Publications [#269050] of G. Allan Johnson

Papers Published
  1. Johnson, GA; Thompson, MB; Gewalt, SL; Hayes, CE, Nuclear magnetic resonance imaging at microscopic resolution, Journal of Magnetic Resonance (1969), vol. 68 no. 1 (1986), pp. 129-137, Elsevier BV [doi] .

    Resolution limits in NMR imaging are imposed by bandwidth considerations, available magnetic gradients for spatial encoding, and signal to noise. This work reports modification of a clinical NMR imaging device with picture elements of 500 × 500 × 5000 μm to yield picture elements of 50 × 50 × 1000 μm. Resolution has been increased by using smaller gradient coils permitting gradient fields >0.4 mT/cm. Significant improvements in signal to noise are achieved with smaller rf coils, close attention to choice of bandwidth, and signal averaging. These improvements permit visualization of anatomical structures in the rat brain with an effective diameter of 1 cm with the same definition as is seen in human imaging. The techniques and instrumentation should open a number of basic sciences such as embryology, plant sciences, and teratology to the potentials of NMR imaging. © 1986.