th  - 1988 - 51st ENC Conference

IN VIVO 31p AND IH NMR SPECTROSCOPY AND IMAGING
I-- OF RAT LIVER EXPOSED TO HALOCARBONS
1 68 IRheal A. Towner$, Manfred Brauer*t, David Foxallt, and Edward G. Janzent.
Guelph~Waterloo Centre for Graduate Work in Chemistry, Department of Chemistry and
Biochemistry, University of Guelph, Guelph, Ontario, Canada NIG 2WI; $ Spectroscopy
Imaging Systems Corp., 1120 Auburn St., Fremont, California USA 94538.
Intoxication by hepatotoxins such as carbon tetrachloride (CCI~) is characterized
by centrilobular necrosis and fatty degeneration of the liver. The specific damage to
the liver is directly related to the metabolism of CCI~ by the liver.
3~p-NMR in vivo spectroscopy was used to demonstrate metabolic changes in rat
liver as a function of time after exposure to either CCI~ or bromotrichloromethane
(BrCCI3). The inorganic phosphate peak shifts upfield which is associated with a
decrease in cytosolic pH. CCI~ or BrCCI3 intoxication causes an intracellular acidosis
to pH 7.02 or 6.80 (±0.05), respectively. Also, it has been found that halocarbon
exposure alters the relative amounts of phosphomonoesters and phosphodiesters detected.
CCl~ and BrCCI3 induced changes which were readily detectable by NMR imaging
techniques. Respiratory gating was used to attenuate motion artefacts due to
breathing, and standard transverse multi~slice images were obtained on a SIS 200/330
system (TE 18 ms). Two to four hours after the administration of either CCI~ or
BrCC1 a, regions of high signal intensity appeared in the rat liver images. These
affected areas were in the region where the portal vein enters the liver. Localized
~H NMR spectra, using the VOSY technique, indicated that the high proton signal
intensity was due to water, rather than a localized fatty infiltration. T 2
determinations of the water resonance within the affected regions of the liver showed
a significantly longer water T2 relaxation time than unaffected areas of the liver.
Interestingly,3the administration Of halothane anesthetic alone produced very similar
results. These studies indicate localized tissue damage, with cell rupture and
release of intracellular water. (Financial support from the Univ. of Guelph
MRI Facility, University of Guelph.)
; 169
SPECTROSCOPY WITH EXACT APODIZATION TRANSFORMATION ( SWEAT );
M. Lisicki, A. A. Bothner-By, R. Shukla, J. Dadok, P.C.M. van Zijl,
Carnegie Mellon University, Pittsburgh, PA., 15213
The finite discrete Fourier Transform applied to a theoretical time
function of infinite duration produces frequency domain spectra distorted by
truncation effects (sync wiggles) which interfere with precise spectral
measurement. For example, doublet splittings determined by measuring the
frequency separation between line maxima will be incorrect if the sync
wiggles from one llne produce a significant slope at the maxima of the other
line.
On the other hand, a line shape created in the frequency domain will
have a unique inverse transform. The inverse transform of this novel line-
shape used as an apodization function will produce the exact desired llne
shape in the experimental spectra once the natural line shape has been
removed from the experimental fid. The removal of the natural llne shape
can be accomplished by using the inverse transform of a singlet in the
experimental spectra which contains the desired natural line shape.
We will demonstrate the application of deconvolution and line-shape
generation using exact apodization. Furthermore, we will show their use in
exact spectral measurement. The computer program SWEAT which will implement
these techniques will be available.
18S