Differences

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--- biac:analysis:topup_correction [2021/08/24 16:04] – cmp12
+++ biac:analysis:topup_correction [2021/08/24 18:22] – cmp12
@@ Line 10: / Line 10: @@
 the readout time in seconds for the parameter file will be:
-<code>readout = (echospacing * (acquisitionmatrix[0] * (percentsampling/100))) / 1e6
+<code>
+**For singleband images :**
+readout = (echospacing * (acquisitionmatrix[0] * (percentsampling/100))) / 1e6
 echospacing in the BXH header is in microseconds
+**For mutli-band images the readout calculation is more complex:**
+readout = ( ( ceil ((1/Round_factor) * AcquisitionMatrixPE / Asset_R_factor ) * Round_factor) - 1 ) * EchoSpacing * 0.000001
+EffectiveEchoSpacing = TotalReadoutTime/ (reconMatrixPE - 1)
+AcquisitionMatrixPE = the acquisition size of the data ( acquisitionmatrix[0] )
+reconMatrixPE = the size of the reconstructed data ( may be different from acquisition because of FFT rules )
+Round_factor = 4 if partial fourier ( PFF is in scanoptions ), 2 if full fourier.  most all scans will be 4
+Asset_R_factor = the reciprocal of the first value of dcm tag (0043,1083)
 </code>