Number of Phase Encoding Steps

Below is from DICOM header of a MRI image:
NumberOfPhaseEncodingSteps: 420
EchoTrainLength: 15
PercentSampling: 70
PercentPhaseFieldOfView: 100
PixelBandwidth: 250
AcquisitionMatrix: [0 320 224 0]
InPlanePhaseEncodingDirection: ‘ROW’
Private_0019_10xx_Creator: ‘SIEMENS MR HEADER’
Rows: 320
Columns: 320
PixelSpacing: [0.6875 0.6875]
Acquisition: 224 * 320
FieldOfView: 220 * 220

How to match the NumberOfPhaseEncodingSteps: 420 with all other parameters?

Thanks.

Apple