1,720,992 research outputs found
Head-to-head comparison of prospectively triggered vs retrospectively gated coronary computed tomography angiography: Meta-analysis of diagnostic accuracy, image quality, and radiation dose
No full textBackground In coronary computed tomography (CT) angiography (CTA) prospective electrocardiography triggering requires less radiation dose than retrospective electrocardiography gating but provides less cardiac phases for interpretation. This meta-analysis presents a concise and comprehensive head-to-head comparison of image quality, diagnostic accuracy, and radiation dose of prospectively triggered coronary CTA vs retrospectively gated CTA in patients with suspected or known coronary artery disease (CAD). Methods In patients with CAD and without tachyarrhythmia, eligible studies (selected from 4 databases) compared prospectively triggered vs retrospectively gated CTA (performed with >= 64-slice CT or dual-source CT) in 2 groups having approximately similar patient characteristics, scored CTA image quality, and/or assessed how accurately CTA diagnoses >= 50% coronary stenoses compared with catheter angiography and reported the radiation dose. The data were meta-analyzed by random-effects models, with CIs provided in the text. Results Among 3,330 patients from 20 included studies, 91.3% of CTAs (segments: 97.8%) had diagnostic quality with prospective triggering and 93.3% of CTAs (segments: 98.4%) with retrospective gating (P > .05). Among 664 patients from 5 studies, the pooled sensitivity/specificity of diagnostic CTAs was 98.7%/91.3% (segment level: 91.3%/97.7%) with prospective triggering and 96.9%/95.8% (segment level: 93.1%/97.6%) with retrospective gating (P > .05). The pooled effective dose was 3.5 mSv with prospective triggering and thus, by a factor of 3.5, lower than the pooled effective dose of retrospective gating, which was 12.3 mSv (P < .01). Conclusions In patients with CAD and without tachyarrhythmia, prospectively triggered coronary CTA provides image quality and diagnostic accuracy comparable with retrospectively gated CTA, but at a much lower radiation dose. (Am Heart J 2013;165:154-163.e3.
Effects of age on negative BOLD signal changes in the primary somatosensory cortex
No full textIn addition to a contralateral activation of the primary and secondary somatosensory cortices, peripheral sensory stimulation has been shown to elicit responses in the ipsilateral primary somatosensory cortex (SI). In particular, evidence is accumulating that processes of interhemispheric inhibition as depicted by negative blood oxygenation level dependent (BOLD) signal changes are part of somatosensory processes. The aim of the study was to analyze age-related differences in patterns of cerebral activation in the somatosensory system in general and processes of interhemispheric inhibition in particular. For this, a functional magnetic resonance imaging (fMRI) study was performed including 14 younger (mean age 23.3 0.9 years) and 13 healthy older participants (mean age 73.2 +/- 8.3 years). All subjects were scanned during peripheral electrical median nerve stimulation (40 Hz) to obtain BOLD responses in the somatosensory system. Moreover, the individual current perception threshold (CPT) as a quantitative measure of sensory function was determined in a separate psychophysical testing. Significant increases in BOLD signal across the entire group could be measured within the contralateral SI, in the bilateral secondary somatosensory cortex (SII), the contralateral supplementary motor area and the insula. Negative BOLD signal changes were delineated in ipsilateral SI/MI as well as in the ipsilateral thalamus and basal ganglia. After comparing the two groups, only the cortical deactivation in ipsilateral SI in the early stimulation phase as well as the activation in contralateral SI and SII in the late stimulation block remained as statistically significant differences between the two groups. The psychophysical experiments yielded a significant age-dependent effect of CPT change with less difference in the older group which is in line with the significantly smaller alterations in maximal BOLD signal change in the contra- and ipsilateral SI found between the two groups. Healthy aging seems to be associated with a decrease in intracerebral inhibition as reflected by smaller negative BOLD signal changes during fMRI tasks. This finding could constitute an important link between age-related neurophysiological changes and behavioral alterations in humans. (C) 2012 Elsevier Inc. All rights reserved
Current role and future potential of magnetic resonance cholangiopancreatography with an emphasis on incidental findings
No full textPurpose: Aim of this study was to investigate the incidence of relevant biliary and extrabiliary findings in patients undergoing magnetic resonance cholangiopancreatography (MRCP). Materials and Methods: Three hundred eighty-four patients underwent 1.5-Tesla MRCP, and relevant biliary and extra-biliary findings were identified. Results: Four hundred twenty-two biliary findings were identified in 384 patients (75%; 1.1 per patient). Ninety-five patients were free of any relevant biliary finding (25%). Incidental extrabiliaiy findings were observed in 763 patients (1.98/patient). Conclusion: Most of the findings can be diagnosed by MRCP, while others require further examination. Interdisciplinary involvement is recommended to optimize clinical categorization, management, and treatment of these incidental findings. (C) 2014 Elsevier Inc. All rights reserved
Accelerometer and Gyroscope Based Gait Analysis Using Spectral Analysis of Patients with Osteoarthritis of the Knee
Full text link[Purpose] A wide variety of accelerometer tools are used to estimate human movement, but there are no adequate data relating to gait symmetry parameters in the context of knee osteoarthritis. This study's purpose was to evaluate a 3D-kinematic system using body-mounted sensors (gyroscopes and accelerometers) on the trunk and limbs. This is the first study to use spectral analysis for data post processing. [Subjects] Twelve patients with unilateral knee osteoarthritis (OA) (10 male) and seven age-matched controls (6 male) were studied. [Methods] Measurements with 3-D accelerometers and gyroscopes were compared to video analysis with marker positions tracked by a six-camera optoelectronic system (VICON 460, Oxford Metrics). Data were recorded using the 3D-kinematic system. [Results] The results of both gait analysis systems were significantly correlated. Five parameters were significantly different between the knee OA and control groups. To overcome time spent in expensive post-processing routines, spectral analysis was performed for fast differentiation between normal gait and pathological gait signals using the 3D-kinematic system. [Conclusions] The 3D-kinematic system is objective, inexpensive, accurate and portable, and allows long-term recordings in clinical, sport as well as ergonomic or functional capacity evaluation (FCE) settings. For fast post-processing, spectral analysis of the recorded data is recommended
Remote magnetic navigation for circumferential pulmonary vein ablation: single-catheter technique or additional use of a circular mapping catheter?
No full textRemote magnetic navigation (RMN) is utilized for catheter guidance during pulmonary vein ablation (PVA). We aimed to determine whether the additional use of a circular mapping catheter (CMC) influences efficacy and outcome of RMN-guided PVA. A total of 80 consecutive subjects (65 % male, age 62 +/- 9 years) underwent circumferential PVA with a 3D mapping system and an RMN-guided irrigated catheter. Procedural endpoint was complete PV isolation (PVI), total radiofrequency (RF) time > 60 min, or procedure duration > 5 h. PVI was defined as an entrance and/or exit block, diagnosed with a CMC within the PV ostium or by pacing via the roving RMN-guided catheter (single-catheter technique). Prolonged Holter monitoring after 3 and 6 months was used to detect atrial tachyarrhythmia (AT/AF) recurrences. Complete PVI was achieved in 56 % (45/80) of all subjects (isolated PVs per patient, 3.1 +/- 1.2; RF time, 56.3 +/- 17.2 min; procedure duration, 3.8 +/- 0.8 h). Prospective validation of the single-catheter technique for diagnosing PVI demonstrated high concordance (94 %) with blinded CMC results. CMC use in first-time PVA was associated with similar total RF and procedure times but higher PV isolation rate. Upon multivariate analysis, CMC use, female gender, left PV, smaller PV ostium and repeat PVA predicted PVI during RMN-guided ablation. Persistent AF and mitral regurgitation at baseline and the number of non-isolated PVs predicted AT/AF recurrence during follow-up. Concomitant CMC use for first-time, RMN-guided PVA is associated with similar procedure duration but higher PV isolation rates as compared to a single-catheter approach. Since the number of isolated PVs predicts freedom from AT/AF, CMC utilization appears advisable for first-time, RMN-guided PVA
Giant bypass aneurysm, a cause of suspected cardiac mass
Full text linkIntroduction: A 66-years old man suffering from coronary artery disease appeared without symptoms for routine follow-up in our clinic. Case description: The echocardiogram revealed a tumorous mass of the right atrium and right ventricle. In the past, coronary revascularization with venous grafts of the right coronary artery and circumflex artery as well as internal mammaria graft to the left anterior descending artery was performed 20 years before. The general clinicians presented the case to the surgeons and it was decided to perform cardiac MRI as a preoperative diagnostic modality. Discussion and evaluation: Following cardiac magnetic resonance imaging (MRI) showed a mass in the pericardium in the right atrioventricular groove with thrombotic material. Due to the MRI the patient underwent coronary angiography to confirm an aneurysm. Conclusions: The learning points from this case are that cardiac MRI is a very useful tool for further evaluation of suspected cardiac masses and should be performed for further characterization
Quantitative Phasenkontrast-MRT der Aorta in Echtzeit: radiales FLASH mit Unterabtastung und nichtlinearer inverser Rekonstruktion
No full textFragestellung: Quantitative geschwindigkeitskodierte Phasenkontrast-MRT des Blutflusses beruht in der Regel auf einer EKG-synchronisierten Datenaufnahme von multiplen Herzschlägen, aus der ein durchschnittlicher Herzzyklus interpoliert wird. Methode: Wir stellen eine neue Methode zur Durchführung einer Phasenkontrast-MRT in Echtzeit vor, die flusskodierte Gradienten mit hochgradiger Unterabtastung (radiales FLASH) und phasensensitiver Bildrekonstruktion durch regularisierte, nichtlineare Inversion kombiniert. Ergebnis: Mit dieser Technik wurde eine Echtzeitsequenz mit folgenden Parametern realisiert: 1,8mm Bild-Auflösung, 6mm Schichtdicke und 24ms Messzeit in einer 3-Tesla-MRT Umgebung (TIM Trio, Siemens, VB17; TR/TE=3,03/2,56ms, Anregung 10°, 7 radiale Speichen pro Bild). Dementsprechend erreichen Phasenkontrastkarten und korrespondierende Geschwindigkeitsprofile eine zeitliche Auflösung von realen 42,5ms. Die Sequenz wurde zunächst im Modell validiert. Danach wurde die Echtzeit-Flussmessung als „through-plane“ Messung in der Aorta ascendens bei 6 gesunden Probanden durchgeführt. Dabei wurden jeweils mindestens 20 konsekutive Herzschläge dokumentiert und ausgewertet. Schlussfolgerung: Ermittelte Spitzengeschwindigkeiten, Schlagvolumina, Flussraten und jeweilige Abweichungen stehen im Einklang mit vorherigen Studienergebnissen
Diagnosing flow residuals in coiled cerebral aneurysms by MR angiography: meta-analysis
Full text linkThis meta-analysis summarizes the accuracy of magnetic resonance angiography (MRA) for diagnosing residuals in coiled cerebral aneurysms by using the threefold Roy classification (residuals: none, neck, or sac). Four databases were searched from 2000 to June 2013 for eligible studies that compared MRA to digital subtraction angiography (DSA) and reported 3 x 3 count data of threefold Roy classification, or a reduced scheme of 2 x 2 count data. Bivariate and trivariate Bayesian random-effects models were used for meta-analysis. Among 27 included studies (2,119 coiled aneurysms in 1,809 patients) the average prevalence of DSA-confirmed sac residuals was 18.2 % (range 0-43 %). The pooled sensitivity was 88.0 % (95 % CI 81.4-94.0) and specificity was 97.2 % (94.6-99.0 %) for assessing sac residuals by MRA. In the trivariate meta-analysis, a "sac residual" finding at MRA had a high positive likelihood ratio of 28.2 (14.0-79.0). A "neck residual" finding had a moderate negative likelihood ratio of 0.246 (0.111-0.426), and the MRA finding of "no residual" had a good negative likelihood ratio of 0.044 (0.013-0.096). Subgroup analyses identified no significant influence of covariates on diagnostic accuracy (P > 0.05). In conclusion, in coiled cerebral aneurysms MRA with application of the threefold Roy classification is well suited for detecting or excluding sac residuals that might require retreatment
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