Missing Dwell Time Information

[Marco Pipoly]

Hello Experts,

I am working with HCPpipelines to process Seimans 3T MAGNETON Vida scanner T1w and FLAIR data. HCPpipelines requires(?) spacing information for both the T1w and FLAIR images, sometimes reffered to as dwell time. In my data, this information is absent from the json side car files. I believe this is because the DICOM field (0019,1018) does not exist for these subjects structural images.

Resources on how to calculate this information manually have been unclear. Is it something like, DwellTime = 1/(bandwidthperpixel x readoutpoints) ? Any advice or direction is welcome.

Thank you,

Marco

[Glasser, Matthew]

Can you try to run dcm2niix and post what is in the JSON.

Matt.

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[Glasser, Matthew]

I would update to the latest version of dcm2niix.

Matt.

 

From: Marco Pipoly <mapl...@gmail.com>
Date: Tuesday, August 12, 2025 at 11:27 AM
To: HCP-Users <hcp-...@humanconnectome.org>
Cc: "Glasser, Matthew" <glas...@wustl.edu>
Subject: Re: [hcp-users] Missing Dwell Time Information

 

Sure - see below

{
    "Modality": "MR",
    "MagneticFieldStrength": 3,
    "ImagingFrequency": 123.24,
    "Manufacturer": "Siemens",
    "ManufacturersModelName": "MAGNETOM Vida",
    "InstitutionName": "UNT Healthcare",
    "DeviceSerialNumber": "4zbO6JROdtUA",
    "BodyPartExamined": "BRAIN",
    "PatientPosition": "HFS",
    "SoftwareVersions": "syngo MR XA20",
    "MRAcquisitionType": "3D",
    "SeriesDescription": "SAG MPRAGE",
    "ProtocolName": "SAG MPRAGE",
    "SequenceVariant": "SK\\SP\\MP",
    "ImageType": [
        "ORIGINAL",
        "PRIMARY",
        "M",
        "NONE"
    ],
    "SeriesNumber": 5,
    "AcquisitionNumber": 1,
    "SliceThickness": 1,
    "EchoTime": 0.00298,
    "RepetitionTime": 2.3,
    "InversionTime": 0.9,
    "FlipAngle": 9,
    "CoilString": "Spine_24_RS",
    "PercentPhaseFOV": 93.75,
    "PercentSampling": 100,
    "AcquisitionMatrixPE": 240,
    "ReconMatrixPE": 240,
    "PixelBandwidth": 238,
    "ImageOrientationPatientDICOM": [
        0.0446964,
        0.962347,
        0.268123,
        0.0207095,
        0.267441,
        -0.963352
    ],
    "InPlanePhaseEncodingDirectionDICOM": "ROW",
    "ConversionSoftware": "dcm2niix",
    "ConversionSoftwareVersion": "v1.0.20210317",
    "Dcm2bidsVersion": "2.1.6"
}

[Marco Pipoly]

Hi Matt,

Thank you! It seems the update provided the missing information. 

[Marco Pipoly]