T2 and T quantification using optimal B1 image reconstruction for multicoil arrays

✍ Scribed by Martin J. Graves; Daniel Emmens; Hubert Lejay; Hari Hariharan; Jason Polzin; David J. Lomas

• Book ID: 102378068
• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 235 KB
• Volume: 28
• Category: Article
• ISSN: 1053-1807
• DOI: 10.1002/jmri.21420

✦ Synopsis

Abstract

Purpose

To investigate the accuracy of low signal‐to‐noise ratio (SNR) T~2~ and T measurements using array coils and optimal B~1~ image reconstruction (OBR) compared to the standard root sum of squares (RSS) reconstruction.

Materials and Methods

Calibrated gels were used for the in vitro study of T~2~. T~2~ and T measurements were obtained from a volunteer's knee and liver, respectively. T~2~ and T measurements were performed using multiecho spin echo and multiecho gradient echo sequences, respectively. SNR was deliberately kept low. The same raw data were used for both reconstructions. For the in vivo studies the effect of signal averaging was also investigated.

Results

The optimal reconstructions demonstrated a lower mean background noise level than RSS. In vitro, the T~2~ measurements made with OBR images agreed better with a reference high SNR measurement than measurements made from RSS images; the RSS image results overestimated the T~2.~ In vivo, increasing the signal averages decreased the difference between the measurements obtained using the OBR and RSS methods, with RSS resulting in longer relaxation times.

Conclusion

This work demonstrates improvements to the accuracy of T~2~ and T measurements obtained when OBR is used compared to RSS, particularly in the case of low SNR. J. Magn. Reson. Imaging 2008;28:278–281. © 2008 Wiley‐Liss, Inc.