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Operator-bias-free Comparison of Quantitative Perfusion Maps Acquired with Pulsed-continuous Arterial Spin Labeling and Single-photon-emission Computed Tomography
摘要： Purpose: We compared the regional cerebral blood ?ow (rCBF) obtained by pulsed continuous arterial spin labeling (pCASL) and iodine-123-N-isopropyl-p-iodoamphetamine (IMP) single photon emission computed tomography (SPECT) using 3-dimensional stereotactic region-of-interest (ROI) software for automated de?nition of ROIs in anatomic regions of the brain. Methods: Thirteen patients with cerebrovascular occlusive disease and three with transient ischemic attacks underwent pCASL and IMP SPECT imaging. We compared rCBF values of each anatomic region and calculated the correlation coef?cients between pCASL and IMP SPECT. We also calculated the asymmetry index (AI) using ROIs in contralateral regions of the hemispheres. Results: The rCBF values calculated from pCASL and IMP SPECT were comparable in most segments, but rCBF in the thalamus (P < 0.0001) and hippocampus (P = 0.0006) was signi?cantly higher measured by pCASL than IMP SPECT. The correlation of rCBF between pCASL and IMP SPECT in the affected hemisphere (r = 0.50) tended to be lower than that in the normal hemisphere (r = 0.59), but not signi?cantly different (P = 0.25). Moreover, there was a ?xed bias for underestimation of rCBF by pCASL (P = 0.0047) in the affected hemisphere. The calculated AI showed a signi?cant relationship between methods (r = 0.79, P < 0.0001). Conclusion: The rCBF obtained by pCASL had positive relationships with IMP SPECT. However, it should be considered that pCASL tends to have a weak relationship with IMP SPECT in some normal regions and regions affected by cerebrovascular occlusive disease.
关键词： iodine-123-N-isopropyl-p-iodoamphetamine,3-dimensional stereotactic region-of-interest software,pulsed continuous arterial spin labeling,arterial spin labeling,regional cerebral blood ?ow
更新于2025-09-23 15:19:57
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Dual-Energy CT Material Density Iodine Quantification for Distinguishing Vascular From Nonvascular Renal Lesions: Normalization Reduces Intermanufacturer Threshold Variability
摘要： OBJECTIVE. The purpose of this study was to determine whether a single, uniform normalized iodine threshold reduces variability and enables reliable differentiation between vascular and nonvascular renal lesions independent of the dual-energy CT (DECT) platform used. MATERIALS AND METHODS. In this retrospective, HIPAA-compliant, institutional review board–approved study, 247 patients (156 men, 91 women; mean age ± SD, 67 ± 12 years old) with 263 renal lesions (193 nonvascular, 70 vascular) underwent unenhanced single-energy and contrast-enhanced DECT scans. One hundred and six nonvascular and 38 vascular lesions were scanned on two dual-source DECT (dsDECT) scanners, and 87 nonvascular and 32 vascular lesions were scanned on two rapid-kilovoltage-switching single-source DECT (rsDECT) scanners. Optimal absolute and normalized (to aorta) lesion iodine thresholds were determined for each platform type and for the entire cohort combined. RESULTS. Mean optimal absolute discriminant thresholds were 1.3 mg I/mL (95% CI, 1.2–1.9 mg I/mL), 1.6 mg I/mL (95% CI, 0.9–1.5 mg I/mL), and 1.5 mg I/mL (95% CI, 1.4–1.7 mg I/mL) for dsDECT, rsDECT, and combined cohorts, respectively. Optimal normalized discriminant thresholds were 0.3 mg I/mL (95% CI, 0.2–0.4 mg I/mL) for both the dsDECT and rsDECT cohorts, and 0.3 mg I/mL (0.3–0.4 mg I/mL) for the combined cohort. The AUC, sensitivity, and specificity for the combined optimal normalized discriminant threshold of 0.3 mg I/mL was 0.96 (95% CI, 0.92–1.00), 0.93 (0.84–0.97), and 0.95 (0.91–0.98), respectively. Normalization resulted in decreased variability and better lesion separation (effect size, 1.77 vs 1.69, p < 0.0001). CONCLUSION. The optimal absolute discriminant threshold for evaluating renal lesions varies depending on the type of DECT platform, though this difference is not statistically significant. Variation can be reduced with a better separation of vascular and nonvascular lesions by normalizing iodine quantification to the aorta.
关键词： renal lesions,dual-energy CT,rapid-kilovoltage switching,iodine,dual source,variability
更新于2025-09-19 17:15:36
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High-Pitch Wide-Coverage Fast-Kilovoltage-Switching Dual-Energy CT: Impact of Pitch on Noise, Spatial Resolution, and Iodine Quantification in a Phantom Study
摘要： OBJECTIVE. The purpose of this study was to assess the impact of high pitch values on image noise, spatial resolution, and iodine quantification in single-source wide-coverage fast-kilovoltage-switching dual-energy CT (DECT). MATERIALS AND METHODS. Two phantom experiments were conducted. First, image noise and spatial resolution in the x-, y-, and z-directions were assessed. Second, the accuracy of iodine quantification was investigated with multiple-size phantoms with pure iodine and blood-iodine inserts. Both phantoms were scanned repeatedly with a third-generation fast-kilovoltage-switching DECT scanner with a collimation width of 80 mm at four different pitch values (0.5, 0.99, 1.375, 1.53) and three different gantry rotation times (0.6, 0.8, 1.0 second). Image noise, spatial resolution, and absolute error of iodine concentration (E) were measured. A linear mixed effects model was used to determine the effect of pitch, rotation time, and size on the error of iodine concentration. RESULTS. Image noise and xy spatial resolution were comparable among the four pitch values. Spatial resolution in the z-direction was inferior and had higher variance at a low pitch of 0.5 compared with pitches of 0.99, 1.375, and 1.53. Error of iodine concentration was significantly affected by pitch and rotation time (p < 0.001). E decreased with increasing pitch and decreasing rotation time. In detail, mean E was 0.91 ± 0.47 mg I/mL for a pitch of 0.5, 0.52 ± 0.29 mg I/mL for 0.99, 0.44 ± 0.25 mg I/mL for 1.375, and 0.40 ± 0.25 mg I/mL for 1.53. CONCLUSION. High-pitch wide-coverage fast-kilovoltage-switching DECT can be performed without impairing image quality or iodine quantification, and the results are superior to those of imaging at a low pitch of 0.5.
关键词： iodine quantification,spatial resolution,fast kilovoltage switching,pitch,dual-energy CT
更新于2025-09-19 17:15:36
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Photocontrolled Iodine-Mediated Green Reversible-Deactivation Radical Polymerization of Methacrylates: Effect of Water in the Polymerization System
摘要： Photocontrolled iodine-mediated reversible-deactivation radical polymerization (RDRP) is a facile and highly efficient access to precision polymers. Herein, a facile photocontrolled iodine-mediated green RDRP strategy was successfully established in water by using 2-iodo-2-methylpropionitrile (CP-I) as the initiator and water-soluble functional monomers including poly(ethylene glycol) methyl ether methacrylate (PEGMA), 2-hydroxyethyl methacrylate (HEMA), and 2-hydroxypropyl methacrylate (HPMA) as the model monomers under blue-light-emitting diode (LED) irradiation at room temperature. Well-defined polymers (PPEGMA, PHEMA, PHPMA) with narrow polydispersities (1.09?1.21) were obtained, and amphiphilic block copolymers which can form nanospheres in situ in water (PPEGMA-b-poly(benzyl methacrylate) (PPEGMA-b-PBnMA) and PPEGMA-b-PHPMA) were prepared. To explore the role of water in our polymerization, control experiments were successfully carried out by using oil-soluble monomer methyl methacrylate (MMA) with the help of trace amounts of water. Notably, the green solvent—water—has an additionally positive effect in accelerating the polymerization and makes our polymerization system an environmentally friendly polymerization system. Therefore, this simple strategy conducted in the presence of water enables the green preparation of well-defined water-soluble or water-insoluble polymers and clean synthesis of amphiphilic copolymer nanoparticles in situ.
关键词： blue-light-emitting diode,water-soluble functional monomers,amphiphilic block copolymers,green solvent,RDRP,Photocontrolled iodine-mediated reversible-deactivation radical polymerization
更新于2025-09-19 17:13:59
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Blue LED Irradiation of Iodonium Ylides Gives Diradical Intermediates for Efficient Metal-free Cyclopropanation with Alkenes
摘要： A facile and highly chemoselective synthesis of doubly activated cyclopropanes is reported where mixtures of alkenes and b-dicarbonyl-derived iodonium ylides are irradiated with light from blue LEDs. This metal-free synthesis gives cyclopropanes in yields up to 96 %, is operative with cyclic and acyclic ylides, and proceeds with a variety of electronically-diverse alkenes. Computational analysis explains the high selectivity observed, which derives from exclusive HOMO to LUMO excitation, instead of free carbene generation. The procedure is operationally simple, uses no photocatalyst, and provides access in one step to important building blocks for complex molecule synthesis.
关键词： hypervalent iodine,cyclopropanation,LED photochemistry,iodonium ylides,computational analysis
更新于2025-09-19 17:13:59
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Improve the quality of HC(NH2)2PbIxBr3?x through iodine vacancy filling for stable mixed perovskite solar cells
摘要： Formamidinium-based (FA-based) with broader light absorption spectra have been attracted enormous attention. However, the FAI-PbI2-DMSO intermediate anisotropic ?bers can easily produce yellow δ-FAPbI3 and uncontrolled excess PbI2, which signi?cantly increased the defect and reducing the reproducibility of devices. Furthermore, the iodine defect in polycrystalline ?lms would enlarge the perovskite tolerance factor and trigger ion migration. This ion migration within perovskite layer leads to device degradation and impedes large scale commercial applications. Herein, we develop a vacancy ?lling (VF) method to repair iodine vacancy as well as yield pure black phase FA perovskite. Upon post treatment with FABr, the point defects on surface and the notorious δ-FAPbI3 caused by lager tolerance are removed though vancancy fulling. The champion of obtained FAPbIxBr3?x device presents the power conversion e?ciency (PCE) up to 18.2% and could remain > 85% of the original PCE after 20 days in the dark at room temperature (10–25 °C) and humidity of 10–40%. Therefore, this VF technique provides an interesting entry for obtaining high pure black perovskite phase.
关键词： Iodine vacancy,Nonperovskite phase,Formamidinium perovskite solar cells,Post-treating
更新于2025-09-19 17:13:59
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Glycerin-based electrolyte for reduced drying of dye-sensitized solar cells
摘要： Dye-sensitized solar cells (DSSCs) are of high interest especially for applications on flexible or even stretchable substrates, such as architectural textiles. One of the main challenges for such use is the electrolyte which is usually fluid and thus leaks not only through porous textile structures, but also through the edges of common glass-based DSSCs. Possibilities to overcome this problem are complete sealing of glass-based cells, preparation of solid-state electrolytes or embedding a fluid electrolyte in a textile-based matrix. Here we report on a new route to avoid evaporation of the electrolyte. Using glycerin as the base for a iodine-triiodide electrolyte, glass-based DSSCs showed constant or even increasing efficiencies during more than three months, while the reference cells based on a commercially available water-based iodine-triiodide electrolyte showed decreasing efficiencies already after four weeks and were completely dried after two months. Our results suggest using glycerin-based fluid electrolyte, possibly in combination with a textile-based matrix, to create durable DSSCs without the necessity to perfectly seal them.
关键词： glycerin,iodine-triiodide,natural dye,electrolyte,textile fabric,dye-sensitized solar cells (DSSCs)
更新于2025-09-16 10:30:52
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Direct analysis bromine and iodine of dried serum spots by laser ablation‐Inductively coupled plasma mass spectrometry
摘要： Rationale: Accurate quantitative analysis of bromine and iodine in serum is an important aspect of monitoring body condition, but the volatile loss of halogen in sample pretreatment is troublesome problem. We present a validated and flexible high-throughput method for quantification of bromine and iodine in dried serum spots (DSS) using LA-ICP-MS and an external aqueous standard calibration curve. The influence of serum matrix and laser ablation conditions on analysis of bromine and iodine in DSS were researched systematically. Methods: Aqueous standards without matrix matching were used for calibration to analyze bromine and iodine in serum by LA-ICP-MS. 5-μL volumes of the aqueous standard solution and serum samples in 10 times diluted concentration were deposited on the PTFE paper to form dried standard calibration spots (DSCS) and DSS, with less than 2 mm in diameter. Laser ablation was performed using a focused Nd:YAG laser beam in raster lineal scan mode. Results: The limit of detection (LOD) for bromine and iodine in DSS were 0.23 and 0.03 mg L-1, respectively. The relative standard deviation (RSD) for this method was less than 10%. The samples were also detected with matrix matching calibration by ICP-MS. The accuracy of the method was verified by statistical analysis of these results from ICP -MS and LA-ICP-MS. The accuracy is satisfactory with recoveries range from 81.5 to 118%. Conclusions: A novel and simple approach for high-throughput screening of bromine and iodine in DSS screening analysis has been established by LA-ICP-MS. Calibration could achieved using aqueous standard solution instead of matrix matching solution. The method allowed analysis of low-volume biological samples without decomposition preparation and decreased the risk of contamination or loss.
关键词： Dried serum spots (DSS),iodine,LA-ICP-MS,bromine
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - An Iodine-Stabilized Laser using a 1542-nm Light Source
摘要： Frequency-stabilized lasers at the telecom wavelengths are of great interest for a wide range of applications, including wavelength standards for optical communication systems [1], and an absolute frequency marker of an optical frequency comb. Especially in astro-comb application [2], it is considered to be a good candidate of an optical frequency reference laser since it has a good frequency connection to a fiber-based frequency comb. Frequency-stabilized lasers at the telecom wavelengths are usually based on the acetylene combination band transitions [1], however, these transitions are relatively weak for frequency stabilization to realize high stability. On the other hand, molecular iodine has very strong absorption lines in the 500-nm wavelength region. Highly stable and reliable iodine-stabilized lasers have been realized by using frequency-doubled 1-μm lasers [3]. In this study, we developed an iodine-stabilized laser at the telecom wavelength by using frequency-tripled 1542-nm laser. In the previous study [4], third harmonic generation (THG) of a 1.5 μm laser has been demonstrated by using two periodically poled lithium niobate (PPLN) waveguides. On the other hand, as shown in the inset of Fig. 1(a), we used a dual-pitch PPLN waveguide (NTT Electronics Corporation WS-0514-000-A-C-C-TEC) which consists of two stages of PPLN with different polling periods for second harmonic generation (SHG, 1542 nm →771 nm) and sum frequency generation (SFG, 1542 nm + 771 nm →514 nm). Figure 1(a) shows the phase-matching curve of the waveguide for both SHG and SFG. The phase-matching curve for SHG is broadened because the PPLN has a chirped polling period in the first stage, which enables the satisfaction of both phase-matching conditions for SHG and SFG simultaneously. A maximum power of 1.7 mW was obtained when the 1.5-μm-laser output power was 200 mW. Doppler-free transition signals of molecular iodine were observed by saturation spectroscopy based on the modulation transfer technique [3]. The inset of Fig. 1(b) shows the obtained entire hyperfine components of the R(73)46-0 transition at 514 nm. The laser frequency was stabilized to the a1 hyperfine component of the observed transition. To evaluate the stability of the laser frequency, we measured the laser frequency using an optical frequency comb referenced to a H-maser. Figure 1(b) shows the measured Allan standard deviation that indicates the frequency stability of the developed laser. The Allan standard deviation was 1×10-11 for a 1-s averaging time. The short-term stability, limited by the signal-to-noise ratio of the transition signal, will be improved by increasing the laser power using a high-power erbium-doped fiber amplifier. As for the long-term stability, we need to verify the uncertainty factors that cause the long-term drift and remove them as possible.
关键词： iodine-stabilized laser,frequency-tripled 1542-nm laser,dual-pitch PPLN waveguide,Frequency-stabilized lasers,telecom wavelengths
更新于2025-09-16 10:30:52
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A Novel Nano-approach for Targeted Inner Ear Imaging
摘要： During the last decade, there have been major improvements in imaging modalities and the development of molecular imaging in general. However detailed inner ear imaging still provides very limited information to physicians. This is unsatisfactory as sensorineural hearing loss is the main cause of permanent hearing loss in adults and at least 134 genetic mutations that result in congenital hearing loss have been identified. We are still unable, in most cases where gross anatomical changes are not observed, to determine the exact cause of hearing loss at a cellular or molecular level in patients using non-invasive techniques. This limitation in inner ear diagnostic modalities is a major obstacle behind the delay in discovering treatments for many of the causes of sensorineural hearing loss. This paper initially investigated the use of targeted gold nanoparticles as contrast agents for inner ear imaging. These nanoparticles have many useful characteristics such as being easy to target and possessing minimal cytotoxicity. We were able to detect the nanoparticles diffusing in the hair cells using confocal microscopy. Regrettably, despite their many admirable characteristics, the gold nanoparticles were unable to significantly enhance CT imaging of the inner ear. Consequently, we investigated liposomal iodine as a potential solution for the unsatisfactory CT contrast obtained with the gold nanoparticles. Fortunately, significant enhancement of the micro-CT image was observed with either Lugol’s solution or liposomal iodine, with Lugol’s solution enabling fine inner ear structures to be detected.
关键词： Targeted contrast agents,Liposomal iodine,Inner ear imaging,Gold nanoparticles
更新于2025-09-16 10:30:52