Ts. Sachs et al., THE DIMINISHING VARIANCE ALGORITHM FOR REAL-TIME REDUCTION OF MOTION ARTIFACTS IN MRI, Magnetic resonance in medicine, 34(3), 1995, pp. 412-422
A technique has been developed whereby motion can be detected in real
time during the acquisition of data, This enables the implementation o
f several algorithms to reduce or eliminate motion effects from an ima
ge as it is being acquired. One such algorithm previously described is
the acceptance/rejection method, This paper deals with another real-t
ime algorithm called the diminishing variance algorithm (DVA), With th
is method, a complete set of preliminary data is acquired along with i
nformation about the relative motion position of each frame of data, A
fter all the preliminary data are acquired, the position information i
s used to determine which data frames are most corrupted by motion, Fr
ames of data are then reacquired, starting with the most corrupted one
, The position information is continually updated in an iterative proc
ess; therefore, each subsequent reacquisition is always done on the wo
rst frame of data. The algorithm has been implemented on several diffe
rent types of sequences, Preliminary in vivo studies indicate that mot
ion artifacts are dramatically reduced.