Ideal Technique (ideal + technique)

Distribution by Scientific Domains

Selected Abstracts

Multiecho reconstruction for simultaneous water-fat decomposition and T2* estimation,

Huanzhou Yu PhD
Abstract Purpose To describe and demonstrate the feasibility of a novel multiecho reconstruction technique that achieves simultaneous water-fat decomposition and T2* estimation. The method removes interference of water-fat separation with iron-induced T2* effects and therefore has potential for the simultaneous characterization of hepatic steatosis (fatty infiltration) and iron overload. Materials and Methods The algorithm called "T2*-IDEAL" is based on the IDEAL water-fat decomposition method. A novel "complex field map" construct is used to estimate both R2* (1/T2*) and local B0 field inhomogeneities using an iterative least-squares estimation method. Water and fat are then decomposed from source images that are corrected for both T2* and B0 field inhomogeneity. Results It was found that a six-echo multiecho acquisition using the shortest possible echo times achieves an excellent balance of short scan and reliable R2* measurement. Phantom experiments demonstrate the feasibility with high accuracy in R2* measurement. Promising preliminary in vivo results are also shown. Conclusion The T2*-IDEAL technique has potential applications in imaging of diffuse liver disease for evaluation of both hepatic steatosis and iron overload in a single breath-hold. J. Magn. Reson. Imaging 2007;26:1153,1161. 2007 Wiley-Liss, Inc. [source]

HR-MAS NMR spectroscopy in the characterization of human tissues: Application to healthy gastric mucosa

Luisa Schenetti
Abstract The HR-MAS is an ideal technique for the investigation of intact tissue specimens (10,50 mg) and permits the obtainment of spectra with a resolution comparable to that observed in solution in a time that does not exceed a half of an hour for a routine analysis. The potentialities of HR-MAS NMR spectroscopy in the identification of the metabolites characterizing the healthy gastric mucosa are here presented. The direct inspection of the 1D 1H NMR spectra enables only few metabolites to be confidently assigned, and the use of selected 2D experiments strongly amplify the analytical effectiveness of the technique. 2006 Wiley Periodicals, Inc. Concepts Magn Reson Part A 28A: 430,443, 2006 [source]

Iron K -edge anomalous small-angle X-ray scattering at 15-ID-D at the Advanced Photon Source

Nigel Kirby
Small-angle X-ray scattering (SAXS) is an ideal technique for characterizing inorganic nanoparticles in biological specimens large enough to be representative of tissues. As tissues consist of complex mixtures of structures, identifying particular structural features from single-wavelength scattering data can be problematic. Synchrotron SAXS can supply element-specific structural information in complex samples, using anomalous scattering close to absorption edges. Anomalous dispersion is a secondary effect that produces relatively subtle changes in scattering patterns. In order to utilize this effect for anomalous SAXS analysis, stringent control of instrument performance is required. This work outlines the development of high-quality data collection and processing strategies for Fe K -edge anomalous SAXS on the ChemMatCARS beamline at the Advanced Photon Source (APS), Chicago, with an emphasis on intensity normalization. The methods reported here were developed during a study of iron-loaded mammal tissues, but could equally well be applied to other complex specimens. [source]

Noncontact photo-acoustic defect detection in drug tablets

Ivin Varghese
Abstract Quality assurance monitoring is of great importance in the pharmaceutical industry for the reason that if defects such as coating layer irregularities, internal cracks, and delamination are present in a drug tablet, the desired dose delivery and bioavailability can be compromised. The U.S. Food and Drug Administration (FDA) established the Process Analytical Technology (PAT) initiative, in order to ensure efficient quality monitoring at each stage of the manufacturing process by the integration of analysis systems into the evaluation procedure. Improving consistency and predictability of tablet action by improving quality and uniformity of tablet coatings as well as ensuring core integrity is required. An ideal technique for quality monitoring would be noninvasive, nondestructive, have a short measurement time, intrinsically safe, and relatively inexpensive. In the proposed acoustic system, a pulsed laser is utilized to generate noncontact mechanical excitations and interferometric detection of transient vibrations of the drug tablets is employed for sensing. Two novel methods to excite vibrational modes in drug tablets are developed and employed: (i) a vibration plate excited by a pulsed-laser and (ii) pulsed laser-induced plasma generated shockwave expansion. Damage in coat and/or core of a tablet weakens its mechanical stiffness and, consequently, affects its acoustic response to an external dynamic force field. From the analysis of frequency spectra and the time,frequency spectrograms obtained under both mechanisms, it can be concluded that defective tablets can be effectively differentiated from the defect-free ones and the proposed proof-of-concept techniques have potential to provide a technology platform to be used in the greater PAT effort. 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:2125,2133, 2007 [source]

Neutron reflectivity of polymer-plasticiser diffusion

J.S. Higgins
Neutron reflectivity (NR) has been widely exploited to look at polymer thin films and in many ways is an ideal technique for studying polymer interfaces and surfaces, providing high-resolution concentration - depth profiles across the film thickness. Most NR studies to date have concentrated on thin films of amorphous polymers which possess Tg values well above room temperature. These polymers are ideally suited to NR measurements, firstly because they form homogeneously flat films and, secondly, heat-quench cycles can be used to study time-dependent processes. This has been used to great effect in NR studies of the initial stages of polymer - polymer interdiffusion or the kinetics of surface segregated layers for instance. One of the biggest drawbacks to this approach is that in polymer systems where one or more of the components has a Tg close to or less than room temperature, the polymers can still move during the measurement time of an NR profile, which typically takes 1-2 h for a full profile. Therefore, in order to study such systems, we have developed an approach to NR measurements that allows us to investigate diffusion processes in situ. Our new approach allows us to take NR profiles in only 20 s. This paper describes the method of real-time NR measurements in detail and illustrates the capabilities of the technique with highlights from some of our recent work on the early stages of polymer-plasticiser interdiffusion. [source]