DPA714. We also studied the BAT uptake of [18F]DPA714 in CT26, A549 and LLC tumor models. The dynamic distribution of [18F]FDG is quite variable among animals, even in mice of the same tumor model (%ID/g-mean: mean ± SDM, 8.61 ± 8.90, n = 16). Contrarily, [18F]DPA714 produced high-quality and stable BAT imaging in different tumor models and different animals of the same model. Interestingly, %ID/g-mean of [18F]DPA714 in BAT was significantly higher on day 26 than that on day 7 in CT26 xenograft model. Taken together, these results strongly indicate the potential feasibility of [18F]DPA714 PET imaging in investigating BAT and energy metabolism during tumor progression in preclinical and clinical study.

[Clinical application of radionuclide bone scintigraphy in diagnosis of avascular osteonecrosis in patients with severe acute respiratory syndrome in convalescence].

OBJECTIVE: To evaluate the clinical value of radionuclide bone scintigraphy in diagnosis of avascular osteonecrosis in patients with severe acute respiratory syndrome (SARS) in convalescence. METHODS: We performed three-phase bone scintigraphy of femoral head regions and whole-body bone scan in SARS patients 4-6 months after they recovered from the syndrome, and then compared the results with simultaneous MRI. RESULTS: Typical avascular necrosis at different stages and severities was found on bone scintigraphy at 31 femoral heads of 16 SARS patients, 97% of which were MRI positive. Suspicious necrosis was found at 42 femoral heads of 23 patients, 67% of which were MRI negative. Among 30 patients with normal three-phase scintigraphic results, 10% of whom were suspicious on MRI. In addition, abnormal distributions of radioactivity were observed in other bones on the whole-body bone scans of 29 patients, including osteonecrosis of knees in 15 patients. CONCLUSIONS: Radionuclide bone scintigraphy is valuable in early diagnosis of osteonecrosis in SARS patients in convalescence. It provides a mutually supplementary tool for MRI.

Performance evaluation of a new high-sensitivity time-of-flight clinical PET/CT system.

BACKGROUND: PoleStar m660 is a newly developed clinical PET/CT system with time-of-flight (TOF) capability. The aim of this study is to characterize the performance of the new system. Spatial resolution, sensitivity, scatter fraction, and noise equivalent count rate (NECR) were measured on the scanner according to the NEMA NU 2-2012 protocol. The timing resolution was measured using a rotating line source that orbited around the center of field of view (CFOV) at a radius of 20 cm. The image quality phantom was also imaged to quantify the percent contrast, percent background variability, and residual error. The impacts of data acquisition time and bed overlap on the PET image quality were also evaluated using phantom and patient studies. RESULTS: The transverse (axial) spatial resolutions were 3.59 mm (3.67), 4.08 mm (4.65), and 5.32 mm (6.48) full width at half maximum (FWHM) at 1 cm, 10 cm, and 20 cm, respectively, off the CFOV. The measured sensitivity was 10.7 cps/kBq at the CFOV and 10.4 cps/kBq at 10 cm off the CFOV. The peak NECR was 216.7 kcps at an activity concentration of 29.1 kBq/ml, and the scatter fraction was 38.2%. An average of 435 ps FWHM timing resolution was measured. For the image quality phantom, the contrast recovery ratios ranged from 33.9 to 76.4%, while the background variability ranged from 4.7 to 2.0%. In the preliminary clinical study, no noticeable difference in the image quality was observed when the scan time for the whole body and brain was reduced to 1 min/bed and 3 min, respectively. The tested 21% bed overlap showed no significant difference in the image quality compared with the default 38% bed overlap setting. CONCLUSIONS: The physical performances of the PoleStar m660 PET/CT system showed good sensitivity, count rate performance, and timing resolution. The improved performance could help to reduce the acquisition time and bed overlap in the clinical application without detectable compromise in the image quality.

[Safety, biodistribution, and dosimetry of myocardial imaging agent 99Tc(m)N-NOET in healthy volunteers].

OBJECTIVE: To study the safety, biodistribution, and dosimetry of myocardial perfusion imaging agent 99Tc(m)N-NOET in 10 healthy volunteers. METHODS: 744-792 MBq of 99Tc(m)N-NOET was injected to each volunteer. Safety parameters and adverse event was measured in 24 hours of injection. Biodistribution was studied by whole-body imaging 1, 30 minutes, 1, 2, 4, 8, and 24 hours after the injection of 99Tc(m)N-NOET. The estimation of dosimetry was based on the standard medical internal radiation dose method using MIRDOSE 3.0 analysis program. Myocardial single photon emission computed tomography (SPECT) imaging was performed at 1 and 4 hours after injection. RESULTS: No undesirable effects were reported by the subject during 24 hours after injection of 99Tc(m)N-NOET. No clinically significant changes were found in vital signs (heart rate, blood pressure, and electrocardiogram). No biochemical aspects and serology changes were measured. The myocardial SPECT imaging was clear. Cardiac uptake of 99Tc(m)N-NOET was as high as 2.68% at 2 hours after injection. The heart to lung ratio was more than 1 from 30 minutes after injection, reaching a maximum of 1.91 +/- 0.53 at 2 hours after injection. Radiation dosimetry calculations indicated an effective absorbed dose of 1.28 x 10(-5) Sv/MBq. The dosimetry in each main organ is lower then 50 mGy given 740 MBq of 99Tc(m)N-NOET in once imaging. CONCLUSIONS: 99Tc(m)N-NOET exhibits high cardiac uptake and low estimated effective absorbed dose. It's a safe myocardial perfusion imaging agent.

[Three-dimensional assessment of the remnant hepatic function following surgery using single photon emission computed tomography in an animal model].

OBJECTIVE: The predictive value of postoperative hepatic function evaluated by liver functional imaging combined with single photon emission computed tomography (SPECT) technique was appraised in the present study. METHODS: Twenty New Zealand white rabbits were divided randomly into two groups, including the Hepatic Fibrosis with Carcinoma Group (FC-Group, n = 10) and the Control Group (C-Group, n = 10). All the rabbits underwent the resection of outer-right lobe of the liver. The whole hepatic function indexes, such as HCI(5), HLI(5) and Ex(15), and the hepatic function remnant indexes, including HCI(5P), HLI(5P) and Ex(15P), were calculated by 99mTc-EHIDA liver imaging. RESULTS: Ex(15) of FC-Group was lower than that of C-Group (P < 0.05). HCI(5) and HLI(5) of FC-Group had the trends to increase compared with the C-Group. Ex(15) was positively correlated with ALB, and negatively correlated with TBil and GGT (P < 0.05). HCI(5) had a positive correlation with CHE (P < 0.05), while HLI(5) had a negative correlation with A/G (P < 0.05). HLI(5P) had the negative correlation with postoperative A/G (P < 0.05), and Ex(15P) had the negative correlation with postoperative TBil and GGT (P < 0.05). CONCLUSIONS: This study has established a method of 3-D liver function evaluation system on an animal model. Among the indexes, Ex(15) can exactly represent the whole liver function while Ex(15P) and HLI(5P) can predict the liver function after the liver resection. The results may help the future clinical use of this technique to evaluate the risk of operation.

A novel liver function evaluation system using radiopharmacokinetic modeling of technetium-99m-DTPA-galactosyl human serum albumin.

BACKGROUND: A new kinetic model of technetium-99m-labeled diethylenetriaminepentaacetic acid-galactosyl human serum albumin (Tc-GSA) was developed to show the speed of asialoglycoprotein receptor-mediated endocytosis. MATERIALS AND METHODS: Ten healthy volunteers and 17 patients with liver cirrhosis were intravenously injected with 185 MBq of Tc-GSA, and dynamic planar images were acquired. The absolute amounts of Tc-GSA in the liver and extrahepatic blood were estimated from the time-activity curves for the liver, heart, and lungs. A two-compartment model was represented with two parameters as variables to estimate the uptake index (UI) of Tc-GSA transport through the hepatic cell membrane from the total plasma at any given time. RESULTS: The dynamic curve of Tc-GSA uptake by the liver was generated. Analysis of individuals with normal livers and patients with liver cirrhosis showed statistically significant differences in their UI. The UI for normal livers was high and that for cirrhotic livers was low. Linear regression correlation of UI with albumin, prealbumin, and prothrombin time was 0.841, 0.746, and -0.723, respectively. CONCLUSION: UI reflects the cellular transport of asialoglycoproteins as ascertained by the two-compartment model on the basis of GSA dynamic images. It is useful for measuring liver function.