Computed tomography of the head

Computed tomography (CT) has become the diagnostic modality of choice for head trauma due to its accuracy, reliability, safety, and wide availability. The changes in microcirculation, impaired auto-regulation, cerebral edema, and axonal injury start as soon as head injury occurs and manifest as clinical, biochemical, and radiological changes. Proper therapeutic management of brain injury is based on correct diagnosis and appreciation of the temporal course of the disease process. CT scan detects and precisely localizes the intracranial hematomas, cerebral contusions, edema and foreign bodies.

Even in emergency situations, when a head injury is minor as determined by a physician's evaluation and based on established guidelines, CT of the head should be avoided for adults and delayed pending clinical observation in the emergency department for children.{{Citation |title = Five Things Physicians and Patients Should Question |publisher = American College of Emergency Physicians |work = Choosing Wisely: an initiative of the ABIM Foundation |url = http://www.choosingwisely.org/clinician-lists/american-college-emergency-physicians-ct-scans-of-head-for-emergency-department-patients-with-minor-head-injury/|access-date = January 24, 2014}}, which cites

• {{cite journal|last1=Jagoda|first1=Andy S.|last2=Bazarian|first2=Jeffrey J.|last3=Bruns|first3=John J.|last4=Cantrill|first4=Stephen V.|last5=Gean|first5=Alisa D.|last6=Howard|first6=Patricia Kunz|last7=Ghajar|first7=Jamshid|last8=Riggio|first8=Silvana|last9=Wright|first9=David W.|last10=Wears|first10=Robert L.|last11=Bakshy|first11=Aric|last12=Burgess|first12=Paula|last13=Wald|first13=Marlena M.|last14=Whitson|first14=Rhonda R.|title=Clinical Policy: Neuroimaging and Decisionmaking in Adult Mild Traumatic Brain Injury in the Acute Setting|journal=Annals of Emergency Medicine|volume=52|issue=6|year=2008|pages=714–748|issn=0196-0644|doi=10.1016/j.annemergmed.2008.08.021|pmid=19027497|display-authors=1|doi-access=free}}
• {{cite journal|last1=Haydel|first1=Micelle J.|last2=Preston|first2=Charles A.|last3=Mills|first3=Trevor J.|last4=Luber|first4=Samuel|last5=Blaudeau|first5=Erick|last6=DeBlieux|first6=Peter M.C.|s2cid=25844133|title=Indications for Computed Tomography in Patients with Minor Head Injury|journal=New England Journal of Medicine|volume=343|issue=2|year=2000|pages=100–105|issn=0028-4793|doi=10.1056/NEJM200007133430204|pmid=10891517|doi-access=free}}

Many people visit emergency departments for minor head injuries. CT scans of the head can confirm a diagnosis of skull fracture or brain bleeding, but even in the emergency department, such things are uncommon and not minor injuries, so CT of the head is usually not necessary. Clinical trials have shown the efficacy and safety of using CT of the head in emergency settings only when indicated, which would be at the indication of evidence-based guidelines following the physical examination and a review of the person's history.

Concussion is not a routine indication for having brain CT or brain MRI and can be diagnosed by a healthcare provider trained to manage concussions.{{Citation |date=24 April 2014 |title=Five Things Physicians and Patients Should Question |publisher=American Medical Society for Sports Medicine |work=Choosing Wisely: an initiative of the ABIM Foundation |url=http://www.choosingwisely.org/doctor-patient-lists/american-medical-society-for-sports-medicine/ |access-date=29 July 2014}}, which cites

• {{cite journal|vauthors=McCrory P, Meeuwisse WH, Aubry M, Cantu B, Dvorák J, Echemendia RJ, Engebretsen L, Johnston K, Kutcher JS, Raftery M, Sills A, Benson BW, Davis GA, Ellenbogen, RG, Guskiewicz K, Herring SA, Iverson GL, Jordan BD, Kissick J, McCrea M, McIntosh AS, Maddocks D, Makdissi M, Purcell L, Putukian M, Schneider K, Tator CH, Turner M |title=Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012 |journal=British Journal of Sports Medicine |date=Apr 2013 |volume=47 |issue=5 |pages=250–258 |pmid=23479479 |doi=10.1136/bjsports-2013-092313 |display-authors=1 |doi-access=free|hdl=11250/171236 |hdl-access=free }} People with concussions usually do not have relevant abnormalities about which brain imaging could give insight, so brain imaging should not routinely be ordered for people with concussions. If there is concern about a skull fracture, focal neurological symptoms present or worsening symptoms, then CT imaging may be useful. MRI may be useful for people whose symptoms worsen over time or when structural pathology is suspected.

CT of the head is sometimes used for people who have sudden hearing loss.{{Citation |title = Five Things Physicians and Patients Should Question |publisher = American Academy of Otolaryngology–Head and Neck Surgery |work = Choosing Wisely: an initiative of the ABIM Foundation |url = http://www.choosingwisely.org/doctor-patient-lists/american-academy-of-otolaryngology-head-and-neck-surgery-foundation// |access-date = August 1, 2013}}, which cites

• {{Cite journal | vauthors=Stachler RJ, Chandrasekhar SS, Archer SM, Rosenfeld RM, Schwartz SR, Barrs DM, Brown SR, Fife TD, Ford P, Ganiats TG, Hollingsworth DB, Lewandowski CA, Montano JJ, Saunders JE, Tucci DL, Valente M, Warren BE, Yaremchuk KL, Robertson PJ | title = Clinical Practice Guideline: Sudden Hearing Loss | doi = 10.1177/0194599812436449 | journal = Otolaryngology–Head and Neck Surgery | volume = 146 | issue = 3 Suppl | pages = S1–35 | year = 2012 | pmid = 22383545 |display-authors=1| doi-access = }} However, when there are not other neurological findings, a history of trauma, or a history of ear disease, CT scans are not useful and should not be used in response to sudden hearing loss.

CT of the head is also used in CT-guided stereotactic surgery and radiosurgery for treatment of intracranial tumors, arteriovenous malformations and other surgically treatable conditions.{{cite book | last1 = Tse | first1 = VCK | last2 = Kalani | first2 = MYS | last3 = Adler | first3 = JR | editor1-last = Chin | editor1-first = LS | editor2-last = Regine | editor2-first = WF |title = Principles and Practice of Stereotactic Radiosurgery | chapter = Techniques of Stereotactic Localization | page = 28 | publisher = Springer | location = New York | year = 2015|isbn= 978-1-4614-8363-2}}{{cite book | last1 = Khan | first1 = FR | last2 = Henderson | first2 = JM | editor1-last = Lozano | editor1-first = AM | editor2-last = Hallet | editor2-first = M |title = Brain Stimulation: Handbook of Clinical Neurology | volume = 116 |chapter = Deep Brain Stimulation Surgical Techniques | pages = 28–30 | publisher = Elsevier | location = Amsterdam | year = 2013|isbn=978-0-444-53497-2|series=Handbook of Clinical Neurology}}

Special views focusing on the orbit of the eye may be taken to investigate concerns relating to the eye.{{cite book|last=Kunimoto|first=Derek |author2=Kunal Kanitkar |author3=Mary Makar |title=The Wills eye manual: office and emergency room diagnosis and treatment of eye disease|year=2004|publisher=Lippincott Williams & Wilkins|location=Philadelphia, PA|isbn=978-0781742078|pages=360–361|edition=4th}} CT scans are used by physicians specializing in treating the eye (ophthalmologists) to detect foreign bodies (especially metallic objects), fractures, abscesses, cellulitis, sinusitis, bleeding within the skull (intracranial bleeding), proptosis, Graves disease changes in the eye, and evaluation of the orbital apex and cavernous sinus.

Magnetic resonance imaging (MRI) of the head provides superior information as compared to CT scans when seeking information about headache to confirm a diagnosis of neoplasm, vascular disease, posterior cranial fossa lesions, cervicomedullary lesions, or intracranial pressure disorders.{{Citation |date=September 2013 |title=Five Things Physicians and Patients Should Question |publisher=American Headache Society |work=Choosing Wisely: an initiative of the ABIM Foundation |url=http://www.choosingwisely.org/doctor-patient-lists/american-headache-society/ |access-date=10 December 2013 |archive-url=https://web.archive.org/web/20131203001051/http://www.choosingwisely.org/doctor-patient-lists/american-headache-society/ |archive-date=3 December 2013 |url-status=dead}}, which cites

• {{Cite journal | last1 = Health Quality | first1 = O. | title = Neuroimaging for the evaluation of chronic headaches: An evidence-based analysis | journal = Ontario Health Technology Assessment Series | volume = 10 | issue = 26 | pages = 1–57 | year = 2010 | pmid = 23074404 | pmc = 3377587}}
• {{Cite journal | last1 = Evans | first1 = R. W. | title = Diagnostic Testing for Migraine and Other Primary Headaches | doi = 10.1016/j.ncl.2008.11.009 | journal = Neurologic Clinics | volume = 27 | issue = 2 | pages = 393–415 | year = 2009 | pmid = 19289222 }}
• {{Cite journal | last1 = Semelka | first1 = R. C. | last2 = Armao | first2 = D. M. | last3 = Elias Jr | first3 = J. | last4 = Huda | first4 = W. | title = Imaging strategies to reduce the risk of radiation in CT studies, including selective substitution with MRI | doi = 10.1002/jmri.20895 | journal = Journal of Magnetic Resonance Imaging | volume = 25 | issue = 5 | pages = 900–909 | year = 2007 | pmid = 17457809 | s2cid = 5788891 | doi-access = free }}
• {{Cite journal | last1 = Brenner | first1 = D. J. | last2 = Hall | first2 = E. J. | s2cid = 2760372 | doi = 10.1056/NEJMra072149 | title = Computed Tomography — an Increasing Source of Radiation Exposure | journal = New England Journal of Medicine | volume = 357 | issue = 22 | pages = 2277–2284 | year = 2007 | pmid = 18046031 | url = https://repositorio.unal.edu.co/handle/unal/79492 }} It also does not carry the risks of exposing the person to ionizing radiation. CT scans may be used to diagnose headaches when neuroimaging is indicated and MRI is not available, or in emergency settings when hemorrhage, stroke, or traumatic brain injury is suspected.

MRI (magnetic resonance imaging) provides more sensitivity in the evaluation of the cavernous sinus and the orbital apex.

One advantage over a brain MRI is in the evaluation of intracerebral calcifications.{{cite book|last1=Ebel|first1=Klaus-Dietrich|last2=Benz-Bohm|first2=Gabriele|title=Differential diagnosis in pediatric radiology|url=https://books.google.com/books?id=SGMrGn49QZUC&pg=PA538|access-date=18 July 2011|year=1999|publisher=Thieme|isbn=978-3-13-108131-5|pages=538–}}

Several different views of the head are available, including axial, coronal, reformatted coronal, and reformatted sagittal images. However, coronal images require the person to hyperextend their neck, which must be avoided if any possibility of neck injury exists.

CT scans of the head increase the risk of brain cancer, especially for children. As of 2018, it appeared that there was a risk of one excess cancer per 3,000–10,000 head CT exams in children under the age of 10.{{cite journal |last1=Sheppard |first1=JP |last2=Nguyen |first2=T |last3=Alkhalid |first3=Y |last4=Beckett |first4=JS |last5=Salamon |first5=N |last6=Yang |first6=I |title=Risk of Brain Tumor Induction from Pediatric Head CT Procedures: A Systematic Literature Review. |journal=Brain Tumor Research and Treatment |date=April 2018 |volume=6 |issue=1 |pages=1–7 |doi=10.14791/btrt.2018.6.e4 |pmid=29717567 |pmc=5932294}}

{{Commons category|CT images of brain}}

• Neuroimaging

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{{Central nervous system tests and procedures}}

{{Medical imaging}}

Category:Diagnostic radiology

Category:X-ray computed tomography