• DICOM tag for Field-of-view in MRI

    From Serafeim Loukas@21:1/5 to Yves Martel on Mon Sep 6 02:47:43 2021
    On Thursday, September 20, 2001 at 3:31:44 PM UTC+2, Yves Martel wrote:
    Bonjour Thomas,
    There is the (0018,1100) tag, "Reconstruction Diameter",
    but it is optional (type 3) and I have not seen it in Gyroscan images.
    Can't you get the information by :
    Rows (0028,0010) * Pixel Spacing (0028,0030) ?
    Yves
    Hi colleagues!
    Does anybody know if there is a DICOM tag in the MRI - IOD for the "FOV" (field of view)?
    Attention: I do not mean the "Percent phase filed of view (0018,0094)!
    We are currently using aPhilips Gyroscan NT R6.1 and have the urgent need for getting this information out of digital images within our pacs for the reason of exact repeating of follow - up`s.

    thanks for aour help
    thomas



    Hi all.

    I am also trying to estimate the FOV (field of view) using information that is available in the header of my dicom fMRI image.

    There is no FOV tag in my Dicom header.

    Is it correct to use the below equation as suggested in this forum?
    FOVx = “Columns (0028,0011)” * first element of “Pixel Spacing (0028,0030)” ?
    FOVy = “Rows (0028,0010)” * second element of “Pixel Spacing (0028,0030)” ?

    PS: Pixel Spacing is the voxel size in x and y axis in mm.

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  • From Mathieu Malaterre@21:1/5 to Serafeim Loukas on Mon Sep 6 05:29:07 2021
    On Monday, September 6, 2021 at 11:47:45 AM UTC+2, Serafeim Loukas wrote:
    On Thursday, September 20, 2001 at 3:31:44 PM UTC+2, Yves Martel wrote:
    Bonjour Thomas,
    There is the (0018,1100) tag, "Reconstruction Diameter",
    but it is optional (type 3) and I have not seen it in Gyroscan images. Can't you get the information by :
    Rows (0028,0010) * Pixel Spacing (0028,0030) ?
    Yves
    Hi colleagues!
    Does anybody know if there is a DICOM tag in the MRI - IOD for the "FOV" (field of view)?
    Attention: I do not mean the "Percent phase filed of view (0018,0094)! We are currently using aPhilips Gyroscan NT R6.1 and have the urgent need
    for getting this information out of digital images within our pacs for the
    reason of exact repeating of follow - up`s.

    thanks for aour help
    thomas


    Hi all.

    I am also trying to estimate the FOV (field of view) using information that is available in the header of my dicom fMRI image.

    There is no FOV tag in my Dicom header.

    Is it correct to use the below equation as suggested in this forum?
    FOVx = “Columns (0028,0011)” * first element of “Pixel Spacing (0028,0030)” ?
    FOVy = “Rows (0028,0010)” * second element of “Pixel Spacing (0028,0030)” ?

    PS: Pixel Spacing is the voxel size in x and y axis in mm.

    Given the definition of Pixel Spacing:

    Physical distance in the patient between the center of each pixel, specified by a numeric pair - adjacent row spacing (delimiter) adjacent column spacing in mm. See Section 10.7.1.3 for further explanation.

    ref:
    * http://dicom.nema.org/medical/dicom/current/output/chtml/part03/sect_C.7.6.2.html#table_C.7-10

    I suspect the above equations should read instead:

    FOVx = “Columns (0028,0011)” * second element of “Pixel Spacing (0028,0030)” ?
    FOVy = “Rows (0028,0010)” * first element of “Pixel Spacing (0028,0030)” ?

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  • From David Gobbi@21:1/5 to All on Tue Sep 7 08:11:30 2021
    Be careful. The PixelSpacing and the Rows/Columns relate to the reconstructed image, rather than to the acquisition. During reconstruction it's not uncommon to pad the k-space (which modifies the spacing), and the image space (which modifies the size).

    In other words, the acquisition FOV cannot always be reliably calculated from PixelSpacing and Rows/Columns. The calculation will work for some MR reconstructions, but not for all.

    A more reliable (but still not perfect) way to get the field of view is "Reconstruction Diameter (0018,1100)," which is often used to store the FOV in the frequency-encode direction. Multiply this by "PercentPhaseFieldOfView (0018,0094)" (and divide by
    100) to get the FOV in the phase-encode direction.

    Use the "InPlanePhaseEncodingDirection (0018,1312)" to figure out whether phase encoding is in the COL or ROW direction. The "AcquisitionMatrix (0018,1310)", if present, is a reliable way to get the rows/columns for the acquisition.

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