Nuclear Medical Imaging Research Articles

Protection management and procedures of nuclear medicine imaging during novel coronavirus (2019-nCov) infection epidemic period

At the end of December 2019, acute respiratory infectious diseases caused by a new type of coronavirus were prevalent in Wuhan and other cities of China. Different from radiology examinations, the protocols of nuclear medical imaging examinations are complicated, in which more workplaces and staff are needed, resulting more complex management of patients and higher protection requirements. Combined with the characteristics of SPECT and PET imaging procedures, this paper puts forward some suggestions on the protective process of imaging examinations for patients with confirmed or suspected noval coronavirus infec- tion. The main purpose is to protect medical staff from virus infection, effectively reduce the risk of virus transmission during the examination process, and ensure the medical quality and safety. Key words: Coronavirus infections; Nuclear medicine; Protection and control

2020 IEEE Nuclear Science Symposium and Medical Imaging Conference

2020 IEEE Nuclear Science Symposium and Medical Imaging Conference

2020 IEEE Nuclear Science Symposium and Medical Imaging Conference

2020 IEEE Nuclear Science Symposium and Medical Imaging Conference

Development of Novel Nuclear Medical Imaging Probes for Quantification of Matrix Metalloproteinases in Diseases

Matrix metalloproteinases (MMPs) regulate various cellular functions, such as motility, invasion, differentiation, and apoptosis. Precise in vivo quantification of MMPs in disease can provide beneficial information for both basic and clinical research studies. To this end, various types of probes have been developed for imaging MMPs in vivo. In this review, representative MMP-targeted probes, such as binding probes and activatable probes, are outlined, including highlights of our own research. In addition, strategies for the development of probes that apply "theranostics," a concept that integrates therapy and diagnostics, are elucidated with reference to [18F]IPFP, a new probe developed in our laboratory. [18F]IPFP was prepared by iodination of a known MMP inhibitor to enhance its affinity and labeled with the compact prosthetic agent 4-nitrophenyl 2-[18F]fluoropropionate ([18F]NFP) for MMP-targeted positron-emission tomography (PET) and other therapeutic properties. IPFP demonstrated high inhibitory activity toward MMP-12 (IC50 value=1.5 nM). Radioactivity accumulation in the lungs 90 min after administration of [18F]IPFP was 4-fold higher in chronic obstructive pulmonary disease (COPD) mice overexpressing MMPs compared with normal mice. Ex vivo PET confirmed the radioactivity distribution in tissues, and autoradiography analysis demonstrated accumulation differences between COPD and normal mice. Consequently, [18F]IPFP showed potent inhibitory activities against MMPs and suitable pharmacokinetics for imaging pulmonary disease. Thus, [18F]IPFP is a promising theranostic probe for pulmonary disease and is expected to be applied to various other MMP-related diseases. Strategies for MMP probe development introduced in this review are anticipated to lead to the development of superior imaging probes in the future.

Application of nuclear medical imaging in the diagnosis of myocardial amyloidosis

Amyloidosis is a disease caused by abnormal deposition of amyloid protein, and the main types of amyloidosis involving myocardium are light chain amyloidosis (AL) and transthyretin-related amyloidosis (ATTR). Different types of myocardial amyloidosis have different prognosis and treatment methods. Therefore, early diagnosis and classification are particularly important. Nuclear medical imaging can diagnose and classify myocardial amyloidosis noninvasively. Radiotracers for bone scintigraphy has high sensitivity and specificity for the diagnosis of ATTR, and have certain value for prognosis. Sympathetic innervation imaging tracers can detect cardiac sympathetic innervation, which may show myocardial involvement of amyloidosis earlier than bone scintigraphy. Amyloid protein specific imaging agent, which was first used in the diagnosis of amyloidosis in nervous system, has also yielded good results from preliminary studies in myocardial amyloidosis, and the diagnostic specificity in AL is slightly better than that in ATTR. This review introduces the application of nuclear medical imaging in myocardial amyloidosis. Key words: Amyloidosis; Myocardium; Radionuclide imaging; Positron-emission tomography; 3-idobenzylguanidine; Amyloid; Trends

Radioiodinated Nitroxide Derivative for the Detection of Lipid Radicals.

Thus far, no accurate measurement technology has been developed to detect lipid alkyl radicals (lipid radicals), which cause lipid peroxidation. Therefore, we aimed to develop a nuclear medical imaging probe that can be taken up in the lipophilic site in cells such as biological membranes, by reacting specifically with the lipid radicals generated there. We designed and synthesized 4-(4-[125I]iodobenzamido)-2,2,6,6-tetramethylpiperidine-1-oxyl, which shows high reactivity to lipid radicals with a high radiochemical yield and purity. Intracellular retention was found to increase significantly when lipid radicals were produced.

High-Throughput Architecture for Both Lossless and Near-lossless Compression Modes of LOCO-I Algorithm

Real-time image lossless and near-lossless compression based on LOCO-I algorithm is in great demand in many critical missions, such as satellite remote sensing, space exploration, and nuclear medical imaging, for its excellent complexity/compression rate tradeoff. However, the real-time implementation of LOCO-I encounters two bottlenecks in error prediction: the context conflict in context update and the pixel reconstruction loop in near-lossless mode, which always limit the overall throughput in practice. This paper adopts a patch-wise compression method and proposes a high-performance globally pipelined hardware architecture with spatial parallelism in local, in which patch-wise dual parallel error prediction (PEP) modules are designed. The PEP gains an extra pixel cycle and thus, alleviates both the two bottlenecks. Besides, an equivalent simplification scheme is designed to accelerate the error quantization computation, the most time and resource consuming procedure in the pixel reconstruction loop, saving the resource usage, and reducing computing delay. The proposed encoder is able to compress each image patch independently in either lossless or near-lossless mode by parameter setting. It facilitates the Region of Interests compression so as to improve the overall compression ratio and achieves excellent information fidelity. Moreover, the possible error propagation can be prevented and constrained within one single patch. The proposed architecture is implemented on a XILINX Virtex6-75t FPGA and achieves a maximum throughput up to 51.684 MPixel/s. It is the fastest architecture reported in the literature which implements both lossless and near-lossless compression modes.

The Current State of Nuclear Medicine and Nuclear Radiology: Workforce Trends, Training Pathways, and Training Program Websites

Nuclear medicine (NM) is a multidisciplinary field. Its overlap with nuclear radiology (NR) creates unique training considerations, opportunities, and challenges. Various factors impact the workforce, training needs, and training pathways. This state of flux may be perplexing to prospective NM/NR trainees. To evaluate the state of NM/NR training by assessing the (1) workforce trends and job prospects for NM/NR trainees, (2) NM and NR training pathways, and (3) applicant-accessible online presence of training programs. Workforce trends were analyzed using data collected from the 2017 American College of Radiology Commission on Human Resources Workforce Survey. Information regarding the training pathways leading to board certification(s) for NM and NR physicians were obtained through the American Board of Nuclear Medicine, the American Board of Radiology (ABR), and the Society of Nuclear Medicine and Medical Imaging. Each Accreditation Council for Graduate Medical Education-accredited NM residency or NR fellowship training program's website was reviewed for 20 content items to assess its comprehensiveness for those seeking information regarding eligibility, applications, training curriculum, and program characteristics. Number of hires for NM/NR physicians has exceeded the projected number of hires from 2014 to 2017. In the last decade, there has been a greater than 25% decrease in the combined number of traditional NM residencies and NR fellowships (79-58 programs) and a greater than 50% decrease in the combined number of NM and NR trainees (173-82 trainees). In 2017, the ABR redesigned its 16-month pathway leading to specialty certification in diagnostic radiology and subspecialty certification in NR. As of March 24, 2019, there are 36 diagnostic radiology or IR residency programs with 64 trainees participating in this redesigned NR pathway. Of the 93.1% (54/58) of traditional Accreditation Council for Graduate Medical Education-accredited NM and NR training programs having websites in the 2017-2018 academic year, the mean number of online criteria met per program was 7.74 ± 3.2 of 20 (38.7%). Recruitment into the traditional NM/NR training pathways has been steadily declining, but there has been a renewed interest with the redesigned ABR 16-month pathway. There is a paucity of online information available to prospective NM/NR applicants. In this rapidly evolving and unique field, it is important to streamline NM/NR training and bolster the information accessible to potential NM/NR applicants as they weigh career options.

Application of the multichannel front-end chip for SiPM-based gamma detector

A prototype of a multichannel application specific integrated circuit(ASIC)analog front-end chip was recently developed at the Department of Microelectronics in MEPhI for SiPM-based applications[1]. The chip designed as an analog front-end for the detectors using scintillation crystals NaI(Tl) or CsI(Tl) coupled with a SiPM photosensor.The chip can be used to build multichannel systems in such fields as nuclear science, medical imaging and homeland security.

Structure and Tracer Kinetics-Driven Dynamic PET Reconstruction

Dynamic positron emission tomography (dPET) is a nuclear medical imaging technology that shows the changes in radioactivity over time. In this article, we propose a structure and tracer kinetics-constrained reconstruction framework for dPET imaging. Given the Poisson nature of PET imaging, we integrate the sparse penalty on a dual dictionary into a Poisson-likelihood estimator. Explicit anatomical constraints with a structural dictionary constructed from magnetic resonance or computed tomography images are employed to take advantage of the anatomical imaging modalities. In the kinetic dictionary, we treat tracer kinetics as random variables in a physiologically plausible range based on a compartmental model. We demonstrate the performance of our proposed framework with a direct simulated data set and real patient data.

1206 Gastric Emptying Scans: Adherence to National Guidelines

INTRODUCTION: Gastric-emptying scintigraphy (GES), routinely used to measure gastric emptying, is an essential tool to diagnose gastroparesis. An accurate diagnosis of gastroparesis relies upon the GES being performed according to a validated protocol. Jointly published protocol guidelines have been available for over a decade; however, the extent to which these guidelines are adhered to is unknown. This study aimed to assess national compliance with established GES protocol guidelines. METHODS: We developed a questionnaire addressing key protocol measures outlined in the published Procedure Guideline for Adult Solid-Meal Gastric Emptying Study 3.0. Survey questions addressed patient information collection (15), patient preparation and procedure protocol (16), meal content and preparation (7), imaging (3), interpretation (4), and reporting (7). Demographic data was also collected. The anonymous questionnaire was distributed electronically to members of the Society of Nuclear Medicine and Medical Imaging (SNMMI) and non-member recipients of the SNMMI daily email newsletter. One response per medical institution was permitted. Data were entered manually and statistically assessed using JMP®, Version 14.0. SAS Institute Inc., Cary, NC. RESULTS: 121 medical institutions (MI) responded; 49 (40.4%) were academic/teaching medical centers. The mean number of annual GES procedures was 199.9 (range, 5 to 2000 GES/year). On average, MI performed 64% (33.5/52) of protocol measures according to guidelines while academic medical centers performed 61% (31.5/52) of protocol measures according to guidelines. Only 59% of MI use the validated meal. 42% of MI reported stopping imaging prior to the validated 4-hour interval. Only 16% of MI test blood glucose levels prior to GES while 71% cancel or reschedule GES if blood glucose levels are above the validated cut-off. 68% of MI ask patients if they take narcotic pain medications; only 49% require that patients stop taking narcotic pain medications at least two days prior to the GES. Only 4.5% of MI perform GES while adhering to 3 critical measures: validated study duration; controlling blood glucose levels; and properly restricting medication use. CONCLUSION: Low compliance with GES protocol guidelines, even among academic medical centers, raises the likely possibility of misdiagnosis and thus improper management of upper gastrointestinal symptoms. These results highlight a need for increased awareness of protocol guidelines.

Image reconstruction for positron emission tomography based on patch-based regularization and dictionary learning.

PurposePositron emission tomography (PET) is an important tool for nuclear medical imaging. It has been widely used in clinical diagnosis, scientific research, and drug testing. PET is a kind of emission computed tomography. Its basic imaging principle is to use the positron annihilation radiation generated by radionuclide decay to generate gamma photon images. However, in practical applications, due to the low gamma photon counting rate, limited acquisition time, inconsistent detector characteristics, and electronic noise, measured PET projection data often contain considerable noise, which results in ill‐conditioned PET images. Therefore, determining how to obtain high‐quality reconstructed PET images suitable for clinical applications is a valuable research topic. In this context, this paper presents an image reconstruction algorithm based on patch‐based regularization and dictionary learning (DL) called the patch‐DL algorithm. Compared to other algorithms, the proposed algorithm can retain more image details while suppressing noise.MethodsExpectation‐maximization (EM)‐like image updating, image smoothing, pixel‐by‐pixel image fusion, and DL are the four steps of the proposed reconstruction algorithm. We used a two‐dimensional (2D) brain phantom to evaluate the proposed algorithm by simulating sinograms that contained random Poisson noise. We also quantitatively compared the patch‐DL algorithm with a pixel‐based algorithm, a patch‐based algorithm, and an adaptive dictionary learning (AD) algorithm.ResultsThrough computer simulations, we demonstrated the advantages of the patch‐DL method over the pixel‐, patch‐, and AD‐based methods in terms of the tradeoff between noise suppression and detail retention in reconstructed images. Quantitative analysis shows that the proposed method results in a better performance statistically [according to the mean absolute error (MAE), correlation coefficient (CORR), and root mean square error (RMSE)] in considered region of interests (ROI) with two simulated count levels. Additionally, to analyze whether the results among these methods have significant differences, we used one‐way analysis of variance (ANOVA) to calculate the corresponding P values. The results show that most of the P < 0.01; some P> 0.01 < 0.05. Therefore, our method can achieve a better quantitative performance than those of traditional methods.ConclusionsThe results show that the proposed algorithm has the potential to improve the quality of PET image reconstruction. Since the proposed algorithm was validated only with simulated 2D data, it still needs to be further validated with real three‐dimensional data. In the future, we intend to explore GPU parallelization technology to further improve the computational efficiency and shorten the computation time.

Visual clarity methylammonium lead trichloride perovskite single crystals for X and gamma rays protection

Ionization radiation photons such as X-ray and gamma ray have been widely applied in the nuclear power industry, medical imaging, scientific research, and aerospace exploration. Developing a protective material with excellent shielding properties and clear visibility is an urgent demand in order to protect people who are working in a radiation environment. Hence, we present a highly efficient radiation shielding material based on lead halide organic-inorganic perovskite single crystals with visual clarity, high efficiency and attenuation coefficient, and thin half-value layer. Our results indicate that the shielding performances (mass attenuation coefficients, effective atomic numbers and half value layer) of the perovskite crystals are at least one order higher than the current commercial products, such as Bone-equivalent plastic, Polyethylene terephthalate, and colorless glass. In addition, physical properties (density), and optical properties (transmission, refractive index), can be slightly tuned by the dopant Br concentration in crystals. The present results demonstrate that the organic-inorganic perovksite single crystals are optimized for high attenuation radiation shielding materials with visual clarity.

Development of 99mTc radiolabeled A85380 derivatives targeting cerebral nicotinic acetylcholine receptor: Novel radiopharmaceutical ligand 99mTc-A-YN-IDA-C4

Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that have been implicated in higher brain functions. To elucidate the functional mechanisms underlying nAChRs and contribute significantly to development of drugs targeting neurological and neuropsychiatric diseases, non-invasive nuclear medical imaging can be used for evaluation. In addition, technetium-99m (99mTc) is a versatile radionuclide used clinically as a tracer in single-photon emission computed tomography. Because A85380 is known as a potent α4β2-nAChR agonist, we prepared A85380 derivatives labeled with 99mTc using a bifunctional chelate system. A computational scientific approach was used to design the probe efficiently. We used non-radioactive rhenium (Re) for a 99mTc analog and found that one of the derivatives, Re-A-YN-IDA-C4, exhibited high binding affinity at α4β2-nAChR in both the docking simulation (−19.3 kcal/mol) and binding assay (Ki = 0.4 ± 0.04 nM). Further, 99mTc-A-YN-IDA-C4 was synthesized using microwaves, and its properties were examined. Consequently, we found that 99mTc-A-YN-IDA-C4, with a structure optimized by using computational chemistry techniques, maintained affinity and selectivity for nAChR in vitro and possessed efficient characteristics as a nuclear medicine molecular imaging probe, demonstrated usefulness of computational scientific approach for molecular improvement strategy.

Ammonium Fluoride Passivation of CdZnTeSe Sensors for Applications in Nuclear Detection and Medical Imaging.

Cadmium zinc telluride selenide (Cd1−xZnxTe1−ySey or CZTS) is one of the emerging CdTe-based semiconductor materials for detecting X- and gamma-ray radiation at or near room temperature (i.e., without cryogenic cooling). Potential applications of CZTS sensors include medical imaging, X-ray detection, and gamma-ray spectroscopy. Chemical passivation of CZTS is needed to reduce the conductivity of Te-rich surfaces, which reduces the noise and improves the device performance. In this study, we focus on the effect of surface passivation of CZTS using a 10% aqueous solution of ammonium fluoride. The effects of the chemical treatment were studied on the leakage current, charge transport measured as the electron mobility-lifetime (µτ) product, and the spectral resolution measured as the full-width at half-maximum (FWHM) of specific peaks. After passivation, the leakage current increased and began to decrease towards pre-passivation levels. The energy resolutions were recorded for eight applied voltages between −35 V and −200 V. The results showed an average of 25% improvement in the detector’s energy resolution for the 59.6 keV gamma peak of Am-241. The electron µτ product was unchanged at 2 × 10−3 cm2/V. These results show that ammonium fluoride is effective for chemical passivation of CZTS detectors.

Nuclear medical imaging as part of dementia diagnostics in psychiatric day-care clinics and inpatient care settings.

Current guidelines support the use of nuclear medical imaging (NMI) techniques for differential diagnostics of certain cases of dementia. We aimed at studying the association between using NMI and the accuracy of dementia diagnoses. Additionally, we evaluated the effect of conducting NMI on the duration of hospital treatment. This study was based on data collected according to §21 of the German hospital remuneration law, including relevant diagnostic and procedural codes for NMI in dementia patients. In total, more than 7.2 million cases treated in German psychiatric and somatic hospitals between 2015 and 2017 were included. Associations between the frequency of NMI and the accuracy of dementia diagnoses in terms of specific vs. unspecific diagnostic codes were analyzed using Fischer's exact test. In total, 351,106 cases with a dementia diagnosis were encoded during the study period. NMI was performed in 1.03% or 0.15% of all patients with dementia in psychiatric or somatic clinics, respectively. In psychiatric clinics, the proportion of unspecific dementia diagnoses decreased from 20.86% in 2015 to 17.73% in 2017. NMI was mainly performed within psychiatric day-care settings. Interestingly, patients receiving NMI stayed shorter within day-care settings (8.1 ± 16.0days) compared to inpatient settings (38.3 ± 44.7days). Nuclear medical imaging is often performed in psychiatric day-care settings. Further studies are warranted to understand the predictive diagnostic value of NMI in dementia diagnosis compared with clinical, CSF and structural imaging in different healthcare settings.

Comparison of diagnostic accuracy of stress myocardial perfusion imaging for detecting hemodynamically significant coronary artery disease between cardiac magnetic resonance and nuclear medical imaging: A meta-analysis

AimsThis study aimed to compare the diagnostic accuracy of stress myocardial perfusion imaging between cardiac magnetic resonance (CMR) and nuclear medical imaging, including single-photon emission computed tomography (SPECT) and positron emission tomography (PET), for the diagnosis of hemodynamically significant coronary artery disease (CAD) with fractional flow reserve (FFR) as the reference standard. Methods and resultsWe searched PubMed and Embase for all published studies that evaluated the diagnostic accuracy of stress myocardial perfusion imaging modalities, including CMR, SPECT, and PET, to diagnose hemodynamically significant CAD with FFR as the reference standard. A total of 28 articles met the inclusion criteria and were included in the meta-analysis: 14 CMR, 13 SPECT, and 5 PET articles. The results demonstrated a pooled sensitivity of 0.88 (95% confidence interval [CI]: 0.80–0.93), 0.69 (95% CI: 0.56–0.79), and 0.83 (95% CI: 0.70–0.91), and a pooled specificity of 0.89 (95% CI: 0.85–0.93), 0.85 (95% CI, 0.80–0.89), and 0.89 (95% CI, 0.86–0.91) for CMR, SPECT, and PET, respectively. The area under the curve (AUC) of CMR, PET, and SPECT was 0.94 (95% CI, 0.92–0.96), 0.92 (95% CI, 0.89–0.94), and 0.87 (95% CI, 0.83–0.89), respectively. ConclusionsCMR and PET both have high accuracy and SPECT has moderate accuracy to detect hemodynamically significant CAD with FFR as the reference standard. Furthermore, the diagnostic accuracy of CMR at 3.0 T is superior to 1.5 T.

2019 ieee nuclear science symposium and medical imaging conference

2019 ieee nuclear science symposium and medical imaging conference

18F-labeled benzimidazopyridine derivatives for PET imaging of tau pathology in Alzheimer’s disease

Hyperphosphorylated tau proteins are one of the neuropathological hallmarks in the Alzheimer’s disease (AD) brain. The in vivo imaging of tau aggregates with nuclear medical imaging probes is helpful for the further comprehension of and medical intervention in the AD pathology. For tau-selective PET imaging, we newly designed and synthesized 18F-labeled benzimidazopyridine (BIP) derivatives with fluoroalkylamino groups, [18F]IBIPF1 and [18F]IBIPF2, and evaluated their utilities as tau imaging probes. They both bound selectively to tau against amyloid β (Aβ) aggregates in AD brain sections in vitro, and showed good pharmacokinetics in mouse brains in vivo. Notably, [18F]IBIPF1 exhibited high tau-selectivity (Tau/Aβ ratio = 34.8), high brain uptake (6.22% ID/g at 2 min postinjection), and subsequent washout (2.77% ID/g at 30 min postinjection). In vivo analysis of radiometabolites indicated that [18F]IBIPF1 was stable against metabolism in the mouse brain. These encouraging preclinical results suggest that further structural optimization based on the BIP scaffold may lead to the development of more useful tau imaging probes.

Radioluminescent nuclear battery containing CsPbBr 3 quantum dots: Application of a novel wave‐shifting agent

Radioluminescent nuclear battery has been widely studied for its miniaturization and long life. In this study, all-inorganic perovskite quantum dots (CsPbBr3 QDs) were selected as a novel wave-shifting agent combined with liquid scintillator PPO (2,5-diphenyloxazole). The QDs were used to regulate the emission spectrum to match different GaAs devices. The maximum output power of the RL nuclear battery was greatly enhanced by 1.91 to 2.53 times. Perovskite QDs with adjustable emission spectra were used as wave-shifting agents and exhibited more excellent properties and application prospects than traditional wave-shifting agents. The Monte Carlo method was used to simulate the energy deposition of fluorescent materials under various radioactive source models. Results verified the advantages of using liquid radioactive sources and liquid fluorescent materials. The application and reference value of perovskite QDs in nuclear detection and nuclear medical imaging were also discussed.