Separate MRI quantification of dispersed (ferritin-like) and aggregated (hemosiderin-like) storage iron.
A new MRI method is proposed for separately quantifying the two principal forms of tissue storage (nonheme) iron: ferritin iron, a dispersed, soluble fraction that can be rapidly mobilized, and hemosiderin iron, an aggregated, insoluble fraction that serves as a long-term reserve. The method utilizes multiple spin echo sequences, exploiting the fact that aggregated iron can induce nonmonoexponential signal decay for multiple spin echo sequences. The method is validated in vitro for agarose phantoms, simulating dispersed iron with manganese chloride, and aggregated iron with iron oxide microspheres. To demonstrate feasibility for human studies, preliminary in vivo data from two healthy controls and six patients with transfusional iron overload are presented. For both phantoms and human subjects, conventional R(2) and R(2)* relaxation rates are also measured in order to contrast the proposed method with established MRI iron quantification techniques. Quantification of dispersed (ferritin-like) iron may provide a new means of monitoring the risk of iron-induced toxicity in patients with iron overload and, together with quantification of aggregated (hemosiderin-like) iron, improve the accuracy of estimates for total storage iron.
Jensen
Jens H
JH
Department of Radiology, New York University School of Medicine, Center for Biomedical Imaging, New York, New York 10016-3295, USA. jj33@nyu.edu
Tang
Haiying
H
Tosti
Christina L
CL
Swaminathan
Srirama V
SV
Nunez
Alvaro
A
Hultman
Kristi
K
Szulc
Kamila U
KU
Wu
Ed X
EX
Kim
Daniel
D
Sheth
Sujit
S
Brown
Truman R
TR
Brittenham
Gary M
GM
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis; D005260:Female; D005293:Ferritins / Q000378:metabolism*; D006485:Hemosiderin / Q000378:metabolism*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D055815:Young Adult; D017086:beta-Thalassemia / Q000175:diagnosis* / Q000378:metabolism*
D015415:Biomarkers; D005293:Ferritins; D006485:Hemosiderin