Introduction - Additionnal parameters - Example

Introduction

A Nifti file doesn't contain the metadata needed for the analysis of MRI images. So, Json files are generated during the conversion of MRI data to Nifti and allow to record all MRI parameters needed for futur analyses. They take the same name as the Nifti files (but with different extensions). The MRI labels are provided by the 2 yaml files : DictionaryMRI_System.yml and DictionaryMRI_User.yml in the 'Json' field and the 'tagJson' subfield (see 'MRI Dictionaries' page).
For each MRI label, the structures in Json have the following form :

"MRI label": {
	"format": xxxx,
	"description": xxxx,
	"units": xxxx,
	"type": xxxx,
	"value": [
		xxxx
		]
	},
		

        "format" reserved for time parameters (ex 'Acquisition Date') and allows to specify the date format (ex "yyyy-MM-dd HH:mm:ss")
        "description" gives more details on the MRI parameter.
        "units" indicates the unit of the parameter (s, ms, Hz, ....).
        "type" indicates the type of value (int, float, string).
        "value" gives the value of the parameter. It may be a simple value ([ ]) or a list of value ([[ ]]) .

Example :

"EchoTime": {
	"format": null,
	"description": "Time in ms between the middle of the excitation pulse and the peak of the echo produced ",
	"units": "ms",
	"type": "float",
	"value": [
		[
			8.81
		],
		[
			17.62
		],
		[
			26.43
		],
		[
			35.24
		],
		[
			44.05
		],
		[
			52.86
		],
		[
			61.67
		],
		[
			70.48
		],
		[
			79.29
		],
		[
			88.1
		],
		[
			96.91
		]
  	]
	},
		
		

Additional parameters

In addition to the MRI parameters, 2 other parameters supplement the Json file :

        - "Json_Version" that indicates the Json version.
        - "DataAnonymized" that indicates if the export has been anonymized.

	"Json_Version": [
		"Irmage2018"
	],
	"DataAnonymized: {	
		"format": "",
		"description": "",
		"units": "",
		"type": "string",
		"value": [
			"yes"
		]
	},
		

Example

Example of a Json file created by MRI File Manager :     13-SO2_MSME_SENSE.json