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'''Contrast CT''' is '''[[CT scan|Computed tomography]]''' using (CT) with intravenous (IV) [[radiocontrastcontrast medium]], and in Radlines it refers to a CT scan using IV contrast except otherwise noted. ''':

==Contrast-induced nephropathy=====Risk factors===The Roxana Mehran score predictor applies In Swedish practice<ref>{{NU Hospital Group}}</ref> the following ten variablesstandard risk factor questions include presence or absence of:*Renal or urinary disease*Thyroid disorders*Myasthenia gravis: Older forms of iodinated contrast have caused an increased risk of exacerbation of the disease, but modern forms have no immediate increased risk.<ref name=Modi2017"MehriziPascuzzi2014">{{cite webjournal|urllast1=https://www.ncbi.nlm.nihMehrizi|first1=Mehyar|last2=Pascuzzi|first2=Robert M.gov/books/NBK448066/|title=Contrast-Induced NephropathyComplications of radiologic contrast in patients with myasthenia gravis|journal=Muscle & Nerve|websitevolume=StatPearls Publishing50|issue=3|year=20172014|pages=443–444|authorissn=Kalgi Modi, Scott C0148639X|doi=10.1002/mus. Dulebohn24254|pmid=24677227}} [http://creativecommons.org/licenses/by/4.0/ CC-BY-4.0]</ref>*Age (4 points if older than 75 years old)*Anemia (3 points)*Use of an intra-aortic balloon pump (5 points)*eGFR 60 to 40 (2 points)*eGFR 40 to 20 (4 points)*eGFR less than 20 (6 points)*Hypotension (5 points, if systolic BP less than 80 mmHg for at least one hour requiring inotropic support)*Contrast media volume (1 point per 100 ml)*Congestive Diabetes and heart failure disease: These are aggravating factors in low renal function (5 pointssee [[CT with IV contrast in low renal function]])*Diabetes (3 points).A risk score of less than 6 carries a risk of 7.5% to score more than 16 carries up to 57% risk.

===AlternativesLow renal function===In people {{Main|CT with IV contrast in low renal function}}Decreased renal function and several other conditions increase the risk factors, the main alternatives are:*of '''Adjustmentcontrast-induced nephropathy''' of the contrast dose. Evidence suggests that contrast doses should be limited to , which is a ratio of grams of iodine potentially lethal renal injury to glomerular filtration rate (I_gram / GFR_ml/min) of a maximum of 1the kidney following intravenous radiocontrast.<ref name="KeaneyHannon2013RudnickFeldman2008">{{cite journal|last1=KeaneyRudnick|first1=J. JM.|last2=HannonFeldman|first2=C. M.|last3=Murray|first3=P. TH.|title=Contrast-induced acute kidney injuryInduced Nephropathy: how much contrast is safeWhat Are the True Clinical Consequences?|journal=Clinical Journal of the American Society of Nephrology Dialysis Transplantation|volume=283|issue=61|year=20132008|pages=1376–1383263–272|issn=09311555-05099041|doi=10.10932215/ndt/gfs602CJN.03690907}}</ref> The local practice at NU Hospital Group has a I_gram/GFR ratio of maximum 0.7 in patients with GFR ≥45 ml/min. It recommends a ratio of maximum 0.5 if GFR is lower ;When it mattersAccording to European guidelines, or in the presence of main risk factors.of ''contrast-induced nephropathy'':<ref name="NymanAhlkvist2018">{{cite journal|last1=Nyman|first1=Ulf|last2=Ahlkvist|first2=Joanna|last3=Aspelin|first3=Peter|last4=Brismar|first4=Torkel|last5=Frid|first5=Anders|last6=Hellström|first6=Mikael|last7=Liss|first7=Per|last8=Sterner|classfirst8="wikitable" alignGunnar|last9="center"Leander|+ Volume for various I_gram / GFR_ml/min ratios! Iodine<br>concentration !! 1 !! 0.7 !! 0.5first9=Peter|title=Preventing contrast medium-induced acute kidney injury|journal=European Radiology| 240 mg/ml year=2018|issn=0938-7994| 4doi=10.2 ml *GFR1007/s00330-018-5678-6}}<sub/ref>*Estimated glomerular filtration rate (eGFR) of less than '''30 ml/min<'''/sub> || 21.73 m2 before intra-venous or intra-arterial radiocontrast administration with second-pass renal exposure (passing lungs or other tissues before the kidneys).9 ml *GFR_{eGFR of less than 45 ml/min} || 21.1 ml *GFR73 m<subsup>ml/min2</subsup>before intra-arterial administration with first-pass renal exposure or in ICU patients*Known or suspected acute renal failure|*Large doses of radiocontrast given IA with first-pass renal exposure| 350 mg/ml || 2.9 ml *Multiple radiocontrast injections within 48-72 h [[File:Contrast CT in low GFR_ml/min .png|thumb| 2 ml *GFR_ml/min 260px|center| 1In case of low GFR, other risk factors need to be checked. Subsequently, the procedure depends on whether the dose that can be given is larger or less than the needed dose.4 ml *GFR_ml/min]]|}*Using ''no intravenous Further reading: [[CT with IV contrastin low renal function]]''' for the investigation.*Switching to '''another modality''' such as ===Allergy===[[ultrasonographyFile:Intramuscular site of adrenaline.jpg|150px|thumb]] or {{Main|Contrast medium reaction}}In a more severe reaction:<ref name=SURF>Unless otherwise specified in lists and table: {{cite web|url=http://www.mastcellssjukdom.se/wp-content/uploads/2015/12/Nationella_rekommendationer_%C3%B6verk%C3%A4nslighetsreaktioner_kontrastmedel__PDF_2014-10-17.pdf|title=Hypersensitivity reactions against contrast media - Swedish Society of Uroradiology [[MRISwedish: Överkänslighetsreaktioner mot kontrastmedel – SURFs kontrastmedelsgrupp]], 2014-10-17}}</ref>*'''Treating or mitigating risk factorsAdrenaline'''shot, 0.3-0.5mg in adults, given intramuscularly. :*Summon an '''Hydrationanesthesiologist''' by drinking  ;Prevention{{Main|Prevention of contrast medium reaction}}Before a contrast CT of a patient with known allergic-like or intravenous volume expanderunknown-type of contrast reaction to the same class of contrast medium (such as iodinated), the American College of of Radiology recommends premedication with a glucocorticoid, either preferably starting 12 or 13 hours before or after contract contrast administration.<ref>{{cite web|url=https://www.acr.org/-/media/ACR/Files/Clinical-Resources/Contrast_Media.pdf#page=11|title=Page 9 in: ACR Manual On Contrast Media|website=American College of Radiology, decreases the Committee on Drugs and Contrast Media|accessdate=2018-08-25}} Version 10.3. 2018. ACR </ref> ===Hyperthyroidism===Patients at risk of for contrast-induced nephropathyhyperthyroidism are mainly those with diagnosed yet untreated hyperthyroidism, which may motivate contrast-free alternatives such as using a different modality.<ref name="YangHiremath2013"UpToDate-thyr>{{cite journalweb|last1url=Yanghttps://www.uptodate.com/contents/iodine-induced-thyroid-dysfunction|first1title=XiaomingIodine-induced thyroid dysfunction|last2author=HiremathMartin I Surks, MD|first2website=UpToDate}} This topic last updated: Apr 02, 2019.</ref> In older patients with multinodular goiter and borderline low or subnormal TSH concentrations, a suggested measure is measurement of thyroid function tests three to four weeks after contrast administration.<ref name=UpToDate-thyr/> Limited evidence suggests that antithyroid agents before the investigation may blunt or prevent hyperthyroidism.<ref name=Swapnil|last3UpToDate-thyr/> =Akbari|first3=Ayub|last4=Shabana|first4Pregnancy=Wael|last5=Fergusson|first5=Dean AIodinated contrast in pregnancy, when orally administered, is harmless.|last6<ref name=Knollacog>{{cite web|first6url=Greg Ahttps://www.acog.org/Resources-And-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Guidelines-for-Diagnostic-Imaging-During-Pregnancy-and-Lactation|title=Prevention Guidelines for Diagnostic Imaging During Pregnancy and Lactation|website=[[American Congress of Contrast-Induced Acute Kidney Injury: Is Simple Oral Hydration Similar To Obstetricians and Gynecologists]]}} February 2016</ref> Intravenous? A Systematic Review administration of iodinated radiocontrast agents can cross the placenta and enter the fetal circulation, but animal studies have reported no teratogenic or mutagenic effects from its use. There have been theoretical concerns about potential harm of free iodide on the Evidence|journalfetal thyroid gland,<ref name=PLoS ONEacog/> but multiple studies have shown that a single dose of intravenously administered iodinated contrast medium to a pregnant mother has no effect on neonatal thyroid function.<ref>{{cite web|volumeurl=8https://www.acr.org/~/media/37D84428BF1D4E1B9A3A2918DA9E27A3.pdf|issuetitle=ACR Manual on Contrast Media. Version 10.3|year=20132017|pageswebsite=e60009American College of Radiology|issnpublisher=American College of Radiology Committee on Drugs and Contrast Media|accessdate=19322017-07-620330}}</ref> Nevertheless, it generally is recommended that radiocontrast only be used if absolutely required to obtain additional diagnostic information that will improve the care of the fetus or mother.<ref name=acog/> ===Breastfeeding===American College of Radiology guidelines state that iodinated contrast administration to a breastfeeding mother is considered safe for both the mother and child.<ref name=yale>{{cite web|doiurl=10https://medicine.yale.1371edu/diagnosticradiology/patientcare/policies/journalbreastfeeding.pone.0060009aspx|title=Diagnostic Radiology Procedures on Breastfeeding Patients|website=[[Yale School of Medicine]]|accessdate=2019-07-08}}</ref> Still, mothers who remain concerned about any potential adverse effects to the child are recommended to have the option of abstaining from breastfeeding for 24 hours, with continued milk extraction such as by a breast pump during that period.<ref name=yale/> Mothers that opt for this for non-emergent exams may also use a breast pump to obtain milk before the exam in order to feed the child during the 24-hour abstinence period.<ref name=yale/>

Depending on the purpose of the investigation, there are standardized protocols for time intervals between intravenous radiocontrast administration and image acquisition, in order to visualize the dynamics of contrast enhancements in different organs and tissues.<ref name="Bae2010">{{cite journal|last1=Bae|first1=Kyongtae T.|title=Intravenous Contrast Medium Administration and Scan Timing at CT: Considerations and Approaches|journal=Radiology|volume=256|issue=1|year=2010|pages=32–61|issn=0033-8419|doi=10.1148/radiol.10090908}}</ref> The main phases thereof are as follows:in table below.<ref name=radiologyassistant>{{cite web|url=http://www.radiologyassistant.nl/en/p52c04470dbd5c/ct-contrast-injection-and-protocols.html|title=CT contrast injection and protocols|author=Robin Smithuis|website=Radiology Assistant|accessdate=2017-12-13}}</ref> '''CT angiography''' is a CT scan corresponding with contrast filling one or more blood vessels of interest.

*[[Pulmonary CT of pulmonary embolism]](can use [[bolus tracking]] in [[pulmonary trunk]] + 6 seconds)<ref>{{cite web|url=https://posterng.netkey.at/esr/viewing/index.php?module=viewing_poster&doi=10.1594/ecr2018/C-1831|title=Introducing the use of Flash CTPA; how does it compare to standard CTPA?|website=Postering|author=Pavan Nandra|year=2018}}</ref>

==Gastrointestinal contrastLocations==See '''Rectally administered contrast[[CT#By location]]''' (CT with IV contrast, including CT angiography, is indicated in cases where a suspicion remains of penetrating trauma to the colon where an initial organized as other CT shows no reason for immediate surgeryexaminations).<ref>{{cite web|url=http://www.radiologyassistant.nl/en/p466181ff61073/acute-abdomen-role-of-ct-in-trauma.html#i466184acd2fdb|title=Acute Abdomen - Role of CT in Trauma|author=Stephen Ledbetter and Robin Smithuis|website=Radiopaedia|date=2007-08-02}}</ref> ==References=={{reflistBottom}}