9 research outputs found
Alterations of the amygdala in post-COVID olfactory dysfunction
No full textAbstract Olfactory dysfunction (OD) as a symptom of COVID-19 has received significant attention in research due to its high prevalence. While it is transient in the majority of individuals, post-COVID OD persists in a notable subset of patients even months to years after the acute infection. A deeper understanding of the underlying factors driving this phenomenon is essential. There is increasing evidence for an involvement of the central nervous system in this deficit. The objective of this study was to investigate the structural connectivity and integrity of white matter pathways in brain regions associated with olfactory processing using MRI with diffusion tensor imaging (DTI) in patients with persistent post-COVID OD. The study involved 61 patients, divided into two groups: 31 participants with post-COVID OD (PC-OlfDys) and 30 post-COVID normosmic controls (PC-N). For MRI analyses, a region of interest (ROI)-based approach and voxelwise statistical comparisons between the groups with age as a covariate was used. Fractional anisotropy (FA) in the left amygdala was higher in the PC-OlfDys than in the PC-N group, and radial diffusivity (RD) in the right amygdala was higher in the PC-OlfDys group than in PC-N. The PC-OlfDys group exhibited higher depression and anxiety scores, as measured by the eight-item Patient Health Questionnaire depression scale and the Generalized Anxiety Disorder 7 questionnaire, respectively. This study shows that post-COVID OD is associated with significant changes in the myelination or axonal diameter of olfactory-related brain regions. As the amygdala, putamen and piriform cortex (all involved in olfactory function and emotional well-being) showed associations with depression and anxiety scores, we hypothesise that post-COVID OD and depression and anxiety are interrelated, although the direction of this relationship remains to be elucidated
Experimental Evaluation of the Effectiveness of Aspiration-Based Techniques to Treat Different Types of Acute Thromboembolic Occlusions in the Femoropopliteal Vascular System Using an In Vitro Flow Model
No full textPurpose!#!In this in vitro study, the effectiveness and safety of four aspiration-based techniques for thrombectomy are evaluated for three types of thrombi in a flow model simulating the femoropopliteal segment.!##!Material and methods!#!Red, white, and mixed thrombi were produced in a standardized manner and used to simulate occlusion of a superficial femoral artery using a pulsatile flow model. Four techniques were compared: aspiration alone, aspiration + stent retriever, exposing thrombus to laser by an excimer laser system and a laser catheter + aspiration, and aspiration + mechanical fragmentation by a separator. Rate of first-pass recanalization, embolic events, and number of embolized fragments > 1 mm were compared.!##!Results!#!Aspiration alone, stent retriever, laser, and separator differed in rates of first-pass recanalization (53.3%; 86.6%; 20%; and 100%) and embolic events (40%; 93.3%; 73.3%; and 60%). Number of embolized fragments was lowest with aspiration and higher with separator, laser, and stent retriever. Rates of first-pass-recanalization (75%; 75%; and 45%) and embolic events (65%; 60%; and 75%) differed for red, white, and mixed thrombi. The mixed thrombus caused the highest number of embolized fragments, which was particularly high using the stent retriever.!##!Conclusion!#!Additional use of mechanical techniques significantly enhances the effectiveness of thrombectomy but simultaneously provokes more embolism. Laser seems to negatively alter the structure of a thrombus and thus diminishes the effectiveness, while provoking embolism. All techniques had lowest effectiveness, but highest embolism with the mixed thrombus. This was particularly striking when a stent retriever was used with the mixed thrombus
Spectral cardiac CT in acute stroke patients
No full textCardiac CT obtained in acute ischemic stroke patients can facilitate timely detection of cardiac sources of embolism and guide secondary prevention strategies. Spectral CT exploiting the simultaneous acquisition of separate higher-energy and lower-energy photon spectrum datasets has the potential to improve contrast between thrombi and cardiac structures. This study aimed to investigate the diagnostic value of spectral cardiac CT compared to conventional CT for the detection of cardiac thrombi in acute stroke patients. Patients with acute ischemic stroke undergoing spectral cardiac CT were retrospectively included. Conventional CT images, virtual 55 keV monoenergetic (monoE55), z-effective (zeff), and iodine density images were evaluated for the presence of thrombi. Diagnostic certainty was rated on a 5-point Likert scale. Contrast ratios were calculated for all reconstructions. 63 patients with 20 thrombi were included. Four thrombi were missed on conventional images but detected on spectral reconstructions. MonoE55 achieved the highest scores for diagnostic certainty. Contrast ratios were highest on iodine density images, followed by monoE55, conventional and zeff (p < 0.005). Spectral cardiac CT adds diagnostic benefit for the detection of intra-cardiac thrombi in acute ischemic stroke patients compared to conventional CT
Visualization of gadolinium transport across the blood-brain barrier along perivascular clearance pathways
No full textStandardization of a CT Protocol for Imaging Patients with Suspected COVID-19—A RACOON Project
No full textComputed tomography for the detection of myocardial hypoperfusion in acute myocardial infarction and the associated CT-to-catheter time
No full textAbstract Emergency computed tomography (CT) often does not allow for comprehensive coronary artery assessment. However, CT may reveal pathological myocardial hypoperfusion suggestive of acute myocardial infarction (AMI), especially in patients presenting with a different diagnostic hypothesis. CT hypoperfusion is known to be associated with myocardial infarction, however the diagnostic value of CT hypoperfusion for the detection of AMI is still not well evaluated. This was a single-centre retrospective study including patients who underwent invasive coronary angiography (ICA) due to suspected AMI based on incidental perfusion defects upon emergency CT imaging between 2018 and 2023. A total of 22 patients (mean age 66.3 ± 10.8 years, 11 female) were included in this analysis. The diagnosis of AMI was established in all cases leading to ICA. Culprit coronary artery lesions with an indication of percutaneous coronary intervention were detected in all patients who underwent ICA. Spearmann correlation for hypoperfused segments on CT imaging and the corresponding vascular territory upon ICA was significantly substantial (ρ = 0.73, p = < 0.001). The higher the number of affected myocardial segments, the faster ICA was initiated. Mean time between the suspicion of AMI on CT imaging and ICA was 196 (29–4044) minutes. Myocardial hypoperfusion on emergency CT imaging should be considered as AMI until proven otherwise, independent of the clinical scenario leading to performance of CT imaging and whether imaging was performed for the exclusion of non-cardiac pathologies. Early initiation of further diagnostic workup may potentially avoid delays to invasive treatment and reduce the CT-to-catheter-time. Our study explicitly underlines that myocardial hypoperfusion upon contrast enhanced CT imaging needs to be considered as sign of acute myocardial infarction and indicates targeted clinical workup to rule out this diagnosis and to shorten the timeframe from imaging diagnosis to interventional treatment
Cardiac CT in Large Vessel Occlusion Stroke for the Evaluation of Non-Thrombotic and Non-Atrial-Fibrillation-Related Embolic Causes
No full textBackground: The purpose of this study is the evaluation of imaging findings of acute-phase cardiac CT (cCT) in stroke patients with large vessel occlusion (LVO) to identify potential cardioembolic sources (CES) in patients without intracardiac thrombi and atrial fibrillation (AF). Material and Methods: This retrospective study included 315 patients with LVO who underwent cCT imaging in the acute stroke setting. The images were analysed for 15 imaging findings following the established minor and major cardioembolic risk factors. The final stroke aetiology was determined using the TOAST classification through interdisciplinary consensus following a thorough clinical evaluation. Multivariate regression analysis was performed to identify imaging findings associated with CES. Results: A cardioembolic aetiology was identified on cardiac CT in 211 cases (70%). After adjustment for AF and intracardiac thrombi, the multivariate regression analysis revealed significant associations with left ventricular dilation (adjusted odds-ratio (AOR) 32.4; 95% CI 3.0–349; p = 0.004), visible interatrial right-to-left shunt (AOR 30.8; 95% CI 2.7–341.3; p = 0.006), valve implants (AOR 24.5; 95% CI 2.2–270.9; p = 0.009), aortic arch atheroma grade > II (AOR 6.9; 95% CI 1.5–32.8; p = 0.015) and post-ischaemic myocardial scars (AOR 6.3, 95% CI 1.2–34.1; p = 0.032) as independent risk factors for a cardioembolic aetiology. The combined model achieved an area under the ROC curve of 0.83. Conclusions: In patients with LVO without AF and intracardiac thrombi as a cause, the presence of left ventricular dilatation, interatrial right-to-left shunts, valve implants, post-ischaemic myocardial scarring and advanced aortic arch atheroma (grade > 2) in particular is significantly associated with a cardioembolic cause of stroke and should be add-on evaluated in acute-phase cCT. Further investigations are warranted to confirm these associations
Disease- and stage-specific alterations of the oral and fecal microbiota in Alzheimer's disease
No full textMicrobial communities in the intestinal tract are suggested to impact the ethiopathogenesis of Alzheimer's disease (AD). The human microbiome might modulate neuroinflammatory processes and contribute to neurodegeneration in AD. However, the microbial compositions in patients with AD at different stages of the disease are still not fully characterized. We used 16S rRNA analyses to investigate the oral and fecal microbiota in patients with AD and mild cognitive impairment (MCI; n = 84), at-risk individuals (APOE4 carriers; n = 17), and healthy controls (n = 50) and investigated the relationship of microbial communities and disease-specific markers via multivariate- and network-based approaches. We found a slightly decreased diversity in the fecal microbiota of patients with AD (average Chao1 diversity for AD = 212 [SD = 66]; for controls = 215 [SD = 55]) and identified differences in bacterial abundances including Bacteroidetes, Ruminococcus, Sutterella, and Porphyromonadaceae. The diversity in the oral microbiota was increased in patients with AD and at-risk individuals (average Chao1 diversity for AD = 174 [SD = 60], for at-risk group = 195 [SD = 49]). Gram-negative proinflammatory bacteria including Haemophilus, Neisseria, Actinobacillus, and Porphyromonas were dominant oral bacteria in patients with AD and MCI and the abundance correlated with the cerebrospinal fluid biomarker. Taken together, we observed a strong shift in the fecal and the oral communities of patients with AD already prominent in prodromal and, in case of the oral microbiota, in at-risk stages. This indicates stage-dependent alterations in oral and fecal microbiota in AD which may contribute to the pathogenesis via a facilitated intestinal and systemic inflammation leading to neuroinflammation and neurodegeneration
Standardization of a CT protocol for imaging patients with suspected COVID-19: a RACOON project
No full textCT protocols that diagnose COVID-19 vary in regard to the associated radiation exposure and the desired image quality (IQ). This study aims to evaluate CT protocols of hospitals participating in the RACOON (Radiological Cooperative Network) project, consolidating CT protocols to provide recommendations and strategies for future pandemics. In this retrospective study, CT acquisitions of COVID-19 patients scanned between March 2020 and October 2020 (RACOON phase 1) were included, and all non-contrast protocols were evaluated. For this purpose, CT protocol parameters, IQ ratings, radiation exposure (CTDIvol), and central patient diameters were sampled. Eventually, the data from 14 sites and 534 CT acquisitions were analyzed. IQ was rated good for 81% of the evaluated examinations. Motion, beam-hardening artefacts, or image noise were reasons for a suboptimal IQ. The tube potential ranged between 80 and 140 kVp, with the majority between 100 and 120 kVp. CTDIvol was 3.7 ± 3.4 mGy. Most healthcare facilities included did not have a specific non-contrast CT protocol. Furthermore, CT protocols for chest imaging varied in their settings and radiation exposure. In future, it will be necessary to make recommendations regarding the required IQ and protocol parameters for the majority of CT scanners to enable comparable IQ as well as radiation exposure for different sites but identical diagnostic questions
