Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Patent
1997-04-11
1999-01-19
Lateef, Marvin M.
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
324307, 324309, A61B 5055
Patent
active
058609210
ABSTRACT:
A technique for accurately measuring two different spin configurations of transverse magnetization from which the reversible dephasing rate constant R.sub.2 ' can be calculated. Such reversible dephasing may be caused by magnetic field inhomogeneity such as arising from intravascular changes in the oxidation state of hemoglobin, from brain iron, or from cancellous bone, which allows these characteristics to be measured. The different spin configurations can be measured in a single scan by deriving a small R.sub.2 ' through independent and separate measurements of the two magnetization configurations generated by two RF pulses. The two configurations can be recalled independently of each other since they are affected differently by respective gradients flanking the .beta.-pulse which permit one spin configuration to decay with T.sub.2 while the other decays with T.sub.2 * from the same RF pulse. Since the spin configurations come from the same RF pulse, they have the same relaxation time, thus permitting small changes in T.sub.2 ', and hence R.sub.2 ', to be measured by setting the relaxation time of both configurations to be long.
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Ma Jingfei
Wehrli Felix
Lateef Marvin M.
Mantis Mercader Eleni
Trustees of the University of Pennyslvania
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