Imaging of Myocarditis Following mRNA COVID-19 Booster Vaccination.

Keywords: Echocardiography, MR-Functional Imaging, MRI, Cardiac Supplemental material is available for this article.

Functional brain imaging interventions for radiation therapy planning in patients with glioblastoma: a systematic review.

RATIONALE: This systematic review aims to synthesise the outcomes of different strategies of incorporating functional biological markers in the radiation therapy plans of patients with glioblastoma to support clinicians and further research. METHODS: The systematic review protocol was registered on PROSPERO (CRD42021221021). A structured search for publications was performed following PRISMA guidelines. Quality assessment was performed using the Newcastle-Ottawa Scale. Study characteristics, intervention methodology and outcomes were extracted using Covidence. Data analysis focused on radiation therapy target volumes, toxicity, dose distributions, recurrence and survival mapped to functional image-guided radiotherapy interventions. RESULTS: There were 5733 citations screened, with 53 citations (n = 32 studies) meeting review criteria. Studies compared standard radiation therapy planning volumes with functional image-derived volumes (n = 20 studies), treated radiation therapy volumes with recurrences (n = 15 studies), the impact on current standard target delineations (n = 9 studies), treated functional volumes and survival (n = 8 studies), functionally guided dose escalation (n = 8 studies), radiomics (n = 4 studies) and optimal organ at risk sparing (n = 3 studies). The approaches to target outlining and dose escalation were heterogeneous. The analysis indicated an improvement in median overall survival of over two months compared with a historical control group. Simultaneous-integrated-boost dose escalation of 72-76 Gy in 30 fractions appeared to have an acceptable toxicity profile when delivered with inverse planning to a volume smaller than 100 cm[Formula: see text]. CONCLUSION: There was significant heterogeneity between the approaches taken by different study groups when implementing functional image-guided radiotherapy. It is recommended that functional imaging data be incorporated into the gross tumour volume with appropriate technology-specific margins used to create the clinical target volume when designing radiation therapy plans for patients with glioblastoma.

CT-derived measurements of pulmonary blood volume in small vessels and the need for supplemental oxygen in COVID-19 patients.

Throughout the COVID-19 pandemic, a portion of those affected have evolved toward acute hypoxic respiratory failure. Initially, this was hypothesized to result from acute lung injury leading to acute respiratory distress syndrome (ARDS). In previous research, a novel quantitative CT post-processing technique was described to quantify the volume of blood contained within pulmonary blood vessels of a given size. We hypothesized that patients with lower BV5 blood flow would have higher supplemental oxygen needs and less favorable arterial blood gas profiles. From the initial data analysis, 111 hospitalized COVID-19 patients were retrospectively selected based on the availability of CT scans of the lungs with a slice thickness of 1.5 mm or less, as well as PCR-confirmed SARS-CoV2 infection. Three-dimensional (3-D) reconstructions of the lungs and pulmonary vasculature were created. Further analysis was performed on 50 patients. Patients were divided into groups based on their need for oxygen at the time of CT scan acquisition. Eighteen out of 50 patients needed >2 L/min supplemental oxygen and this group demonstrated a significantly lower median percentage of total blood flow in the BV5 vessels compared with the 32 patients who needed <2 L/min supplemental oxygen (41.61% vs. 46.89%, P = 0.023). Both groups had significantly less blood as a proportion in BV5 vessels compared with healthy volunteers. These data are consistent with the hypothesis that reduced blood volume within small (BV5) pulmonary vessels is associated with higher needs for supplemental oxygen and more severe gas exchange anomalies in COVID-19 infections.NEW & NOTEWORTHY This research provides, by using new imaging analysis on CT imaging, an insight into the pathophysiology of patients with COVID-19 infection. By visualizing and quantifying the blood in small vessels in the lung, we can link these results to the clinical need for oxygen in patients with COVID-19 infection.

Molecular imaging as a tool for evaluation of COVID-19 sequelae - A review of literature.

Coronavirus disease 2019 (COVID-19) is caused by the novel viral pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 primarily involves the lungs. Nucleic acid testing based on reverse-transcription polymerase chain reaction of respiratory samples is the current gold standard for the diagnosis of SARS-CoV-2 infection. Imaging modalities have an established role in triaging, diagnosis, evaluation of disease severity, monitoring disease progression, extra-pulmonary involvement, and complications. As our understanding of the disease improves, there has been substantial evidence to highlight its potential for multi-systemic involvement and development of long-term sequelae. Molecular imaging techniques are highly sensitive, allowing non-invasive visualization of physiological or pathological processes at a cellular or molecular level with potential for detection of functional changes earlier than conventional radiological imaging. The purpose of this review article is to highlight the evolving role of molecular imaging in evaluation of COVID-19 sequelae. Though not ideal for diagnosis, the various modalities of molecular imaging play an important role in assessing pulmonary and extra-pulmonary sequelae of COVID-19. Perfusion imaging using single photon emission computed tomography fused with computed tomography (CT) can be utilized as a first-line imaging modality for COVID-19 related pulmonary embolism. 18F-fluorodeoxyglucose positron emission tomography (PET)/CT is a sensitive tool to detect multi-systemic inflammation, including myocardial and vascular inflammation. PET in conjunction with magnetic resonance imaging helps in better characterization of neurological sequelae of COVID-19. Despite the fact that the majority of published literature is retrospective in nature with limited sample sizes, it is clear that molecular imaging provides additional valuable information (complimentary to anatomical imaging) with semi-quantitative or quantitative parameters to define inflammatory burden and can be used to guide therapeutic strategies and assess response. However, widespread clinical applicability remains a challenge owing to longer image acquisition times and the need for adoption of infection control protocols.

Correlation between BNT162b2 mRNA Covid-19 vaccine-associated hypermetabolic lymphadenopathy and humoral immunity in patients with hematologic malignancy.

PURPOSE: Vaccine-associated hypermetabolic lymphadenopathy (VAHL) is frequently observed on [18F]FDG PET-CT following BNT162b2 administration. Recent data suggest a prominent B cell germinal-center (GC) response elicited by mRNA vaccines in draining lymph nodes. Thus, in this study we aimed to explore the correlation between VAHL and humoral immunity as reflected by post-vaccination serologic testing and by comparing the incidence of VAHL between lymphoma patients treated recently with B cell depleting therapy and those that were not. METHODS: A total of 137 patients with hematologic malignancy that had post-vaccination [18F]FDG PET-CT were included (All-PET group), 86 received both vaccine doses before imaging (PET-2 group). Their VAHL status and grade on imaging were recorded. Among 102 lymphoma patients, 34 (33.3%) were treated during the year prior vaccination with anti-CD20 antibody containing therapy. A subgroup of 54 patients also underwent serologic testing 2-3 weeks after the booster dose, and their anti-spike titers were recorded and graded as well. RESULTS: The overall incidence of VAHL in patients with hematologic malignancy was 31.4%. The 34 lymphoma patients treated during the year prior vaccination with anti-CD20 antibody containing therapy had significantly lower rates of VAHL comparted with all other lymphoma patients (8.8 versus 41.2% in all-PET patients, Pv < 0.01). VAHL rates were 10% in patients with negative serology, 31.3% in patients with low anti-spike titers, and 72.2% in patients with high anti-spike titers. The positive predictive values of VAHL were 90 and 93.3% in all-PET and PET-2 patients, respectively. A positive statistically significant correlation was found between VAHL and serology ranks in All-PET patients (rs = 0.530, Pv < 0.001), and stronger correlation was found in PET-2 patients (rs = 0.642, Pv < 0.001). CONCLUSION: VAHL on [18F]FDG PET-CT of patients with hematologic malignancy may reflect GC B cell proliferation and an effective humoral response elicited by BNT162b2 vaccine.

Dynamic Chest X-Ray Using a Flat-Panel Detector System: Technique and Applications.

Dynamic X-ray (DXR) is a functional imaging technique that uses sequential images obtained by a flat-panel detector (FPD). This article aims to describe the mechanism of DXR and the analysis methods used as well as review the clinical evidence for its use. DXR analyzes dynamic changes on the basis of X-ray translucency and can be used for analysis of diaphragmatic kinetics, ventilation, and lung perfusion. It offers many advantages such as a high temporal resolution and flexibility in body positioning. Many clinical studies have reported the feasibility of DXR and its characteristic findings in pulmonary diseases. DXR may serve as an alternative to pulmonary function tests in patients requiring contact inhibition, including patients with suspected or confirmed coronavirus disease 2019 or other infectious diseases. Thus, DXR has a great potential to play an important role in the clinical setting. Further investigations are needed to utilize DXR more effectively and to establish it as a valuable diagnostic tool.