Ultrashort T2* relaxometry for quantitation of highly concentrated superparamagnetic iron oxide (SPIO) nanoparticle labeled cells.
A new method was developed to measure ultrashort T(2)* relaxation in tissues containing a focal area of superparamagnetic iron oxide (SPIO) nanoparticle-labeled cells in which the T(2)* decay is too short to be accurately measured using regular gradient echo T(2)* mapping. The proposed method utilizes the relatively long T(2) relaxation of SPIO-labeled cells and acquires a series of spin echo images with the readout echo shifted to sample the T(2)* decay curve. MRI experiments in phantoms and rats with SPIO-labeled tumors demonstrated that it can detect ultrashort T(2)* down to 1 ms or less. The measured T(2)* values were about 10% higher than those from the ultrashort TE (UTE) technique. The shorter the TE, the less the measurements deviated from the UTE T(2)* mapping. Combined with the regular T(2)* mapping, this technique is expected to provide quantitation of highly concentrated iron-labeled cells from direct cell transplantation.
Liu
Wei
W
Philips Research, North America, Briarcliff Manor, New York 10510, USA. wei.liu_1@philips.com
Dahnke
Hannes
H
Rahmer
Juergen
J
Jordan
E Kay
EK
Frank
Joseph A
JA
D000818:Animals; D045744:Cell Line, Tumor; D003287:Contrast Media; D005260:Female; D005290:Ferric Compounds; D005910:Glioma / Q000473:pathology*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008280:Magnetics; D053758:Nanoparticles; D019047:Phantoms, Imaging; D051381:Rats; D011923:Rats, Nude; D017207:Rats, Sprague-Dawley; D013113:Spin Labels
D003287:Contrast Media; D005290:Ferric Compounds; D013113:Spin Labels; C000499:ferric oxide