Digital Imaging and Communications in Medicine (DICOM)dicom.nema.org/Dicom/News/June2015/docs/sups/sup181.pdf · >>>Include Table 8.8-1 “Code Sequence Macro Attributes” Defined
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Digital Imaging and Communications in Medicine (DICOM) 6
Supplement 181: MR Diffusion Tractography Storage SOP Class 8
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Prepared by:
DICOM Standards Committee, Working Group 16 (MR) & 24 (Surgery) 18
1300 N. 17th Street, Suite 1752
Rosslyn, Virginia 22209 USA 20
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VERSION: Letter Ballot, 2015/06/23 24
Developed in accordance with: DICOM Workitem 2014-08-A
This is a draft document. Do not circulate, quote, or reproduce it except with the approval of NEMA. 26
This Supplement to the DICOM Standard specifies a new DICOM Information Object for storing magnetic 44 resonance diffusion tractography (MR DT) results (tracks and measurements), which is referred to as MR Diffusion Tractography IOD. It also includes the corresponding Storage SOP Class so that this IOD can be 46 used for network and media storage exchanges.
A tracking algorithm produces tracks (i.e. fibers), which are collected into track sets. A track contains the 48 set of x, y and z coordinates of each point making up the track. Depending upon the algorithm and software used, additional quantities like Fractional Anisotropy (FA) values or color etc. may be associated 50 with the data, by track set, track or point, either to facilitate further filtering or for clinical use. Descriptive statistics of quantities like FA may be associated with the data by track set or track. 52
Examples of tractography applications include:
• Visualization of white matter tracks to aid in resection planning or to support image guided 54 (neuro)surgery;
• Determination of proximity and/or displacement versus infiltration of white matter by tumor 56 processes;
• Assessment of white matter health in neurodegenerative disorders, both axonal and myelin 58 integrity, through sampling of derived diffusion parameters along the white matter tracks.
The MR Diffusion Tractography Storage IOD encodes diffusion tractography results into a collection of track sets. A track set collects a set of tracks containing the set of x, y and z coordinates of each point 80 making up the track. Additional quantities like FA values, color, descriptive statistical values, etc. may be associated with track 82 set, track or point.
A.X.2 MR Diffusion Tractography Storage IOD Entity-Relationship Model 84
The E-R Model in Section A.1.2 of this Part depicts those components of the DICOM Information Model that directly reference the MR Diffusion Tractography IOD. Below the Diffusion Tractography IE is used for 86 representation of track sets.
Include Table 10-12 “Content Identification Macro Attributes”
Content Date (0008,0023) 1 The date the content creation started.
Content Time (0008,0033) 1 The time the content creation started.
Track Set Sequence (gggg,eee1) 1 Describes the track sets that are contained within the data.
One or more Items shall be included in this sequence.
>Track Set Number (gggg,eee5) 1 Identification number of the Track Set. The value of Track Set Number (gggg,eee5) shall be unique within this instance, start at a value of 1, and increase monotonically by 1.
>Track Set Label (gggg,eee6) 1 User-defined label identifying this Track Set. This may be the same as Code Meaning (0008,0104) of Track Set Property Type Code Sequence (gggg,eee8).
>Track Set Description (gggg,eee7) 3 User-defined description for this Track Set.
>Track Set Anatomical Type Code Sequence (gggg,eee8) 1 Sequence defining the specific property type of this Track Set.
Only a single item shall be included in this sequence.
>Track Sequence (gggg,eee2) 1 Describes individual tracks part of the track set.
One or more Items shall be included in this sequence.
>>Point Coordinates Data (0066,0016) 1 Point coordinates that define the track, encoded as successive x,y,z points, in mm in the patient-based coordinate system associated with the Frame of Reference. The order of the encoded points is from the first point to the last point of the track.
>>Recommended Display CIELab Value List (gggg,eee3) 1C Default triplet values in which it is recommended that the point shall be rendered. The units are specified in PCS-Values and the value is encoded as CIELab.
See Section C.10.7.1.1.
The number of triplets shall match the number of points stored in Point Coordinates Data (0066, 0016), and be encoded in the same order so as to correspond.
Shall be present if Recommended Display CIELab Value (0062, 000D) is not present in this Sequence Item nor in the containing Track Set Sequence (gggg,eee1) Item.
>>Recommended Display CIELab Value (0062,000D) 1C Default triplet value in which it is recommended that the track shall be rendered. The units are specified in PCS-Values and the value is encoded as CIELab.
See Section C.10.7.1.1.
Shall be present if Recommended Display CIELab Value List (gggg,eee3) is not present in this Sequence Item and Recommended Display CIELab Value (0062, 000D) is not present in the containing Track Set Sequence (gggg,eee1) Item.
>Recommended Display CIELab Value (0062,000D) 1C Default triplet value in which it is recommended that the track set be rendered. The units are specified in PCS-Values, and the value is encoded as CIELab.
See Section C.10.7.1.1.
Shall be present if neither Recommended Display CIELab Value (0062, 000D) nor Recommended Display CIELab Value List (gggg,eee3) are present in every Item of the Track Sequence (gggg,eee2).
>Track Point Values Sequence (gggg,ee21) 3 Additional values for some or all points along the tracks.
See section C.8.X.1.1 for more details.
One or more Items shall be included in this sequence.
>>Track Point Value Type Code Sequence (gggg,ee22) 1 Defines the type of value data stored in this Item.
Only a single item shall be included in this sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” Defined CID XXX4 Diffusion Tractography Value Types
>>Measurement Units Code Sequence (0040,08EA) 1 Units of measurement for the value in this item.
Only a single item shall be included in this sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” Defined CID 82 “Units of Measurement”.
>>Values Sequence (gggg,ee32) 1 The additional values for each track.
The number and order of items shall equal the items in Track Sequence (gggg,eee2).
>>>Floating Point Values (gggg,ee25) 1C A value for every point stored in Point Coordinates Data (0066, 0016) of the corresponding track in Track Sequence (gggg,eee2).
Number of values shall match the number of points stored in Point Coordinates Data (0066, 0016), and be encoded in the same order so as to correspond.
Required if Coordinate Value Pairs Sequence (gggg,ee26) is not present.
>>>Coordinate Value Pairs Sequence (gggg,ee26) 1C The value for a subset of points stored in Point Coordinates Data (0066, 0016) of the corresponding track in Track Sequence (gggg,eee2).
Required if Floating Point Values (gggg,ee25) is not present.
One or more Items shall be included in this sequence.
>>>>Point Index (gggg,ee29) 1 The index of an (x,y,z) point encoded in Point Coordinates Data (0066,0016) such that the first point ((x,y,z) tuple) is numbered 1, the second point is 2, etc.
Note: This is the index of the (x,y,z) tuple, not the offset of the individual x, y and z values. I.e., the second point is 2, not 4.
>>>>Floating Point Value (0040,A161) 1 The value for the point specified by Point Index (gggg,ee29).
>Track Statistics Sequence (gggg,ee30) 3 One statistic for one data value per track in the Track Sequence (gggg,eee2).
See section C.8.X.1.1 for more details.
One or more Items shall be included in this sequence.
>>Value Summarized Type Code Sequence (gggg,ee27) 1 The value (quantity) for which the statistic is a summary.
Only a single item shall be included in this sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” Defined CID XXX4 Diffusion Tractography Value Types
>>Summary Statistic Type Code Sequence (gggg,ee28) 1 The type of the statistic.
Only a single item shall be included in this sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” Defined CID 7464 General Region of Interest Measurement Modifiers.
>>Measurement Units Code Sequence (0040,08EA) 1 Units of measurement for the statistic.
Only a single item shall be included in this sequence.
>>>Include Table 8.8-1 “Code Sequence Macro Attributes” Defined CID 82 “Units of Measurement”.
>>Floating Point Values (gggg,ee25) 1 A value per track in the Track Sequence (gggg,eee2).
The number and order of values shall equal the items in the Track Sequence (gggg,eee2).
>Track Set Statistics Sequence (gggg,ee24) 3 Statistics derived from the values for this Track Set.
One or more Items shall be included in this sequence.
>>Include Table C8.X-2 “Summary Statistics Macro Attributes” Defined CID for Value Summarized Type Code Sequence (gggg,ee27) is CID XXX4 Diffusion Tractography Value Types
>Diffusion Acquisition Sequence (gggg,ee33) 3 The diffusion acquisition (including post-processing) used to derive this track set.
See section C.8.X.1.2 for more details.
Only a single item shall be included in this sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” Defined CID XXX1 Diffusion Acquisition Value Types
>Diffusion Model Sequence (gggg,ee34) 1 The diffusion model used to derive this track set.
See section C.8.X.1.2 for more details.
Only a single item shall be included in this sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” Defined CID XXX2 Diffusion Model Value Types
>Tracking Algorithm Identification Sequence (gggg,eee4) 1 The tractography algorithms used to derive this track set.
See section C.8.X.1.2 for more details.
One or more items shall be included in this sequence.
>>Include Table 10-19 “Algorithm Identification Macro Attributes” For Algorithm Family Code Sequence (0066,002F) Defined CID XXX3 “MR Diffusion Tractography Algorithm Families”.
C.8.X.1.1 Diffusion Tractography Module Attributes This Module encodes one or more Track Sets, each of which consists of one or more Tracks, which is 110 defined by one or more points. For each Track, optionally one or more values may be defined, either for every point or a subset of points. The values are described by coded type and unit. For each Track and/or 112 Track Set, summary statistics derived from point values may be included (whether or not the actual values are encoded). 114
For a particular value type (item of Track Point Values Sequence (gggg,ee21)), when a value is encoded for every point in a track, then Floating Point Values (gggg,ee25) contains the corresponding value for 116 every point. When only a subset of points in a track are encoded with values then one or more (point index, value) tuples are encoded in Coordinate Value Pairs Sequence (gggg,ee26). 118
More than one Track Point Values Sequence (gggg,ee21) Item may be used, for example to encode different types of values, such as FA and ADC, or to encode different components of a value that is a 120 tuple, e.g. a diffusion tensor. In the latter case, which component, and which tensor, will be identified by the fully pre-coordinated code in the Track Point Value Type Code Sequence (gggg,ee22). 122
Within one Track Set the different types of additional values or statistics must be the same for all Tracks within that set (i.e. it is not allowed to store one track to a set that does not contain an additional value of a 124 specific type in case all other tracks within that set do).
C.8.X.1.2 Acquisition, Model and Algorithm Attributes 126
The attributes Diffusion Acquisition Sequence (gggg,eee5), Diffusion Model Sequence (gggg,eee6) and Tracking Algorithm Identification Sequence (gggg,eee4) describe the main parameters influencing the 128 tractography calculation. They are for documentation purposes. With these parameters it is for example possible to make assumptions on the reliability / quality of the tractography result. 130
C.8.X.2 Summary Statistics Macro This Macro encodes summary statistics derived from a set of values. 132
110808 Fractional Anisotropy Coefficient reflecting the fractional anisotropy of the tissues, derived from a diffusion weighted MR image. Fractional anisotropy is proportional to the square root of the variance of the Eigen values divided by the square root of the sum of the squares of the Eigen values.
110809 Relative Anisotropy Coefficient reflecting the relative anisotropy of the tissues, derived from a diffusion weighted MR image.
110810 Volumetric Diffusion Dxx Component
Dxx Component of the diffusion tensor, quantifying the molecular mobility along the X axis.
110811 Volumetric Diffusion Dxy Component
Dxy Component of the diffusion tensor, quantifying the correlation of molecular displacements in the X and Y directions.
110812 Volumetric Diffusion Dxz Component
Dxz Component of the diffusion tensor, quantifying the correlation of molecular displacements in the X and Z directions.
110813 Volumetric Diffusion Dyy Component
Dyy Component of the diffusion tensor, quantifying the molecular mobility along the Y axis.
110814 Volumetric Diffusion Dyz Dyz Component of the diffusion tensor, quantifying the correlation of molecular displacements in the Y
Dzz Component of the diffusion tensor, quantifying the molecular mobility along the Z axis.
113041 Apparent Diffusion Coefficient The image is derived by calculation of the apparent diffusion coefficient.
… … … …
sup181_dddd01 Trace Tr = λ1+ λ2+ λ3 sum of the diffusion tensor eigenvalues,
where λ1 ≥ λ2 ≥ λ3
Winston GP. The physical and biological basis of quantitative parameters derived from diffusion MRI. Quantitative Imaging in Medicine and Surgery. 2012;2(4):254-265. doi:10.3978/j.issn.2223-4292.2012.12.05. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3533595/)
sup181_dddd02 Mean Diffusivity MD = (λ1+ λ2+ λ3)/3 average of the diffusion tensor eigenvalues in all directions
Winston GP. The physical and biological basis of quantitative parameters derived from diffusion MRI. Quantitative Imaging in Medicine and Surgery. 2012;2(4):254-265. doi:10.3978/j.issn.2223-4292.2012.12.05. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3533595/)
sup181_dddd03 Radial Diffusivity DR= (λ2+ λ3)/2 average of the two non-principal (i.e. perpendicular) diffusion tensor eigenvalues (a/k/a transverse, perpendicular)
Winston GP. The physical and biological basis of quantitative parameters derived from diffusion MRI. Quantitative Imaging in Medicine and Surgery. 2012;2(4):254-265. doi:10.3978/j.issn.2223-4292.2012.12.05.
sup181_dddd04 Axial Diffusivity DA = λ1 diffusion tensor eigenvalue of the principal axis (a/k/a longitudinal, parallel)
Winston GP. The physical and biological basis of quantitative parameters derived from diffusion MRI. Quantitative Imaging in Medicine and Surgery. 2012;2(4):254-265. doi:10.3978/j.issn.2223-4292.2012.12.05. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3533595/)
sup181_dddd05 Mean Kurtosis MK = diffusional kurtosis averaged over all gradient directions, analogous to MD
Tabesh A, Jensen JH, Ardekani BA, Helpern JA. Estimation of Tensors and Tensor-Derived Measures in Diffusional Kurtosis Imaging. Magnetic Resonance in Medicine. 2011;65(3):823-836. doi:10.1002/mrm.22655. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3042509/)
Liu C, Mang SC, Moseley ME. In Vivo Generalized Diffusion Tensor Imaging (GDTI) Using Higher-Order Tensors (HOT). Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine. 2010;63(1):243-252. doi:10.1002/mrm.22192. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824337/)
sup181_dddd06 Apparent Kurtosis Coefficient AKC = diffusional kurtosis in a given direction, analogous to ADC
Liu C, Mang SC, Moseley ME. In Vivo Generalized Diffusion Tensor Imaging (GDTI) Using Higher-Order Tensors (HOT). Magnetic
resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine. 2010;63(1):243-252. doi:10.1002/mrm.22192. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824337/)
sup181_dddd09 Fractional Kurtosis Anisotropy
FKA = fractional kurtosis of diffusion in tissues, analogous to FA
Liu C, Mang SC, Moseley ME. In Vivo Generalized Diffusion Tensor Imaging (GDTI) Using Higher-Order Tensors (HOT). Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine. 2010;63(1):243-252. doi:10.1002/mrm.22192. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824337/)
sup181_dddd08 Axial Kurtosis KA = diffusional kurtosis in the direction of the highest diffusion (a/k/a longitudinal, parallel), analogous to DA
Tabesh A, Jensen JH, Ardekani BA, Helpern JA. Estimation of Tensors and Tensor-Derived Measures in Diffusional Kurtosis Imaging. Magnetic Resonance in Medicine. 2011;65(3):823-836. doi:10.1002/mrm.22655. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3042509/)
sup181_dddd07 Radial Kurtosis KR = diffusional kurtosis perpendicular to the direction of the highest diffusion (a/k/a transverse, perpendicular), analogous to DR
Tabesh A, Jensen JH, Ardekani BA, Helpern JA. Estimation of Tensors and Tensor-Derived Measures in Diffusional Kurtosis Imaging. Magnetic Resonance in Medicine. 2011;65(3):823-836. doi:10.1002/mrm.22655. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3042509/)
sup181_ee01 Deterministic Tracking based on local directionality Descoteaux M, Deriche
R, Knösche TR, Anwander A. Deterministic and probabilistic tractography based on complex fibre orientation distributions. IEEE Trans Med Imaging. 2009; 28(2):269-86 (http://www.ncbi.nlm.nih.gov/pubmed/19188114)
sup181_ee02 Probabilistic Tracking using local fiber orientation likelihood derive global connectivity likelihood
Descoteaux M, Deriche R, Knösche TR, Anwander A. Deterministic and probabilistic tractography based on complex fibre orientation distributions. IEEE Trans Med Imaging. 2009; 28(2):269-86 (http://www.ncbi.nlm.nih.gov/pubmed/19188114)
sup181_ee03 Global Tracking all fibers simultaneously, searching for a global optimum.
Reisert M, Mader I, Anastasopoulos C, Weigel M, Schnell S, Kiselev V. Global fiber reconstruction becomes practical. NeuroImage. 2011 Jan 15;54(2):955–62. (http://www.ncbi.nlm.nih.gov/pubmed/20854913)
sup181_ee04 FACT Fiber Assessment by Continuous Tracking Mori S, Crain BJ,
Chacko VP, van Zijl PC. Three-dimensional tracking of axonal projections in the brain by magnetic resonance imaging. Ann Neurol. 1999 Feb;45(2):265-9 (http://www.ncbi.nlm.nih.gov/pubmed/9989633)
Anwander A. Deterministic and probabilistic tractography based on complex fibre orientation distributions. IEEE Trans Med Imaging. 2009; 28(2):269-86 (http://www.ncbi.nlm.nih.gov/pubmed/19188114)
Pierpaoli C, Duda J, Aldroubi A. In vivo fiber tractography using DT-MRI data. Magn Reson Med. 2000 Oct;44(4):625-32 (http://www.ncbi.nlm.nih.gov/pubmed/11025519)
sup181_ee06 TEND Tensor Deflection Lazar M, Weinstein DM,
Tsuruda JS, Hasan KM, Arfanakis K, Meyerand ME, Badie B, Rowley HA, Haughton V, Field A, Alexander AL. White matter tractography using diffusion tensor deflection. Hum Brain Mapp. 2003 Apr;18(4):306-21. (http://www.ncbi.nlm.nih.gov/pubmed/12632468)
sup181_ee07 Bootstrap Non-parametric estimation of fiber tracking dispersion
Lazar M, Alexander AL. Bootstrap white matter tractography (BOOT-TRAC). Neuroimage. 2005 Jan 15;24(2):524-32. Epub 2004 Nov 24. (http://www.ncbi.nlm.nih.gov/pubmed/15627594)
Jones DK, Pierpaoli C. Confidence mapping in diffusion tensor magnetic resonance imaging tractography using a bootstrap approach. Magn Reson Med. 2005 May;53(5):1143-9. (http://www.ncbi.nlm.ni
sup181_ee08 Euler Integration method, 1st order Basser PJ, Pajevic S,
Pierpaoli C, Duda J, Aldroubi A. In vivo fiber tractography using DT-MRI data. Magn Reson Med. 2000 Oct;44(4):625-32 (http://www.ncbi.nlm.nih.gov/pubmed/11025519)
Descoteaux M, Deriche R, Knösche TR, Anwander A. Deterministic and probabilistic tractography based on complex fibre orientation distributions. IEEE Trans Med Imaging. 2009; 28(2):269-86 (http://www.ncbi.nlm.nih.gov/pubmed/19188114)
sup181_ee09 Runge-Kutta Integration method, 2nd or 4th order Basser PJ, Pajevic S,
Pierpaoli C, Duda J, Aldroubi A. In vivo fiber tractography using DT-MRI data. Magn Reson Med. 2000 Oct;44(4):625-32 (http://www.ncbi.nlm.nih.gov/pubmed/11025519)
Anwander A. Deterministic and probabilistic tractography based on complex fibre orientation distributions. IEEE Trans Med Imaging. 2009; 28(2):269-86 (http://www.ncbi.nlm.nih.gov/pubmed/19188114)
sup181_aa02 DKI Diffusion(al) Kurtosis Imaging Jensen JH, Helpern JA,
Ramani A, Lu H, Kaczynski K. Diffusional kurtosis imaging: the quantification of non-gaussian water diffusion by means of magnetic resonance imaging. Magn Reson Med. 2005 Jun;53(6):1432-40. (http://www.ncbi.nlm.nih.gov/pubmed/15906300)
sup181_aa03 DTI Diffusion Tensor Imaging Winston GP. The physical and biological basis of quantitative parameters derived from diffusion MRI. Quantitative Imaging in Medicine and Surgery. 2012;2(4):254-265. doi:10.3978/j.issn.2223-4292.2012.12.05. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3533595/)
sup181_aa04 DSI Diffusion Spectrum Imaging Wedeen VJ, Wang RP, Schmahmann JD, Benner T, Tseng WY, Dai G, Pandya DN, Hagmann P, D'Arceuil H, de Crespigny AJ. Diffusion spectrum magnetic resonance imaging (DSI) tractography of crossing fibers. Neuroimage. 2008 Jul 15;41(4):1267-77. doi: 10.1016/j.neuroimage.2008.03.036. (http://www.ncbi.nlm.ni
sup181_bb01 Single Tensor Modeling anisotropic diffusion in a volume with a tensor following a Gaussian distribution (six degrees of freedom)
Basser PJ, Mattiello J, LeBihan D. Estimation of the effective self-diffusion tensor from the NMR spin echo. J Magn Reson B. 1994 Mar;103(3):247-54. (http://www.ncbi.nlm.nih.gov/pubmed/8019776) Hagmann P1, Jonasson L, Maeder P, Thiran JP, Wedeen VJ, Meuli R. Understanding diffusion MR imaging techniques: from scalar diffusion-weighted imaging to diffusion tensor imaging and beyond. Radiographics. 2006 Oct;26 Suppl 1:S205-23. (http://www.ncbi.nlm.nih.gov/pubmed/17050517)
sup181_bb02 Multi Tensor Modeling anisotropic diffusion in a volume by fitting of multiple tensors
Ozarslan E, Mareci TH. Generalized diffusion tensor imaging and analytical relationships between diffusion tensor imaging and high angular resolution diffusion imaging. Magn Reson Med. 2003 Nov;50(5):955-65. (http://www.ncbi.nlm.nih.gov/pubmed/14587006) Pasternak O, Assaf Y, Intrator N, Sochen N. Variational multiple-tensor fitting of fiber-ambiguous diffusion-weighted magnetic resonance imaging voxels. Magn Reson Imaging. 2008 Oct;26(8):1133-44. doi: 10.1016/j.mri.2008.01.006. (http://www.ncbi.nlm.nih.gov/pubmed/18524529 )
sup181_bb03 Model Free Reconstruction of anisotropic diffusion in a volume without imposing an underlying statistical model (data-driven approach)
magnetic resonance imaging. Magn Reson Med. 2005 Dec;54(6):1377-86. (http://www.ncbi.nlm.nih.gov/pubmed/16247738) Hagmann P, Jonasson L, Maeder P, Thiran JP, Wedeen VJ, Meuli R. Understanding diffusion MR imaging techniques: from scalar diffusion-weighted imaging to diffusion tensor imaging and beyond. Radiographics. 2006 Oct;26 Suppl 1:S205-23. (http://www.ncbi.nlm.nih.gov/pubmed/17050517)
sup181_bb04 CHARMED Composite Hindered and Restricted Model of Diffusion
Assaf Y, Basser PJ. Composite hindered and restricted model of diffusion (CHARMED) MR imaging of the human brain. Neuroimage. 2005 Aug 1;27(1):48-58. (http://www.ncbi.nlm.nih.gov/pubmed/17050517)
sup181_bb05 DSI Diffusion Spectrum Imaging Wedeen VJ, Wang RP, Schmahmann JD, Benner T, Tseng WY, Dai G, Pandya DN, Hagmann P, D'Arceuil H, de Crespigny AJ. Diffusion spectrum magnetic resonance imaging (DSI) tractography of crossing fibers. Neuroimage. 2008 Jul 15;41(4):1267-77. doi: 10.1016/j.neuroimage.2008.03.036. (http://www.ncbi.nlm.nih.gov/pubmed/18495497) Hagmann P, Jonasson L, Maeder P, Thiran JP, Wedeen VJ, Meuli R. Understanding diffusion MR imaging techniques: from scalar diffusion-weighted
imaging to diffusion tensor imaging and beyond. Radiographics. 2006 Oct;26 Suppl 1:S205-23. (http://www.ncbi.nlm.nih.gov/pubmed/17050517)
sup181_bb06 DOT Diffusion Orientation Transform Ozarslan E, Shepherd TM, Vemuri BC, Blackband SJ, Mareci TH. Resolution of complex tissue microarchitecture using the diffusion orientation transform (DOT). Neuroimage. 2006 Jul 1;31(3):1086-103. Epub 2006 Mar 20. (http://www.ncbi.nlm.nih.gov/pubmed/16546404)
sup181_bb07 PAS Persistent Angular Structure Jansons KM, Alexander DC. Persistent Angular Structure: new insights from diffusion MRI data. Dummy version. Inf Process Med Imaging. 2003 Jul;18:672-83. (http://www.ncbi.nlm.nih.gov/pubmed/15344497)
sup181_bb08 Spherical Deconvolution A method to estimate the distribution of fiber orientations by deconvolution of the diffusion-weighted signal attenuation measured over the surface of a sphere expressed as the convolution over the sphere of a response function.
Tournier JD, Calamante F, Gadian DG, Connelly A. Direct estimation of the fiber orientation density function from diffusion-weighted MRI data using spherical deconvolution. NeuroImage. 2004 Nov;23(3):1176–85. (http://www.ncbi.nlm.nih.gov/pubmed/15528117)
XX Diffusion Tractography Storage Encoding Example (Informative) This section illustrates the usage of the MR Diffusion Tractography Module (PS 3.3 C.X.1) in the context of 174 the MR Diffusion Tractography Storage IOD.
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Figure XX-1. Two Example Track Sets. “Track Set Left” with two tracks, “Track Set Right” with one track.
178
Figure XX-1 shows two example track sets. The example consists of:
• Two track sets “Track Set Left” and “Track Set Right” 180
- Track Set Sequence (gggg,eee1) => each item describes one track set. 182
• Track Set “Track Set Left” contains two tracks “A” and “B” 184
- Track Sequence (gggg,eee2) => each item describes one track. 186
• Track “A” consists of: 188
o 4 points 190
- Point Coordinates Data (0066,0016) => describes the coordinates for all points in 192 the track.
- Recommended Display CIELab Value List (gggg,eee3) => describes the colors for all points in the track. 198
o Fractional anisotropy for each point 200
- On how the values are stored, see description in “Encoding of Additional Values” 202 below. 204
o Apparent diffusion coefficient for point 1 and 3 206
- On how the values are stored, see description in “Encoding of Additional Values” below. 208
• Track “B” consists of: 210
o 3 points 212
- Point Coordinates Data (0066,0016) => describes the coordinates for all points in 214
the track. 216
o Same color for each point 218
- Recommended Display CIELab Value (0062,000D) => describes the color for all points in the track. 220
o Fractional anisotropy for each point 222
- On how the values are stored, see description in “Encoding of Additional Values” 224
below. 226
o Apparent diffusion coefficient for point 2 228
- On how the values are stored, see description in “Encoding of Additional Values” below. 230
• Encoding of Additional Values for Tracks “A” and “B” 232
o General explanatory comment to C.8.X.1.1: For storing additional values like Fractional 234
anisotropy or Apparent diffusion coefficient values on specific points on a track the overall view over all tracks of a given track set is needed. Only tracks shall be grouped in track sets 236 that share a specific type of additional value. 238
o Track Point Value Sequence (gggg,ee21) => each item describes one value type of all tracks in the track set (here: “Track Set Left” contains two value types: Fractional anisotropy 240 and Apparent diffusion coefficient).
242 o Values Sequence (gggg,ee32) => one item for each and every track of a track set.
244 - When used to store Fractional anisotropy values:
Since a Fractional anisotropy value is stored for each and every point in both tracks 246 of “Track Set Left”, Floating Point Values (gggg,ee25) is used containing an array of Fractional anisotropy values for tracks “A” and “B” respectively. 248
- When used to store Apparent diffusion coefficient values: 250
Since an Apparent diffusion coefficient value is stored only for a subset of points in both tracks of “Track Set Left”, Coordinate Value Pairs Sequence (gggg,ee26) is 252 used containing the index to the point in Point Coordinates Data (0066,0016) the additional value corresponds to and the value itself. 254
256
• Track Set “Track Set Right” contains one track “C” 258
• Track “C” consists of: 260
o 3 points 262
- Point Coordinates Data (0066,0016) => describes the coordinates for all points in the track. 264
o Same color for all points 266
- Recommended Display CIELab Value (0062,000D) => describes the color for all 268 points in the track set (Note: In this example this attribute is stored on Track Set level). 270
o No additional values 272
The table XX-1 shows the encoding of the Diffusion Tractography module for the example above. In addition to the two example track sets the table XX-1 also encodes the following information: 274
• Within “Track Set Left” the mean fractional anisotropy values for track “A” (0.475) and “B” (0.667). • For “Track Set Left” the maximum fractional anisotropy value (0.9). 276 • Diffusion acquisition, model and tracking algorithm information. • Image instance references used to define the tractography instance. 278
Table XX-1. Example of the Diffusion Tractography Module 280
Name Tag Value Comment Instance Number (0020,0013) 1 Content Label (0070,0080) Left and Right Content Description (0070,0081) Two Sample Tracksets
Content Creator’s Name (0070,0084) <empty> Type 2 Attribute
Content Date (0008,0023) 20150529 Content Time (0008,0033) 121933.000000 Track Set Sequence (gggg,eee1)
Item 1 (First Track Set “Track Set Left”) >Track Set Number (gggg,eee5) 1 >Track Set Label (gggg,eee6) Track Set Left
Item 2 (Second Track Set “Track Set Right”) >Track Set Number (gggg,eee5) 2 >Track Set Label (gggg,eee6) Track Set Right >Track Set Anatomical Type Code Sequence (gggg,eee8)