Nuclear Imaging Methods Research Articles

Infective endocarditis: epidemiology, etiology, clinic (modern aspects). Literary review

The literature review presents an analysis of domestic and foreign publications, modern clinical recommendations for infective endocarditis. Based on the analysis of literature data, a change in the structure of pathogens of infective endocarditis was established, where Staphylococcus aureus occupies the leading place. Algorithms for examining patients with infective endocarditis have been analyzed. It has been shown that the role of nuclear imaging methods in the diagnosis of this pathology has increased. According to the latest recommendations for the management of patients with infective endocarditis, the diagnostic criteria for this disease have not changed significantly.

Nuclear Imaging Applications in Dentistry

This review discusses the indications, limitations, and diagnostic implications of nuclear imaging in the oral and maxillofacial region. In contrast to conventional imaging modalities, such as panoramic radiography and cone beam computed tomography, nuclear medicine offers unique information specific to the functional aspects of oral and maxillofacial tissues. This study aims to emphasize the current and potential applications of nuclear imaging methods in dentistry to increase dentists' knowledge of functional imaging methods and gain a different perspective, as well as their effects on diagnostic accuracy, treatment planning, and treatment outcomes. Future research will allow for a detailed evaluation of the effectiveness and reliability of nuclear imaging technologies in dentistry.

Utility of multimodal molecular imaging in the diagnosis and decision-making in arterial diseases

Arterial diseases are prevalent in the general population, particularly in the elderly, and they are among the main causes of morbidity and mortality worldwide. Nuclear imaging is a useful tool in diagnosis and follow-up in different areas of medicine, and over the last 2 decades, these study modalities have become more relevant in the field of angiology and vascular surgery due to their potential benefit in the interpretation of pathophysiological mechanisms associated with the natural history and severity of diseases that affect the circulation such as vasculitis, degenerative aortic aneurysms (AA), peripheral arterial disease (PAD), and complications following reconstructive procedures such as graft infections. The literature has shown evidence of an important number of radiotracers for specific molecules involved in the activity of these entities and their utility as predictors during surveillance and possible therapeutic targets. <br /> The present narrative review aims to describe the use of nuclear medicine, imaging methods, and radiotracers that have been applied in arterial diseases, as well as the advantages and considerations, their importance in the diagnosis and follow-up of these complex groups of patients, and future perspectives.

Ventilation Heterogeneity Is a Treatable Trait in Severe Asthma

BackgroundVentilation heterogeneity is a feature of asthma and indicates small airway disease. Nuclear imaging methods assess ventilation heterogeneity which can facilitate clinical diagnosis and further our understanding of disease aetiology. ObjectiveWe sought to assess ventilation heterogeneity in severe eosinophilic asthma using ventilation/perfusion single-photon emission computed tomography (V/P SPECT), and to assess its use as an objective test of the effect of biologic treatment for ventilation defects in severe eosinophilic asthma. MethodsAdults (≥18 years) with severe asthma were recruited to participate in a cross-sectional observational study. Participants underwent a clinical assessment and V/P SPECT/CT using Technegas as the ventilation agent. Measures were repeated for a nested before-after treatment study in people with severe eosinophilic asthma commencing biologics. ResultsA total of 62 participants with severe asthma were recruited. From this, 38 participants with severe eosinophilic asthma were included in the before-after study. Ventilation heterogeneity was associated with clinical variables such as lung function impairment and significantly improved after monoclonal antibody treatment in the severe asthma group. The changes in ventilation heterogeneity correlated with change in post bronchodilator FEV1%predicted (r=-0.503, p=0.001) and post bronchodilator FEV1/FVC (r=-0.415, p=0.01). ConclusionVentilation heterogeneity is clinically significant, measurable, and treatable, which establishes ventilation heterogeneity as a treatable trait in severe asthma.

Radiolabeling of Platelets with 99mTc-HYNIC-Duramycin for In Vivo Imaging Studies

Following the in vivo biodistribution of platelets can contribute to a better understanding of their physiological and pathological roles, and nuclear imaging methods, such as single photon emission tomography (SPECT), provide an excellent method for that. SPECT imaging needs stable labeling of the platelets with a radioisotope. In this study, we report a new method to label platelets with 99mTc, the most frequently used isotope for SPECT in clinical applications. The proposed radiolabeling procedure uses a membrane-binding peptide, duramycin. Our results show that duramycin does not cause significant platelet activation, and radiolabeling can be carried out with a procedure utilizing a simple labeling step followed by a size-exclusion chromatography-based purification step. The in vivo application of the radiolabeled human platelets in mice yielded quantitative biodistribution images of the spleen and liver and no accumulation in the lungs. The performed small-animal SPECT/CT in vivo imaging investigations revealed good in vivo stability of the labeling, which paves the way for further applications of 99mTc-labeled-Duramycin in platelet imaging.

Gastroenteropancreatic Neuroendocrine Tumors-Current Status and Advances in Diagnostic Imaging.

Gastroenteropancreatic neuroendocrine neoplasia (GEP-NEN) is a heterogeneous and complex group of tumors that are often difficult to classify due to their heterogeneity and varying locations. As standard radiological methods, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET/CT) are available for both localization and staging of NEN. Nuclear medical imaging methods with somatostatin analogs are of great importance since radioactively labeled receptor ligands make tumors visible with high sensitivity. CT and MRI have high detection rates for GEP-NEN and have been further improved by developments such as diffusion-weighted imaging. However, nuclear medical imaging methods are superior in detection, especially in gastrointestinal NEN. It is important for radiologists to be familiar with NEN, as it can occur ubiquitously in the abdomen and should be identified as such. Since GEP-NEN is predominantly hypervascularized, a biphasic examination technique is mandatory for contrast-enhanced cross-sectional imaging. PET/CT with somatostatin analogs should be used as the subsequent method.

Imaging in Heart Failure with Preserved Ejection Fraction: A Multimodality Imaging Point of View.

Heart failure with preserved ejection fraction (HFpEF) is an important global health problem. Despite increased prevalence due to improved diagnostic options, limited improvement has been achieved in cardiac outcomes. HFpEF is an extremely complex syndrome and multimodality imaging is important for diagnosis, identifying its different phenotypes and determining prognosis. Evaluation of left ventricular filling pressures using echocardiographic diastolic function parameters is the first step of imaging in clinical practice. The role of echocardiography is becoming more popular and with the recent developments in deformation imaging, cardiac MRI is extremely important as it can provide tissue characterisation, identify fibrosis and optimal volume measurements of cardiac chambers. Nuclear imaging methods can also be used in the diagnosis of specific diseases, such as cardiac amyloidosis.

Liver PET Reloaded: Automated Synthesis of [68Ga]Ga-BP-IDA for Positron Imaging of the Hepatobiliary Function and First Clinical Experience.

Hepatobiliary scintigraphy is a well-established nuclear imaging method for evaluating liver function and displaying the biliary system, but the spatial and temporal resolution is limited, and, there is still no established PET equivalent. Adapted from the work of Schuhmacher et al. in 1983, the production of a 68Gallium-labeled substitute, tetrabromophthalein ([68Ga]Ga-BP-IDA), was undertaken according to current Good Manufacturing Practice (GMP) standards and proved feasible and reproducible. PET/CT with the radiotracer was performed in two complex patients with hepatocellular carcinoma in preparation for transarterial radioembolization. Due to its high spatial and temporal resolution, localization of areas with impaired liver function and visualization of the biliary system were possible. We could demonstrate that this 68Gallium-labeled, IDA-based PET tracer is feasible and could advance hepatic and biliary function PET imaging.

Recovering a function from its integrals over conical surfaces through relations with the Radon transform

This paper addresses the overdetermined problem of inverting the n-dimensional cone (or Compton) transform that integrates a function over conical surfaces in . The study of the cone transform originates from Compton camera imaging, a nuclear imaging method for the passive detection of gamma-ray sources. We present a new identity relating the n-dimensional cone and Radon transforms through spherical convolutions with arbitrary weight functions. This relationship, which generalizes a previously obtained identity, leads to various inversion formulas in n-dimensions under a mild assumption on the geometry of detectors. We present two such formulas along with the results of their numerical implementation using synthetic phantoms. Compared to our previously discovered inversion techniques, the new formulas are more stable and simpler to implement numerically.

Diagnostic accuracy of fluorine-18 fluorodeoxyglucose positron emission tomography for suspected primary and postoperative pyogenic spondylitis

ObjectiveFluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) and PET/CT have been suggested for confirming or excluding musculoskeletal infection but the diagnostic value of this tool for pyogenic spondylitis remains to be confirmed. This meta-analysis was performed to verify the accuracy of 18F-FDG PET and PET/CT in diagnosing suspected pyogenic spondylitis by performing a systematic review and meta-analysis.MethodsWe conducted a comprehensive literature search of PubMed, Embase and Cochrane Library to retrieve diagnostic accuracy studies in which suspected pyogenic spondylitis was assessed with 18F-FDG PET or PET/CT. The pooled sensitivity, specificity, likelihood ratios, diagnostic odds ratio (DOR), summarized receiver operating characteristic curve (sROC) and the area under the sROC (AUC) were calculated by using Stata software.ResultsA total of 18 eligible studies (660 patients) with suspected pyogenic spondylitis were included in the quantitative analysis. 18F-FDG PET and PET/CT illustrated relatively high sensitivity (0.91, 95% CI: 0.84–0.95) and specificity (0.90, 95% CI: 0.79–0.95) for the diagnosis of pyogenic spondylitis. The pooled DOR and AUC were 86.00 (95% CI, 31.00–240.00) and 0.96 (95% CI, 0.94–0.97), respectively. For diagnosing pyogenic spondylitis without previous spine surgery, the pooled sensitivity, specificity, DOR and AUC were 0.93 (95% CI, 0.85–0.97), 0.91 (95% CI, 0.77–0.97), 136 (95% CI, 35–530) and 0.97 (95% CI, 0.95–0.98), respectively. For diagnosing postoperative pyogenic spondylitis, the pooled sensitivity, specificity, DOR and AUC were 0.85 (95% CI, 0.71 to 0.93), 0.87 (95% CI, 0.66 to 0.96), 38 (95% CI, 9 to 167) and 0.92 (95% CI, 0.89 to 0.94), respectively.Conclusion18F-FDG PET and PET/CT presented satisfactory accuracy for diagnosing pyogenic spondylitis. The diagnostic effect of this nuclear imaging method for pyogenic spondylitis without previous spine surgery seems to be better than that for the postoperative ones. However, whether 18F-FDG PET and PET/CT could become a routine in patients with suspected pyogenic spondylitis remains to be confirmed.Level of evidenceLevel I evidence, a summary of meta-analysis.

A Quality Analysis of Scintigraphy Videos on YouTube

Objective: Scintigraphy is an important nuclear medicine imaging method that is used for detecting various pathological conditions and provides very useful functional information for clinicians. YouTube is the website that patients commonly use to get any information. This study aims to examine the scintigraphy related videos on YouTube. Material and Method: This study was conducted in June 2023. Videos were accessed using the keyword "scintigraphy" on YouTube. These videos were evaluated using the Journal of the American Medical Association (JAMA) benchmarks, global quality scale (GQS) and the DISCERN scale. Results: All videos accessed using the keyword "scintigraphy" on YouTube were reviewed. The study includes twenty-six of the examined videos. The source of most of the videos was non-physician. Physician-sourced videos had higher Discern scores, JAMA scores, and the number of likes and comments. However, those who were followed the most and had the highest view ratio were of non-physician-sourced. Physician-sourced videos were of higher quality than non-physician-sourced videos in the quality review (p:0.015). Furthermore, the GQS score, DISCERN score and JAMA score were positively correlated. Conclusions: Patients and caregivers can use YouTube for any disease and treatment. For this reason, official videos should be uploaded to the YouTube platform so that patients can access qualified, complete and accurate content. The URLs of these videos can be added to the patient information forms as QR codes.

Development of a Radioiodinated Probe for in Vivo Detection of Lipid Radicals and Evaluation Using Middle Cerebral Artery Occlusion Model

Free radicals, such as hydroxyl radical, superoxide, and lipid-derived radical, have unpaired electrons, making them a highly reactive chemical species. They play important physiological roles, for example, in the removal of xenobiotic substances, such as bacteria and viruses, and in the production of chemical mediators, like prostaglandins and leukotrienes. However, excessive production of free radicals can cause structural defects in biomolecules like DNA and proteins, resulting in a loss of their normal functions. Hence, free radicals have been implicated in the onset and progression of various diseases such as cancer, atherosclerosis, and neurodegenerative diseases. However, there is very little clarity on the substantial amount, type, and location of free radicals in vivo, under pathological conditions. An investigation on the actual state of free radicals in vivo could lead to the diagnosis of pathological conditions and the elucidation of the mechanisms of their onset and progression; therefore, the development of in vivo radical detection methods is being widely pursued. Toward this end, nuclear medical imaging methods have recently attracted attention. In this study, we discuss the development of a nuclear medical imaging probe for the specific targeting of lipid radicals.

Nuclear Methods for Immune Cell Imaging: Bridging Molecular Imaging and Individualized Medicine.

Inflammation is a key mechanistic contributor to the progression of cardiovascular disease, from atherosclerosis through ischemic injury and overt heart failure. Recent evidence has identified specific roles of immune cell subpopulations in cardiac pathogenesis that diverges between individual patients. Nuclear imaging approaches facilitate noninvasive and serial quantification of inflammation severity, offering the opportunity to predict eventual outcome, stratify patient risk, and guide novel targeted molecular therapies against specific leukocyte subpopulations. Here, we will discuss the established and emerging nuclear imaging methods to label and track exogenous and endogenous immune cells, with a particular focus on clinical situations in which targeted molecular inflammation imaging would be advantageous. The expanding options for imaging inflammation provide the foundation to bridge between molecular imaging and individual therapy.

The Possibilities of Nuclear Medicine Methods in Inflammation Diagnosis

Modern nuclear medicine is a rapidly developing field that includes various non-invasive molecular imaging techniques with the ability to examine the whole body.Inflammation is a frequent complication in surgical and traumatological practices, which is a complex, local and general pathological process that occurs in the body in response to injury. Having arisen under the influence of a damaging factor, inflammation is characterized by the development of a dynamic complex of changes. However, the search for inflammation foci of inflammation by traditional diagnostic methods in some cases is difficult even with a detailed clinical picture. In this case, nuclear medicine, which is able to visualize pathological processes, including those with a pathological increase in metabolism, may be the best option for finding the affected area.A wide variety of radiopharmaceutical drugs makes it possible to determine the localization of the inflammatory focus in a short time and with high accuracy and makes nuclear imaging methods a priority for the early diagnosis of pathophysiological reactions.This paper presents a review of domestic and foreign literature on the use of specific and nonspecific radiopharmaceuticals in the diagnosis of inflammation. Own cases is also presented.

What is New in Nuclear Medicine Imaging for Dementia.

Advances in the molecular biology, pathology and genetics of Alzheimer's disease (AD) and other degenerative dementias have led to the development of biomarkers specific to these diseases and radiotracers that are used in nuclear medicine. Imaging and non-imaging markers have enabled very early recognition of these diseases and have caused significant changes in their definitions. Amyloid positron emission tomography (PET) and tau PET, which are molecular imaging methods, [F18]fluorodeoxyglucose (FDG) PET showing the glucose metabolism pattern in the brain, dopamine transporter single photon emission computerized tomography (SPECT) that marks dopaminergic terminals are valuable tools for early recognition and differentiation of AD and its atypical variants, frontotemporal dementias and dementia with Lewy bodies. These imaging methods, which have different advantages over each other, have different indications for use and sometimes provide complementary information. In addition, research on radiotracers targeting neuroinflammation, astrocytes, synaptic density, and cholinergic terminals is ongoing. In this review, routinely used and newly developed nuclear imaging methods in AD and other neurodegenerative dementias, the agents used and their diagnostic features will be presented together with case examples.

Evaluation of 99mTechnetium-Vancomycin Imaging Potential in Experimental Rat Model for the Diagnosis of Infective Endocarditis.

Infective endocarditis (IE) is an infection of the heart's endocardial surface. In recent years, nuclear imaging methods have gained importance in the diagnosis of IE. The present study aims to investigate the imaging potential of 99mTc-labeled vancomycin (99mTc-Vancomycin) as a new agent that would enable the diagnosis of IE in its early stages when it is difficult to diagnose or has small vegetation in the experimental rat model. 99mTc-Vancomycin scintigraphy was evaluated for its accumulation in IE with Staphylococcus aureus performed in an experimental rat model. Serial planar scintigraphic and biodistribution analysis of infected vegetations are compared to rats with sterile vegetations. The heart was identified as an infected organ, the liver was identified as a non-infected organ and the heart/liver uptake ratio (T / NT ratio) was compared between infective endocarditis and sterile endocarditis groups. Planar scintigrams (in vivo measurements) showed more uptake in the heart of rats in the infective endocarditis group compared to the uptake in the heart of rats in the sterile endocarditis group, but this difference was not statistically significant (p>0.05). From the ex vivo measurements, the 99mTc-Vancomycin heart uptake increased significantly (p = 0.016), liver uptake was significantly decreased (p = 0.045) and the T/NT ratio was significantly higher (p = 0.014) in the infective endocarditis group compared to the sterile endocarditis group. In this experimental study, 99mTc-Vancomycin scintigraphy ensured the detection of ex vivo infected tissue in a rat model of IE. In addition, the absence of significant 99mTc-Vancomycin uptake in the sterile endocarditis group indicates that this agent targeted the infected tissue instead of the sterile inflammatory tissue. Finally, this agent should also be evaluated with animal- specific imaging devices.

Characterization of the decay process of Scots pine caused by Coniophora puteana using NMR and MRI

AbstractWood decay is an economically significant process, as it is one of the major causes of wood deterioration in buildings. In this study, the decay process of Scots pine (Pinus sylvestris) samples caused by cellar fungus (Coniophora puteana) was followed by nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) methods. Altogether, 30 wood sample pieces were exposed to fungus for 10 weeks. Based on the decrease of the dry mass, the samples were categorized into three classes: decomposed (mass decrease 50–70%), slightly decomposed (10–50%), and nondecomposed (<10%). MRI made it possible to identify the active regions of fungus inside the wood samples based on the signal of free water brought by the fungus and arisen from the decomposition of wood carbohydrates. MRI implies that free water is not only created by the decay process, but fungal hyphae also transports a significant amount of water into the sample. Two-dimensional1HT1-T2relaxation correlation NMR measurements provided detailed information about the changes in the microstructure of wood due to fungal decomposition. Overall, this study paves the way for noninvasive NMR and MRI detection of fungal decay at early stages as well as the related structural changes.

Role of cardiac imaging in the diagnosis of infective endocarditis

Infective endocarditis is an increasingly common disease in the hospital setting. Although the 2015 guidelines of the European Society of Cardiology deal extensively with many aspects of infective endocarditis, there are still unsolved problems related to diagnosis, in particular to the appropriate use of cardiac imaging methods, that require further study. The aim of this review is to analyze the advantages and limitations of the echocardiographic, radiological and nuclear imaging methods in order to identify diagnostic pathways applicable in clinical practice.

Development of organ-specific dual-head single-photon emission computed tomography using variable pinhole collimator

Single-photon emission computed tomography (SPECT) is a nuclear medical imaging method enabling the user to view functional images of patients. The collimator, which is an essential component of the SPECT, limits the direction of the incident gamma rays, such that the distribution of the gamma photons from the body can be observed. Collimators are composed of shielding materials with high atomic number and density, thus it is difficult to fabricate them in complex shapes. Among the existing collimators, the pinhole collimator consists of a small aperture perforated in a shielding material, and the modification of the pinhole parameters, such as the hole diameter and acceptance angle, during the scan is also challenging. A variable pinhole (VP) collimator comprises several thin tungsten layers with various hole sizes. Thus, the pinhole parameters can be varied for the region of interest (ROI) by forming the desired pinhole shape using a combination of holes. In this study, we implemented the concept of a VP collimator and applied it in a SPECT system to enhance its performance. The collimator was composed of five layers of with a diameter of 170 mm and thickness of 1 mm and with six holes of different sizes in each layer. Two point sources (Co-57, 122 keV) were used for the performance analysis by changing the system parameters. The spatial resolution and sensitivity of the SPECT system were affected by the variation of the pinhole diameters, with the peak-to-valley ratio increasing by up to 3.3 times with the increase in the magnification of the SPECT system. Two line source phantoms (Tc-99m, 140 keV) with an internal diameter of 1 mm were used for the performance evaluation of the system. The phantoms were positioned 20 mm apart inside the ROI with a diameter of 50 mm at a position of 29 mm from the object center. By applying the VP collimator, the resolution and the sensitivity performance were improved, achieving a full width at half maximum value of 2.7 times and counts of 2.8 times those of the conventional SPECT system. In future research, we aim to improve the system efficiency by conducting simultaneous experimental driving test of the dual-head VP collimator SPECT system.

Multifunctional Magnetic Resonance Imaging Probes.

Magnetic resonance imaging is characterized by high spatial resolution and unsurpassed soft tissue discrimination. Development and characterization of both intrinsic and extrinsic magnetic resonance (MR) imaging probes in the last decade has further strengthened the pivotal role MR imaging holds in the assessment of cancer in preclinical and translational settings. Sophisticated chemical modifications of a variety of nanoparticulate probes hold the potential to deliver valuable multifunctional tools applicable in diagnostics and/or treatment in human oncology. MR imaging suffers from a lack of sensitivity achievable by, e.g., nuclear medicine imaging methods. Advantages of including additional functionality/functionalities in a probe suitable for MR imaging are thus numerous, comprising the addition of fundamentally different imaging information (diagnostics), drug delivery (therapy), or the combination of both (theranostics). In recent years, we have witnessed a plethora of preclinical multimodal or multifunctional imaging probes being published mainly as proof-of-principle studies, yet only a handful are readily applicable in clinical settings. This chapter summarizes recent innovations in the development of multifunctional MR imaging probes and discusses the suitability of these probes for clinical transfer.