DICOM PS3.3 2018d - Information Object Definitions

C.8.3 MR Modules

This Section describes the MR Image Module. This Module contains all Attributes that are specific to MR images.

C.8.3.1 MR Image Module

Table C.8-4 contains the Attributes that describe MR images.

Table C.8-4. MR Image Module Attributes

Attribute Name

Tag

Type

Attribute Description

Image Type

(0008,0008)

1

Image identification characteristics. See Section C.8.3.1.1.1 for specialization.

Samples per Pixel

(0028,0002)

1

Number of samples (planes) in this image. See Section C.8.3.1.1.2 for specialization.

Photometric Interpretation

(0028,0004)

1

Specifies the intended interpretation of the pixel data. See Section C.8.3.1.1.3 for specialization.

Bits Allocated

(0028,0100)

1

Number of bits allocated for each pixel sample. Each sample shall have the same number of bits allocated. See Section C.8.3.1.1.4 for specialization.

Bits Stored

(0028,0101)

1

Number of bits stored for each pixel sample. Each sample shall have the same number of bits stored.

High Bit

(0028,0102)

1

Most significant bit for pixel sample data. Each sample shall have the same high bit. High Bit (0028,0102) shall be one less than Bits Stored (0028,0101).

Scanning Sequence

(0018,0020)

1

Description of the type of data taken.

Enumerated Values:

SE

Spin Echo

IR

Inversion Recovery

GR

Gradient Recalled

EP

Echo Planar

RM

Research Mode

Note

Multi-valued, but not all combinations are valid (e.g., SE/GR, etc.).

Sequence Variant

(0018,0021)

1

Variant of the Scanning Sequence.

Defined Terms:

SK

segmented k-space

MTC

magnetization transfer contrast

SS

steady state

TRSS

time reversed steady state

SP

spoiled

MP

MAG prepared

OSP

oversampling phase

NONE

no sequence variant

Scan Options

(0018,0022)

2

Parameters of scanning sequence.

Defined Terms:

PER

Phase Encode Reordering

RG

Respiratory Gating

CG

Cardiac Gating

PPG

Peripheral Pulse Gating

FC

Flow Compensation

PFF

Partial Fourier - Frequency

PFP

Partial Fourier - Phase

SP

Spatial Presaturation

FS

Fat Saturation

MR Acquisition Type

(0018,0023)

2

Identification of data encoding scheme.

Enumerated Values:

2D

frequency x phase

3D

frequency x phase x phase

Repetition Time

(0018,0080)

2C

The period of time in msec between the beginning of a pulse sequence and the beginning of the succeeding (essentially identical) pulse sequence.

Required if Sequence Variant (0018,0021) is SK or if Scanning Sequence (0018,0020) is not EP. May be present otherwise.

Echo Time

(0018,0081)

2

Time in ms between the middle of the excitation pulse and the peak of the echo produced (kx=0). In the case of segmented k-space, the TE(eff) is the time between the middle of the excitation pulse to the peak of the echo that is used to cover the center of k-space (i.e., -kx=0, ky=0).

Echo Train Length

(0018,0091)

2

Number of lines in k-space acquired per excitation per image.

Inversion Time

(0018,0082)

2C

Time in msec after the middle of inverting RF pulse to middle of excitation pulse to detect the amount of longitudinal magnetization. Required if Scanning Sequence (0018,0020) has values of IR.

Trigger Time

(0018,1060)

2C

Time, in msec, between peak of the R wave and the peak of the echo produced. In the case of segmented k-space, the TE(eff) is the time between the peak of the echo that is used to cover the center of k-space. Required for Scan Options (0018,0022) that include heart gating (e.g., CG, PPG, etc.)

Sequence Name

(0018,0024)

3

User defined name for the combination of Scanning Sequence (0018,0020) and Sequence Variant (0018,0021).

Angio Flag

(0018,0025)

3

Angio Image Indicator. Primary image for Angio processing.

Enumerated Values:

Y

Image is Angio

N

Image is not Angio

Number of Averages

(0018,0083)

3

Number of times a given pulse sequence is repeated before any parameter is changed

Imaging Frequency

(0018,0084)

3

Precession frequency in MHz of the nucleus being addressed

Imaged Nucleus

(0018,0085)

3

Nucleus that is resonant at the imaging frequency. Examples: 31P, 1H

Echo Number(s)

(0018,0086)

3

The echo number used in generating this image. In the case of segmented k-space, it is the effective Echo Number.

Magnetic Field Strength

(0018,0087)

3

Nominal field strength of MR magnet, in Tesla

Spacing Between Slices

(0018,0088)

3

Spacing between slices, in mm. The spacing is measured from the center-to-center of each slice.

Number of Phase Encoding Steps

(0018,0089)

3

Total number of lines in k-space in the 'y' direction collected during acquisition.

Percent Sampling

(0018,0093)

3

Fraction of acquisition matrix lines acquired, expressed as a percent.

Percent Phase Field of View

(0018,0094)

3

Ratio of field of view dimension in phase direction to field of view dimension in frequency direction, expressed as a percent.

Pixel Bandwidth

(0018,0095)

3

Reciprocal of the total sampling period, in hertz per pixel.

Nominal Interval

(0018,1062)

3

Average R-R interval used for the scans, in msec

Beat Rejection Flag

(0018,1080)

3

Beat length sorting has been applied.

Enumerated Values:

Y

yes

N

no

Low R-R Value

(0018,1081)

3

R-R interval low limit for beat rejection, in msec

High R-R Value

(0018,1082)

3

R-R interval high limit for beat rejection, in msec

Intervals Acquired

(0018,1083)

3

Number of R-R intervals acquired.

Intervals Rejected

(0018,1084)

3

Number of R-R intervals rejected.

PVC Rejection

(0018,1085)

3

Description of type of PVC rejection criteria used.

Skip Beats

(0018,1086)

3

Number of beats skipped after a detected arrhythmia.

Heart Rate

(0018,1088)

3

Beats per minute.

Cardiac Number of Images

(0018,1090)

3

Number of images per cardiac cycle.

Trigger Window

(0018,1094)

3

Percent of R-R interval, based on Heart Rate (0018,1088), prescribed as a window for a valid/usable trigger.

Reconstruction Diameter

(0018,1100)

3

Diameter in mm. of the region from within which data were used in creating the reconstruction of the image. Data may exist outside this region and portions of the patient may exist outside this region.

The diameter defines a circular region that is entirely contained within the encoded Pixel Data (7FE0,0010), unless the encoded image has been cropped after reconstruction.

Note

If not cropped or padded, for square images with square pixels, both values of Pixel Spacing (0028,0030) will be equal and equal to Reconstruction Diameter (0018,1100) / Rows (0028,0010) and Reconstruction Diameter (0018,1100) / Columns (0028,0011).

Receive Coil Name

(0018,1250)

3

Receive coil used.

Transmit Coil Name

(0018,1251)

3

Transmit coil used.

Acquisition Matrix

(0018,1310)

3

Dimensions of the acquired frequency /phase data before reconstruction.

Multi-valued: frequency rows\frequency columns\phase rows\phase columns.

In-plane Phase Encoding Direction

(0018,1312)

3

The axis of phase encoding with respect to the image.

Enumerated Values:

ROW

phase encoded in rows.

COL

phase encoded in columns.

Flip Angle

(0018,1314)

3

Steady state angle in degrees to which the magnetic vector is flipped from the magnetic vector of the primary field.

SAR

(0018,1316)

3

Calculated whole body Specific Absorption Rate in watts/kilogram.

Variable Flip Angle Flag

(0018,1315)

3

Flip angle variation applied during image acquisition.

Enumerated Values:

Y

yes

N

no

dB/dt

(0018,1318)

3

The rate of change of the gradient coil magnetic flux density with time (T/s).

Temporal Position Identifier

(0020,0100)

3

Temporal order of a dynamic or functional set of Images.

Number of Temporal Positions

(0020,0105)

3

Total number of temporal positions prescribed.

Temporal Resolution

(0020,0110)

3

Time delta between Images in a dynamic or functional set of Images.

Include Table 10-7 “General Anatomy Optional Macro Attributes”

Defined CID for the Anatomic Region Sequence is 4030.

Include Table 10-25 “Optional View and Slice Progression Direction Macro Attributes”

Isocenter Position

(300A,012C)

3

Isocenter coordinates (x,y,z), in mm. Specifies the location of the machine isocenter in the Patient-Based Coordinate System associated with the Frame of Reference. It allows transformation from the Equipment-Based Coordinate System to the Patient-Based Coordinate System.

B1rms

(0018,1320)

3

B1+ rms value in units of micro_tesla (uT) for the acquisition producing the image. See [IEC 60601-2-33].


C.8.3.1.1 MR Image Attribute Descriptions
C.8.3.1.1.1 Image Type

For MR Images, Image Type (0008,0008) is specified to be Type 1.

Defined Terms for Value 3:

DENSITY MAP

DIFFUSION MAP

IMAGE ADDITION

MODULUS SUBTRACT

MPR

OTHER

PHASE MAP

PHASE SUBTRACT

PROJECTION IMAGE

T1 MAP

T2 MAP

VELOCITY MAP

C.8.3.1.1.2 Samples Per Pixel

Enumerated Values:

1

C.8.3.1.1.3 Photometric Interpretation

Enumerated Values:

MONOCHROME1

MONOCHROME2

See Section C.7.6.3.1.2 for definition of these terms.

C.8.3.1.1.4 Bits Allocated

Enumerated Values:

16

DICOM PS3.3 2018d - Information Object Definitions