Format

Send to

Choose Destination
J Magn Reson Imaging. 2016 Mar;43(3):756-61. doi: 10.1002/jmri.25027. Epub 2015 Aug 13.

Selecting the reference image for registration of CEST series.

Author information

1
Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.
2
F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.

Abstract

BACKGROUND:

To compare different reference images selected for registration among chemical exchange saturation transfer (CEST) series.

MATERIALS AND METHODS:

Five normal volunteers and eight brain tumor patients were studied on a 3 Tesla scanner. Image registration was performed by choosing each of the acquired CEST saturation or unsaturation dynamic images as the reference. CEST images at 3.5 ppm (amide proton transfer, APT) were computed for each motion-corrected data set after main magnetic field inhomogeneity correction. A uniformity index was defined to quantify the efficacy of image registration using different reference images. Joint histograms and the structural similarity index (SSIM) were used to analyze the intrinsic image similarity between various dynamic images.

RESULTS:

Image registration increased the average uniformity index by 18% if the 3.5 ppm saturated image was selected as the reference image. However, registering to the unsaturated dynamic image reduced the uniformity index by 13% on average. The joint histogram analysis showed that the saturated dynamic images were highly similar (SSIM = 0.89 ± 0.01), and were considerably different from the unsaturated dynamic image (SSIM = 0.58 ± 0.03).

CONCLUSION:

The selection of the 3.5 ppm dynamic image as the reference image generated the highest uniformity index for APT imaging though other saturated images were equally suited as reference images.

KEYWORDS:

APT imaging; CEST imaging; brain tumor; image registration

PMID:
26268435
PMCID:
PMC4752933
[Available on 2017-03-01]
DOI:
10.1002/jmri.25027
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center