A population-specific symmetric phase model to automatically analyze susceptibility-weighted imaging (SWI) phase shifts and phase symmetry in the human brain.
OBJECTIVE
To create a population-specific symmetric phase model and to evaluate the susceptibility-weighted imaging (SWI) phase in terms of phase shift using different segmentation methods (manual and automatic) and phase shift symmetry, which is expected as a marker for lateralized Parkinson's disease (PD) symptoms.


METHODS
SWI and T(1)-weighted data from 25 PD patients and five healthy controls were acquired on a 3T MRI system. A population-specific, symmetric phase model was developed. Regions of interest (ROIs) were defined manually on the phase model, manually on each individual data set, and automatically using model-based segmentation (MBS). Manually- and MBS-defined ROIs were compared using kappa values, and left-right phase symmetry was evaluated using correlation analysis.


RESULTS
Independent of the analysis method, a phase increase from the anterior to the posterior putamen, and the average phase value relationship substantia nigra > globus pallidus > red nucleus was found. Phase symmetry analysis shows a difference between lateralized and symmetric PD.


CONCLUSIONS
The symmetric phase model helps to analyze phase data with similar accuracy, but a greatly reduced tracing effort compared to individual tracing and also allows evaluating left-right phase symmetries.
Grabner
Günther
G
Department of Radiology, Medical University of Vienna, Vienna, Austria.
Haubenberger
Dietrich
D
Rath
Jakob
J
Beisteiner
Roland
R
Auff
Eduard
E
Trattnig
Siegfried
S
Barth
Markus
M
D000328:Adult; D000368:Aged; D000465:Algorithms; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D010300:Parkinson Disease / Q000175:diagnosis*; D011699:Putamen / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity