Comparison of methods for obtaining longitudinal whole-brain magnetization transfer measurements.
OBJECTIVE
To investigate whether the method of applying image masks can alter quantifiable measures determined from whole-brain MTR calculations.


METHODS
Thirty-five T1/MT image pairs were obtained from five normal volunteers. For each pair a mask was used to specify the regions to be analyzed. Using these regions, a histogram was used to calculate seven global MTR metrics. This process was performed three ways: 1) using a unique mask for each T1/MT pair, 2) sharing a single mask for each subject and registering all intrasubject images to the image corresponding to their mask, and 3) sharing a single mask for each subject and transforming that mask into alignment with each of their original T1/MT image pairs.


RESULTS
With respect to the first method, the latter two methods caused small but significant differences in several parameters.


CONCLUSIONS
The method of applying image masks can affect whole-brain MTR values.
Ostuni
John L
JL
Laboratory of Diagnostic Radiology Research, National Institutes of Health, Bethesda, Maryland, USA. ostuni@helix.nih.gov
Richert
Nancy
N
Wisniewski
Ruth
R
Lewis
Bobbi K
BK
Howard
Thomas
T
Patel
Jay
J
Frank
Joseph A
JA
D000328:Adult; D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged