Multipoint mapping for imaging of semi-solid materials.
Multipoint k-space mapping is a hybrid between constant-time (single-point mapping) and spin-warp imaging, involving sampling of a k-line segment of r points per TR cycle. In this work the method was implemented for NMR imaging of semi-solid materials on a 400 MHz micro-imaging system and two different k-space sampling strategies were investigated to minimize the adverse effects from relaxation-induced k-space signal modulation. Signal attenuation from T(2) decay results in artifacts whose nature depends on the k-space sampling strategy. The artifacts can be minimized by increasing the readout gradient amplitude, by PSF deconvolution or by oversampling in readout direction. Finally, implementation of a T(2) selective RF excitation demonstrates the feasibility of obtaining short-T(2) contrast even in the presence of tissues with long-T(2). The method's potential is illustrated with 3D proton images of short-T(2) materials such as synthetic polymers and bone.
Fernández-Seara
M A
MA
Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA.
Wehrli
S L
SL
Wehrli
F W
FW
D000818:Animals; D016477:Artifacts; D001853:Bone Marrow / Q000000981:diagnostic imaging; D018483:Diaphyses / Q000000981:diagnostic imaging*; D017352:Echo-Planar Imaging / Q000379:methods*; D021621:Imaging, Three-Dimensional; D019047:Phantoms, Imaging; D011817:Rabbits; D011859:Radiography