Editing Magnetic resonance imaging (section)

== Diagnostics ==

=== Usage by organ or system ===
[[File:Siemens Magnetom Aera MRI scanner.jpg|thumb|Patient being positioned for MR study of the head and abdomen]]

MRI has a wide range of applications in [[medical diagnosis]] and around 50,000 scanners are estimated to be in use worldwide.<ref>{{cite web |title=Magnetic Resonance, a critical peer-reviewed introduction |publisher=European Magnetic Resonance Forum |access-date=17 November 2014 |url=http://www.magnetic-resonance.org/ch/21-01.html}}</ref> MRI affects diagnosis and treatment in many specialties although the effect on improved health outcomes is disputed in certain cases.<ref name="ACPfive" /><ref name="backimage" />
[[File:Radiologist interpreting MRI.jpg|thumb|[[Radiology|Radiologist]] interpreting MRI images of head and neck]]
MRI is the investigation of choice in the preoperative [[cancer staging|staging]] of [[Colorectal cancer|rectal]] and [[prostate cancer]] and has a role in the diagnosis, staging, and follow-up of other tumors,<ref>{{cite book | vauthors=Husband J | title=Recommendations for Cross-Sectional Imaging in Cancer Management: Computed Tomography – CT Magnetic Resonance Imaging – MRI Positron Emission Tomography – PET-CT | date=2008 | url=http://www.rcr.ac.uk/docs/oncology/pdf/Cross_Sectional_Imaging_12.pdf | publisher=Royal College of Radiologists | isbn=978-1-905034-13-0 | access-date=2014-05-29 | archive-date=2012-09-07 | archive-url=https://web.archive.org/web/20120907100310/http://www.rcr.ac.uk/docs/oncology/pdf/Cross_Sectional_Imaging_12.pdf | url-status=dead }}</ref> as well as for determining areas of tissue for sampling in biobanking.<ref>{{cite journal | vauthors = Heavey S, Costa H, Pye H, Burt EC, Jenkinson S, Lewis GR, Bosshard-Carter L, Watson F, Jameson C, Ratynska M, Ben-Salha I, Haider A, Johnston EW, Feber A, Shaw G, Sridhar A, Nathan S, Rajan P, Briggs TP, Sooriakumaran P, Kelly JD, Freeman A, Whitaker HC | display-authors = 6 | title = PEOPLE: PatiEnt prOstate samPLes for rEsearch, a tissue collection pathway utilizing magnetic resonance imaging data to target tumor and benign tissue in fresh radical prostatectomy specimens | journal = The Prostate | volume = 79 | issue = 7 | pages = 768–777 | date = May 2019 | pmid = 30807665 | pmc = 6618051 | doi = 10.1002/pros.23782 }}</ref><ref>{{cite journal | vauthors = Heavey S, Haider A, Sridhar A, Pye H, Shaw G, Freeman A, Whitaker H | title = Use of Magnetic Resonance Imaging and Biopsy Data to Guide Sampling Procedures for Prostate Cancer Biobanking | journal = Journal of Visualized Experiments | issue = 152 | date = October 2019 | pmid = 31657791 | doi = 10.3791/60216 | doi-access = free }}</ref>

==== Neuroimaging ====
{{Main|Magnetic resonance imaging of the brain}}
{{See also|Neuroimaging}}
[[File:White Matter Connections Obtained with MRI Tractography.png|thumb|MRI diffusion tensor imaging of [[white matter]] tracts]]

MRI is the investigative tool of choice for neurological cancers over CT, as it offers better visualization of the [[posterior cranial fossa]], containing the [[brainstem]] and the [[cerebellum]]. The contrast provided between [[Grey matter|grey]] and [[white matter]] makes MRI the best choice for many conditions of the [[central nervous system]], including [[demyelinating disease]]s, [[dementia]], [[cerebrovascular disease]], [[List of infections of the central nervous system|infectious diseases]], [[Alzheimer's disease]] and [[epilepsy]].<ref>{{cite web |url=http://www.acr.org/~/media/ACR/Documents/PGTS/guidelines/MRI_Brain.pdf |title=ACR-ASNR Practice Guideline for the Performance and Interpretation of Magnetic Resonance Imaging (MRI) of the Brain |author=American Society of Neuroradiology |date=2013 |access-date=2013-11-10 |archive-url=https://web.archive.org/web/20170712013017/https://www.acr.org/~/media/ACR/Documents/PGTS/guidelines/MRI_Brain.pdf |archive-date=2017-07-12 |url-status=dead }}</ref><ref>{{cite journal| vauthors = Rowayda AS |title=An improved MRI segmentation for atrophy assessment|journal= International Journal of Computer Science Issues  |date=May 2012|volume=9|issue=3 }}</ref><ref>{{cite journal| vauthors = Rowayda AS |title=Regional atrophy analysis of MRI for early detection of alzheimer's disease|journal= International Journal of Signal Processing, Image Processing and Pattern Recognition |date=February 2013|volume=6|issue=1|pages=49–53}}</ref> Since many images are taken milliseconds apart, it shows how the brain responds to different stimuli, enabling researchers to study both the functional and structural brain abnormalities in psychological disorders.<ref name="Abnormal Psychology">{{cite book | vauthors = Nolen-Hoeksema S |title=Abnormal Psychology |date=2014 |publisher=McGraw-Hill Education |location=New York |page=67 |edition=Sixth}}</ref> MRI also is used in [[image guided surgery|guided]] [[stereotactic surgery]] and [[radiosurgery]] for treatment of intracranial tumors, arteriovenous malformations, and other surgically treatable conditions using a device known as the [[N-localizer]].<ref>{{cite journal | vauthors = Brown RA, Nelson JA | title = The Invention and Early History of the N-Localizer for Stereotactic Neurosurgery | journal = Cureus | volume = 8 | issue = 6 | pages = e642 | date = June 2016 | pmid = 27462476 | pmc = 4959822 | doi = 10.7759/cureus.642 | doi-access = free }}</ref><ref>
{{cite journal | vauthors = Leksell L, Leksell D, Schwebel J | title = Stereotaxis and nuclear magnetic resonance | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 48 | issue = 1 | pages = 14–8 | date = January 1985 | pmid = 3882889 | pmc = 1028176 | doi = 10.1136/jnnp.48.1.14 }}</ref><ref>{{cite journal | vauthors = Heilbrun MP, Sunderland PM, McDonald PR, Wells TH, Cosman E, Ganz E | title = Brown-Roberts-Wells stereotactic frame modifications to accomplish magnetic resonance imaging guidance in three planes | journal = Applied Neurophysiology | volume = 50 | issue = 1–6 | pages = 143–52 | year = 1987 | pmid = 3329837 | doi = 10.1159/000100700 }}</ref> New tools that implement [[artificial intelligence in healthcare]] have demonstrated higher image quality and morphometric analysis in [[neuroimaging]] with the application of a denoising system.<ref name="JON-December-2021">{{cite journal|title=The effect of a post-scan processing denoising system on image quality and morphometric analysis|first1=Noriko|last1=Kanemaru|first2=Hidemasa|last2=Takao|first3=Shiori|last3=Amemiya|first4=Osamu|last4=Abe|journal=Journal of Neuroradiology|date=2 December 2021|volume=49 |issue=2 |pages=205–212 |doi=10.1016/j.neurad.2021.11.007|pmid=34863809|s2cid=244907903|doi-access=free}}</ref>

The record for the highest spatial resolution of a whole intact brain (postmortem) is 100 microns, from Massachusetts General Hospital. The data was published in NATURE on 30 October 2019.<ref>{{Cite web|url=https://www.sciencealert.com/100-hour-mri-marathon-gives-the-world-its-closest-ever-3d-view-of-the-human-brain|title = 100-Hour-Long MRI of Human Brain Produces Most Detailed 3D Images Yet| date=10 July 2019 }}</ref><ref>{{Cite web|url=https://medicalxpress.com/news/2019-10-team-publishes-highest-resolution-brain.html|title = Team publishes on highest resolution brain MRI scan}}</ref>

Though MRI is used widely in research on mental disabilities, based on a 2024 systematic literature review and meta analysis commissioned by the Patient-Centered Outcomes Research Institute (PCORI), available research using MRI scans to diagnose ADHD showed great variability.<ref name=":0">{{Cite journal |title=ADHD Diagnosis and Treatment in Children and Adolescents |url=https://effectivehealthcare.ahrq.gov/products/attention-deficit-hyperactivity-disorder/research |access-date=2024-06-19 |website=effectivehealthcare.ahrq.gov |date=2024 |language=en |doi=10.23970/ahrqepccer267 |last1=Peterson |first1=Bradley S. |last2=Trampush |first2=Joey |last3=Maglione |first3=Margaret |last4=Bolshakova |first4=Maria |last5=Brown |first5=Morah |last6=Rozelle |first6=Mary |last7=Motala |first7=Aneesa |last8=Yagyu |first8=Sachi |last9=Miles |first9=Jeremy |last10=Pakdaman |first10=Sheila |last11=Gastelum |first11=Mario |last12=Nguyen |first12=Bich Thuy (Becky) |last13=Tokutomi |first13=Erin |last14=Lee |first14=Esther |last15=Belay |first15=Jerusalem Z. |last16=Schaefer |first16=Coleman |last17=Coughlin |first17=Benjamin |last18=Celosse |first18=Karin |last19=Molakalapalli |first19=Sreya |last20=Shaw |first20=Brittany |last21=Sazmin |first21=Tanzina |last22=Onyekwuluje |first22=Anne N. |last23=Tolentino |first23=Danica |last24=Hempel |first24=Susanne |pmid=38657097 }}</ref> The authors conclude that MRI cannot be reliably used to assist in making a clinical diagnosis of ADHD.<ref name=":0" />

==== Cardiovascular ====
{{Main|Cardiac magnetic resonance imaging}}
[[File:PAPVR.gif|thumb|MR angiogram in congenital heart disease]]

Cardiac MRI is complementary to other imaging techniques, such as [[echocardiography]], [[Computed tomography of the heart|cardiac CT]], and [[nuclear medicine]]. It can be used to assess the structure and the function of the heart.<ref>{{cite journal | vauthors = Petersen SE, Aung N, Sanghvi MM, Zemrak F, Fung K, Paiva JM, Francis JM, Khanji MY, Lukaschuk E, Lee AM, Carapella V, Kim YJ, Leeson P, Piechnik SK, Neubauer S | display-authors = 6 | title = Reference ranges for cardiac structure and function using cardiovascular magnetic resonance (CMR) in Caucasians from the UK Biobank population cohort | journal = Journal of Cardiovascular Magnetic Resonance | volume = 19 | issue = 1 | pages = 18 | date = February 2017 | pmid = 28178995 | pmc = 5304550 | doi = 10.1186/s12968-017-0327-9 | publisher = Springer Science and Business Media LLC | doi-access = free }}</ref> Its applications include assessment of [[Coronary artery disease|myocardial ischemia and viability]], [[Cardiomyopathy|cardiomyopathies]], [[myocarditis]], [[iron overload]], vascular diseases, and [[congenital heart defect|congenital heart disease]].<ref>{{cite journal | title = ACCF/ACR/SCCT/SCMR/ASNC/NASCI/SCAI/SIR 2006 appropriateness criteria for cardiac computed tomography and cardiac magnetic resonance imaging. A report of the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group | journal = Journal of the American College of Radiology | volume = 3 | issue = 10 | pages = 751–71 | date = October 2006 | pmid = 17412166 | doi = 10.1016/j.jacr.2006.08.008 | author1 = American College of Radiology | author2 = Society of Cardiovascular Computed Tomography | author3 = Society for Cardiovascular Magnetic Resonance | author4 = American Society of Nuclear Cardiology | author5 = North American Society for Cardiac Imaging | author6 = Society for Cardiovascular Angiography Interventions | author7 = Society of Interventional Radiology }}</ref>

==== Musculoskeletal ====
{{Main|Spinal fMRI}}
Applications in the musculoskeletal system include [[Spinal cord|spinal imaging]], assessment of [[joint]] disease, and [[Soft tissue pathology|soft tissue tumors]].<ref>{{cite book | vauthors=Helms C | title=Musculoskeletal MRI | date=2008 | publisher=Saunders | isbn=978-1-4160-5534-1 }}</ref> MRI techniques can also be used for diagnostic imaging of
[[Myopathy#Systemic diseases|systemic muscle diseases]] including genetic muscle diseases.<ref>{{cite journal |last1=Aivazoglou |first1=LU |last2=Guimarães |first2=JB |last3=Link |first3=TM |last4=Costa |first4=MAF |last5=Cardoso |first5=FN |last6=de Mattos Lombardi Badia |first6=B |last7=Farias |first7=IB |last8=de Rezende Pinto |first8=WBV |last9=de Souza |first9=PVS |last10=Oliveira |first10=ASB |last11=de Siqueira Carvalho |first11=AA |last12=Aihara |first12=AY |last13=da Rocha Corrêa Fernandes |first13=A |title=MR imaging of inherited myopathies: a review and proposal of imaging algorithms. |journal=European Radiology |date=21 April 2021 |volume=31 |issue=11 |pages=8498–8512 |doi=10.1007/s00330-021-07931-9 |pmid=33881569|s2cid=233314102 }}</ref><ref>{{cite journal | vauthors = Schmidt GP, Reiser MF, Baur-Melnyk A | title = Whole-body imaging of the musculoskeletal system: the value of MR imaging | journal = Skeletal Radiology | volume = 36 | issue = 12 | pages = 1109–19 | date = December 2007 | pmid = 17554538 | pmc = 2042033 | doi = 10.1007/s00256-007-0323-5 | publisher = Springer Nature | doi-access = free }}</ref>

Swallowing movements of the throat and esophagus can cause motion artifacts over the imaged spine. Therefore, a saturation pulse{{clarify|date=March 2022}} applied over this region the throat and esophagus can help to avoid these artifacts. Motion artifacts arising due to pumping of the heart can be reduced by timing the MRI pulse according to heart cycles.<ref name="pmid28611728">{{cite journal | vauthors = Havsteen I, Ohlhues A, Madsen KH, Nybing JD, Christensen H, Christensen A | title = Are Movement Artifacts in Magnetic Resonance Imaging a Real Problem?-A Narrative Review | journal = Frontiers in Neurology | volume = 8 | issue = | pages = 232 | date = 2017 | pmid = 28611728 | pmc = 5447676 | doi = 10.3389/fneur.2017.00232 | url = | doi-access = free }}</ref> Blood vessel flow artifacts can be reduced by applying saturation pulses above and below the region of interest.<ref>{{Cite journal |last1=Taber |first1=K H |last2=Herrick |first2=R C |last3=Weathers |first3=S W |last4=Kumar |first4=A J |last5=Schomer |first5=D F |last6=Hayman |first6=L A |date=November 1998 |title=Pitfalls and artifacts encountered in clinical MR imaging of the spine. |url=http://pubs.rsna.org/doi/10.1148/radiographics.18.6.9821197 |journal=RadioGraphics |language=en |volume=18 |issue=6 |pages=1499–1521 |doi=10.1148/radiographics.18.6.9821197 |pmid=9821197 |issn=0271-5333}}</ref>

==== Liver and gastrointestinal ====
[[Hepatobiliary system|Hepatobiliary]] MR is used to detect and characterize lesions of the [[liver]], [[pancreas]], and [[bile duct]]s. Focal or diffuse disorders of the liver may be evaluated using [[Diffusion MRI|diffusion-weighted]], opposed-phase imaging and [[Dynamic Contrast Enhanced MRI|dynamic contrast enhancement]] sequences. Extracellular contrast agents are used widely in liver MRI, and newer hepatobiliary contrast agents also provide the opportunity to perform functional biliary imaging. Anatomical imaging of the bile ducts is achieved by using a heavily T2-weighted sequence in [[Magnetic resonance cholangiopancreatography|magnetic resonance cholangiopancreatography (MRCP)]]. Functional imaging of the pancreas is performed following administration of [[secretin]]. MR enterography provides non-invasive assessment of inflammatory bowel disease and small bowel tumors. MR-colonography may play a role in the detection of large polyps in patients at increased risk of colorectal cancer.<ref name="FrydrychowiczLubner2012">{{cite journal | vauthors = Frydrychowicz A, Lubner MG, Brown JJ, Merkle EM, Nagle SK, Rofsky NM, Reeder SB | title = Hepatobiliary MR imaging with gadolinium-based contrast agents | journal = Journal of Magnetic Resonance Imaging | volume = 35 | issue = 3 | pages = 492–511 | date = March 2012 | pmid = 22334493 | pmc = 3281562 | doi = 10.1002/jmri.22833 }}</ref><ref name="SandrasegaranLin2010">{{cite journal | vauthors = Sandrasegaran K, Lin C, Akisik FM, Tann M | title = State-of-the-art pancreatic MRI | journal = AJR. American Journal of Roentgenology | volume = 195 | issue = 1 | pages = 42–53 | date = July 2010 | pmid = 20566796 | doi = 10.2214/ajr.195.3_supplement.0s42 }}</ref><ref name="MasselliGualdi2012">{{cite journal | vauthors = Masselli G, Gualdi G | title = MR imaging of the small bowel | journal = Radiology | volume = 264 | issue = 2 | pages = 333–48 | date = August 2012 | pmid = 22821694 | doi = 10.1148/radiol.12111658 }}</ref><ref name="ZijtaBipat2009">{{cite journal | vauthors = Zijta FM, Bipat S, Stoker J | title = Magnetic resonance (MR) colonography in the detection of colorectal lesions: a systematic review of prospective studies | journal = European Radiology | volume = 20 | issue = 5 | pages = 1031–46 | date = May 2010 | pmid = 19936754 | pmc = 2850516 | doi = 10.1007/s00330-009-1663-4 }}</ref>

==== Angiography ====
[[File:mra1.jpg|thumb|Magnetic resonance angiography]]
{{Main|Magnetic resonance angiography}}

Magnetic resonance [[angiography]] (MRA) generates pictures of the arteries to evaluate them for [[stenosis]] (abnormal narrowing) or [[aneurysm]]s (vessel wall dilatations, at risk of rupture). MRA is often used to evaluate the arteries of the neck and brain, the thoracic and abdominal aorta, the renal arteries, and the legs (called a "run-off"). A variety of techniques can be used to generate the pictures, such as administration of a [[paramagnetic]] contrast agent ([[gadolinium]]) or using a technique known as "flow-related enhancement" (e.g., 2D and 3D time-of-flight sequences), where most of the signal on an image is due to blood that recently moved into that plane (see also [[FLASH MRI]]).<ref name="Wheaton Miyazaki pp. 286–304">{{cite journal | vauthors = Wheaton AJ, Miyazaki M | title = Non-contrast enhanced MR angiography: physical principles | journal = Journal of Magnetic Resonance Imaging | volume = 36 | issue = 2 | pages = 286–304 | date = August 2012 | pmid = 22807222 | doi = 10.1002/jmri.23641 | publisher = Wiley | s2cid = 24048799 | doi-access = free }}</ref>

Techniques involving phase accumulation (known as phase contrast angiography) can also be used to generate flow velocity maps easily and accurately. Magnetic resonance venography (MRV) is a similar procedure that is used to image veins. In this method, the tissue is now excited inferiorly, while the signal is gathered in the plane immediately superior to the excitation plane—thus imaging the venous blood that recently moved from the excited plane.<ref name="haacke">{{cite book | vauthors = Haacke EM, Brown RF, Thompson M, Venkatesan R |title=Magnetic resonance imaging: Physical principles and sequence design |publisher=J. Wiley & Sons |location=New York |date=1999 |isbn=978-0-471-35128-3 }}{{page needed|date=July 2013}}</ref>

{{anchor|Contrast agents}}