Rotating-Frame Imaging

Abstract

The rotating-frame counterpart to (Larmor) frequency encoding in laboratory-frame imaging experiments is “nutation frequency encoding” [199]. Instead of gradients of the external magnetic field, rotating-frame imaging is based on gradients of the RF amplitude B₁. That is, the effective field in the resonantly rotating frame has the form

$$ B_{1}=B_{1}\left (r\right)=B_{1}^{(0)}+G_{1}.\ r $$

((34.1))

where we have neglected the influence of local fields by spin interactions. The B₁ gradient is defined by¹

$$ G_{1}=\bigtriangledown B_{1} $$

((34.2))