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Expert Review of Medical Devices Aug 2019: Radioguided surgery is an ever-evolving part of nuclear medicine. In fact, this nuclear medicine sub-discipline actively bridges non-invasive molecular imaging with... (Review)
Review
: Radioguided surgery is an ever-evolving part of nuclear medicine. In fact, this nuclear medicine sub-discipline actively bridges non-invasive molecular imaging with surgical care. Next to relying on the availability of radio- and bimodal-tracers, the success of radioguided surgery is for a large part dependent on the imaging modalities and imaging concepts available for the surgical setting. With this review, we have aimed to provide a comprehensive update of the most recent advances in the field. : We have made an attempt to cover all aspects of radioguided surgery: 1) the use of radioisotopes that emit γ, β, and/or β radiation, 2) hardware developments ranging from probes to 2D cameras and even the use of advanced 3D interventional imaging solutions, and 3) multiplexing solutions such as dual-isotope detection or combined radionuclear and optical detection. : Technical refinements in the field of radioguided surgery should continue to focus on supporting its implementation in the increasingly complex minimally invasive surgical setting, e.g. by accommodating robot-assisted laparoscopic surgery. In addition, hybrid concepts that integrate the use of radioisotopes with other image-guided surgery modalities such as fluorescence or ultrasound are likely to expand in the future.
Topics: Humans; Nuclear Medicine; Positron-Emission Tomography; Radioisotopes; Surgery, Computer-Assisted; Tomography, Emission-Computed, Single-Photon
PubMed: 31287715
DOI: 10.1080/17434440.2019.1642104 -
Circulation. Cardiovascular Imaging Jun 2022Single photon emission computed tomography (SPECT) has limited ability to identify multivessel and microvascular coronary artery disease. Gamma cameras with cadmium zinc...
Accuracy and Reproducibility of Myocardial Blood Flow Quantification by Single Photon Emission Computed Tomography Imaging in Patients With Known or Suspected Coronary Artery Disease.
BACKGROUND
Single photon emission computed tomography (SPECT) has limited ability to identify multivessel and microvascular coronary artery disease. Gamma cameras with cadmium zinc telluride detectors allow the quantification of absolute myocardial blood flow (MBF) and myocardial flow reserve (MFR). However, evidence of its accuracy is limited, and of its reproducibility is lacking. We aimed to validate Tc-sestamibi SPECT MBF and MFR using standard and spline-fitted reconstruction algorithms compared with N-ammonia positron emission tomography in a cohort of patients with known or suspected coronary artery disease and to evaluate the reproducibility of this technique.
METHODS
Accuracy was assessed in 34 participants who underwent dynamic Tc-sestamibi SPECT and N-ammonia positron emission tomography and reproducibility in 14 participants who underwent 2 Tc-sestamibi SPECT studies, all within 2 weeks. A rest/pharmacological stress single-day SPECT protocol was performed. SPECT images were reconstructed using a standard ordered subset expectation maximization (OSEM) algorithm with (N=21) and without (N=30) application of spline fitting. SPECT MBF was quantified using a net retention kinetic model' and MFR was derived as the stress/rest MBF ratio.
RESULTS
SPECT global MBF with splines showed good correlation with N-ammonia positron emission tomography (r=0.81, <0.001) and MFR estimates (r=0.74, <0.001). Correlations were substantially weaker for standard reconstruction without splines (r=0.61, <0.001 and r=0.34, =0.07, for MBF and MFR, respectively). Reproducibility of global MBF estimates with splines in paired SPECT scans was good (r=0.77, <0.001), while ordered subset expectation maximization without splines led to decreased MBF (r=0.68, <0.001) and MFR correlations (r=0.33, =0.3). There were no significant differences in MBF or MFR between the 2 reproducibility scans independently of the reconstruction algorithm (>0.05 for all).
CONCLUSIONS
MBF and MFR quantification using Tc-sestamibi cadmium zinc telluride SPECT with spatiotemporal spline fitting improved the correlation with N-ammonia positron emission tomography flow estimates and test/retest reproducibility. The use of splines may represent an important step toward the standardization of SPECT flow estimation.
Topics: Ammonia; Cadmium; Coronary Artery Disease; Coronary Circulation; Humans; Myocardial Perfusion Imaging; Positron-Emission Tomography; Reproducibility of Results; Technetium Tc 99m Sestamibi; Tomography, Emission-Computed, Single-Photon; Zinc
PubMed: 35674051
DOI: 10.1161/CIRCIMAGING.122.013987 -
Circulation. Cardiovascular Imaging May 2024
Review
Topics: Humans; Cardiology; Nuclear Medicine; History, 21st Century; Forecasting; History, 20th Century; Cardiovascular Diseases; Predictive Value of Tests; Myocardial Perfusion Imaging
PubMed: 38771905
DOI: 10.1161/CIRCIMAGING.124.016875 -
Cancer Journal (Sudbury, Mass.)Antibody-drug conjugates (ADCs) are designed to deliver cytotoxic payloads to distinctive target-expressing cancer cells. Following internalization, the ADCs are routed... (Review)
Review
Antibody-drug conjugates (ADCs) are designed to deliver cytotoxic payloads to distinctive target-expressing cancer cells. Following internalization, the ADCs are routed to different compartments in the cells, where cleavage of the linker causes release of the cytotoxic cargo. With such a delivery system, more effective payloads can reach cancer cells, allowing for more efficient treatment and dosing schedule. The monoclonal antibody (mAb) component of ADC plays a crucial role in the effective targeting of cancer cell-specific antigens while minimizing binding to normal cells. Often, the same mAbs used in ADCs can be labeled instead with radionuclides suitable for positron emission tomography or gamma-camera scintigraphy. To achieve high sensitivity and specificity for imaging, radiolabeled mAbs must have high affinity for the antigen, favorable pharmacokinetic properties, and a low toxicity profile. The use of radiolabeled mAbs permits the noninvasive interrogation of specific target expression on tumor cells and assessment of tumor heterogeneity in vivo by a simple diagnostic imaging scan that may include the whole body in the field of view. With this approach, radiolabeled mAbs can serve as important imaging biomarkers to predict the optimal delivery of ADCs to tumors and be used to monitor therapy with follow-up scans. Moreover, the same mAb can then be radiolabeled with an analogous radionuclide for the delivery of β-emitters, α-particles, or Auger electrons as part of a radioimmunotherapy approach. The purpose of this review is to introduce key concepts regarding radiolabeled mAbs targeting various tumor antigens (CD20, CDH3, type I insulinlike growth factor receptor, prostate-specific membrane antigen, and human epidermal growth factor receptor 2) that are being used in the clinical setting or undergoing development.
Topics: Male; Humans; Antibodies, Monoclonal; Immunoconjugates; Neoplasms; Antineoplastic Agents; Positron-Emission Tomography; Antineoplastic Agents, Immunological
PubMed: 36383907
DOI: 10.1097/PPO.0000000000000625 -
EJNMMI Physics Jul 2020It has been proposed, and preclinically demonstrated, that Tb is a better alternative to Lu for the treatment of small prostate cancer lesions due to its high emission...
BACKGROUND
It has been proposed, and preclinically demonstrated, that Tb is a better alternative to Lu for the treatment of small prostate cancer lesions due to its high emission of low-energy electrons. Tb also emits photons suitable for single-photon emission computed tomography (SPECT) imaging. This study aims to establish a SPECT protocol for Tb imaging in the clinic.
MATERIALS AND METHODS
Optimal settings using various γ-camera collimators and energy windows were explored by imaging a Jaszczak phantom, including hollow-sphere inserts, filled with Tb. The collimators examined were extended low-energy general purpose (ELEGP), medium-energy general purpose (MEGP), and low-energy high resolution (LEHR), respectively. In addition, three ordered subset expectation maximization (OSEM) algorithms were investigated: attenuation-corrected OSEM (A-OSEM); attenuation and dual- or triple-energy window scatter-corrected OSEM (AS-OSEM); and attenuation, scatter, and collimator-detector response-corrected OSEM (ASC-OSEM), where the latter utilized Monte Carlo-based reconstruction. Uniformity corrections, using intrinsic and extrinsic correction maps, were also investigated. Image quality was assessed by estimated recovery coefficients (RC), noise, and signal-to-noise ratio (SNR). Sensitivity was determined using a circular flat phantom.
RESULTS
The best RC and SNR were obtained at an energy window between 67.1 and 82.1 keV. Ring artifacts, caused by non-uniformity, were removed with extrinsic uniformity correction for the energy window between 67.1 and 82.1 keV, but not with intrinsic correction. Analyzing the lower energy window between 48.9 and 62.9 keV, the ring artifacts remained after uniformity corrections. The recovery was similar for the different collimators when using a specific OSEM reconstruction. Recovery and SNR were highest for ASC-OSEM, followed by AS-OSEM and A-OSEM. When using the optimized parameter setting, the resolution of Tb was higher than for Lu (8.4 ± 0.7 vs. 10.4 ± 0.6 mm, respectively). The sensitivities for Tb and Lu were 7.41 and 8.46 cps/MBq, respectively.
CONCLUSION
SPECT with high resolution is feasible with Tb; however, extrinsic uniformity correction is recommended to avoid ring artifacts. The LEHR collimator was the best choice of the three tested to obtain a high-resolution image. Due to the complex emission spectrum of low-energy photons, window-based scatter correction had a minor impact on the image quality compared to using attenuation correction only. On the other hand, performing attenuation, scatter, and collimator-detector correction clearly improved image quality. Based on these data, SPECT-based dosimetry for Tb-labeled radiopharmaceuticals is feasible.
PubMed: 32613587
DOI: 10.1186/s40658-020-00314-x -
Journal of Nuclear Cardiology :... Aug 2022With the appearance of cadmium-zinc-telluride (CZT) cameras, dynamic myocardial perfusion imaging (MPI) has been introduced, but comparable data to other MPI modalities,... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
With the appearance of cadmium-zinc-telluride (CZT) cameras, dynamic myocardial perfusion imaging (MPI) has been introduced, but comparable data to other MPI modalities, such as quantitative coronary angiography (CAG) with fractional flow reserve (FFR) and positron emission tomography (PET), are lacking. This study aimed to evaluate the diagnostic accuracy of dynamic CZT single-photon emission tomography (SPECT) in coronary artery disease compared to quantitative CAG, FFR, and PET as reference.
MATERIALS AND METHODS
Different databases were screened for eligible citations performing dynamic CZT-SPECT against CAG, FFR, or PET. PubMed, OvidSP (Medline), Web of Science, the Cochrane Library, and EMBASE were searched on the 5th of July 2020. Studies had to meet the following pre-established inclusion criteria: randomized controlled trials, retrospective trails or observational studies relevant for the diagnosis of coronary artery disease, and performing CZT-SPECT and within half a year the methodological references. Studies which considered coronary stenosis between 50% and 70% as significant based only on CAG were excluded. Data extracted were sensitivity, specificity, likelihood ratios, and diagnostic odds ratios. Quality was assessed with QUADAS-2 and statistical analysis was performed using a bivariate model.
RESULTS
Based on our criteria, a total of 9 studies containing 421 patients were included. For the assessment of CZT-SPECT, the diagnostic value pooled analysis with a bivariate model was calculated and yielded a sensitivity of 0.79 (% CI 0.73 to 0.85) and a specificity of 0.85 (95% CI 0.74 to 0.92). Diagnostic odds ratio (DOR) was 17.82 (95% CI 8.80 to 36.08, P < 0.001). Positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 3.86 (95% CI 2.76 to 5.38, P < 0.001) and 0.21 (95% CI 0.13 to 0.33, P < 0.001), respectively.
CONCLUSION
Based on the results of the current systematic review and meta-analysis, dynamic CZT-SPECT MPI demonstrated a good sensitivity and specificity to diagnose CAD as compared to the gold standards. However, due to the heterogeneity of the methodologies between the CZT-SPECT MPI studies and the relatively small number of included studies, it warrants further well-defined study protocols.
Topics: Cadmium; Coronary Angiography; Coronary Artery Disease; Fractional Flow Reserve, Myocardial; Humans; Myocardial Perfusion Imaging; Retrospective Studies; Tellurium; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Zinc
PubMed: 34350553
DOI: 10.1007/s12350-021-02721-8 -
Nuclear Medicine and Molecular Imaging Dec 2021We review the history of nuclear medicine physics, instrumentation, and data sciences in Korea to commemorate the 60 anniversary of the Korean Society of Nuclear... (Review)
Review
We review the history of nuclear medicine physics, instrumentation, and data sciences in Korea to commemorate the 60 anniversary of the Korean Society of Nuclear Medicine. In the 1970s and 1980s, the development of SPECT, nuclear stethoscope, and bone densitometry systems, as well as kidney and cardiac image analysis technology, marked the beginning of nuclear medicine physics and engineering in Korea. With the introduction of PET and cyclotron in Korea in 1994, nuclear medicine imaging research was further activated. With the support of large-scale government projects, the development of gamma camera, SPECT, and PET systems was carried out. Exploiting the use of PET scanners in conjunction with cyclotrons, extensive studies on myocardial blood flow quantification and brain image analysis were also actively pursued. In 2005, Korea's first domestic cyclotron succeeded in producing radioactive isotopes, and the cyclotron was provided to six universities and university hospitals, thereby facilitating the nationwide supply of PET radiopharmaceuticals. Since the late 2000s, research on PET/MRI has been actively conducted, and the advanced research results of Korean scientists in the fields of silicon photomultiplier PET and simultaneous PET/MRI have attracted significant attention from the academic community. Currently, Korean researchers are actively involved in endeavors to solve a variety of complex problems in nuclear medicine using artificial intelligence and deep learning technologies.
PubMed: 34868376
DOI: 10.1007/s13139-021-00721-7 -
Biomedical Physics & Engineering Express Dec 2023The Dynamic Cardiac SPECT (DC-SPECT) system is being developed at the Massachusetts General Hospital, featuring a static cardio focus asymmetrical geometry enabling...
The Dynamic Cardiac SPECT (DC-SPECT) system is being developed at the Massachusetts General Hospital, featuring a static cardio focus asymmetrical geometry enabling simultaneous high-resolution and high-sensitivity imaging. Among 14 design iterations of the DC-SPECT with varying number of detector heads, system sensitivity and resolution, the current version under development features 10 mm FWHM geometrical resolution (without resolution recovery) and 0.07% sensitivity at the center of the FOV, this is 1.5× resolution gain and 7× sensitivity gain compared to a conventional dual head gamma camera (0.01% sensitivity and 15-mm resolution). This work presents improvement in imaging resolution by implementing a spatially variant point spread function (SV-PSF) with list mode MLEM reconstruction. A resolution recovery method by PSF deconvolution is validated on list mode MLEM reconstruction for the DC-SPECT. A spatial invariant PSF is included as an additional test to show the influence of the PSF modelling accuracy on reconstructed image quality. We compare the MLEM reconstruction with and without PSF deconvolution; an analytic model is used for the calculation of system response, and the results are compared to the reconstruction with system modelling using Monte Carlo (MC) based methods. Results show that with PSF modelling applied, the quality of the reconstructed image is improved, and the DC-SPECT system can achieve a 4.5 mm central spatial resolution with average 795 counts/Mbq. Both the SV-PSF and the spatial-invariant PSF improve the image quality, and the reconstruction with SV-PSF generates line profiles closer to the ground truth. The results show substantial improvement over the GE Discovery 570c performance (7 mm spatial resolution with an average 460 counts/MBq, 5.8 mm resolution at the FOV center). The impact of PSF deconvolution is significant, improvement of the reconstructed image quality is evident in comparison to MC simulated system matrix with the same sampling size in the simulation.
Topics: Image Processing, Computer-Assisted; Algorithms; Phantoms, Imaging; Tomography, Emission-Computed, Single-Photon; Positron-Emission Tomography
PubMed: 37995364
DOI: 10.1088/2057-1976/ad0f40 -
Proceedings of the National Academy of... Jul 2019Plasmons, the collective oscillations of mobile electrons in metallic nanostructures, interact strongly with light and produce vivid colors, thus offering a new route to...
Plasmons, the collective oscillations of mobile electrons in metallic nanostructures, interact strongly with light and produce vivid colors, thus offering a new route to develop color printing technologies with improved durability and material simplicity compared with conventional pigments. Over the last decades, researchers in plasmonics have been devoted to manipulating the characteristics of metallic nanostructures to achieve unique and controlled optical effects. However, before plasmonic nanostructures became a science, they were an art. The invention of the daguerreotype was publicly announced in 1839 and is recognized as the earliest photographic technology that successfully captured an image from a camera, with resolution and clarity that remain impressive even by today's standards. Here, using a unique combination of daguerreotype artistry and expertise, experimental nanoscale surface analysis, and electromagnetic simulations, we perform a comprehensive analysis of the plasmonic properties of these early photographs, which can be recognized as an example of plasmonic color printing. Despite the large variability in size, morphology, and material composition of the nanostructures on the surface of a daguerreotype, we are able to identify and characterize the general mechanisms that give rise to the optical response of daguerreotypes. Therefore, our results provide valuable knowledge to develop preservation protocols and color printing technologies inspired by past ones.
PubMed: 31182585
DOI: 10.1073/pnas.1904331116 -
Journal of Visualized Experiments : JoVE Sep 2022Measuring brown adipose tissue (BAT) activity by positron emission tomography computed tomography (PET-CT) via the accumulation of F-fluorodeoxyglucose (FDG) after a...
Measuring brown adipose tissue (BAT) activity by positron emission tomography computed tomography (PET-CT) via the accumulation of F-fluorodeoxyglucose (FDG) after a meal or in obese or diabetic patients fails as the method of choice. The main reason is that F-FDG competes with the postprandial high glucose plasma concentration for the same glucose transporter on the membrane of BAT cells. In addition, BAT uses fatty acids as a source of energy as well, which is not visible with PET-CT and could be changed along with glucose concentration in obese and diabetic patients. Therefore, to estimate the physiological importance of BAT in animals and humans, a new infrared thermography method used in recent publications is applied. After overnight fasting, BAT activity was measured by infrared thermography before and after a meal in human volunteers and female wild-type mice. The camera software calculates the object's temperature using distance from the object, skin emissivity, reflected room temperature, air temperature, and relative humidity. In mice, the shaved area above the BAT was a region of interest for which average and maximal temperatures were measured. The phase of the estrous cycle in female mice was determined after an experiment by vaginal smears stained with cresyl violet (0.1%) stain solution. In healthy volunteers, two skin areas of the neck were selected: the supraclavicular area (above the collarbone, where BAT cells are present) and the interclavicular area (between the collarbones, where there is no BAT tissue detected). BAT activity is determined by the subtraction of those two values. Also, the average and maximal temperatures of skin areas could be determined in animals and human participants. Changes in BAT activity after a meal measured by infrared thermography, a non-invasive and more sensitive method, were shown to be sex, age, and phase of the estrous cycle dependent in laboratory animals. As part of diet-induced thermogenesis, BAT activation in humans was also proven to be sex, age, and body mass index dependent. Further determining the pathophysiological changes in BAT activity after a meal will be of great importance for participants with high glucose plasma concentrations (obesity and diabetes mellitus type 2), as well as in different laboratory animals (knock-out mice). This method is also a variable tool for determining possible activating drugs that could rejuvenate BAT activity.
Topics: Humans; Female; Animals; Mice; Adipose Tissue, Brown; Fluorodeoxyglucose F18; Positron Emission Tomography Computed Tomography; Thermography; Obesity; Glucose; Fatty Acids; Glucose Transport Proteins, Facilitative; Positron-Emission Tomography
PubMed: 36279537
DOI: 10.3791/64463