Premium
Novel encoding technology for ultrafast MRI in a limited spatial region
Author(s) -
Patz S.,
Hrovat M. I.,
Pulyer Y. M.,
Rybicki F. J.
Publication year - 1999
Publication title -
international journal of imaging systems and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.359
H-Index - 47
eISSN - 1098-1098
pISSN - 0899-9457
DOI - 10.1002/(sici)1098-1098(1999)10:3<216::aid-ima3>3.0.co;2-q
Subject(s) - perl , field (mathematics) , pulse sequence , dimension (graph theory) , bessel function , electromagnetic coil , magnetic field , ultrashort pulse , physics , laplace transform , image resolution , optics , computer science , mathematical analysis , mathematics , nuclear magnetic resonance , algorithm , quantum mechanics , pure mathematics , laser , world wide web
A new magnetic field geometry for spatial encoding of magnetic resonance imaging (MRI) is presented. The field is given by: B z ( x, y ) = g y y cos( q x x ), and is called a PERL field because it is PERiodic in x and Linear in y . Both imaging pulse sequences and encoding field design are analyzed theoretically. A two‐dimensional (2D) imaging sequence is shown to require a Fourier transform to resolve the x dimension and the solution of a Bessel function integral transform equation to resolve the y dimension. By examining solutions to Laplace's equation that approximate the PERL field, it is shown that the PERL field can only be produced in a limited spatial region. An unusual feature is that the number of gradient switches needed during a 2D data acquisition depends on the field of view and is fundamentally determined by the finite penetration depth δ of the PERL field into the sample. For very thin sections near the PERL coil, no gradient switching is required. To increase δ, q x is decreased. To keep the spatial resolution in y constant however, a phase θ is added: B z ( x, y ) = g y y cos( q x x + θ), together with additional data acquisitions (and additional gradient switches) for different values of θ. In addition, an explicit example of a PERL coil with rectangular geometry is presented and its field plotted. © 1999 John Wiley & Sons, Inc. Int J Imaging Syst Technol 10, 216–224, 1999