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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==={{Main|classCT with IV contrast in low renal function}}Decreased renal function and several other conditions increase the risk of '''contrast-induced nephropathy''', which is a potentially lethal renal injury to the kidney following intravenous radiocontrast.<ref name="wikitableRudnickFeldman2008"! Iodine>{{cite journal|last1=Rudnick|first1=M.|last2=Feldman|first2=H.|title=Contrast-Induced Nephropathy: What Are the True Clinical Consequences?|journal=Clinical Journal of the American Society of Nephrology|volume=3|issue=1|year=2008|pages=263–272|issn=1555-9041|doi=10.2215/CJN.03690907}}<br/ref>concentration !! Maximum volume ;When it mattersAccording to European guidelines, the main risk factors of ''contrast-induced nephropathy'':<ref name="KeaneyHannon2013NymanAhlkvist2018">{{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|first8=Gunnar|last9=Leander|first9=Peter|title=Preventing contrast medium-induced acute kidney injury|journal=European Radiology|year=2018|issn=0938-7994|doi=10.1007/s00330-018-5678-6}}</ref>*Estimated glomerular filtration rate (eGFR) of less than '''30 ml/min'''/1.73 m2 before intra-venous or intra-arterial radiocontrast administration with second-pass renal exposure (passing lungs or other tissues before the kidneys).*eGFR of less than 45 ml/min/1.73 m² 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*Multiple radiocontrast injections within 48-72 h [[File:Contrast CT in low GFR.png|thumb|260px|center|In 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.]] ''Further reading: [[CT with IV contrast in low renal function]]'' ===Allergy===[[File:Intramuscular site of adrenaline.jpg|150px|thumb]]{{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 [Swedish: Överkänslighetsreaktioner mot kontrastmedel – SURFs kontrastmedelsgrupp] ], 2014-10-17}}</ref>*'''Adrenaline''' shot, 0.3-0.5mg in adults, given intramuscularly.*Summon an '''anesthesiologist''' ;Prevention{{Main|Prevention of contrast medium reaction}}Before a contrast CT of a patient with known allergic-like or unknown-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, preferably starting 12 or 13 hours before contrast administration.<ref>{{cite web| 240 mgurl=https://ml 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, Committee on Drugs and Contrast Media| 4accessdate=2018-08-25}} Version 10.3. 2018. ACR </ref> ===Hyperthyroidism===Patients at risk for contrast-induced hyperthyroidism are mainly those with diagnosed yet untreated hyperthyroidism, which may motivate contrast-free alternatives such as using a different modality.2 ml *GFR<subref name=UpToDate-thyr>ml{{cite web|url=https://www.uptodate.com/contents/miniodine-induced-thyroid-dysfunction|title=Iodine-induced thyroid dysfunction|author=Martin I Surks, MD|website=UpToDate}} This topic last updated: Apr 02, 2019.</subref>|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=UpToDate-thyr/> ===Pregnancy===Iodinated contrast in pregnancy, when orally administered, is harmless.<ref name=acog>{{cite web| 350 mgurl=https:/ml /www.acog.org/Resources-And-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Guidelines-for-Diagnostic-Imaging-During-Pregnancy-and-Lactation|title=Guidelines for Diagnostic Imaging During Pregnancy and Lactation| 2website=[[American Congress of Obstetricians and Gynecologists]]}} February 2016</ref> Intravenous 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 fetal thyroid gland,<ref name=acog/> 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.9 ml *GFR<subref>ml{{cite web|url=https://www.acr.org/~/media/37D84428BF1D4E1B9A3A2918DA9E27A3.pdf|title=ACR Manual on Contrast Media. Version 10.3|year=2017|website=American College of Radiology|publisher=American College of Radiology Committee on Drugs and Contrast Media|accessdate=2017-07-30}}</minref> 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/sub>

In people with risk factors, the main alternatives are:===Breastfeeding===*'''Adjustment''' American College of the contrast dose. Evidence suggests Radiology guidelines state that iodinated contrast doses should be limited administration to a ratio of grams of iodine to glomerular filtration rate (I_gram / GFR_ml/min) of a maximum of 1breastfeeding mother is considered safe for both the mother and child.<ref name="KeaneyHannon2013"yale>{{cite journalweb|last1url=Keaney|first1=Jhttps://medicine. Jyale.|last2=Hannon|first2=C. Medu/diagnosticradiology/patientcare/policies/breastfeeding.aspx|last3title=MurrayDiagnostic Radiology Procedures on Breastfeeding Patients|first3website=P. T.[[Yale School of Medicine]]|titleaccessdate=Contrast2019-induced acute kidney injury: how much contrast is safe?|journal=Nephrology Dialysis Transplantation|volume=28|issue=6|year=2013|pages=1376–1383|issn=093107-0509|doi=10.1093/ndt/gfs60208}}</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 lowerStill, or in mothers who remain concerned about any potential adverse effects to the child are recommended to have the presence option of risk factors.*Using ''no intravenous contrast''' abstaining from breastfeeding for the investigation.*Switching to '''another modality''' 24 hours, with continued milk extraction such as [[ultrasonography]] or [[MRI]]*'''Treating or mitigating risk factors'''. :*'''Hydration''' by drinking or intravenous volume expander, either before or after contract administration, decreases the risk of contrast-induced nephropathya breast pump during that period.<ref name="YangHiremath2013"yale/>{{cite journal|last1=Yang|first1=Xiaoming|last2=Hiremath|first2=Swapnil|last3=Akbari|first3=Ayub|last4=Shabana|first4=Wael|last5=Fergusson|first5=Dean A.|last6=Knoll|first6=Greg A.|title=Prevention of ContrastMothers that opt for this for non-Induced Acute Kidney Injury: Is Simple Oral Hydration Similar To Intravenous? A Systematic Review of emergent exams may also use a breast pump to obtain milk before the exam in order to feed the child during the Evidence|journal=PLoS ONE|volume=8|issue=3|year=2013|pages=e60009|issn=193224-6203|doi=10.1371/journal.ponehour abstinence period.0060009}}<ref name=yale/ref>

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}}