- Torch Ginger (Lei Crime, Book 2).
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- The Manual- A guide to the Ultimate Study Method (USM); covering Speed Reading, Super Memory, Laser Concentration, Rapid Mental Arithmetic and the Ultimate Study Method (USM).
However, multimodality systems typically come with trade-offs that have to be balanced against the perceived added value. Possible negatives and other considerations include: i any reduction in imaging performance compared with stand-alone system, ii system cost if greater than the individual components, iii space requirements, iv additional operational complexity increased downtime? Yet the history of this example also serves to illustrate that it is not easy to predict the impact of a hybrid system until it has been developed sufficiently to be applied to biomedical or clinical problems.
Therefore, it is important that research into the development and optimization of new hybrid imaging systems continue to be supported, as it offers one of the best opportunities for major technical innovation and impact in contemporary medical imaging science.
Molecular Anatomic Imaging: PET-CT and SPECT-CT Integrated Modality Imaging - Google книги
In part, this was due to the substantial difficulties posed by operating these systems in close proximity, and in part due to initial lack of industry interest and concerns over the cost of such a combined device. This opens up a wealth of interesting research opportunities, and with these advanced MR techniques finding increased clinical utility, there likely will be range of clinical applications that combine anatomic MR, some form of functional MR measurement and molecular imaging with PET or SPECT.
This is of particular importance for studies that are monitoring disease progression and response to therapy with multiple scans. While these are all good reasons for developing hybrid systems with MR rather than CT, there is one significant drawback of MR that must be acknowledged.
MR does not directly provide the information required for attenuation correction of the nuclear medicine study. In particular, it is challenging to separate air and bone, and to measure the density variations in the lung with MRI. This is a radical departure from the approach used for fusion with CT, where the scanners were arranged in a tandem rather than concentric configuration, and where scans were acquired sequentially.
The PET or SPECT system must operate in a high magnetic field environment, which suggests the use of scintillators coupled to magnetic field insensitive solid state light detectors such as avalanche photodiodes [ 29 , 30 ] or silicon photomultipliers [ 31 ]. Alternatively, if traditional photomultiplier tubes are to be used, they need to be placed outside of the magnet in an area where the fringe field is low enough that they can be effectively shielded against the field [ 20 , 32 , 33 ].
The MRI system requires very good uniformity of its magnetic field typically 1 part in 10 6 or better and foreign objects placed in or around the magnet have the potential to perturb that field. The third and generally most challenging issue relates to electromagnetic interference between the two systems.