th  - 1987 - 51st ENC Conference

MF69
28th ENC Poster Abstract
DOUBLE QUANTUM FILTERED NMR IMAGING,
PROGRESS TOWARD METABOLITE SPECIFIC IMAGES
Paul J. Kellerea, Petra Schmalbrockb,and Charles Dumoulin c
a) Barrow Neurological Institute, 350 W. Thomas Rd.
Phoenix, AZ 85013 (602)285-3179
b) Dept. of Radiolo~, Ohio State University, 1630 Upham Dr.
Columbus, OH 43210
c) General Electric Research and Development Center, PO Box 8
Schenectady, NY 12301
We are currently exploring proton double quantum
filtration methods as the basis for production of metabolize
specific images using a clinical 1.5 Tesla MR imaging system
equipped with a 1 meter bore solenoid. Lactic acid is an
attractive target metabolite since it is formed in high
concentration in ischemic tissues and its 1H-NMR pattern
approaches a first order A3X system at 1.5 T. Double quantum
filtration is accomplished-by the RF sequence, 90O-TJ-180 o-
TJ-9OO-TV-90 ° where TJ=I/8J and TV is the double quantum
evolution time. Double quantum selection is done by both RF
phase cycling and by pulsed magnetic field gradients. One
field gradient pulse is given during TV and a second pulse of
twice She amplitude is given immediately after the last RF
pulse. ~ This sequence of RF and gradient pulses is followed
by a slice selective 180 ° pulse and the usual spin-warp phase
and frequency image encoding.
The suppression of water, as well as other non-J-coupled
signals is accomplished by, a) RF phase cycling, b) gradient
induced dephasing, and c) the temporal separation of the
coherence transfer echoes arising from double and single
quantum coherence during TV. Substantial suppression of
lipid methylene signals is obtained due to the use of 1/8J
for TJ which leads to inefficient double quantum excitation
of second order systems.
Work thus far has been conducted using a phantom
consisting of three bottles containing water, cooking oil and
aqueous sodium lactate, respectively. Images showing only
i M lactate have been obtained using a 128 x 256 image matrix
and two excitations (8 min. acquisition time). Current
efforts are aimed at further suppression of unwanted signals
arising from double quantum coherence and programing to
permit smaller image matrices.
1) A.Bax, P.G.de Jong~ A.F.Mehlkopf, J.Smidt, J.Phys.Lett.,
6_2.567 ( 198o ).