CardiOvaScular Mechanisms In Covid-19: methodology of a prospective observational multimodality imaging study (COSMIC-19 study)

Background: 8-28% of patients infected with COVID-19 have evidence of cardiac injury, and this is associated with an adverse prognosis. The cardiovascular mechanisms of injury are poorly understood and speculative. We aim to use multimodality cardiac imaging including cardiac magnetic resonance (CMR) imaging, computed tomography coronary angiography (CTCA) and positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro- D-glucose integrated with computed tomography (18F-FDG-PET/CT) to identify the cardiac pathophysiological mechanisms related to COVID-19 infections. Methods: This is a single-centre exploratory observational study aiming to recruit 50 patients with COVID-19 infection who will undergo cardiac biomarker sampling. Of these, 30 patients will undergo combined CTCA & 18F-FDG-PET/CT, followed by CMR. Prevalence of obstructive and non-obstructive atherosclerotic coronary disease will be assessed using CTCA. CMR will be used to identify and characterise myocardial disease including presence of cardiac dysfunction, myocardial fibrosis, myocardial oedema and myocardial infarction. 18F-FDG-PET/CT will identify vascular and cardiac inflammation. Primary endpoint will be the presence of cardiovascular pathology and the association with troponin levels. Discussion: The results of the study will identify the presence and modality of cardiac injury associated COVID-19 infection, and the utility of multi-modality imaging in diagnosing such injury. This will further inform clinical decision making during the pandemic

Comparison of Image Quality in High Pitch Free Breathing Versus Standard Pitch Breath-Holding Computed Tomographic Pulmonary Angiography.

Background: Pulmonary embolism (PE) is the third most common acute cardiovascular disease. Missed diagnosis is responsible for most preventable deaths associated with PE. Artefacts from cardiac and breathing motion are a main pitfall. Advances in Computed Tomographic imaging have enabled rapid imaging in an attempt to overcome these pitfalls. Objective: To compare image quality when using high pitch free breathing versus standard pitch breath holding Computed Tomographic Pulmonary Angiography (CTPA) using a dual source scanner. Methods: This was a randomised control trial whereby patients referred to the radiology department for CTPA examination for suspected pulmonary embolism were randomly selected into two arms: Arm A underwent the standard CTPA protocol using a pitch of 1.2 with breath-holding instructions while those in arm B underwent the examination using a pitch of 3.2 with quiet free breathing. Two blinded reviewers subjectively assessed the image quality while a single blinded reviewer recorded objective image parameters. The primary endpoint was to demonstrate non-inferiority of high pitch free breathing CTPA. Continuous variables were expressed as mean ± SD. Categorical variables were expressed as frequency (percentage). For calculation of statistically significant differences between both groups, Chi-square test was performed to assess categorical variables and t test for continuous variables. P-values of ≤0.05 were considered statistically significant. Cohen kappa testing was used to assess the degree of agreement between the 2 independent readings, with results expressed in terms of kappa statistics and proportional agreement. Results: A total of 112 patients were randomly selected into the two arms of the study. The patients in the high pitch group received a lower mean radiation dose compared to those in the standard pitch group (P\u3c0.001). There was no statistically significant difference in the mean main pulmonary artery attenuation between the two groups (P=0.215). There was no significant difference in the qualitative analysis of the images between the two groups. Inter reader agreement for the subjective measurements ranged from moderate to almost perfect agreement between the 2 independent readers. Conclusion: Main pulmonary artery contrast opacification in high pitch CTPA is non-inferior to standard pitch CTPA using a dual source 256 slice scanner. High pitch dual source CTPA can be performed on all patients with no compromise on the image quality and with the added advantage of reduction in the radiation dose

Activity of the spleen and bone marrow in relation to cardio-pulmonary injury in patients with acute covid-19 evaluated by 18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging

Objective: COVID-19 primarily causes pneumonitis but can also cause myocarditis. Injury may be due to a generalised inflammatory immune process or by direct viral infection. Using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) and cardiac magnetic resonance (CMR) imaging we correlated the metabolic activity/injury between the reticuloendothelial system (bone marrow [BM] and spleen) and myocardial/pulmonary tissue. Methods: 18F-FDG-PET/CT (n=29, fasted n=27) and CMR (n=23) were performed on hospitalised patients with acute COVID-19. 18F-FDG PET/CT standardised uptake values (SUV) were measured in the spleen, spinal BM, myocardial and pulmonary tissue. Cardiac target-to-background ratio (TBR) was calculated by indexing to blood-pool SUV. Myocarditis was assessed using the sensitive 2018 Lake Louise criteria (LLC), and viral load (by cycle threshold). Results: 13 patients had myocarditis on CMR (57%), 8 (30%) visually on 18F-FDG-PET/CT. There was no statistical difference comparing LLC positive and negative patients for BM (4.21±0.30, 4.98±0.56, P=0.23), spleen (4.40±0.40, 5.15±0.08, P=0.38) and lung (4.08±0.72, 4.16±0.91, P=0.94) SUV. Lung SUV was significantly associated with BM (r=0.61, P0.05 for all). Cycle threshold did not correlate with either cardiac TBR and T1 or T2 (p\u3e0.05 for all). Conclusion: Reticuloendothelial system activation strongly correlated with lung activity, suggesting pulmonary injury is part of a systemic inflammatory process. Cardiac inflammation was not associated with either spleen, BM or viral load, suggesting injury is multifactorial