European radiology
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Randomized Controlled Trial Comparative Study
Dose comparison of single versus double dose in contrast-enhanced magnetic resonance angiography of the renal arteries: intra-individual cross-over blinded trial using Gd-DTPA.
This study was planned as an open-label, single-centre trial with blinded evaluations by two independent radiologists, aimed at the intra-individual comparison of single-dose and double-dose Gd-DTPA-enhanced MRA in the renal arterial territory. Ten healthy volunteers were included in the study. Renal MRAs were carried out on a clinical 1.5-T MR system using a body phased-array coil. ⋯ Signal intensity, SNR and CNR were significantly higher for the double-dose group. Our results demonstrate that while a double dose of contrast agent increases SNR, it does not lead to further improvement in visual and perceptual image quality. A single dosage of approximately 0.1 mmol/kg bw Gd-DTPA may be the preferable dosage to demonstrate the renal arteries.
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Interpretation of brain images from older patients requires knowledge of changes that occur with healthy ageing. We constructed and tested a reference template for older subjects. We used MR images from normal subjects aged 65-70 and 75-80 to generate average age-specific images. ⋯ Reference templates of the brain at older ages can "calibrate" radiology reporting. They could also be useful for research into ageing and related conditions. Larger numbers of examinations from more diverse populations and at different ages are required to increase the versatility of these templates.
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Comparative Study
Use of dynamic CT in acute respiratory distress syndrome (ARDS) with comparison of positive and negative pressure ventilation.
Negative pressure ventilation via an external device ('iron lung') has the potential to provide better oxygenation with reduced barotrauma in patients with ARDS. This study was designed to see if oxygenation differences between positive and negative ventilation could be explained by CT. Six anaesthetized rabbits had ARDS induced by repeated saline lavage. ⋯ Aeration differences were not significant at end-inspiration. Dynamic CT can show differences in lung aeration between positive and negative ventilation in ARDS. These differences would not be appreciated if only static breath-hold CT was used.
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To characterize the heartbeat-related distension of dissected and non-dissected thoracic aortic segments in chronic aortic dissection type b (CADB) ECG-gated computed tomography angiography was performed in ten CADB patients. For 20 time points of the R-R interval, multiplanar reformations were taken at non-dissected (A, B) and dissected (C) aorta: ascending aorta (A), aortic vertex (B), 10 cm distal to left subclavian (Ct, true channel; Cf, false channel). Relative amplitudes of aortic area and major and minor axis diameter changes were quantified. ⋯ Minor axis diameter amplitudes were significantly the greatest at Ct (p < 0.05). In CADB, the heartbeat-related distension of aortic area and diameter is evenly distributed over the non-dissected aortic arch. As a result from different blood flow properties, there are significantly greater conformational changes in the true channel of the dissected aorta.
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The aim of the study was to evaluate radiation exposure of a chest pain protocol with ECG-gated dual-source computed tomography (DSCT). An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a dual-source computed tomography system with a standard protocol for chest pain evaluation (120 kV, 320 mAs/rot) with different simulated heart rates (HRs). ⋯ The average radiation dose of a standard chest CT examination is about 36.5% that of a CT examination performed for chest pain. Using DSCT, the evaluated chest pain protocol revealed a higher radiation exposure compared with standard chest CT. Furthermore, HRs markedly influenced the dose exposure when using the ECG-gated chest pain protocol.