J Korean Radiol Soc.  2005 Feb;52(2):87-92. 10.3348/jkrs.2005.52.2.87.

Histogram Analysis of Noise Performance on Fractional Anisotropy Brain MR Image with Different Diffusion Gradient Numbers

• Chang Y
• Lee YJ
• Kim YS
• Kang DS
• Sohn CH
• Woo SK
• Suh KJ

• KMID: 1945419
• DOI: http://doi.org/10.3348/jkrs.2005.52.2.87

Abstract

PURPOSE: We wished to analyze, qualitatively and quantitatively, the noise performance of fractional anisotropy brain images along with the different diffusion gradient numbers by using the histogram method.
MATERIALS AND METHODS
Diffusion tensor images were acquired using a 3.0 T MR scanner from ten normal volunteers who had no neurological symptoms. The single-shot spin-echo EPI with a Stejskal-Tanner type diffusion gradient scheme was employed for the diffusion tensor measurement. With a b-valuee of 1000 s/mm2, the diffusion tensor images were obtained for 6, 11, 23, 35 and 47 diffusion gradient directions. FA images were generated for each DTI scheme. The histograms were then obtained at selected ROIs for the anatomical structures on the FA image. At the same ROI location, the mean FA value and the standard deviation of the mean FA value were calculated.
RESULTS
The quality of the FA image was improved as the number of diffusion gradient directions increased by showing better contrast between the WM and GM. The histogram showed that the variance of FA values was reduced as the number of diffusion gradient directions increased. This histogram analysis was in good agreement with the result obtained using quantitative analysis.
CONCLUSION
The image quality of the FA map was significantly improved as the number of diffusion gradient directions increased. The histogram analysis well demonstrated that the improvement in the FA images resulted from the reduction in the variance of the FA values included in the ROI.

Keyword

Brain, MR; Magnetic resonance (MR), diffusion; Magnetic resonance (MR), pulse sequence

MeSH Terms

Anisotropy*
Brain*
Diffusion*
Healthy Volunteers
Noise*