Biomedical subjects

George D Sergiadis

Publications and source records attributed to George D Sergiadis.

2 recordsLinked to original sources

PubMed2003

Multirate SPAMM tagging.

Many magnetic resonance tagging sequences rely on periodicity in order to produce a uniform tagging grid that covers the whole image plane. This, however, is not always desirable, since motion may be restricted to specific parts of the image, and also different motion characteristics may call for different tagging grid densities. In this paper, we present a combination of the spatial modulation of magnetization 1-1 method with selective excitation pulses that can be used in order to restrict the tagging grid only to regions of interest and produce tagging grid of different density in each region. The method is fast and easy to implement even on older or less expensive systems, since it does not require extensive gradient switching.

Algorithms↗

PubMed2002

A rotational approach to localized SPAMM 1-1 tagging.

Magnetic resonance tagging usually relies on controlling the phase dispersion of the transverse magnetization component. Phase dispersion is, however, affected by the inherent phase of selective excitation pulses, thus limiting their combination with tagging sequences to the application of refocusable pulses, as in the localized spatial modulation of magnetization (L-SPAMM) technique. In this study, we examine the effect of selective excitation pulses on a L-SPAMM 1-1 sequence, showing that in the case of two identical pulses the phase component is canceled out, and thus preemphasis and refocus gradients are not needed, allowing us to take advantage of a constant gradient throughout the tagging sequence, and also that one might choose nonrefocusable maximum and minimum phase pulses.

Journal Article↗