Comparing MR image intensity standardization against tissue characterizability of magnetization transfer ratio imaging.
OBJECTIVE
To evaluate existing methods of standardization by exploiting the well-known tissue characterizing property of magnetization transfer ratio (MTR) values obtained from MT imaging, and compare the tissue characterizability of standardized T2, proton density (PD), and T1 images against the MTR images.


METHODS
Image intensity standardization is a postprocessing method that was designed to correct for acquisition-to-acquisition signal intensity variations (nonstandardness) inherent in magnetic resonance (MR) images. The main idea of this technique is to deform the volume image histogram of each study to match a standard histogram, and to utilize the resulting transformations to map the image intensities into a standard scale. The method has been shown to produce a significant gain in similarity of resulting images and to achieve numeric tissue characterization. In this work we compared PD-, T2-, and T1-weighted images before and after standardization with the corresponding MT images for 10 patient MRI studies of the brain, in terms of the normalized median values on the corresponding image histograms.


RESULTS
No statistically significant difference was observed between the standardized PD-, T2-, and T1-weighted images and the corresponding MTR images. However, a statistically significant difference was found between the pre- and poststandardized PD-, T2-, and T1-weighted images, and between the prestandardized PD-, T2-, and T1-weighted images and the corresponding MTR images.


CONCLUSIONS
These results suggest that standardized T2, PD, and T1 images and their tissue-specific intensity signatures may be useful for characterizing disease.
Madabhushi
Anant
A
Department of Biomedical Engineering, Rutgers University, New Brunswick, New Jersey, USA.
Udupa
Jayaram K
JK
Moonis
Gul
G
D001921:Brain / Q000473:pathology; D019786:Gadolinium DTPA / Q000494:pharmacology; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008280:Magnetics; D015233:Models, Statistical; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000473:pathology; D012015:Reference Standards
D019786:Gadolinium DTPA