Determination of NMR relaxation times (T1 and T2) from multislice, multiecho MR imaging
In proton MR imaging the determination of fundamental MR constants such as spin lattice (T1) and spin spin (T2) relaxation times is essential for an understanding of image contrast and for insight into the question of optimal field vis a vis disease state. Multislice, multiecho imaging is attractive because imaging time per slice is reduced; however, slice selecting radiofrequency (RF) pulses may cause interference from adjacent slices to the slice being imaged. This interference will cause incorrect relaxation time measurements and ''false'' image contrast between tissues which could result in improper diagnosis. To observe the effect of slice separation on T1 and T2 the authors imaged bottles of various concentrations of MnCl/sub 2/, with T1 values ranging from 215 to 1003 msec and T2 values from 39 to 240 msec. For T1 determinations two sets of multi-slice images (5 slices with nominal thickness of 1 cm) were taken both with an echo time (TE) of 30 msec and repetition times (TR) of 500 and 2000 msec. Slice separation was varied from 0 to 1 cm in 0.25 cm intervals. Reliable T1 values were obtained only when the slice separation was 0.75 or 1 cm. When slice separation was less than this, the TR500 images showed severe reversals in expected contrast when outside slices were compared with central slices. The effect of slice separation on T2 relaxation was investigated using a 5 slice multiecho technique (8 echoes per slice) with TR of 1400 msec and TE varying from 30 to 240 msec in intervals of 30 msec and nominal thickness set at 1 cm. Acquisitions were taken for slice separations from 0 to 1 cm and accurate T2 values for all 5 slices were only obtained when slice separation was 1 cm.
- Research Organization:
- Institute and Nuclear Medicine Dept., St. Joseph's Hospital and Univ. of Western Ontario, London
- OSTI ID:
- 6639329
- Report Number(s):
- CONF-850611-
- Journal Information:
- J. Nucl. Med.; (United States), Vol. 26:5; Conference: 32. annual meeting of the Society of Nuclear Medicine, Houston, TX, USA, 2 Jun 1985
- Country of Publication:
- United States
- Language:
- English
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DISEASES
DIAGNOSIS
NUCLEAR MAGNETIC RESONANCE
SPIN-LATTICE RELAXATION
SPIN-SPIN RELAXATION
ACCURACY
DIAGNOSTIC TECHNIQUES
IMAGE PROCESSING
IMAGES
MANGANESE CHLORIDES
RADIOWAVE RADIATION
RELAXATION TIME
RF SYSTEMS
TIMING PROPERTIES
CHLORIDES
CHLORINE COMPOUNDS
ELECTROMAGNETIC RADIATION
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HALOGEN COMPOUNDS
MAGNETIC RESONANCE
MANGANESE COMPOUNDS
MANGANESE HALIDES
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RELAXATION
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