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The human lung and its functions are extremely sensitive to gravity; however, the conventional high-field magnets used for most laser-polarized 3He MRI of the human lung restrict subjects to lying horizontally. Imaging of human lungs using inhaled laser-polarized 3He gas is demonstrated in an open-access very-low-magnetic-field (<5 mT) MRI instrument. This prototype device employs a simple, low-cost electromagnet, with an open geometry that allows variation of the orientation of the imaging subject in a two-dimensional plane. As a demonstration, two-dimensional lung images were acquired with 4-mm in-plane resolution from a subject in two orientations: lying supine and sitting in a vertical position with one arm raised. Experience with this prototype device will guide optimization of a second-generation very-low-field imager to enable studies of human pulmonary physiology as a function of subject orientation. Magn Reson Med 53:745-749, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

We introduce a new magnetic field geometry, Bx(x, y) = gyy cos(qxx), to spatially encode magnetic resonance imaging (MRI). The field is called the PERL field since it is PERiodic in x and Linear in y. A technique is proposed to acquire two-dimensional (2D) data without switching the encoding fields. The time-domain PERL signal and image are not related by a two-dimensional Fourier transform (2DFT). They are related by a 1DFT in the x-dimension and a new Bessel function integral transform, called the PERL transform, in the y-dimension. We numerically solve this equation and develop a reconstruction algorithm. The algorithm is evaluated by assuming a known spin density which is then used to calculate the PERL signal. This signal is the input for the algorithm. We show the reconstructed image matches the convolution of the initial assumed spin density and a point spread function (PSF). We identify the PSF and describe the conditions under which it approaches δ. © 1999 John Wiley & Sons, Inc. Int J Imaging Syst Technol 10, 209–215, 1999 [ABSTRACT FROM AUTHOR]

A new magnetic field geometry for spatial encoding of magnetic resonance imaging (MRI) is presented. The field is given by: Bz(x, y) = gyy cos(qxx), 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, qx is decreased. To keep the spatial resolution in y constant however, a phase θ is added: Bz(x, y) = gyy cos(qxx + 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 [ABSTRACT FROM AUTHOR]

A correction to the article "GABAC receptors are expressed in GABAergic and non-GABAergic neurons of the rat superior colliculus and visual cortex," e-published 2009 in "Experimental Brain Research" is presented.