- MeSH
- artefakty * MeSH
- lidé MeSH
- rentgendiagnostika zubní * MeSH
- senioři MeSH
- Check Tag
- lidé MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
The pressure reactivity index (PRx) is a parameter for the assessment of cerebrovascular autoregulation, but its calculation is affected by artifacts in the source biosignals-intracranial pressure (ICP) and arterial blood pressure. We sought to describe the most common short-duration artifacts and their effect on the PRx. A retrospective analysis of 935 h of multimodal monitoring data was conducted, and five types of artifacts, characterized by their shape, duration, and amplitude, were identified: rectangular, fast impulse, isoline drift, saw tooth, and constant ICP value. Subsequently, all types of artifacts were mathematically modeled and inserted into undisturbed segments of biosignals. Fast impulse, the most common artifact, did not alter the PRx index significantly when inserted into one or both signals. Artifacts present in one signal exceeded the threshold PRx in less than 5% of samples, except for isoline drift. Compared to that, the shortest rectangular artifact inserted into both signals changed PRx to a value above the set threshold in 55.4% of cases. Our analysis shows that the effect of individual artifacts on the PRx index is variable, depending on their occurrence in one or both signals, duration, and shape. This different effect suggests that potentially not all artifacts need to be removed.
Úvod: Hrudní pás umožňuje pořídit 1svodový EKG záznam. Získaná data byla validována pro měření srdeční frekvence a rovněž i pro detekci fibrilace síní díky srovnání s krátkými EKG záznamy z holterovského EKG měření u selektovaných pacientů. Zatím ale nebyla ověřena možnost vyhodnocení dlouhých EKG záznamů u neselektovaných kardiologických pacientů se širokým spektrem srdečních chorob. Metodologie a výsledky: Do studie bylo zařazeno 54 hospitalizovaných a 53 ambulantních pacientů a 54 zdravých kontrol (n = 161 celkově). U všech účastníků studie byl pomocí hrudního pásu Polar H10 pořízen 1-2hodinový EKG záznam (celkově 1 153 229 úderů srdce; průměrná srdeční frekvence 76,6/min; sinusový rytmus u 86,3 %, fibrilace síní zjištěna u 13,7 %; dokumentováno 0,46 % síňových extrasystol a 0,49 % komorových extrasystol). Z výše uvedeného počtu 1 153 229 srdečních tepů jich 1 128 319 bylo hodnoceno lékařem jako snadno interpretovatelných. Celkově tak bylo 2,16 % záznamu vyhodnoceno jako obtížně interpretovatelný nebo neinterpretovatelný šum (A: 2,31 %; B: 1,95 %; C: 2,20 %). Z EKG záznamu z hrudního pásu lékař při srovnání s 12svodovým EKG záznamem spolehlivě určil základní srdeční rytmus u většiny účastníků (u 51/54 [94,4 %] hospitalizovaných pacientů a u 100 % ambulantních pacientů a zdravých kontrol). U tří jedinců byl základní rytmus na EKG vyhodnocen jako nejasný. U všech tří byly všechny komplexy QRS stimulované. U hospitalizovaných pacientů byl EKG záznam z hrudního pásu zobrazený v reálném čase na mobilním telefonu srovnatelný s EKG záznamem z telemetrického monitorování (shoda v 53 z 54 případů; 98,1 %). Závěr: EKG záznam z hrudního pásu, pořízený u hospitalizovaných i ambulantních pacientů s různými typy poruch srdečního rytmu, stejně tak jako u zdravých kontrol, lze v každodenní praxi použít pro zhodnocení základního srdečního rytmu, záchyt fibrilace síní i extrasystol, a to při minimálním procentu obtížně hodnotitelných záznamů. Opatrnosti je třeba při interpretaci EKG záznamu u pacientů se stimulovaným rytmem a u pacientů s flutterem síní. Hrudní pás je tak možno použít pro kontinuální EKG monitorování, hodnocení srdečního rytmu i screening fibrilace síní.
Background: The chest-belt can be used to obtain a 1-lead ECG. Data from it have been validated for the determination of heart rate and for the possibility to detect atrial fibrillation (AF) compared to ECG-Holter on a short ECG recording in selected patients. However, validation of the possibility to evaluate long ECG recordings in patients with a wide range of heart diseases has not yet been performed. Methodology and results: 54 hospitalized patients, 53 outpatients and 54 healthy controls were enrolled in the study (n = 161 in total). Using a Polar H10 chest-belt, 1-2 hours of ECG were recorded in all patients (1 153 229 heartbeats, average heart rate 76.6/min, 86.3% in sinus rhythm, 13.7% with atrial fibrillation, 0.46% atrial premature beats, 0.49% ventricular premature beats). The presence of noise was 2.16% (A: 2.31%; B: 1.95%; C: 2.20%). 1 128 319 /1 153 229 were evaluated as easy to interpret. Using ECG from the belt, the basic rhythm was reliably determined by the physician in majority of patients (51/54, 94.4% in hospitalized patients; in 100% of outpatients and healthy controls) when compared to 12-lead ECG. 3 cases were evaluated as unclear; in all of these cases, all QRS complexes were stimulated by a pacemaker. In hospitalized patients, real-time ECG from the belt was comparable to telemetric ECG monitoring (match in 53/54, 98.1%). Conclusion: The ECG obtained from the chest-belt in hospitalized patients and outpatients with a wide range of cardiovascular diseases, as well as in healthy individuals, is usable in real practice for evaluation of baseline rhythm, atrial fibrillation and premature contractions with a minimal proportion of difficulties to interpret recordings due to artefacts. Caution should be exercised in interpretation of the ECG in patients with stimulated rhythm and in patients with atrial flutter. The chest belt can be used as a means for continuous monitoring of ECG, evaluation of rhythm and screening of atrial fibrillation.
The analysis and segmentation of articular cartilage magnetic resonance (MR) images belongs to one of the most commonly routine tasks in diagnostics of the musculoskeletal system of the knee area. Conventional regional segmentation methods, which are based either on the histogram partitioning (e.g., Otsu method) or clustering methods (e.g., K-means), have been frequently used for the task of regional segmentation. Such methods are well known as fast and well working in the environment, where cartilage image features are reliably recognizable. The well-known fact is that the performance of these methods is prone to the image noise and artefacts. In this context, regional segmentation strategies, driven by either genetic algorithms or selected evolutionary computing strategies, have the potential to overcome these traditional methods such as Otsu thresholding or K-means in the context of their performance. These optimization strategies consecutively generate a pyramid of a possible set of histogram thresholds, of which the quality is evaluated by using the fitness function based on Kapur's entropy maximization to find the most optimal combination of thresholds for articular cartilage segmentation. On the other hand, such optimization strategies are often computationally demanding, which is a limitation of using such methods for a stack of MR images. In this study, we publish a comprehensive analysis of the optimization methods based on fuzzy soft segmentation, driven by artificial bee colony (ABC), particle swarm optimization (PSO), Darwinian particle swarm optimization (DPSO), and a genetic algorithm for an optimal thresholding selection against the routine segmentations Otsu and K-means for analysis and the features extraction of articular cartilage from MR images. This study objectively analyzes the performance of the segmentation strategies upon variable noise with dynamic intensities to report a segmentation's robustness in various image conditions for a various number of segmentation classes (4, 7, and 10), cartilage features (area, perimeter, and skeleton) extraction preciseness against the routine segmentation strategies, and lastly the computing time, which represents an important factor of segmentation performance. We use the same settings on individual optimization strategies: 100 iterations and 50 population. This study suggests that the combination of fuzzy thresholding with an ABC algorithm gives the best performance in the comparison with other methods as from the view of the segmentation influence of additive dynamic noise influence, also for cartilage features extraction. On the other hand, using genetic algorithms for cartilage segmentation in some cases does not give a good performance. In most cases, the analyzed optimization strategies significantly overcome the routine segmentation methods except for the computing time, which is normally lower for the routine algorithms. We also publish statistical tests of significance, showing differences in the performance of individual optimization strategies against Otsu and K-means method. Lastly, as a part of this study, we publish a software environment, integrating all the methods from this study.
While various QRS detection and classification methods were developed in the past, the Holter ECG data acquired during daily activities by wearable devices represent new challenges such as increased noise and artefacts due to patient movements. Here, we present a deep-learning model to detect and classify QRS complexes in single-lead Holter ECG. We introduce a novel approach, delivering QRS detection and classification in one inference step. We used a private dataset (12,111 Holter ECG recordings, length of 30 s) for training, validation, and testing the method. Twelve public databases were used to further test method performance. We built a software tool to rapidly annotate QRS complexes in a private dataset, and we annotated 619,681 QRS complexes. The standardised and down-sampled ECG signal forms a 30-s long input for the deep-learning model. The model consists of five ResNet blocks and a gated recurrent unit layer. The model's output is a 30-s long 4-channel probability vector (no-QRS, normal QRS, premature ventricular contraction, premature atrial contraction). Output probabilities are post-processed to receive predicted QRS annotation marks. For the QRS detection task, the proposed method achieved the F1 score of 0.99 on the private test set. An overall mean F1 cross-database score through twelve external public databases was 0.96 ± 0.06. In terms of QRS classification, the presented method showed micro and macro F1 scores of 0.96 and 0.74 on the private test set, respectively. Cross-database results using four external public datasets showed micro and macro F1 scores of 0.95 ± 0.03 and 0.73 ± 0.06, respectively. Presented results showed that QRS detection and classification could be reliably computed in one inference step. The cross-database tests showed higher overall QRS detection performance than any of compared methods.
- MeSH
- algoritmy MeSH
- artefakty MeSH
- elektrokardiografie ambulantní metody MeSH
- elektrokardiografie metody MeSH
- komorové extrasystoly * MeSH
- lidé MeSH
- nositelná elektronika * MeSH
- počítačové zpracování signálu MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Frozen aqueous solutions are an important subject of study in numerous scientific branches including the pharmaceutical and food industry, atmospheric chemistry, biology, and medicine. Here, we present an advanced environmental scanning electron microscope methodology for research of ice samples at environmentally relevant subzero temperatures, thus under conditions in which it is extremely challenging to maintain the thermodynamic equilibrium of the specimen. The methodology opens possibilities to observe intact ice samples at close to natural conditions. Based on the results of ANSYS software simulations of the surface temperature of a frozen sample, and knowledge of the partial pressure of water vapor in the gas mixture near the sample, we monitored static ice samples over several minutes. We also discuss possible artifacts that can arise from unwanted surface ice formation on, or ice sublimation from, the sample, as a consequence of shifting conditions away from thermodynamic equilibrium in the specimen chamber. To demonstrate the applicability of the methodology, we characterized how the true morphology of ice spheres containing salt changed upon aging and the morphology of ice spheres containing bovine serum albumin. After combining static observations with the dynamic process of ice sublimation from the sample, we can attain images with nanometer resolution.
BACKGROUND: The Fetal Imaging Taskforce was established in 2018 by the European Society of Paediatric Radiology. The first survey on European practice of fetal imaging published in 2020 revealed that 30% of fetal magnetic resonance imaging (MRI) is performed at 3 tesla (T). The purpose of this second survey was to identify the impact of 3-T fetal MRI with an emphasis on image quality, diagnostic yield, and technical challenges and artifacts at higher field strengths. OBJECTIVE: To describe the prenatal imaging practice at 3-T MRI units in various centres in Europe and to prepare recommendations on behalf of the Fetal Imaging Taskforce. MATERIALS AND METHODS: A survey was sent to all members performing 3-T fetal MRI. Questions included practitioner experience, magnet brand, protocols, counselling, artifacts and benefits of imaging at higher field strengths. RESULTS: Twenty-seven centres replied and reported improved spatial resolution and improved signal-to-noise ratio when performing fetal MRI at 3 T. Shading and banding artifacts and susceptibility to motion artifacts were common problems identified by practitioners at the higher field strength. For all neurological indications, practitioners reported a benefit of imaging at 3 T, most marked for posterior fossa evaluation and parenchymal lesions. CONCLUSION: The use of 3-T magnets in fetal MRI has improved the availability and quality of advanced imaging sequences and allowed for better anatomical evaluation. There remain significant challenges to minimize the impact of artifacts on image quality. This paper includes guidelines for clinical practice and imaging at 3 T.
Programmed death ligand 1 (PD-L1) immunohistochemistry (IHC) is accepted as a predictive biomarker for the selection of immune checkpoint inhibitors. We evaluated the staining quality and estimation of the tumor proportion score (TPS) in non-small-cell lung cancer during two external quality assessment (EQA) schemes by the European Society of Pathology. Participants received two tissue micro-arrays with three (2017) and four (2018) cases for PD-L1 IHC and a positive tonsil control, for staining by their routine protocol. After the participants returned stained slides to the EQA coordination center, three pathologists assessed each slide and awarded an expert staining score from 1 to 5 points based on the staining concordance. Expert scores significantly (p < 0.01) improved between EQA schemes from 3.8 (n = 67) to 4.3 (n = 74) on 5 points. Participants used 32 different protocols: the majority applied the 22C3 (56.7%) (Dako), SP263 (19.1%) (Ventana), and E1L3N (Cell Signaling) (7.1%) clones. Staining artifacts consisted mainly of very weak or weak antigen demonstration (63.0%) or excessive background staining (19.8%). Participants using CE-IVD kits reached a higher score compared with those using laboratory-developed tests (LDTs) (p < 0.05), mainly attributed to a better concordance of SP263. The TPS was under- and over-estimated in 20/423 (4.7%) and 24/423 (5.7%) cases, respectively, correlating to a lower expert score. Additional research is needed on the concordance of less common protocols, and on reasons for lower LDT concordance. Laboratories should carefully validate all test methods and regularly verify their performance. EQA participation should focus on both staining concordance and interpretation of PD-L1 IHC.
- MeSH
- antigeny CD274 analýza antagonisté a inhibitory MeSH
- artefakty MeSH
- čipová analýza tkání MeSH
- imunohistochemie * MeSH
- inhibitory kontrolních bodů terapeutické užití MeSH
- klinické rozhodování MeSH
- lidé MeSH
- nádorové biomarkery analýza antagonisté a inhibitory MeSH
- nádory plic farmakoterapie imunologie patologie MeSH
- nemalobuněčný karcinom plic farmakoterapie imunologie patologie MeSH
- odchylka pozorovatele MeSH
- prediktivní hodnota testů MeSH
- reprodukovatelnost výsledků MeSH
- testování odbornosti laboratoří MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- Geografické názvy
- Evropa MeSH
