Editing Magnetic resonance imaging (section)

=== Magnetic resonance spectroscopy ===

{{Main|In vivo magnetic resonance spectroscopy|Nuclear magnetic resonance spectroscopy}}

[[In vivo magnetic resonance spectroscopy|Magnetic resonance spectroscopy]] (MRS) is used to measure the levels of different [[metabolites]] in body tissues, which can be achieved through a variety of single voxel or imaging-based techniques.<ref>{{cite journal | vauthors = Landheer K, Schulte RF, Treacy MS, Swanberg KM, Juchem C | title = Theoretical description of modern <sup>1</sup> H in Vivo magnetic resonance spectroscopic pulse sequences | journal = Journal of Magnetic Resonance Imaging | volume = 51 | issue = 4 | pages = 1008–1029 | date = April 2020 | pmid = 31273880 | doi = 10.1002/jmri.26846 | s2cid = 195806833 }}</ref> The MR signal produces a spectrum of resonances that corresponds to different molecular arrangements of the isotope being "excited". This signature is used to diagnose certain metabolic disorders, especially those affecting the brain,<ref>{{cite journal | vauthors = Rosen Y, Lenkinski RE | title = Recent advances in magnetic resonance neurospectroscopy | journal = Neurotherapeutics | volume = 4 | issue = 3 | pages = 330–45 | date = July 2007 | pmid = 17599700 | pmc = 7479727 | doi = 10.1016/j.nurt.2007.04.009 | doi-access = free }}</ref> and to provide information on tumor [[metabolism]].<ref>{{cite journal | vauthors = Golder W | title = Magnetic resonance spectroscopy in clinical oncology | journal = Onkologie | volume = 27 | issue = 3 | pages = 304–9 | date = June 2004 | pmid = 15249722 | doi = 10.1159/000077983 | s2cid = 20644834 }}</ref>

Magnetic resonance spectroscopic imaging (MRSI) combines both spectroscopic and imaging methods to produce spatially localized spectra from within the sample or patient. The spatial resolution is much lower (limited by the available [[Signal-to-noise ratio|SNR]]), but the spectra in each voxel contains information about many metabolites. Because the available signal is used to encode spatial and spectral information, MRSI requires high SNR achievable only at higher field strengths (3 T and above).<ref name="DW Al. 2018">{{cite journal | vauthors = Chakeres DW, Abduljalil AM, Novak P, Novak V | title = Comparison of 1.5 and 8 tesla high-resolution magnetic resonance imaging of lacunar infarcts | journal = Journal of Computer Assisted Tomography | volume = 26 | issue = 4 | pages = 628–32 | year = 2002 | pmid = 12218832 | doi = 10.1097/00004728-200207000-00027 | s2cid = 32536398 }}</ref> The high procurement and maintenance costs of MRI with extremely high field strengths<ref>{{cite web |url=https://www.medischcontact.nl/nieuws/laatste-nieuws/artikel/mri-scanner-van-7-miljoen-in-gebruik.htm |title=MRI-scanner van 7 miljoen in gebruik |trans-title=MRI scanner of €7 million in use |language=nl |publisher=Medisch Contact |date=December 5, 2007 }}</ref> inhibit their popularity. However, recent [[compressed sensing]]-based software algorithms (''e.g.'', [[SAMV (algorithm)|SAMV]]<ref name=AbeidaZhang>{{cite journal |doi=10.1109/tsp.2012.2231676 |title=Iterative Sparse Asymptotic Minimum Variance Based Approaches for Array Processing |journal=IEEE Transactions on Signal Processing |volume=61 |issue=4 |pages=933–44 |year=2013 | vauthors = Abeida H, Zhang Q, Li J, Merabtine N |arxiv=1802.03070 |bibcode=2013ITSP...61..933A |s2cid=16276001 }}</ref>) have been proposed to achieve [[Super-resolution imaging|super-resolution]] without requiring such high field strengths.