Quantitative susceptibility mapping

A volume rendered brain QSM acquired at 3 Tesla and reconstructed with morphology enabled dipole inversion (MEDI).

Quantitative susceptibility mapping (QSM) provides a novel contrast mechanism in magnetic resonance imaging (MRI) different from traditional susceptibility weighted imaging.[1][2][3][4][5]

The voxel intensity in QSM is linearly proportional to the underlying tissue apparent magnetic susceptibility, which is useful for chemical identification and quantification of specific biomarkers including iron, calcium, gadolinium, and super paramagnetic iron oxide (SPIO) nano-particles. QSM utilizes phase images, solves the magnetic field to susceptibility source inverse problem, and generates a three-dimensional susceptibility distribution. Due to its quantitative nature and sensitivity to certain kinds of material, potential QSM applications include standardized quantitative stratification of cerebral microbleeds and neurodegenerative disease, accurate gadolinium quantification in contrast enhanced MRI, and direct monitoring of targeted theranostic drug biodistribution in nanomedicine.

Background

A visualization of the cone in Fourier domain.

In MRI, the local field induced by non-ferromagnetic biomaterial susceptibility along the main polarization B0 field is the convolution of the volume susceptibility distribution with the dipole kernel : . This spatial convolution can be expressed as a point-wise multiplication in Fourier domain:[6][7] . This Fourier expression provides an efficient way to predict the field perturbation when the susceptibility distribution is known. However, the field to source inverse problem involves division by zero at a pair of cone surfaces at the magic angle with respect to B0 in the Fourier domain. Consequently, susceptibility is underdetermined at the spatial frequencies on the cone surface, which often leads to severe streaking artifacts in the reconstructed QSM.

Techniques

Data acquisition

In principle, any 3D gradient echo sequence can be used for data acquisition. In practice, high resolution imaging with a moderately long echo time is preferred to obtain sufficient susceptibility effects, although the optimal imaging parameters depend on the specific applications and the field strength. A multi-echo acquisition is beneficial for accurate B0 field measurement without the contribution from B1 inhomogeneity. Flow compensation may further improve the accuracy of susceptibility measurement in venous blood, but there are certain technical difficulties to devise a fully flow compensated multi-echo sequence.

Background field removal

Estimated local field maps using left) high-pass filtering method, right) projection onto dipole fields (PDF) method.

In human brain quantitative susceptibility mapping, only the local susceptibility sources inside the brain are of interest. However, the magnetic field induced by the local sources is inevitably contaminated by the field induced by other sources such as main field inhomogeneity (imperfect shimming) and the air-tissue interface, whose susceptibility difference is orders of magnitudes stronger than that of the local sources. Therefore, the non-biological background field needs to be removed for clear visualization on phase images and precise quantification on QSM.

Ideally, the background field can be directly measured with a separate reference scan, where the sample of interest is replaced by a uniform phantom with the same shape while keeping the scanner shimming identical. However, for clinical application, such an approach is impossible and post-processing based methods are preferred. Traditional heuristic methods, including high-pass filtering, are useful for the background field removal, although they also tamper with the local field and degrade the quantitative accuracy.

More recent background field removal methods directly or indirectly exploit the fact that the background field is a harmonic function. Two recent methods based on physical principles, projection onto dipole fields (PDF)[8] and sophisticated harmonic artifact reduction on phase data (SHARP),[9] demonstrated improved contrast and higher precision on the estimated local field. Both methods model the background field as a magnetic field generated by an unknown background susceptibility distribution, and differentiate it from the local field using either the approximate orthogonality or the harmonic property. The background field can also be directly computed by solving the Laplace's equation with simplified boundary values, as demonstrated in the Laplacian boundary value (LBV) method.[10]

Field-to-source inversion

The field-to-source inverse problem can be solved by several methods with various associated advantages and limitations.

Calculation of susceptibility through multiple orientation sampling (COSMOS)

The first QSM image reconstructed using COSMOS to quantify gadolinium concentrations in vials. a) magnitude image; b) field map; c) QSM; d) linear regression.

COSMOS solves the inverse problem by oversampling from multiple orientations.[11][12] COSMOS utilizes the fact that the zero cone surface in the Fourier domain is fixed at the magic angle with respect to the B0 field. Therefore, if an object is rotated with respect to the B0 field, then in the object's frame, the B0 field is rotated and thus the cone. Consequently, data that cannot be calculated due to the cone becomes available at the new orientations.

COSMOS assumes a model-free susceptibility distribution and keeps full fidelity to the measured data. This method has been validated extensively in in vitro, ex vivo and phantom experiments. Quantitative susceptibility maps obtained from in vivo human brain imaging also showed high degree of agreement with previous knowledge about brain anatomy. Three orientations are generally required for COSMOS, limiting the practicality for clinical applications. However, it may serve as a reference standard when available for calibrating other techniques.

Morphology enabled dipole inversion (MEDI)

A unique advantage of MRI is that it provides not only the phase image but also the magnitude image. In principle, the contrast change, or equivalently the edge, on a magnitude image arises from the underlying change of tissue type, which is the same cause for the change of susceptibility. This observation is translated into mathematics in MEDI,[13] where edges in a QSM which do not exist in the corresponding magnitude image are sparsified by solving a weighted norm minimization problem.[14]

MEDI has also been validated extensively in phantom, in vitro and ex vivo experiments. In an in vivo human brain, MEDI calculated QSM showed similar results compared to COSMOS without statistically significant difference.[15] MEDI only requires a single angle acquisition, so it is a more practical solution to QSM.

Thresholded K-space division (TKD)

The underdetermined data in Fourier domain is only at the location of the cone and its immediate vicinity. For this region in k-space, spatial-frequencies of the dipole kernel are set to a predetermined non-zero value for the division. Investigation of more advanced strategies for recovering data in this k-space region is also a topic of ongoing research.[16]

Thresholded k-space division[12][17] only requires a single angle acquisition, and benefits from the ease of implementation as well as the fast calculation speed. However, streaking artifacts are frequently present in the QSM and the susceptibility value is underestimated compared to COSMOS calculated QSM.

Potential clinical applications

Differentiating calcification from iron

Differentiation between calcification and iron. From left to right are magnitude, phase and QSM.

It has been confirmed in in vivo and phantom experiments that cortical bones, whose major composition is calcification, are diamagnetic compared to water.[11][18] Therefore, it is possible to use this diamagnetism to differentiate calcifications from iron deposits that usually demonstrate strong paramagnetism.[19] This may allow QSM to serve as a problem solving tool for the diagnosis of confounding hypointense findings on T2* weighted images.

Quantification of contrast agent

For exogenous susceptibility sources, the susceptibility value is theoretically linearly proportional to the concentration of the contrast agent. This provides a new way for in vivo quantification of gadolinium or SPIO concentrations.[20]

References

  1. ^ 1st International Workshop on MRI Phase Contrast and Quantitative Susceptibility Mapping, Jena (2011)
  2. ^ 2nd International Workshop on MRI Phase Contrast & Quantitative Susceptibility Mapping, Cornell (2013)
  3. ^ 3rd International Workshop on MRI Phase Contrast & Quantitative Susceptibility Mapping, Duke (2014)
  4. ^ 4th International Workshop on MRI Phase Contrast & Quantitative Susceptibility Mapping, Graz (2016)
  5. ^ Wang, Yi (2014). "Quantitative susceptibility mapping (QSM): Decoding MRI data for a tissue magnetic biomarker". Magnetic Resonance in Medicine. 73 (1): 82–101. doi:10.1002/mrm.25358. PMC 4297605. PMID 25044035.
  6. ^ Salomir, Rares; De Senneville, Baudouin Denis; Moonen, Chrit TW (2003). "A fast calculation method for magnetic field inhomogeneity due to an arbitrary distribution of bulk susceptibility". Concepts in Magnetic Resonance. 19B: 26–34. doi:10.1002/cmr.b.10083.
  7. ^ Marques, J.P.; Bowtell, R. (2005). "Application of a Fourier-based method for rapid calculation of field inhomogeneity due to spatial variation of magnetic susceptibility". Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering. 25B: 65–78. doi:10.1002/cmr.b.20034. hdl:2066/195319.
  8. ^ Liu, Tian; Khalidov, Ildar; de Rochefort, Ludovic; Spincemaille, Pascal; et al. (2011). "A novel background field removal method for MRI using projection onto dipole fields". NMR in Biomedicine. 24 (9): 1129–36. doi:10.1002/nbm.1670. PMC 3628923. PMID 21387445.
  9. ^ Schweser, Ferdinand; Deistung, Andreas; Lehr, Berengar Wendel; Reichenbach, Jürgen Rainer (2011). "Quantitative imaging of intrinsic magnetic tissue properties using MRI signal phase: an approach to in vivo brain iron metabolism?". NeuroImage. 54 (4): 2789–2807. doi:10.1016/j.neuroimage.2010.10.070. PMID 21040794. S2CID 19593094.
  10. ^ Zhou, Dong; Liu, Tian; Spincemaille, Pascal; Wang, Yi (2014). "Background field removal by solving the Laplacian boundary value problem". NMR in Biomedicine. 27 (3): 312–9. doi:10.1002/nbm.3064. PMID 24395595. S2CID 1815936.
  11. ^ a b Liu, Tian; Spincemaille, Pascal; De Rochefort, Ludovic; Kressler, Bryan; et al. (2009). "Calculation of susceptibility through multiple orientation sampling (COSMOS): A method for conditioning the inverse problem from measured magnetic field map to susceptibility source image in MRI". Magnetic Resonance in Medicine. 61 (1): 196–204. doi:10.1002/mrm.21828. PMID 19097205. S2CID 41444063.
  12. ^ a b Wharton, Sam; Schäfer, Andreas; Bowtell, Richard (2010). "Susceptibility mapping in the human brain using threshold-based k-space division". Magnetic Resonance in Medicine. 63 (5): 1292–304. doi:10.1002/mrm.22334. PMID 20432300. S2CID 206278637.
  13. ^ De Rochefort, Ludovic; Liu, Tian; Kressler, Bryan; Liu, Jing; et al. (2009). "Quantitative susceptibility map reconstruction from MR phase data using bayesian regularization: Validation and application to brain imaging". Magnetic Resonance in Medicine. 63 (1): 194–206. doi:10.1002/mrm.22187. PMID 19953507.
  14. ^ Liu, J; Liu, T; de Rochefort, L; Khalidov, I (2010). "Quantitative susceptibility mapping by regulating the field to source inverse problem with a sparse prior derived from the Maxwell Equation: validation and application to brain" (PDF). Proc. Intl. Soc. Mag. Reson. Med. 18: 4996. Archived from the original (PDF) on October 16, 2015. Retrieved January 26, 2011.
  15. ^ Liu, Tian; Liu, Jing; de Rochefort, Ludovic; Spincemaille, Pascal; et al. (September 2011). "Morphology enabled dipole inversion (MEDI) from a single-angle acquisition: Comparison with COSMOS in human brain imaging". Magnetic Resonance in Medicine. 66 (3): 777–83. doi:10.1002/mrm.22816. PMID 21465541.
  16. ^ Li, Wei; Wu, Bing; Liu, Chunlei (2011). "Quantitative susceptibility mapping of human brain reflects spatial variation in tissue composition". NeuroImage. 55 (4): 1645–56. doi:10.1016/j.neuroimage.2010.11.088. PMC 3062654. PMID 21224002.
  17. ^ Shmueli, Karin; De Zwart, Jacco A.; Van Gelderen, Peter; Li, Tie-Qiang; et al. (2009). "Magnetic susceptibility mapping of brain tissue in vivo using MRI phase data". Magnetic Resonance in Medicine. 62 (6): 1510–22. doi:10.1002/mrm.22135. PMC 4275127. PMID 19859937.
  18. ^ De Rochefort, Ludovic; Brown, Ryan; Prince, Martin R.; Wang, Yi (2008). "Quantitative MR susceptibility mapping using piece-wise constant regularized inversion of the magnetic field". Magnetic Resonance in Medicine. 60 (4): 1003–9. doi:10.1002/mrm.21710. PMID 18816834.
  19. ^ Schweser, Ferdinand; Deistung, Andreas; Lehr, Berengar W.; Reichenbach, JüRgen R. (2010). "Differentiation between diamagnetic and paramagnetic cerebral lesions based on magnetic susceptibility mapping". Medical Physics. 37 (10): 5165–78. Bibcode:2010MedPh..37.5165S. doi:10.1118/1.3481505. PMID 21089750.
  20. ^ De Rochefort, Ludovic; Nguyen, Thanh; Brown, Ryan; Spincemaille, Pascal; et al. (2008). "In vivo quantification of contrast agent concentration using the induced magnetic field for time-resolved arterial input function measurement with MRI". Medical Physics. 35 (12): 5328–39. Bibcode:2008MedPh..35.5328D. doi:10.1118/1.3002309. PMID 19175092.

Read other articles:

Belgae

Peta Galia sebelum masa penaklukan Romawi menurut interpretasi Caesar. Belgae (/ˈbɛldʒiː/ atau /ˈbɛlɡaɪ/[1]) adalah sebuah konfederasi besar[2] suku-suku yang tinggal di Galia utara semenjak abad ke-3 SM. Wilayah mereka terletak di antara Selat Inggris, tepi barat Sungai Rhein, dan tepi utara Sungei Seine. Keberadaan mereka dijelaskan secara rinci oleh Julius Caesar dalam catatan perangnya di Galia. Beberapa suku di Britania juga dijuluki Belgae dan O'Rahilly menyamaka...

 

Iredentisme Tiongkok

Evolusi wilayah Tiongkok sepanjang sejarah Tiongkok. Iredentisme Tiongkok mengacu pada klaim iredentis yang dibuat oleh Republik Tiongkok[a] dan kemudian oleh Republik Rakyat Tiongkok kepada wilayah bekas Kekaisaran Tiongkok. Lihat pula Portal Tiongkok Kolonialisme Ekspansionisme Tiongkok Nasionalisme Tiongkok Sauvinisme Han Sentimen anti-Tiongkok Sinikisasi Sinosentrisme Sistem upeti Tiongkok Pax Sinica Zaman keemasan Tiongkok Sengketa wilayah Republik Rakyat Tiongkok Catatan ^ Repub...

 

Talinaceae

Talinaceae Talinum fruticosum Klasifikasi ilmiah Domain: Eukaryota Kerajaan: Plantae Divisi: Magnoliophyta Ordo: Caryophyllales Famili: Talinaceae(Fenzl) Doweld[1] Genus Amphipetalum Talinum (termasuk Talinella) Talinaceae atau suku kolesom-kolesoman adalah keluarga dari dua genus dan 28 spesies[2] tumbuhan berbunga yang terdiri dari semak, liana, dan spesies herba yang berasal dari Amerika, Afrika, dan Madagaskar. Famili ini baru dikenali melalui penelitian oleh sistem klasi...

Mitch McConnell

Mitch McConnellMcConnell di tahun 2016 Pemimpin Minoritas Dewan SenatPetahanaMulai menjabat 20 Januari 2021WakilJohn Thune PendahuluChuck SchumerPenggantiPetahanaPemimpin Mayoritas Dewan SenatMasa jabatan3 January 2015 – 20 Januari 2021Wakil John Cornyn John Thune PendahuluHarry ReidPenggantiChuck SchumerPemimpin Konferensi Senat Partai RepublikPetahanaMulai menjabat 3 Januari 2007Wakil Trent Lott Jon Kyl John Cornyn John Thune PendahuluBill FristPenggantiPetahanaWhip untuk...

 

İstanbul Efsaneleri: Lale Savaşçıları

This article does not cite any sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: İstanbul Efsaneleri: Lale Savaşçıları – news · newspapers · books · scholar · JSTOR (April 2012) (Learn how and when to remove this template message) 1994 video gameİstanbul Efsaneleri: Lale SavaşçılarıDeveloper(s)SiliconWorxPublisher(s)Raks New MediaPlatform(s)Amiga, ...

 

Giulietta Simionato

Italian opera singer Giulietta Simionato (born Giulia Simionato; Forlì, Romagna, 12 May 1910 – Rome, 5 May 2010) was an Italian mezzo-soprano. Her career spanned the period from the 1930s until her retirement in 1966. Life As a girl she studied in a boarding school with nuns who sensed her musical qualities and invited her to study singing, which she did against the opposition of the family, especially her mother.  After the latter's death, Giulietta studied first in Rovigo, then in P...

Teratai

Artikel ini membutuhkan rujukan tambahan agar kualitasnya dapat dipastikan. Mohon bantu kami mengembangkan artikel ini dengan cara menambahkan rujukan ke sumber tepercaya. Pernyataan tak bersumber bisa saja dipertentangkan dan dihapus.Cari sumber: Teratai – berita · surat kabar · buku · cendekiawan · JSTOR Terate beralih ke halaman ini. Untuk desa di Sumatera Selatan, lihat Terate, Sirah Pulau Padang, Ogan Komering Ilir. Untuk desa di Banten, lihat Ter...

 

St Augustine's, Whitton

Church in EnglandSt Augustine's, WhittonChurch of St Augustine of Canterbury, WhittonThe church in 2009LocationHospital Bridge Road, Whitton, London TW2 6DECountryEngland, United KingdomDenominationChurch of EnglandWebsitewww.st-augustine-of-canterbury-whitton.orgHistoryFounded1935DedicationSt Augustine of CanterburyArchitectureYears built1958AdministrationDioceseLONDONArchdeaconryMiddlesexDeaneryHamptonClergyMinister(s)The Revd Canon John Kafwanka K[1] St Augustine's, Whitton, on Ho...

 

Evelyn Furtsch

Evelyn Furtsch Evelyn Furtsch nel 1932 Nazionalità  Stati Uniti Altezza 158 cm Peso 43 kg Atletica leggera Specialità Velocità Società LAAC Record 100 m 122 (1932) CarrieraNazionale 1932 Stati UnitiPalmarès Competizione Ori Argenti Bronzi Giochi olimpici 1 0 0 Per maggiori dettagli vedi qui   Modifica dati su Wikidata · Manuale Evelyn Pearl Furtsch-Ojeda (San Diego, 17 aprile 1914 – Santa Ana, 5 marzo 2015) è stata una velocista statunitense, campionessa olimpica dell...

Ligoire

la Ligoire Caractéristiques Longueur 20,9 km Bassin collecteur Loire Régime pluvial Cours · Localisation Varennes · Altitude 134 m · Coordonnées 47° 05′ 29″ N, 0° 55′ 54″ E Confluence l'Esves · Localisation Sepmes · Altitude 60 m · Coordonnées 47° 02′ 52″ N, 0° 41′ 41″ E Géographie Pays traversés France Département Indre-et-Loire Régions traversées Centre-Val de Loire Sources : ...

 

Nonena

Artikel ini bukan mengenai Nonana atau Nonuna. Nonena adalah sebuah alkena dengan rumus molekul C9H18. Banyak isomer struktural nonena yang mungkin terjadi, bergantung pada lokasi ikatan rangkap C=C dan percabangan bagian lain dari molekulnya. Secara industri, nonena yang paling penting adalah trimer dari propena: Tripropilena. Campuran nonena bercabang ini digunakan dalam alkilasi fenol untuk menghasilkan nonilfenol, sebuah prekursor detergen, yang juga merupakan polutan kontroversial.[1...

 

Dark Rising

FilmDark RisingDirected byAndrew CymekWritten by Andrew Cymek Mihkel Harilaid Produced by Mihkel Harilaid Brigitte Kingsley Productioncompanies Black Walk Defiant Empire Dark Rising is a sword and sorcery adult-oriented franchise of two made-for-television films, a twelve-episode television miniseries and another five-episode television miniseries, from the husband and wife team of Andrew Cymek and Brigitte Kingsley. The franchise is written by creator Cymek, produced by Kingsley and adapted ...

Buteogallus

Genus of birds ButeogallusTemporal range: Middle Miocene to present Great black hawk (Buteogallus urubitinga) Scientific classification Domain: Eukaryota Kingdom: Animalia Phylum: Chordata Class: Aves Order: Accipitriformes Family: Accipitridae Subfamily: Buteoninae Genus: ButeogallusLesson, RP, 1830 Type species Buteogallus cathartoides[1] = Falco aequinoctialisLesson, 1830 Species see text Synonyms Alectromorphnus Heine & Reichenow, [1890] Heterospizias Harpyhaliaetus Wetmoregyp...

 

Walter Harrison (politician)

British politician Walter HarrisonHarrison when Deputy Chief Whip in the 1970sTreasurer of the Household and Deputy Chief WhipIn office4 March 1974 – 4 May 1979MonarchElizabeth IIPrime MinisterHarold Wilson James CallaghanMember of Parliament for WakefieldIn office15 October 1964 – 18 May 1987Preceded byArthur Creech JonesSucceeded byDavid Hinchliffe Personal detailsBorn2 January 1921Died19 October 2012 (aged 91)NationalityBritishPolitical partyLabour Walter Harrison PC ...

 

Monroe, Washington

City in Washington, United States City in Washington, United StatesMonroeCityMain Street and Lewis Street in downtown MonroeLocation of Monroe, WashingtonCoordinates: 47°51′28″N 121°59′18″W / 47.85778°N 121.98833°W / 47.85778; -121.98833CountryUnited StatesStateWashingtonCountySnohomishFounded1864IncorporatedDecember 20, 1902Government • TypeMayor–council • MayorGeoffrey ThomasArea[1] • Total6.16 sq mi...

Minder (TV series)

British television comedy-drama series (1979–1994, 2009) Arthur Daley redirects here. For the American journalist, see Arthur Daley (sportswriter). MinderOriginal title sequence featuring Dennis Waterman (1979–1989)GenreComedy dramaCreated byLeon GriffithsStarring Dennis Waterman (series 1–7) George Cole (series 1-10) Glynn Edwards Patrick Malahide (series 1–6) Peter Childs (series 1–7) Gary Webster (series 8–10) Shane Richie (series 11) Lex Shrapnel (series 11) Country of originU...

 

Jeans

Disambiguazione – Se stai cercando altri significati, vedi Jeans (disambigua). Disambiguazione – Blue jeans rimanda qui. Se stai cercando altri significati, vedi Blue jeans (disambigua). Questa voce o sezione sull'argomento abbigliamento non cita le fonti necessarie o quelle presenti sono insufficienti. Puoi migliorare questa voce aggiungendo citazioni da fonti attendibili secondo le linee guida sull'uso delle fonti. Un paio di jeans Levi's Il termine jeans[1], o blu...

 

Scialografia

Le informazioni riportate non sono consigli medici e potrebbero non essere accurate. I contenuti hanno solo fine illustrativo e non sostituiscono il parere medico: leggi le avvertenze. ScialografiaProcedura diagnostica Scialografia di un paziente con sospetta Sindrome di SjögrenTipoEsame radiologico AnestesiaNo MeSHD012796 MedlinePlus003812 La scialografia (o sialografia) è una tecnica radiologica, oggi raramente utilizzata, che consiste nell'iniezione di un liquido di contrasto iodato e d...

Batwheels

American superhero children's television series BatwheelsPromotional posterGenre Preschool Comedy Superhero Based onBatmanby Bob KaneBill FingerDeveloped byMichael G. SternVoices of A.J. Hudson Ethan Hawke Jacob Bertrand Jordan Reed Kimberly D. Brooks Leah Lewis Lilimar Madigan Kacmar Mick Wingert Noah Bentley Titus Blake Theme music composerAndy SturmerComposerAlex GeringasCountry of originUnited StatesOriginal languageEnglishNo. of seasons2No. of episodes50ProductionExecutive producers Sam ...

 

Filippo Balatri

Balatri al clavicembalo: particolare dal quadro di Peter Jacob Horemans, 1733 Filippo Balatri (Alfea, 21 febbraio 1682[1] – Fürstenfeld (Baviera), 10 settembre 1756) è stato un sopranista italiano. Fu noto ed apprezzato dalle corti europee per le sue doti canore di soprano evirato[2] e per il suo spirito buffonesco. Indice 1 Biografia 2 Opere 3 Note 4 Bibliografia 5 Altri progetti 6 Collegamenti esterni Biografia Nacque ad Alfea nei pressi di Pisa, da una famiglia nobile.&...