Coronavirus disease 2019 (COVID-19) has become a rapid worldwide pandemic. While COVID-19 primarily manifests as an interstitial pneumonia and severe acute respiratory distress syndrome, severe involvement of other organs has been documented. In this article, we will review the role of non-contrast chest computed tomography in the diagnosis, follow-up and prognosis of patients affected by COVID-19 pneumonia with a detailed description of the imaging findings that may be encountered. Given that patients with COVID-19 may also suffer from coagulopathy, we will discuss the role of CT pulmonary angiography in the detection of acute pulmonary embolism. Finally, we will describe more advanced applications of CT in the differential diagnosis of myocardial injury with an emphasis on ruling out acute coronary syndrome and myocarditis.

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Objectives To assess the frequency, intensity, and clinical impact of [18F]FDG-avidity of axillary lymph nodes after vaccination with COVID-19 vaccines BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) in patients referred for oncological FDG PET/CT. Methods One hundred forty patients referred for FDG PET/CT during February and March 2021 after first or second vaccination with Pfizer-BioNTech or Moderna were retrospectively included. FDG-avidity of ipsilateral axillary lymph nodes was measured and compared. Assuming no knowledge of prior vaccination, metastatic risk was analyzed by two readers and the clinical impact was evaluated. Results FDG PET/CT showed FDG-avid lymph nodes ipsilateral to the vaccine injection in 75/140 (54%) patients with a mean SUVmax of 5.1 (range 2.0 – 17.3). FDG-avid lymph nodes were more frequent in patients vaccinated with Moderna than Pfizer-BioNTech (36/50 [72%] vs. 39/90 [43%] cases, p < 0.001). Metastatic risk of unilateral FDG-avid axillary lymph nodes was rated unlikely in 52/140 (37%), potential in 15/140 (11%), and likely in 8/140 (6%) cases. Clinical management was affected in 17/140 (12%) cases. Conclusions FDG-avid axillary lymph nodes are common after COVID-19 vaccination. The avidity of lymph nodes is more frequent in Moderna compared to that in Pfizer-BioNTech vaccines. To avoid relatively frequent clinical dilemmas, we recommend carefully taking the history for prior vaccination in patients undergoing FDG PET/CT and administering the vaccine contralateral to primary cancer. Key Points • PET/CT showed FDG-avid axillary lymph nodes ipsilateral to the vaccine injection site in 54% of 140 oncological patients after COVID-19 vaccination. • FDG-avid lymphadenopathy was observed significantly more frequently in Moderna compared to patients receiving Pfizer-BioNTech-vaccines. • Patients should be screened for prior COVID-19 vaccination before undergoing PET/CT to enable individually tailored recommendations for clinical management.

BACKGROUND Sonoelastography is an ultrasound imaging technique able to assess mechanical properties of tissues. Strain elastography (SE) is a qualitative sonoelastographic modality with a wide range of clinical applications, but its use in brain tumor surgery has been so far very limited. OBJECTIVE To describe the first large-scale implementation of SE in oncological neurosurgery for lesions discrimination and characterization. METHODS We analyzed retrospective data from 64 patients aiming at (i) evaluating the stiffness of the lesion and of the surrounding brain, (ii) assessing the correspondence between B-mode and SE, and (iii) performing subgroup analysis for gliomas characterization RESULTS (i) In all cases, we visualized the lesion and the surrounding brain with SE, permitting a qualitative stiffness assessment. (ii) In 90% of cases, lesion representations in B-mode and SE were superimposable with identical morphology and margins. In 64% of cases, lesion margins were sharper in SE than in B-mode. (iii) In 76% of cases, glioma margins were sharper in SE than in B-mode. Lesions morphology/dimensions in SE and in B-mode were superimposable in 89%. Low-grade (LGG) and high-grade (HGG) gliomas were significantly different in terms of stiffness and stiffness contrast between tumors and brain, LGG appearing stiffer while HGG softer than brain (all P < ·001). A threshold of 2.5 SE score had 85.7% sensitivity and 94.7% specificity in differentiating LGG from HGG. CONCLUSION SE allows to understand mechanical properties of the brain and lesions in examination and permits a better discrimination between different tissues compared to B-mode. Additionally, SE can differentiate between LGG and HGG.

Purpose To assess whether contrast material-enhanced ultrasonography (US) can be used to differentiate responders from nonresponders among patients with clinically active Crohn disease after 6 weeks of pharmacologic treatment. Materials and Methods This prospective study was approved by our ethics committee, and written informed consent was obtained from all patients. Fifty consecutive patients (26 men and 24 women; mean age, 34.76 years ± 9) with a proved diagnosis of active Crohn disease who were scheduled to begin therapy with biologics (infliximab or adalimumab) were included, with enrollment from June 1, 2013, to June 1, 2015. In each patient, the terminal ileal loop was imaged with contrast-enhanced US before the beginning and at the end of week 6 of pharmacologic treatment. Time-intensity curves obtained in responders (those with a decrease in the Crohn disease endoscopic index of severity score of 25-44 before treatment to 10-15 after treatment, an inflammatory score <7, and/or a decrease ≥70 in the Crohn disease activity index score compared with baseline) and nonresponders were compared with Mann-Whitney test. Results Responders (n = 31) and nonresponders (n = 19) differed (P < .05) in the percent change of peak enhancement (-40.78 ± 62.85 vs 53.21 ± 72.5; P = .0001), wash-in (-34.8 ± 67.72 vs 89.44 ± 145.32; P = .001) and washout (-5.64 ± 130.71 vs 166.83 ± 204.44; P = .002) rate, wash-in perfusion index (-42.29 ± 59.21 vs 50.96 ± 71.13; P = .001), area under the time-intensity curve (AUC; -46.17 ± 48.42 vs 41.78 ± 87.64; P = .001), AUC during wash-in (-43.93 ± 54.29 vs 39.79 ± 70.85; P = .001), and AUC during washout (-49.36 ± 47.42 vs 42.65 ± 97.09; P = .001). Responders and nonresponders did not differ in the percent change of rise time (5.09 ± 49.13 vs 6.24 ± 48.06; P = .93) and time to peak enhancement (8.82 ± 54.5 vs 10.21 ± 43.25; P = .3). Conclusion Analysis of time-intensity curves obtained after injection of microbubble contrast material 6 weeks after beginning pharmacologic treatment can be used to differentiate responders from nonresponders among patients with clinically active Crohn disease. RSNA, 2016.

The investigation of patients with cirrhosis by the West Haven test is not sufficient to identify subclinical forms of encephalopathy. The Trail Making Test (a simple, inexpensive test) in our series evidenced poor psychometric performance in more than half of the patients who were free of manifest encephalopathy. Subclinical hepatic encephalopathy was present mostly in patients with HCV-related cirrhosis. Detecting minimal hepatic encephalopathy in patients with cirrhosis may help improve their quality of life.

Epilepsy surgery can achieve seizure freedom in selected pediatric candidates, but reliable postsurgical predictors of seizure freedom are missing. High frequency oscillations (HFO) in scalp EEG are a new and promising biomarker of treatment response. However, it is unclear if the skull defect resulting from craniotomy interferes with HFO detection in postsurgical recordings. We considered 14 children with focal lesional epilepsy who underwent presurgical evaluation, epilepsy surgery, and postsurgical follow-up of ≥ 1 year. We identified the nearest EEG electrodes to the skull defect in the postsurgical MRI. We applied a previously validated automated HFO detector to determine HFO rates in presurgical and postsurgical EEG. Overall, HFO rates showed a positive correlation with seizure frequency (p < 0.001). HFO rates in channels over the HFO area decreased following successful epilepsy surgery, irrespective of their proximity to the skull defect (p = 0.005). HFO rates in channels outside the HFO area but near the skull defect showed no increase following surgery (p = 0.091) and did not differ from their contralateral channels (p = 0.726). Our observations show that the skull defect does not interfere with postsurgical HFO detection. This supports the notion that scalp HFO can predict postsurgical seizure freedom and thus guide therapy management in focal lesional epilepsy.

The aim of the study described here was to assess whether the analysis of time-intensity curves obtained after microbubble contrast agent injection could differentiate inflammatory from fibrotic ileal strictures among patients with Crohn's disease. Sixty-five consecutive patients (40 male and 25 female; mean age ± SD, 42.2 ± 12.22 y) with stricture of the terminal ileal loop from Crohn's disease were scanned after microbubble injection. Time-intensity curves were obtained from quantitative analysis, and peak enhancement, rise time, time to peak, area under the time-intensity curve (AUC), AUC during wash-in (AUCWI) and AUC during wash-out (AUCWO) were compared between patients with inflammatory strictures and patients with fibrotic strictures. Inflammatory (n = 40) and fibrotic (n = 25) strictures differed (p < 0.05) in peak enhancement, wash-in rate, wash-in perfusion index, AUC, AUCWI and AUCWO. The quantitative analysis of small bowel wall contrast enhancement after microbubble contrast agent injection may differentiate inflammatory from fibrotic ileal strictures in patients with Crohn's disease.