[Determination of tetrodotoxin in urine by liquid chromatography-tandem mass spectrometry with internal standard calibration].

OBJECTIVE: An analytical method was developed for tetrodotoxin(TTX) in urine by liquid chromatography-tandem mass spectrometry(LC-MS/MS) with internal standard calibration. METHODS: TTX in the sample was extracted with the mixture of acetic acid/methanol/acetonitrile(0.005 mL/0.8 mL/1.8 mL), cleaned by solid phase extraction(SPE) with cation exchange cartridge, eluted with 50% acetonitrile/water containing 0.3% hydrochloric acid, and neutralized with ammonia. The extract was separated by a Waters XBridge~(TM) BEH Amide column(150 mm×3.0mm, 1.7 µm) and measured by MS/MS. By optimizing sample extraction and SPE cleanup conditions, the problems of low recovery and strong suppression effects of MS signal for TTX in urine were resolved when cleaned with cation exchange cartridge. RESULTS: Quantitatively calibrated by the internal standard of Kasugamycin, good linear relationship was found for TTX in urine at the range of 0.2-200 µg/L with the correlation coefficient(r~2) of 0.997. The limits of detection and quantitation for TTX in sample matrix were 0.1 and 0.2µg/L, respectively. The average recoveries at three spiking levels(0.2, 10.0 and 200 µg/L) were 89.3%-95.3% with relative standard deviation(n=6) less than 5.1%. The concentrations of TTX in urine from 11 poisoning patients were 0.4-138 µg/L. The detection rate was 100% in urine collected within 3 days after poisoning. CONCLUSION: The established method was simple, accurate and sensitive. It can provide reliable technical support for the rapid treatment of TTX poisoning events and the study of toxin metabolism in vivo.

GINS2 Promotes Osteosarcoma Tumorigenesis via STAT3/MYC Axis.

GINS2 is overexpressed in several cancers, but little is known about its role in osteosarcoma (OS). A series of in vivo and in vitro experiments were conducted to explore the role of GINS2 in OS. In this study, we demonstrated that GINS2 was found to be highly expressed in OS tissues and cell lines, which was associated with poor outcomes in OS patients. GINS2 knockdown hindered the growth and induced apoptosis in OS cell lines in vitro. Furthermore, GINS2 knockdown effectively inhibited the growth of a xenograft tumor in vivo. By using an Affymetrix gene chip and intelligent pathway analysis, it was demonstrated that the GINS2 knockdown could reduce the expression of several targeted genes and reduce the activity of the MYC signaling pathway. Mechanically, LC-MS, CoIP, and rescue experiments revealed that GINS2 promoted tumor progression through the STAT3/MYC axis in the OS. Moreover, GINS2 was associated with tumor immunity and may be a potential immunotherapeutic target for OS.

Use of different endpoints to determine the bioavailability of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in Sprague-Dawley rats.

Liver, fat (adipose tissue), blood, and feces are common endpoints used to determine the bioavailability of persistent organic pollutants (POPs). However, it is not known whether the bioavailability of each endpoints is comparable or whether there is a comprehensive endpoint that can be used for all congeners for the measurement of bioavailability. In this study, we observed the accumulation and distribution of 10 polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and 18 polychlorinated biphenyls (PCBs) in different organs of Sprague-Dawley (SD) rats and calculated the bioavailability based on feces, liver, and fat endpoints. Our results indicated that PCB 126, PCB 169, and 50% of PCDD/F congeners were mainly accumulated in the liver, with a bioavailability ranging from 28.9 to 50.6%. On the other hand, higher chlorinated (> 5 Cl) PCB congeners were mainly accumulated in adipose tissues, with a bioavailability ranging from 20.1 to 82.2%, while lower chlorinated (< 5 Cl) pollutants, such as 2,3,7,8-TeCDF, 2,3,7,8-TeCDD, 1,2,3,7,8-PeCDF, and PCB 28, 52, 77, 81, were likely metabolized over 36% in rats during the 8-week experimental period. If we considered metabolization (degradation) as a type of bioavailable process, then the fecal endpoint was a feasible option. However, if we considered the selective accumulation behavior of some congeners in different organs/tissues, then there was no single comprehensive endpoint suitable for all congeners. Lastly, female rats showed significantly higher PCDD bioavailability than male rats at low dose level (0.2 ng/100 g b.w./d); however, the difference in PCB bioavailability between female and male rats was not significant.

Breastfed infants' exposure to polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans, and per- and polyfluoroalkyl substances: A cross-sectional study of a municipal waste incinerator in China.

A municipal waste incinerator (MWI) in Zhejiang, China, operating since 2008 was completely reconstructed from 2016 to 2019. In 2013, we conducted a cross-sectional study of breastfeeding mothers living near the MWI. We evaluated the concentrations of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the mothers' breast milk and their infants' estimated daily intake (EDI). To investigate the temporal variations of these pollutants, we conducted a cross-sectional study of 29 mothers in 2019. We assessed the levels of 18 PCB congeners, 17 PCDD/F congeners, and 21 per- and polyfluoroalkyl substance (PFAS) congeners in breast milk and estimated the EDI. The mean total concentrations of PCDD/Fs (ΣPCDD/Fs) and PCBs (ΣPCBs) were 81.2 and 4.90 ng/g lipid, respectively, while the toxic equivalent quantity (TEQ) levels of ΣPCDD/Fs and dioxin-like PCBs (ΣDL-PCBs) were 2.7 and 1.4 pg WHO-TEQ/g lipid, respectively. Compared to our 2013 measurements, the mass concentrations of ΣPCDD/Fs and ΣPCBs decreased by 13% and 35%, respectively (3.361 vs. 2.915 pg/g wet weight [ww] and 269.1 vs. 175.0 pg/g ww, respectively). The TEQ-ΣPCDD/F levels decreased by 67% (0.241 vs. 0.080 pg/g ww), but the TEQ-ΣDL-PCB levels increased by 11% (0.046 vs. 0.051 pg WHO-TEQ/g ww). The median concentration of PFASs was 0.250 ng/mL, ranging from 0.151 to 0.833 ng/mL. The infants' mean EDI of total PCDD/Fs and DL-PCBs was 17.7 pg TEQ/kg body weight [bw], representing a 20% decline compared to 2013. The average EDI levels of PFOS, PFOA, and PFNA were 5.8, 17.9, and 1.7 ng/kg bw, respectively. A comprehensive comparison of the results with studies from around the world showed that the potential health risks posed by legacy PCDD/F and PCB pollutants were not as grave for mothers and infants living near this MWI, but the emerging PFAS pollutants represented a new cause for concern. MAIN FINDINGS: The potential health risks posed by legacy PCDD/F and PCB pollutants were not particularly serious for mothers and infants living near the MWI, but the emerging PFAS pollutants raised new concerns.

Current epidemiological profile and characteristics of traumatic cervical spinal cord injury in Nanchang, China.

STUDY DESIGN: A hospital-based retrospective epidemiological study. OBJECTIVE: To describe the recent epidemiological profile and characteristics of traumatic cervical spinal cord injury (TCSCI) in Nanchang, Jiangxi Province, China. SETTING: The First Affiliated Hospital of Nanchang University, The Second Affiliated Hospital of Nanchang University and The Third Affiliated Hospital of Nanchang University. METHODS: We retrieved the medical records of 1290 persons with TCSCI admitted to The First Affiliated Hospital of Nanchang University, The Second Affiliated Hospital of Nanchang University and The Third Affiliated Hospital of Nanchang University between January 2012 and December 2018. The characteristics recorded were age, sex, aetiology of the injury, neurological level, American Spinal Injury Association (ASIA) impairment scale, patient source, and associated trauma. Categorical data were reported as frequency and proportions and compared using the Fisher's exact or Chi-square test. P < 0.05 was considered to be statistically significant. RESULTS: A total of 1290 persons with TCSCI were included in the present study. The largest age group was 46-60 years, accounting for 31.6% of the patients; the mean age was 53.1 ± 16.2 years, and the male/female ratio was 7.06:1. More than 87.4% of persons were transferred from a primary or secondary hospital. The leading cause of injury was motor vehicle collision (41.3%), followed by low fall (26.5%). The most common cervical spine injury level was the C5 segment, accounting for 24.3% of cases. As for severity, ASIA grade D was encountered most frequently, with a total of 518 persons (40.2%). Among all participants, 56.8% had associated trauma, the most common being head injuries (18.2%). Surgery was the major treatment choice (51.2%), and the number of patients undergoing surgery is increasing from 2012 to 2018, P = 0.02. CONCLUSION: Persons with TCSCI in Nanchang had specific epidemiological characteristics, and preventive measures should focus on middle-aged and older adults. In addition, more attention should be paid to balancing development of medical resources and technology between urban and rural areas.

Effects of curcumin on the bioavailability of dioxin-like pollutants in rats.

The effects of curcumin on the bioavailability of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were investigated in Sprague-Dawley rats. Tetra- and penta-chlorinated PCDFs had the lowest bioavailability and hexa-chlorinated PCDD/Fs had the highest, while there was no obvious change in that of DL-PCBs. Curcumin markedly reduced the toxic equivalent (TEQ) of PCDD/Fs in rats, illustrating the potential to competitively inhibit absorption of PCDD/Fs by the epithelial cells of the small intestine due to the similar chemical structure (diphenyl) between curcumin and PCDD/Fs. Moreover, curcumin lowered the TEQ of DL-PCBs in the liver of male rats, but not female rats. The significant decrease in the bioavailability of PCDD/Fs and DL-PCBs demonstrates the potential detoxification mechanisms of curcumin.

iTRAQ-based proteomic analysis of the molecular mechanisms and downstream effects of fatty acid synthase in osteosarcoma cells.

BACKGROUND: Fatty acid synthase (FASN) is a lipogenic enzyme that participates in tumor progression. We previously showed that FASN is dysregulated in OS malignancy, but the molecular mechanism(s) of these effects remained unclear. METHODS: We examined differentially expressed proteins (DEPs) in FASN-silenced osteosarcoma 143B cells and their parental cells by isobaric tags for relative and absolute quantitation (iTRAQ). Differentially expressed proteins were classified using GO and KEGG analysis. The association between FASN and heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1) was confirmed using qPCR, Western blot, and immunohistochemistry. The function of HNRNPA1 in osteosarcoma was determined using CCK-8, colony formation, wound healing, transwell migration, and invasion assays. RESULTS: Among the 4971 identified proteins, 567 DEPs (325 upregulated and 242 downregulated) were identified. The top 10 upregulated proteins comprised HIST1H2AB, INA, INTS5, MTCH2, EIF1, MAPK1IP1L, PXK, RPS27, PM20D2, and ZNF800, while the top 10 downregulated proteins comprised NDRG1, CNTLN, STON2, GDF7, HECTD3, HBB, TPM1, PPP4R4, PTTG1IP, and PLCB3. Bioinformatic analysis indicated that the DEPs were related to cellular processes, metabolic processes, biological regulation, binding, and catalytic activity. HNRNPA1 was dysregulated in FASN-silenced 143B and HOS cells. qPCR, Western blot, and immunohistochemistry showed that FASN expression positively correlates with HNRNPA1 expression. Further studies indicated that HNRNPA1 correlates with OS diagnosis and prognosis. And HNRNPA1 silence inhibits the proliferation, migration, and invasion in OS cells. CONCLUSION: HNRNPA1 acts as targets downstream of FASN and potential biomarker and oncogene in OS.

Determination of ibotenic acid and muscimol in wild mushroom by dansyl chloride derivatization-liquid chromatography-tandem mass spectrometry / 预防医学

Objective @#To develop an analytical method of ibotenic acid (IBA) and muscimol (MUS) in wild mushroom by dansyl chloride (DNSCl) derivatization-liquid chromatography-tandem mass spectrometry (LC-MS/MS), and to provide technical support for etiological identification of mushroom poisoning events.@*Methods @#The sample was extracted with hydrochloric acid solution, derived by bimolecular DNSCl, diluted and inorganic salts precipitated with acetonitrile. The extract was separated by a waters XBridgeTM BEH C18 column and measured by LC-MS/MS.@*Results @#The limits of detection for IBA and MUS in wild mushroom were 0.15 mg/kg and 0.1 mg/kg, respectively. Good linear relationship was obtained for IBA and MUS at the range of 0.5-250 mg/kg with the correlation coefficient of 0.997 and 0.999, respectively. The average recoveries at three spiking levels were 84.5%-102.0% with relative standard deviations (RSDs, n=6) of 4.7%-8.6% for IBA. The average recoveries were 88.6%-95.4% with RSDs (n=6) of 4.9%-7.5% for MUS. @*Conclusion @#The optimized sample extraction and bimolecular DNSCl derivatization conditions can achieve rapid and accurate analysis of IBA and MUS in wild mushroom poisoning sample.

[Fat-soluble vitamins in different eggs and egg products in Hangzhou City].

OBJECTIVE: To analyze the contents of fat-soluble vitamins in different kinds of eggs and egg products in Hangzhou City. METHODS: The contents of fat-soluble vitamin A, vitamin E, vitamin K_1 and vitamin K_2(menaquinone-4, menaquinone-7 and menaquinone-9) in eggs and egg products were determined by the high-performance liquid chromatography method. The contents of vitamin D were determined by high performance liquid chromatography-tandem mass spectrometry. The determined contents were compared with the corresponding nutrient reference values. RESULTS: The contents of vitamin A, vitamin D, vitamin E and vitamin K in different eggs and egg products were 64-278 µg RAE/100 g edible, 0. 2-9. 6 µg/100 g edible, 0. 59-2. 31 mg α-TE/100 g edible and 9. 5-84. 8 µg/100 g edible, respectively, accounting for 4%-192% of the corresponding nutrient reference values. The contents of fat-soluble vitamin A, vitamin D, vitamin E and vitamin K in duck, goose and quail eggs were higher than those in chicken eggs and pigeon eggs. CONCLUSION: There are some differences in fat-soluble vitamin A, vitamin D, vitamin E and vitamin K in different eggs and egg products, but there is no significant difference between groups.

[Eight vitamin E congeners in seafood and aquatic products in Zhejiang Province].

OBJECTIVE: Comparison and analysis of α-, ß-, γ-, δ-tocopherol(T) and α-, ß-, γ-, δ-tocotrienol(T3) in 44 species of seafood and aquatic products is under processed to enrich the database of food composition in China and provide a scientific reference for dietary intake choice. METHODS: Quantitative and correlation analysis of eight vitamin E isomers were based on external calibration method with reversed-phase high-performance liquid chromatography-fluorescence detector, after hot saponification with alkaline and liquid-liquid extraction. RESULTS: The content of α-tocopherol equivalent(α-TE) in seafood and aquatic products varied greatly(from 0. 10 to 4. 01 mg/100 g edible), as well as the isomer forms. Aspect of vitamin E forms in aquatic fish, detection rates of α-T and α-T3 were both 100%, while the rates of γ-T and γ-T3 were 31. 58% and 68. 42%, respectively. Aspect of vitamin E forms in sea fish, detection rates α-T3, γ-T and γ-T3 were 28. 57%, 28. 57% and 35. 71%, respectively, while the rate of α-T was 100%. The form of vitamin E isomers in fish was at some extent different when they raise up in wild and farming environment, whereas there was no significant different in content of isomers. For shrimp and crabs, the content of α-TE was also various(from 0. 31 to 14. 27 mg/100 g edible), whereas α-T was the primary vitamin E form. And the content of α-T in female crabs was a little higher than that in male crabs, without statistic difference. With respect to correlation analysis, there was a strong correlation between γ-T and α-T3 in sea fish, while weak correlation of isomers in aquatic fish and certain correlations of isomers in shrimp and crab. CONCLUSION: The level of vitamin E content in seafood and aquatic products are quite different. Thus, it will bring in different effects on total activity and intake of vitamin E isomers by consumption of different species of seafood and aquatic products.

Contamination status of bisphenol A and its analogues (bisphenol S, F and B) in foodstuffs and the implications for dietary exposure on adult residents in Zhejiang Province.

An effective method has been developed for the simultaneous determination of four bisphenols (bisphenol A, S, F and B) in various foodstuffs. The contaminants were extracted by QuEChERS-based strategy and subjected to ion-exchange solid-phase extraction for further clean-up. The critical variables were screened by Plackett-Burman design and then optimized by central composite design. Under the optimized conditions, satisfactory accuracy (recoveries 76%-116%) and precision (RSDs < 12%) were achieved. The established method was then used to assess the contamination status of 379 real samples. Bisphenol A was demonstrated to be the predominant bisphenol with highest incidence (79.7%) and average concentration (14.3 µg/kg). The positive rates (mean concentration) of bisphenol S, F and B were 37.7% (1.6 µg/kg), 26.9% (1.4 µg/kg) and 0.0% (not detected), respectively. Finally, the daily dietary intakes of ∑4bisphenolsfor adult residents were estimated (55.9-76.1 ng/kg bw/day) according to the contamination concentrations and the daily recommended intakes.

[Determination of 22 antibiotics in disinfection products by ultra-performance liquid chromatography tandem mass spectrometry].

OBJECTIVE: To develop a method for simultaneous determination of 5 nitroimidazole antibiotics and 17 sulfonamides antibiotics in disinfection products by ultra-performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS). METHODS: Samples were spiked with isotope internal standard, and then extracted by 2% formic acid solution and acetonitrile with ultrasonic, followed by MCX column to remove matrix interference and for enrichment. The supernatants were diluted with 2% formic acid solution before loading on the columns, then washed with 2% formic acid solution and methanol respectively, eluted with 5% ammonium methanol. The separation was performed on a CORTECS~(TM) UPLC C_(18)(100 mm×2. 1 mm, 1. 6 µm) column by using 0. 1% formic acid solution and 0. 1% formic acid acetonitrile as mobile phase with gradient elution. The antibiotics were analyzed by UPLC-MS/MS. RESULTS: The linear ranges of 22 antibiotics were 0. 05-5. 0 ng/mL and the correlation coefficients were greater than 0. 999. The limits of detection(LODs) were 0. 03-0. 15 µg/kg and the recoveries were 84. 3%-121. 2% with the relative standard deviations were 1. 13%-8. 43%(n=6). The method was successfully used to detect the content of antibiotics in 20 disinfection products, 45% of samples had been detected positively. CONCLUSION: This method is simple, sensitive, selective and accurate, and could be applied for simultaneous detection of antibiotics in disinfection products.

Simultaneous detection of multiple hydroxylated polychlorinated biphenyls from biological samples using ultra-high-performance liquid chromatography with isotope dilution tandem mass spectrometry.

We established a method for the separation and detection of nine hydroxylated polychlorinated biphenyls in whole blood and urine samples using ultra high performance liquid chromatography coupled with electrospray negative ionization tandem mass spectrometry. Clean-up procedures involved a filtration step, and optimization involved a pretreatment step consisting of a simple liquid-liquid extraction using hydrated silica-gel chromatography (5%). Nine hydroxylated polychlorinated biphenyls were separated on an ultra high performance liquid chromatography HSS T3 column using a gradient elution program of 2 mmol ammonium formate aqueous solution (A) and methanol (B). Recovery ranged from 84.0 to 105.4% for the nine different hydroxylated polychlorinated biphenyls in urine with three spiked levels of 0.1, 1, and 2 ng and from 73.5 to 98.6% for the blood with spiked levels of 0.2, 1, and 2 ng. The relative standard deviations were <8.7% (n = 6), and the limits of detection in urine and whole blood for the nine hydroxylated polychlorinated biphenyls were in the range of 1.5-4 and 20-100 pg/g, respectively. This analytical method may enable the simultaneous detection of various hydroxylated polychlorinated biphenyls from complex tissue matrices.

Analysis of plasma proteome from cases of the different traditional Chinese medicine syndromes in patients with chronic hepatitis B.

A proteomic analysis method, two dimensional gel electrophoresis (2-DE) followed by matrix-assisted laser desorption/ionization time-of-flight MS (MALDI-TOF-MS), was used to explore the link between plasma proteome and the different syndromes of traditional Chinese medicine (TCM) in patients with chronic hepatitis B (CHB). In compared with the plasma proteomes from health donors, the alterations in protein expression from cases of the five TCM syndromes, including damp heat stasis in the middle-Jiao syndrome, liver Qi stagnation and spleen deficiency syndrome, spleen and kidney Yang deficiency syndrome, liver and kidney Yin deficiency syndrome, and blood stasis into collateral syndrome with CHB were identified (P<0.05). In the cases of the five TCM syndromes with CHB, immunoglobulin J-chains (IGJ) and C-reactive protein (CRP) were up-regulated, while haptoglobin (HPT), retinol binding protein (RBP) and vitronectin were down-regulated. To further confirm these results, four proteins, including CRP, IGJ, HPT and RBP, from more plasma samples were quantified by ELISA. The results showed that the changes of protein levels were consistent with those from the 2-DE experiment. Importantly, the upregulation tendency of IGJ level in plasma is related with the different TCM syndromes with CHB (P<0.05). Our results show that IGJ may serve as a novel potential biomarker for diagnosis of the different TCM syndromes in patients with CHB.

Blind deblurring reconstruction technique with applications in PET imaging.

We developed an empirical PET model taking into account system blurring and a blind iterative reconstruction scheme that estimates both the actual image and the point spread function of the system. Reconstruction images of high quality can be acquired by using the proposed reconstruction technique for both synthetic and experimental data. In the synthetic data study, the algorithm reduces image blurring and preserves the edges without introducing extra artifacts. The localized measurement shows that the performance of the reconstruction image improved by up to 100%. In experimental data studies, the contrast and quality of reconstruction is substantially improved. The proposed method shows promise in tumor localization and quantification.

MMSE reconstruction for 3D freehand ultrasound imaging.

The reconstruction of 3D ultrasound (US) images from mechanically registered, but otherwise irregularly positioned, B-scan slices is of great interest in image guided therapy procedures. Conventional 3D ultrasound algorithms have low computational complexity, but the reconstructed volume suffers from severe speckle contamination. Furthermore, the current method cannot reconstruct uniform high-resolution data from several low-resolution B-scans. In this paper, the minimum mean-squared error (MMSE) method is applied to 3D ultrasound reconstruction. Data redundancies due to overlapping samples as well as correlation of the target and speckle are naturally accounted for in the MMSE reconstruction algorithm. Thus, the reconstruction process unifies the interpolation and spatial compounding. Simulation results for synthetic US images are presented to demonstrate the excellent reconstruction.

On the convergence of generalized simultaneous iterative reconstruction algorithms.

In this paper, we generalize the widely used simultaneous block iterative reconstruction algorithm and show that it converges, at a linear rate, to a weighted least-squares and weighted minimum-norm reconstruction. Our theoretical result provides a much simpler proof of the convergence properties obtained by Jiang and Wang and covers a much more general class of algorithms. The frequency domain iterative reconstruction algorithm is then introduced as a special application of our theory.

Application of blind deblurring reconstruction technique to SPECT imaging.

An SPECT image can be approximated as the convolution of the ground truth spatial radioactivity with the system point spread function (PSF). The PSF of an SPECT system is determined by the combined effect of several factors, including the gamma camera PSF, scattering, attenuation, and collimator response. It is hard to determine the SPECT system PSF analytically, although it may be measured experimentally. We formulated a blind deblurring reconstruction algorithm to estimate both the spatial radioactivity distribution and the system PSF from the set of blurred projection images. The algorithm imposes certain spatial-frequency domain constraints on the reconstruction volume and the PSF and does not otherwise assume knowledge of the PSF. The algorithm alternates between two iterative update sequences that correspond to the PSF and radioactivity estimations, respectively. In simulations and a small-animal study, the algorithm reduced image blurring and preserved the edges without introducing extra artifacts. The localized measurement shows that the reconstruction efficiency of SPECT images improved more than 50% compared to conventional expectation maximization (EM) reconstruction. In experimental studies, the contrast and quality of reconstruction was substantially improved with the blind deblurring reconstruction algorithm.

Novel transmit aperture for very large depth of focus in medical ultrasound B-scan.

Obtaining high quality ultrasound images at high frame rates has great medical importance, especially in applications in which tissue motion is significant (e.g., the beating heart). Dynamic focus and dynamic aperture can improve image quality significantly, and they have been implemented on the receive beam in state-of-the-art medical ultrasound systems. However, implementing dynamic focus and dynamic aperture on the transmit beam compromises frame rate. We introduce a novel sinc squared-argument transmit aperture that is obtained by coherently integrating the quadratic phase change over a continuum of focal points. Thus uniform sensitivity and uniform point spread function can be achieved over a very large depth without reducing the frame rate. Numerical simulations validate our theoretical analysis and demonstrate significant promises of the new technique.

Lesion radioactivity concentration estimation using dual modality gamma ray/X-ray imaging.

Although the use of dedicated gamma cameras in scintimammography permits closer access to the breast and improved spatial resolution relative to conventional gamma cameras, the task of quantifying the radiotracer concentration in the lesion relative to that in the surrounding breast tissue remains challenging because of the lesion-depth-dependent effects of attenuation and collimator blur. We are developing a dual modality scanner that combines digital x-ray mammography and a dedicated gamma camera on a common upright gantry. Here we present the results of a phantom study evaluating the use of the dual modality system for quantifying radioactivity in breast lesions. In addition to assessment of lesion activity, lesion volume estimates are necessary to quantify lesion radioactivity concentration. We have used multiple view x-ray imaging as a means of estimating lesion volume. Using phantom experiments, we have empirically derived a formula for correction of the measured z dimension of the lesion. The error obtained in quantification of lesion activity is approximately 10%. Lesion volume can be assessed with an accuracy comparable to that of lesion activity assessment using five x-ray views. These results suggest that the error in lesion concentration assessment is approximately 14%.