Dynamic volume imaging

The major challenge in using CTP for the assessment of the core infarct is the questionable reliability of dynamic perfusion imaging. CBV measurements are thought to be more robust than CBF and MTT measurements because the calculation of cerebral blood volume is relatively insensitive to bolus delay and dispersion [85, 86]. However, as a calculated parameter, it remains dependent on postprocessing (e.g., partial volume effects) and patient-specific issues (e.g., hematocrit levels) [87-89]. Additionally, as demonstrated in the DIAS-2 study [90], there is poor interrater agreement in assessing the CBV lesion. 

The 320-detector-row CT scanner (dynamic volume CT system) introduced for clinical application in 2007 has a detector width of 16 cm, resulting in a cone angle of 15.2°, and offers new imaging options for a variety of organs. 

Fig. 2.1a-c. Diagram of the typical cone angle of the X-ray beam in 64-detector-row CT (a). The 16-cm detector width (along the rotational axis of the gantry) results in a 16° cone angle in dynamic volume CT (b) and a rhomboid shape of the image data (c)... 

Dynamic volume scanning provides volumetric imaging over time with a scan range of up to 16 cm, offering functional analysis of entire organs. As there is no table movement during scanning, each individual volume demonstrates just one instance in time. 

Static SIMS is labeled a trace analytical technique because of the very small volume of material (top monolayer) on which the analysis is performed. Static SIMS can also be used to perform chemical mapping by measuring characteristic molecules and fiagment ions in imaging mode. Unlike dynamic SIMS, static SIMS is not used to depth profile or to measure elemental impurities at trace levels. 

Rempp KA, Brix G, Wenz F, Becker CR, Guckel F, Lorenz WJ. Quantification of regional cerebral blood flow and volume with dynamic susceptibility contrast-enhanced MR imaging. Radiology 1994 193 637-641. 

With further understanding how molecular rotors interact with their environment and with application-specific chemical modifications, a more widespread use of molecular rotors in biological and chemical studies can be expected. Ratiometric dyes and lifetime imaging will enable accurate viscosity measurements in cells where concentration gradients exist. The examination of polymerization dynamics benefits from the use of molecular rotors because of their real-time response rates. Presently, the reaction may force the reporters into specific areas of the polymer matrix, for example, into water pockets, but targeted molecular rotors that integrate with the matrix could prevent this behavior. With their relationship to free volume, the field of fluid dynamics can benefit from molecular rotors, because the applicability of viscosity models (DSE, Gierer-Wirtz, free volume, and WLF models) can be elucidated. Lastly, an important field of development is the surface-immobilization of molecular rotors, which promises new solid-state sensors for microviscosity [145]. 

Kaufman, M.J., Levin. J.M., Maas, L.C., et. al. Cocaine decreases relative cerebral blood volume in humans a dynamic susceptibility contrast magnetic resonance imaging study. Psychopharmacology 138(1), 76-81, 1998. 

Beyond imaging, CARS microscopy offers the possibility for spatially resolved vibrational spectroscopy [16], providing a wealth of chemical and physical structure information of molecular specimens inside a sub-femtoliter probe volume. As such, multiplex CARS microspectroscopy allows the chemical identification of molecules on the basis of their characteristic Raman spectra and the extraction of their physical properties, e.g., their thermodynamic state. In the time domain, time-resolved CARS microscopy allows recording of ultrafast Raman free induction decays (RFIDs). CARS correlation spectroscopy can probe three-dimensional diffusion dynamics with chemical selectivity. We next discuss the basic principles and exemplifying applications of the different CARS microspectroscopies. 

Principles of ECT and the latest developments in the technology are highlighted with emphasis on the volume ECT (ECVT) for 3D imaging. The significance of ECT technique in process engineering is presented in the framework of industrial application. Fluidized beds, pneumatic solids conveying, and slurry bubble columns are examples of ECT s capability to provide quantitative and qualitative understanding of the internal process dynamics. 

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