Signal profile measurements for evaluation of the volume-selection performance of ISIS

✍ Scribed by Maria Ljungberg; Göran Starck; Eva Forssell-Aronsson; Magne Alpsten; Sven Ekholm

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 703 KB
• Volume: 8
• Category: Article
• ISSN: 0952-3480
• DOI: 10.1002/nbm.1940080607

✦ Synopsis

High

-resolution signal profiles obtained with a test phantom were used in this study to evaluate the volumeselection performance of an implementation of ISIS (Image Selected In vivo Spectroscopy). The phantom simulated the brain with regard to volume and loading of coil. A remotely controlled, movable signal source inside the phantom was filled with orthophosphoric acid. Signal profiles of the volume of interest (VOI) were measured in three perpendicular directions. Special interest was focused on the transition zones, the position of the profiles, and the effects of off-resonance and TI smearing. The transition zones were on average 5.6 mm wide and the full width at half maximum (FWHM) was 35 mm for a VOI of 40 X 40 X 40 mm3. The positions of the centre of the signal profiles were x=3.2, y = -0.7 and z=3.3mm off-centre. The deviation of the volume position could be explained by off-resonance effects during imaging and spectroscopy. These data illustrate the importance of detailed knowledge of the volume-selection performance when attempting precision measurements using image-guided in vivo MRS.