Magnetic resonance imaging of gases: A single-point ramped imaging with T-1 enhancement (SPRITE) study

A pure phase-encoding MRI technique, single-point ramped imaging with T-1 e nhancement, SPRITE, is introduced for the purpose of gas phase imaging. The technique utilizes broadband RF pulses and stepped phase encode gradients to produce images, substantially free of artifacts, which are sensitive to the gas T-1 and T-2* relaxation times. Images may be acquired from gas phas e species with transverse relaxation times substantially less than 1 ms. Me thane gas images, H-1, were acquired in a phantom study. Sulfur hexafluorid e, F-19, images were acquired from a gas-filled porous coral sample. High p orosity regions of the coral are observed in both the MRI image and an X-ra y image. Sensitivity and resolution effects due to signal modulation during the time-efficient acquisition are discussed. A method to increase the ima ge sensitivity is discussed, and the predicted improvement is shown through 1D images of the methane gas phantom. (C) 1999 Academic Press.