Determination of optimal injection dose in a small animal-dedicated positron emission tomography for non-human primate neurological studies.

This study aimed to determine the optimal injection dose for non-human primate positron emission tomography (PET). We first used a monkey brain phantom with a volume of 80,000 mm3 containing 250 MBq of [18F]FDG. Next, we compared the radioactivity difference between the PET images and the actual radioactivity from the dose calibrator to determine the low-error range. We then evaluated the image quality using the NEMA-NU phantom. Finally, [18F]FP-CIT PET images were obtained from two monkeys with middle and high doses. As a result, PET images with a middle injected dose generated reasonable image quality and showed a high signal-to-noise ratio in monkey brain PET with [18F]FP-CIT. These results are expected to be actively applied in PET research using non-human primates.

Analysis of Optimal Treatment Starting Time for Photothermal Therapy Through Analysis of Diffusion Behavior of Gold Nanoparticles.

Introduction: Due to its distinct advantage of non-invasive application in treatment, photothermal therapy (PTT) is being studied by many researchers to reduce the need for surgical incisions. It is characterized by the injection of nanoparticles into biological tissue as photothermal agents (PTAs) which diffuse within the tissue. In this study, the diffusion behavior of various doses of gold nanoparticles (AuNPs) injected into tumor tissues is analyzed and the effectiveness of PTT at each elapsed time after injection is confirmed by numerical analysis. Methods: The diffusion behavior of AuNPs within biological tissues is assessed using the convection-diffusion equation, while the temperature distribution is determined using the Pennes bioheat transfer equation. In addition, the effect of the diffusion behavior of AuNPs on the effectiveness of PTT is quantitatively confirmed by analyzing the temperature distribution in the medium through the apoptotic variable. Numerical simulation parameters are selected with doses ranging from 100 to 400 µg/mL, elapsed time after injection from 1 min to 24 h, and laser power ranging from 0 to 1 W. Results: After evaluating PTT's efficacy in every situation, it was discovered that a dosage of 100-300 µg/mL produced the best therapeutic result, with the highest impact occurring 12 hours after injection. In contrast, when the dosage was 400 µg/mL, the highest therapeutic effect was achieved after 18 hours post-injection. Additionally, it was discovered that the ideal laser power at each injection dose was 0.22, 0.14, 0.12, and 0.12 W, respectively. Conclusion: The conditions required to achieve the optimal treatment effect at each dosage, presented here, are expected to accelerate the commercialization of PTT.

Optimization of the Contrast Agent Injection Protocol for Carotid Artery Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

BACKGROUND: The injection protocol used in previous carotid artery dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) studies varied. PURPOSE: To investigate the effect of contrast injection protocol and optimize this protocol for carotid artery DCE-MRI. STUDY TYPE: Prospective. SUBJECTS: Digital phantom and seven patients with carotid atherosclerosis. FIELD STRENGTH/SEQUENCE: 3 T, spoiled gradient recalled echo sequence. ASSESSMENT: Different injection doses (0.01-0.3 mmol/kg) and effective injection rates (0.01-1 mmol/sec) were tested using a digital carotid plaque phantom considering the contrast pharmacokinetics, DCE-MRI imaging, contrast variation and flow-related imaging artifacts, random time delay between the contrast injection and image acquisition, and pharmacokinetic analysis process. For each injection protocol, combining the root mean square relative error (RMSRE) of the measured K trans and v P maps within the adventitial vasa vasorum from 10 tested time delays by the root mean square produced RMSREoverall-vv which was used to measure the overall accuracy of the pharmacokinetic parameters. In vivo validation was performed on seven patients with carotid atherosclerosis by imaging them twice using the traditional commonly used protocol and the recommended protocol found by simulation. STATISTICAL TEST: Student's t-test, chi-square test, and paired t-test, P < 0.05 was considered statistically significant. RESULTS: A low region of RMSREoverall-vv with the combination of medium injection dose and low effective injection rate was found. The protocol with injection dose of 0.07 mmol/kg and effective injection rate of 0.06 mmol/sec achieved the minimal RMSREoverall-vv (4.29%), thus was recommended, which showed more accurate arterial input function. Coinciding with the simulation results, this recommended protocol in in vivo experiments produced significantly fewer image artifacts, lower K trans and v P (P all <0.05) than traditional protocol which overestimated these parameters in simulation. DATA CONCLUSION: The contrast injection protocol influenced the accuracy of the pharmacokinetics parameter estimation in carotid artery DCE-MRI. The injection protocol with injection dose of 0.07 mmol/kg and effective injection rate of 0.06 mmol/sec was recommended. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 1.

Optimization of injection dose in 18F-FDG PET/CT based on the 2020 national diagnostic reference levels for nuclear medicine in Japan.

OBJECTIVE: Recently, the national diagnostic reference levels (DRLs) in Japan were revised as the DRLs 2020, wherein the body weight-based injection dose optimization in positron emission tomography/computed tomography using 18F-fluoro-2-deoxy-D-glucose (18F-FDG PET/CT) was first proposed. We retrospectively investigated the usefulness of this optimization method in improving image quality and reducing radiation dose. METHODS: A total of 1,231 patients were enrolled in this study. A fixed injection dose of 240 MBq was administered to 624 patients, and a dose adjusted to 3.7 MBq/kg body weight was given to 607 patients. The patients with body weight-based injection doses were further divided according to body weight: group 1 (≤ 49 kg), group 2 (50-59 kg), group 3 (60-69 kg), and group 4 (≥ 70 kg). The effective radiation dose of FDG PET was calculated using the conversion factor of 0.019 mSv/MBq, per the International Commission on Radiological Protection publication 106. Image quality was assessed using noise equivalent count density (NECdensity), which was calculated by excluding the counts of the brain and bladder. The usefulness of the injection dose optimization in terms of radiation dose and image quality was analyzed. RESULTS: The body weight-based injection dose optimization significantly decreased the effective dose by 11%, from 4.54 ± 0.1 mSv to 4.05 ± 0.8 mSv (p < 0.001). Image quality evaluated by NECdensity was also significantly improved by 10%, from 0.39 ± 0.1 to 0.43 ± 0.2 (p < 0.001). In no case did NECdensity deteriorate when the effective dose was decreased. In group 1, the dose decreased by 32%, while there was no significant deterioration in NECdensity (p = 0.054). In group 2, the dose decreased by 17%, and the NECdensity increased significantly (p < 0.01). In group 3, the dose decreased by 3%, and the NECdensity increased significantly (p < 0.01). In group 4, the dose increased by 14%, but there was no significant change in the NECdensity (p = 0.766). CONCLUSION: Body weight-based FDG injection dose optimization contributed to not only the reduction of effective dose but also the improvement of image quality in patients weighing between 50 and 69 kg.

Research progress on autologous fat transplantation in the treatment of velopharyngeal insufficiency / 口腔疾病防治

@#Autologous fat transplantation in the treatment of velopharyngeal insufficiency has the advantages of good histocompatibility, small local trauma, few complications, reversible operation and simple postoperative nursing, which can effectively increase the velopharyngeal closure area. If the clinical effect is poor, other surgical methods can be used at any time for replacement. Although there are many advantages in the treatment of velopharyngeal insufficiency with autologous fat transplantation, there are still some problems in the selection of indication, donor site, injection dose, recipient site, follow-up evaluation, complications and prevention and treatment. Current research shows that autologous fat transplantation is mainly used in patients with mild or moderate velopharyngeal insufficiency, but with the improvement of fat acquisition and treatment techniques, the indications for autologous fat transplantation continue to expand, and autologous fat transplantation combined with palatoplasty or pharyngoplasty has been proposed for the treatment of severe velopharyngeal insufficiency. However, there are complications, such as fat absorption and obstructive sleep apnea syndrome. In addition, the application of autologous fat transplantation in severe VPI patients and how to improve the long-term stability of autologous fat transplantation need further study.

A computational study of the dual effect of intermittent and continuous administration of parathyroid hormone on bone remodeling.

Bone remodeling is a process known to be governed by constant interactions between osteoblast and osteoclast through complex pathway networks mediated by signaling factors. Experimental studies show that intermittent and continuous administration of PTH/PTHrP led to opposite outcomes in terms of bone mass. To investigate this dual effect of PTH/PTHrP, we develop a computational model based on a simplified signaling pathway network which includes relevant molecular effectors and cells. Multiple ordinary differential equations linking all considered components in the signaling pathway network through reaction kinetics are solved with dose values and patterns of injection from experiments as input. Modeling results show good agreement with experimental observations in that continuous injection of PTH/PTHrP generates catabolic effect on bone mass while intermittent injection yields anabolic effect. The signaling factors governing the interaction between osteoblast and osteoclast indeed play a key role in the dual effect of PTH/PTHrP. Furthermore, there appears to be an optimal interval for intermittent injection of PTH/PTHrP for yielding the most bone regeneration, and a synergistic outcome could be achieved by combining intermittent injection of PTH/PTHrP with application of a treatment (to mimic the filling of bone defects with polymeric scaffolds). This modeling work sheds valuable insights into the influence of temporal control of PTH/PTHrP on bone mass and presents a possible path toward bridging bioengineering approaches with clinical treatment strategies. STATEMENT OF SIGNIFICANCE: A computational model considering simplified signaling pathways containing crucial components of PTH, PTHrP, osteoblast precursor, osteoblast, osteoclast precursor, osteoclast, RANKL and IL-6 family cytokoines has been developed to study the dual effect of PTH/PTHrP on bone metabolism. The model takes the dose values and patterns of injection from experiments as input and yields predictions that convincingly match experimental measurements. This work highlights the importance of providing an optimal hormone treatment strategy for maintaining healthy bone metabolism. Moreover, the integrative approach of relying on experimental observations to find reasonable values for relevant modeling parameters has been proven to be powerful in advancing our understanding of biological interactions among cells and signaling factors.

Amperometric sensing of ascorbic acid by using a glassy carbon electrode modified with mesoporous carbon nanorods.

Mesoporous carbon nanorods (MCNRs) were prepared from honey as the carbon source and by using crab (Brachyuran) shells as the hard template. The unique nanostructure of the MCNRs with their uniform mesoporous size, abundant defective sites and numerous oxygen-functional groups was characterized by nitrogen adsorption-desorption isotherms, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Cyclic voltammograms of a glassy carbon electrode (GCE) modified with MCNRs revel a higher peak current density and lower peak potential (-0.03 V vs. Ag/AgCl) for ascorbic acid (AA) electrooxidation compared to a conventional GCE and a carbon nanotube-modified GCE. Figures of merit for this sensor include (a) a wide linear range (10-2770 µM), (b) high electrochemical sensitivity (216.91 µA mM-1 cm-2) and (c) a low detection limit (2.3 µM). These compare favorably to the respective data for a CNT-modified GCE (50-2150 µM, 5.20 µA mM-1 cm-2 and 26.8 µM) and a plain GCE (100-2000 µM, 0.58 µA mM-1 cm-2 and 54.6 µM). The modified GCE was successfully applied to the determination of AA in (spiked) real samples including an injection, soft drinks and fresh lemon juice. Therefore, the new sensor can be considered as an affordable tool for electrochemical sensing of AA in real samples. Graphical abstract Mesoporous carbon nanorods (MCNRs) were prepared by using honey as the carbon source and crab shells as the hard template. The MCNRs modified a glassy carbon electrode (MCNRs/GCE) was used for the ascorbic acid (AA) detection by amperometry.

The effect of injection speed and serial injection on propidium iodide entry into cultured HeLa and primary neonatal fibroblast cells using lance array nanoinjection.

BACKGROUND: Although site-directed genetic engineering has greatly improved in recent years, particularly with the implementation of CRISPR-Cas9, the ability to deliver these molecular constructs to a wide variety of cell types without adverse reaction is still a challenge. One non-viral transfection method designed to address this challenge is a MEMS based biotechnology described previously as lance array nanoinjection (LAN). LAN delivery of molecular loads is based upon the combinational use of electrical manipulation of loads of interest and physical penetration of target cell membranes. This work explores an original procedural element to nanoinjection by investigating the effects of the speed of injection and also the ability to serially inject the same sample. RESULTS: Initial LAN experimentation demonstrated that injecting at speeds of 0.08 mm/s resulted in 99.3 % of cultured HeLa 229 cells remaining adherent to the glass slide substrate used to stage the injection process. These results were then utilized to examine whether or not target cells could be injected multiple times (1, 2, and 3 times) since the injection process was not pulling the cells off of the glass slide. Using two different current control settings (1.5 and 3.0 mA) and two different cell types (HeLa 229 cells and primary neonatal fibroblasts [BJ(ATCC(®) CRL-2522™)], treatment samples were injected with propidium iodide (PI), a cell membrane impermeable nucleic acid dye, to assess the degree of molecular load delivery. Results from the serial injection work indicate that HeLa cells treated with 3.0 mA and injected twice (×2) had the greatest mean PI uptake of 60.47 % and that neonatal fibroblasts treated with the same protocol reached mean PI uptake rates of 20.97 %. CONCLUSIONS: Both experimental findings are particularly useful because it shows that greater molecular modification rates can be achieved by multiple, serial injections via a slower injection process.

Impact of injection dose, post-reconstruction filtering, and collimator choice on image quality of myocardial perfusion SPECT using cadmium-zinc telluride detectors in the rat.

BACKGROUND: The aims of this study were (1) to evaluate the impact of injection dose, post-reconstruction filtering, and collimator choice on image quality of myocardial perfusion single-photon emission computed tomography (SPECT) using cadmium-zinc telluride (CZT) detectors and (2) to determine how these factors affect measured infarct size in the in vivo rat. METHODS: Twenty-four healthy and eight myocardial infarct (MI) rats underwent myocardial perfusion SPECT imaging after injection of various doses (25 to 200 MBq) of (99m)Tc-tetrofosmin using a standard (STD) five-pinhole collimator and high-sensitivity (HS) five-pinhole collimator. Image quality score, contrast-to-noise ratio, sharpness index, coefficient of variation (CV), and measured defect size were assessed as measures of image quality. RESULTS: The image quality score increased and CV decreased as a function of injection dose. The contrast-to-noise ratio increased and sharpness index decreased as a function of Gaussian kernel size. When STD and HS were compared, HS tended to show higher image quality score and lower CV than STD. The use of post-reconstruction filter significantly improved image quality score and lessened CV. The reproducibility of defect size measurements, as assessed by intraclass correlation coefficients (ICC), between the collimators was poor-to-moderate (ICC = -0.31~0.57) with low (25 MBq) injection dose and with no or light (1.5-mm kernel size) filtering, whereas it was good-to-excellent (ICC = 0.75~0.97) with high (200 MBq) dose or low dose with heavy (2.5-mm kernel size) filtering. The filtering-related reproducibility was poor (ICC = -0.18~0.17) for STD with low injection dose, whereas it was good-to-excellent (ICC = 0.79~0.89) for HS. Furthermore, there was a filtering-related underestimation of defect size particularly with the use of heavy smoothing. CONCLUSIONS: Appropriate imaging setting is important to obtain high quality images and thereby reliable measurements using a preclinical myocardial SPECT in the rat. When only a low injection dose (25 MBq) is allowed, we would recommend to use HS with light (1.5-mm kernel size) filtering.

An Experimental Study about Contrast Medium Injection Rate and Dose in Cerebral CT Perfusion Imaging / 实用放射学杂志

Objective To investigate the suitable injection rate and dose in multi-slice CT perfusion imaging.Methods Randomized block design was adopted in this study.The treatment factor-contrast medium injection rate was classified into 3,4,5,6 and 8 ml/s;thesubjects were divided into 5 blocks grouped by contrast medium injection dose: 0.5,0.75,1,1.25 and 1.5 ml/kg.25 Beagles wererandomly enrolled to undergo cerebral CT perfusion imaging.After post processing,time to peak(TTP) and rise value(RV) were measured in superior sagital venous.Results Injection rate had a significant effect on TTP of superior sagital venous.There was no significant difference among group 5,6 and 8 ml/s.Compared with 8 ml/s,TTP of superior sagital venous was prolonged when injection rate 3,4 ml/swere adopted.Injection dose had a significant effect on RV of superior sagital venous.There was no significant difference among group 1,1.25 and 1.5 ml/kg.In comparison with 1 ml/kg,RV of superior sagital venous was prolonged when injection dose 0.5 and 0.75 ml/kg were adopted.Conclusion The quality of cerebral CT perfusion imaging is well enough even injection rate as low as 5 ml/s or injection dose as few as 1 ml/kg.