Measurement of brain iron distribution in Hallevorden-Spatz syndrome.
OBJECTIVE
To investigate spatial distribution of iron accumulation in the globus pallidus (GP) in patients with Hallevorden-Spatz syndrome (HSS) using phase imaging. We compared sensitivity of a phase imaging technique to relaxation rate measurement methods (R1,R2,R2*) for iron quantification.


METHODS
R1, R2, and R2* were measured in GP structure of the brain of eight pantothenate kinase-associated neurodegeneration (PKAN) patients and a healthy volunteer using a 3T magnetic resonance imaging (MRI) scanner. The phase of gradient-echo images was preprocessed to eliminate phase 2pi wrapping and filtered to remove phase background variations. Phase gap across GP structure was used as a metric for iron effects quantification.


RESULTS
Among the relaxation rates the most sensitive to iron accumulation was the R2* rate. The R1 and R2 rates demonstrated only small variations in this group of subjects. Up to an order of magnitude phase gap changes were measured between one PKAN patient and an age-matched healthy volunteer. Assuming that phase gap differences scale linearly with iron concentration we estimate that up to 2 mg Fe/g ww accumulates in GP of these patients.


CONCLUSIONS
Our results demonstrate significantly higher sensitivity of the phase measurements for quantitative assessment of iron concentration compared to the relaxation rate measurements. Phase measurements could potentially be used for monitoring a progression and a response to therapy in PKAN.
Szumowski
Jerzy
J
Oregon Health Science University Department of Radiology Portland, Oregon, USA. jerzy@ohsu.edu
Bas
Erhan
E
Gaarder
Kirsten
K
Schwarz
Erwin
E
Erdogmus
Deniz
D
Hayflick
Susan
S
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007501:Iron / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D006211:Pantothenate Kinase-Associated Neurodegeneration / Q000175:diagnosis* / Q000378:metabolism*; D013577:Syndrome; D014018:Tissue Distribution; D055815:Young Adult
D015415:Biomarkers; D007501:Iron