To improve imaging quality and to reduce contrast dose and radiation exposure, an adaptive bolus chasing CT angiography was proposed so that the bolus peak position and the imaging aperture can be synchronized. The performance of the proposed adaptive bolus chasing CT angiography was experimentally evaluated based on the actual bolus dynamics. The experimental results show that the controlled t...

Introduction In electron beam therapy bolus is often used to conform as closely as possible to the target volume while avoiding critical structures in the depth. In most cases a flexible bolus can cover the skin without air gap. However, under certain conditions it is difficult –or even not possible– to avoid air gaps between bolus and patient without reducing treatment quality. In a special cl...

Introduction: Accurate measurement of the arterial input function (AIF), essential for quantitative dynamic contrast-enhanced (DCE) MRI, is challenging due to the rapidly-changing high concentration of contrast agent during a bolus injection, particularly during the first pass peak. Temporal undersampling, inflow of unsaturated spins and signal saturation all have the potential to corrupt the m...

BACKGROUND MR techniques have been very powerful in providing indicators of tissue perfusion, particularly in studies of cerebral ischemia. There is considerable interest in performing absolute perfusion measurements, with the aim of improving the characterization of tissue "at risk" of stroke. However, some important caveats relating to absolute measurements need to be taken into account. The ...

Introduction Present methods to image microvascular flow involve mainly the intravenous administration of a bolus injection from a paramagnetic contrast followed by the rapid, time-resolved, MR imaging of the kinetics of its first pass through the microvasculature of the imaged slice . This approach relies both on the chemical nature of the contrast agent used and on the inherent properties of ...

Background and Aims: During Cesarean section, hypotension occurs in the most of parturients, following spinal anesthesia. This prospective observational study was undertaken to determine efficacy two different Bolus Doses Phenylephrine for Prevention Spinal-Induced Hypotension during Section.
 Materials Methods: A total 120 parturients undergoing cesarean section were divided into groups g...

PURPOSE The goal of this study was to introduce a new noncontrast enhanced 4D dynamic MR angiography (dMRA) technique termed multibolus TrueFISP-based spin tagging with alternating radiofrequency (TrueSTAR). METHODS Multibolus TrueFISP-based spin tagging with alternating radiofrequency was developed by taking advantage of the phenomenon that the steady-state signal of TrueFISP is minimally di...

Propofol has been established as a reliable method for sedation in flexible bronchoscopy. There are no data comparing propofol administered as intravenous boluses versus continuous infusion. 702 consecutive patients undergoing flexible bronchoscopy were randomly allocated to receive intravenous propofol using either an intermittent bolus technique or a continuous infusion. The primary end-point...