Prevalence of Adenopathy at Chest Computed Tomography After Vaccination for Severe Acute Respiratory Syndrome Coronavirus 2.

OBJECTIVE: This study aimed to determine the prevalence of axillary and subpectoral (SP) lymph nodes after ipsilateral COVID-19 vaccine administration on chest computed tomography (CT). METHODS: Subjects with chest CTs between 2 and 25 days after a first or second vaccine dose, December 15, 2020, to February 12, 2021, were included. Orthogonal measures of the largest axillary and SP nodes were recorded by 2 readers blinded to vaccine administration and clinical details. A mean nodal diameter discrepancy of ≥6 mm between contralateral stations was considered positive for asymmetry. Correlation with the side of vaccination, using a Spearman rank correlation, was performed on the full cohort and after excluding patients with diseases associated with adenopathy. RESULTS: Of the 138 subjects (81 women, 57 men; mean [SD] age, 74.4 ± 11.7 years), 48 (35%) had asymmetrically enlarged axillary and/or SP lymph nodes, 42 (30%) had ipsilateral, and 6 (4%) had contralateral to vaccination ( P = 0.003). Exclusion of 29 subjects with conditions associated with adenopathy showed almost identical correlation, with asymmetric nodes in 32 of 109 (29%) ipsilateral and in 5 of 109 (5%) contralateral to vaccination ( P = 0.002). CONCLUSIONS: Axillary and/or SP lymph nodes ipsilateral to vaccine administration represents a clinical conundrum. Asymmetric nodes were detected at CT in 30% of subjects overall and 29% of subjects without conditions associated with adenopathy, approximately double the prevalence rate reported to the Centers for Disease Control and Prevention by vaccine manufacturers. When interpreting examinations correlation with vaccine administration timing and site is important for pragmatic management.

Chest CT Angiography for Acute Aortic Pathologic Conditions: Pearls and Pitfalls.

Chest CT angiography (CTA) is essential in the diagnosis of acute aortic syndromes. Chest CTA quality can be optimized with attention to technical parameters pertaining to noncontrast imaging, timing of contrast-enhanced imaging, contrast material volume, kilovolt potential, tube-current modulation, and decisions regarding electrocardiographic-gating and ultra-fast imaging, which may affect the accurate diagnosis of acute aortic syndromes. An understanding of methods to apply to address suboptimal image quality is useful, as the accurate identification of acute aortic syndromes is essential for appropriate patient management. Acute aortic syndromes have high morbidity and mortality, particularly when involving the ascending aorta, and include classic aortic dissection, penetrating atherosclerotic ulcer, and acute intramural hematoma. An understanding of the pathogenesis and distinguishing imaging features of acute aortic syndromes and aortic rupture and some less common manifestations is helpful when interpreting imaging examinations. Related entities, such as ulcerated plaque, ulcerlike projections, and intramural blood pools, and mimics, such as vasculitis and aortic thrombus, are important to recognize; knowledge of these is important to avoid interpretive pitfalls. In addition, an awareness of postsurgical aortic changes can be useful when interpreting CTA examinations when patient history is incomplete. The authors review technical considerations when performing CTA, discuss acute aortic syndromes, and highlight diagnostic challenges encountered when interpreting aortic CTA examinations. ©RSNA, 2021.

SARS-CoV-2 From the Trenches: A Perspective From New York City.

OBJECTIVE. The response to coronavirus disease (COVID-19) is evolving in New York City. We would like to share our experiences, thoughts, and perspectives on coping with the pandemic. CONCLUSION. This article presents experiences that are meant to help foster discussion as the wave of COVID-19 continues. Thoughtful leadership and careful continuous communication will help us minimize anxiety and frustration during this difficult time.

Artificial Intelligence in Cardiothoracic Radiology.

OBJECTIVE. The goal of this article is to examine some of the current cardiothoracic radiology applications of artificial intelligence in general and deep learning in particular. CONCLUSION. Artificial intelligence has been used for the analysis of medical images for decades. Recent advances in computer algorithms and hardware, coupled with the availability of larger labeled datasets, have brought about rapid advances in this field. Many of the more notable recent advances have been in the artificial intelligence subfield of deep learning.

Aortic arch dissection: a controversy of classification.

Aortic dissections originating in the ascending aorta and descending aorta have been classified as type A and type B dissections, respectively. However, dissections with intimal flap extension into the aortic arch between the innominate and left subclavian arteries are not accounted for adequately in the widely used Stanford classification. This gap has been the subject of controversy in the medical and surgical literature, and there is a tendency among many radiologists to categorize such arch dissections as type A lesions, thus making them an indication for surgery. However, the radiologic perspective is not supported by either standard dissection classification or current clinical management. In this special report, the origin of dissection classification and its evolution into current radiologic interpretation and surgical practice are reviewed. The cause for the widespread misconception about classification and treatment algorithms is identified. Institutional review board approval and waiver of informed consent were obtained as part of this HIPAA-compliant retrospective study to assess all aortic dissection studies performed at the University of Maryland Medical Center, Baltimore between 2010 and 2012 to determine the prevalence of arch dissections. Finally, a unified classification system that reconciles imaging interpretation and management implementation is proposed.

Concordance of Pericardial Effusion Size Between Computed Tomography and Echocardiography.

Discrepancy between computed tomography (CT) and transthoracic echocardiography (TTE) regarding pericardial effusion (PEff) size is common, but there is limited data regarding the correlation between these 2 imaging methods. The aim of this study is to examine the real-world concordance of observed PEff size between CT and TTE. We performed a retrospective analysis of all imaging reports available from 2013 to 2019 and identified patients with a PEff who underwent both a chest CT and TTE within a 24-hour period. We evaluated the agreement between CT and TTE in assessing PEff size. Of 1,118 patients included in the study, mean age was 66 (±17 years) and 54% were female. The median time interval between the 2 studies was 9.4 hours (interquartile range 3.5 to 16.6). Patients within a half-grade or full-grade of agreement were 71.9% and 97.2%, respectively. The mean difference in grade of agreement (TTE minus CT) between the 2 imaging methods was -0.1 (±0.6, p <0.0001). CT was more likely to report a higher grade (i.e. larger PEff size) when compared with TTE (261 patients vs 157 patients, p <0.001). The weighted kappa was 0.73 (95% confidence interval 0.69 to 0.76). After excluding patients with trace/no effusion, 42.3% and 94.1% of patients' studies were within a half-grade or full-grade of agreement, respectively. Of the 18 patients who had large discrepancies, 9 patients had loculated effusions, 2 patients had large pleural effusions, and 6 patients had suboptimal TTEs images. In conclusion, TTE and CT showed relatively strong agreement in estimation of PEff size, with CT sizes larger than TTE, on average. Large discrepancies in size may be related to reduced image quality, large pleural effusions, and loculated PEff.

Mapping the binding of the N-terminal extracellular tail of the CXCR4 receptor to stromal cell-derived factor-1alpha.

The solution structure of monomeric stromal cell-derived factor-1alpha (SDF-1alpha), the natural ligand for the CXCR4 G-coupled receptor, has been solved by multidimensional heteronuclear NMR spectroscopy. The structure has a characteristic chemokine fold and is in excellent agreement with the individual subunits observed in the crystal structures of dimeric SDF-1alpha. Using various peptides derived from the N-terminal extracellular tail of the CXCR4 receptor, we show that the principal determinants of binding reside in the N-terminal 17 residues of CXCR4, with a major contribution from the first six residues. From 15N/1HN chemical shift pertubation studies we show that the interaction surface on SDF-1alpha is formed by the undersurface of the three-stranded antiparallel beta-sheet bounded by the N-terminal loop on one side and the C-terminal helix on the other. This surface overlaps with but is not identical to that mapped on several other chemokines for the binding of equivalent peptides derived from their respective receptors.

Magnetic resonance histology: in situ single cell imaging of receptor cells in an invertebrate (Lolliguncula brevis, Cephalopoda) sense organ.

Utilizing contrast-enhanced MR histology, individual cell bodies were identified in situ and compared one-to-one with conventional histology. The squid Lolliguncula brevis served as a model where the receptor cells of the proprioceptive neck receptor organ were labeled with paramagnetic cobalt(II) ions by conventional cobalt iontophoresis. Stimulated echo images were obtained using a 9.4 T magnet and followed by conventional histologic treatment and light microscopy. Images obtained from both these techniques match well and validate MR histology.

Structure of hybrid backbone methylphosphonate DNA heteroduplexes: effect of R and S stereochemistry.

Methyl phosphonate oligonucleotides have been used as antisense and antigene agents. Substitution of a methyl group for oxygen in the phosphate ester backbone introduces a new chiral center. Significant differences in physical properties and hybridization abilities are observed between the R(p) and S(p) diastereomers. Chirally pure methylphosphonate deoxyribooligonucleotides were synthesized, and the solution structures of duplexes formed between a single strand heptanucleotide methylphosphonate, d(Cp(Me)Cp(Me)Ap(Me)Ap(Me)Ap(Me)Cp(Me)A), hybridized to a complementary octanucleotide, d(TpGpTpTpTpGpGpC), were studied by NMR spectroscopy. Stereochemistry at the methylphosphonate center for the heptanucleotide was either RpRpRpRpRpRp (R(p) stereoisomer) or RpRpRpSpRpRp (S(p) stereoisomer, although only one of the six methylphosphonate centers has the S(p) stereochemistry). The results show that the methylphosphonate strands in the heteroduplexes exhibit increased dynamics relative to the DNA strand. Substitution of one chiral center from R(p) to S(p) has a profound effect on the hybridization ability of the methylphosphonate strand. Sugars in the phosphodiester strand exhibit C(2)(') endo sugar puckering while the sugars in the methyl phosphonate strand exhibit an intermediate C(4)(') endo puckering. Bases are well stacked on each other throughout the duplex. The hybridization of the methylphosphonate strand does not perturb the structure of the complementary DNA strand in the hetero duplexes. The sugar residue 5' to the S(p) chiral center shows A-form sugar puckering, with a C(3)(')-endo conformation. Minor groove width in the R(p) stereoisomer is considerably wider, particularly at the R(p) vs S(p) site and is attributed to either steric interactions across the minor groove or poorer metal ion coordination within the minor groove.