JSON Parameters

This page lists all supported fields in the JSON parameter file used by the load_data function in PyASL.

The parameters are grouped into three categories:

• ASL: Acquisition parameters for perfusion scans

• M0: Parameters for the M0 scan

• anat: (Optional) Parameters for anatomical images

Each group should be provided as a dictionary in the top-level JSON structure.

Example JSON structure:

{
    "ASL": { ... },
    "M0": { ... },
    "anat": { ... }
}

Field Descriptions

Name	Description	Defaults
Manufacturer	Manufacturer	Required
ManufacturersModelName	Manufacturers model name	Required
MagneticFieldStrength	Magnetic field strength	Required
RepetitionTime	Repetition time (sec)	Required
EchoTime	Echo time (sec)	Required
FlipAngle	Flip angle (degree)	Required
ArterialSpinLabelingType	PCASL, CASL, or PASL	Required
PostLabelingDelay	A value (sec) for single-delay data when M0Type is not Included; Otherwise should be a vector containing corresponding PLDs for control/label pairs and 0 for M0 scan	Required
LabelingDuration	Labeling duration (sec)	Optional, required when ArterialSpinLabelingType = PCASL or CASL
BolusCutOffDelayTime	Bolus cutOff delay time (TI1) (sec)	Optional, required when ArterialSpinLabelingType = PASL
Looklocker	Flip angle of looklocker acquisition (degree)	Optional, required when using mutli-delay PASL
M0Type	Separate means there is a separate M0 file in the perf folder; Included means that the M0 scan is included in the ASL image file; Estimate means there is no M0 scan	Required
MRAcquisitionType	2D or 3D	Required
SliceDuration	For multi-slice 2D acquisition, the time interval between excitations of adjacent slices (sec)	Optional, required when MRAcquisitionType = 2D
BackgroundSuppression	True or False	Required
BackgroundSuppressionNumberPulses	Background suppression number of pulses	Optional, required when BackgroundSuppressionNumberPulses = True
BackgroundSuppressionPulseTime	Vector containing timing (sec) of the background suppression pulses	Optional, required when BackgroundSuppressionNumberPulses = True
LabelingEfficiency	Labeling efficiency	Required