Theoretical investigation of estimation of steady and pulsatile blood flow and blood vessel cross section by cw NMR excitationt
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In this paper we show theoretically that when a magnetised blood bolus enters
a cw NMR excitor coil of length Le at resonance and the signal from the T2-decaying,
precessing transverse magnetisation of the flowing blood spins is subsequently detected by
a detector coil of length L separated from the excitor coil by a distance !ll, then by recording
cw NMR signals at three positions such as !ll = 0, 0.5 and 1.0 em one can eliminate the
static tissue signal and measure non-invasively the steady component V0 as well as the
total vessel cross section, {3 accurately. The time dependent part of the cw NMR signal
which depends on Vpul,e(1), is also dependent on V0 non-linearly unless both Land Le
are greater than 50 em and !ll is zero. Finally, methods of obtaining true Vpu,,e(l) from
the cw NMR signal after applying proper correction due to the steady flow are discussed.
Keywords
Q Science (General), QC Physics