ABSTRACT
Objectives: COVID-19 posed profound challenges to nuclear medicine (NM) practice and education on an international scope. Initial lessons learned may be useful in understanding and optimizing dissemination of critical information during global disasters. To better understand the pandemic's initial manifold impact and responses that were in turn enacted, we systematically reviewed relevant articles published during the 2020 calendar year. Method(s): A librarian experienced in systematic reviews performed a rapid scoping review of the English language literature indexed in PubMed, Embase and Web of Science by crossing NM and COVID terms;445 citations were returned. Duplicate, extraneous, non-English and non-full text articles were excluded leaving 248 articles which were analyzed by origin, topic, design, and imaging details. Result(s): An array of topics, techniques, journals and countries of origin were encountered. 158 articles appeared in primary NMjournals, 26 appeared in generic radiology journals and 65 in non-imaging journals. Most frequent countries represented were USA (55), Italy (33), France (19) and UK (17), reflecting the hard-hit countries early during the pandemic. 118 clinical articles were case reports or small series of which 80 featured FDG-PET/CT. There were 36 observational studies. Among non-clinical topics, articles focused on safetymeasures (102), economics and recovery (23), remote reading (17) and education (8). There were 17 surveys. Society-based guidelines (47) and individual-group best practices (79) were published relating to cardiology (33), lung scintigraphy (12), andmultiple topics (48). Systematic (10) and narrative reviews (61) were less frequent than opinion articles (75). Frequent modalities discussed were FDG PET (156), nuclear cardiology (56) and lung scintigraphy (35). Conclusion(s): The medical literature has memorialized a robust response of information sharing during the initial challenges the COVID-19 pandemic relating to patient care, operations and education. Through scoping review, we have analyzed the nature of information disseminated. Opinions and single group best practices dominated the literature. Clinical reports during the first year were primarily case reports or small series, frequently FDG-PET/ CT. The nature of the literature matured as the year progressed, and sources of information broadened as the epidemic spread.
ABSTRACT
Aim/Introduction: There is growing interest in the clinical management of children with persisting and debilitating symptoms after Sars-COV-2 infection (Long-COVID). Chronic effects could arise from residual clot burden and small vessel inflammation, both expressing endothelial damage that may lead to lung perfusion impairment. 99mTc-macroaggregated albumin (MAA) SPECT/ CT is a well-established tool to detect lung perfusion defects, even at the small-vessels level. This pilot study aimed at assessing lung perfusion in Long-COVID children with MAA SPECT/CT and at comparing functional patterns with clinical scenarios during acute infection and follow-up. Material(s) and Method(s): Clinical and biochemical data were collected during acute infection and follow-up in 10 children (6 males and 4 females, mean age: 13.6 years) fulfilling Long-COVID diagnostic criteria and complaining of chronic fatigue and post-exertional malaise after mild efforts. All patients underwent a cardiopulmonary test and MAA SPECT/CT scan. Dose activities were properly chosen according to the EANM guidelines for lung scintigraphy in children. Intravenous injections were administered to patients in the supine position immediately before the planar scan, which was followed by the lung SPECT/CT acquisition. Reconstructed studies were visually analyzed. Imaging results were compared with clinical scenarios during acute infection and follow-up. Result(s): The severity of acute disease was mild and moderate in 6/10 (60 %) and 2/10 (20 %) children, respectively;there were no significant symptoms in the remaining 2 cases. Persisting symptoms after the acute phase were observed in 7/10 (70%) patients. Five out of 10 (50.0%) children showed perfusion defects on MAA SPECT/CT scan, without morphological alterations on co-registered CT. In particular, 4/5 (80%) children with lung perfusion abnormalities were previously affected by a mild acute infection, whereas a single child (20%) was asymptomatic. However, during the follow-up, persisting symptoms (e.g., headache and dyspnea after the cardiopulmonary test) were detected in 5/5 (100%) patients. Conversely, among the five children without lung perfusion defects, only 2 (40%) showed persisting symptoms (in particular, headache), while 3 (60%) children had dyspnea after the cardiopulmonary test. Conclusion(s): This pilot study showed lung perfusion defects in Long-COVID children. Despite the small patient sample, perfusion abnormalities on MAA SPECT/CT seem to occur more frequently in children with persisting symptoms following the acute infection and dyspnea after the cardiopulmonary test. Larger cohort studies are needed to confirm these preliminary results, providing a better selection among children who can benefit the most from MAA SPECT/CT imaging.
ABSTRACT
Aim/Introduction: Technegas is fast becoming the gold standard for lung ventilation scintigraphy in Canada. Technegas is a carbonbased nanoparticle bound to 99mTc which is small enough to behave more like a gas than an aerosol. Due to its small size, Technegas can easily perfuse the peripheral airways and does not aggregate in the central airways like larger aerosol particles often do. Furthermore, since the Covid-19 pandemic began, there has been a significant drop in ventilation studies performed due to the risk of exposure to the virus when using traditional aerosols. Improved image quality, fast and easy administration, enhanced patient comfort, and ability to safely administer Technegas with Covid-19 positive patients makes Technegas far superior to traditional Tc-based aerosols. Material(s) and Method(s): A review of the literature comparing Technegas to other commonly used 99mTcbased lung ventilation imaging agents was conducted. Recent purchasers of Technegas units were interviewed to determine their motivation for switching to Technegas and their overall impression with using it after changing over. Result(s): The small particle size, reduced central airways deposition, and lack of lung clearance leads to improved count-statistics and better target-to-non-target ratio, which allows for SPECT imaging, which is not feasible when using traditional aerosols. Technologists report that administering Technegas is far easier and faster than administering traditional aerosols. Often patients only require 1 or 2 breaths of Technegas to achieve the desired count rate, as opposed to 5 or more minutes of breathing an aerosol. Technegas is a 'dry' aerosol, which means that it is considered a non-aerosol generating procedure, so it is safe to use on Covid-19 positive patients. Justifying the small start-up cost to purchase a Technegas generator was the limiting factor for departments delaying their switch to Technegas. Canada's health care system is publicly-funded, which often delays widespread access to technological advancements. The Covid-19 pandemic has increased demand for Technegas across Canada, which has resulted in increased funding to purchase more Generators. Conclusion(s): Technegas is far superior to other 99mTc-based aerosols used in ventilation imaging and is fast replacing Tc-based aerosols as the agent of choice in nuclear medicine departments across Canada.
ABSTRACT
Aim/Introduction: Technegas is fast becoming the gold standard for lung ventilation scintigraphy in Canada. Technegas is a carbonbased nanoparticle bound to 99mTc which is small enough to behave more like a gas than an aerosol. Due to its small size, Technegas can easily perfuse the peripheral airways and does not aggregate in the central airways like larger aerosol particles often do. Furthermore, since the Covid-19 pandemic began, there has been a significant drop in ventilation studies performed due to the risk of exposure to the virus when using traditional aerosols. Improved image quality, fast and easy administration, enhanced patient comfort, and ability to safely administer Technegas with Covid-19 positive patients makes Technegas far superior to traditional Tc-based aerosols. Material(s) and Method(s): A review of the literature comparing Technegas to other commonly used 99mTcbased lung ventilation imaging agents was conducted. Recent purchasers of Technegas units were interviewed to determine their motivation for switching to Technegas and their overall impression with using it after changing over. Result(s): The small particle size, reduced central airways deposition, and lack of lung clearance leads to improved count-statistics and better target-to-non-target ratio, which allows for SPECT imaging, which is not feasible when using traditional aerosols. Technologists report that administering Technegas is far easier and faster than administering traditional aerosols. Often patients only require 1 or 2 breaths of Technegas to achieve the desired count rate, as opposed to 5 or more minutes of breathing an aerosol. Technegas is a 'dry' aerosol, which means that it is considered a non-aerosol generating procedure, so it is safe to use on Covid-19 positive patients. Justifying the small start-up cost to purchase a Technegas generator was the limiting factor for departments delaying their switch to Technegas. Canada's health care system is publicly-funded, which often delays widespread access to technological advancements. The Covid-19 pandemic has increased demand for Technegas across Canada, which has resulted in increased funding to purchase more Generators. Conclusion(s): Technegas is far superior to other 99mTc-based aerosols used in ventilation imaging and is fast replacing Tc-based aerosols as the agent of choice in nuclear medicine departments across Canada.
ABSTRACT
Background-Aim: While there's a wide literature on CT abnormalities in COVID-19 sequelae, the role of lung perfusion scintigraphy have been scarcely investigated. Recent findings reported lung microvascular and endothelial alterations in patients recovered from COVID-19 without pulmonary embolism, presenting persistent dyspnea (POST-COVID). We compared perfusion scintigraphy and CT findings of these patients with dyspneic subjects in whom lung scintigraphy excluded pulmonary embolism (NON-COVID). In POST-COVID patients, the correlation between lung perfusion scintigraphic findings and (1) CT abnormalities, and (2) clinical/ biochemical parameters were also assessed. Methods: 24 POST-COVID and 33 NON-COVID patients who underwent lung perfusion scintigraphy for dyspnea from March 2020 to December 2021 were retrospectively enrolled. High-resolution chest CT performed 15 days before/after lung perfusion scintigraphy were available in 15/24 POST-COVID and 15/33 NON-COVID patients. From scintigraphic images counting rates for upper, middle, and lower fields were calculated in order to compute their ratio with total lung counts (UTR, MTR, and LTR, respectively) for both right and left lungs (RL and LL, respectively). CT images were analyzed using a semi-automated segmentation algorithm of 3D Slicer ( http://www.slicer.org), obtaining total, infiltrated and blood vessels' volumes, in order to calculate the infiltration rate (IR) and vascular density (VD). White blood cells, platelets, PT, INR, PTT, fibrinogen, and D-dimer of 15/24 POST-COVID patients were also collected from blood tests performed before the lung perfusion scintigraphy. Results: POST-COVID patients with persistent dyspnea showed reduced LTR (RL 22.4% ± 6.6%;LL 24.7% ± 3.1%) and higher MTR (RL 55.2% ± 5.2%;LL 49.1% ± 3.3%) compared to non- COVID patients (RL-LTR 29.6% ± 6.0%, p<0.0001;LL-LTR 28.3% ± 4.6%, p = 0.001;RL-MTR 47.3% ± 4.2%, p<0.0001;LL-MTR 47.3% ± 3.0%, p = 0.036), while UTR resulted bilaterally superimposable between the two groups. Similar IR and VD values at CT imaging were documented bilaterally in both groups. In POSTCOVID patients, no significant correlations between lung perfusion scintigraphy and CT findings were observed. Correlation analysis indicated D-dimer levels as associated with UTR (Pearson's r = 0.664;p = 0.007) and MTR (Pearson's r = - 0.555;p = 0.032), while no parameter significantly associated with LTR was observed. Conclusions: Lung perfusion scintigraphy can reveal reduced perfusion rates of lower pulmonary fields in POST-COVID patients with persistent dyspnea in the absence of pulmonary embolism, independently from CT abnormalities, infection duration and coagulation biomarkers. Although mechanisms underlying these findings need to be supported by pathological lung tissue examination, lung nonthrombotic microvascular and endothelial dysfunction may be involved.
ABSTRACT
Because of the inadequate capacity and a substantial surge of probable COVID-19 cases, several health systems around worldwide have collapsed. As a result, the requirement for a rapid, effective, and precise way to reduce radiologists' workload in diagnosing suspected instances has arisen. The goal of the present study is to develop a novel system to automatically diagnose and classify lung CT scans into three categories: suspected covid-19, covid-19, and healthy lung scans. Before feature extraction using convolutional neural network (CNN) and Local Binary Pattern (LBP) approaches, the CT scans are first pre-processed through implementing a set of algorithms. Lastly, with the use of the support vector machine (SVM) model, such features are divided into three groups. The maximum accuracy attained in classifying a dataset of 351 CT scans of the lungs was 98.22%. The outcomes of the experiments show that merging the extracted features increases the effectiveness of lung classification CT scans.