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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 nephropathyRisk factors==Decreased renal function and several other conditions increase In Swedish practice<ref>{{NU Hospital Group}}</ref> the standard risk factor questions include presence or absence of:*Renal or urinary disease*Thyroid disorders*Myasthenia gravis: Older forms of iodinated contrast-induced nephropathyhave caused an increased risk of exacerbation of the disease, which is a potentially lethal renal injury to the kidney following intravenous radiocontrastbut modern forms have no immediate increased risk.<ref name="RudnickFeldman2008MehriziPascuzzi2014">{{cite journal|last1=RudnickMehrizi|first1=M.Mehyar|last2=FeldmanPascuzzi|first2=HRobert M.|title=Contrast-Induced Nephropathy: What Are the True Clinical Consequences?Complications of radiologic contrast in patients with myasthenia gravis|journal=Clinical Journal of the American Society of NephrologyMuscle & Nerve|volume=350|issue=13|year=20082014|pages=263–272443–444|issn=1555-90410148639X|doi=10.22151002/CJNmus.0369090724254|pmid=24677227}}</ref> *Diabetes and heart disease: These are aggravating factors in low renal function (see [[CT with IV contrast in low renal function]])

The main alternatives ===Low renal function==={{Main|CT with IV contrast in people with a low renal function}}Decreased renal function and several other conditions increase the risk of '''contrast-induced nephropathy are:*'''Adjustment''' of , which is a potentially lethal renal injury to the kidney following intravenous radiocontrast dose*'''Treating or mitigating risk factors'''*Using '''no intravenous contrast''' for .<ref name="RudnickFeldman2008">{{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 investigationAmerican Society of Nephrology|volume=3|issue=1|year=2008|pages=263–272|issn=1555-9041|doi=10.*Switching to '''another modality''' such as [[ultrasonography]] or [[MRI]]2215/CJN.03690907}}</ref>

===Risk factors===;When it mattersThe Roxana Mehran score predictor applies According to European guidelines, the following ten variablesmain risk factors of ''contrast-induced nephropathy'':<ref name=Modi2017"NymanAhlkvist2018">{{cite webjournal|last1=Nyman|first1=Ulf|last2=Ahlkvist|first2=Joanna|last3=Aspelin|first3=Peter|urllast4=https://www.ncbi.nlm.nih.gov/books/NBK448066/Brismar|first4=Torkel|last5=Frid|first5=Anders|last6=Hellström|first6=Mikael|last7=Liss|first7=Per|last8=Sterner|first8=Gunnar|last9=Leander|first9=Peter|title=ContrastPreventing contrast medium-Induced Nephropathyinduced acute kidney injury|websitejournal=StatPearls PublishingEuropean Radiology|year=20172018|issn=0938-7994|authordoi=Kalgi Modi, Scott C10. Dulebohn}} [http:1007//creativecommons.org/licenses/by/4.0/ CCs00330-018-BY5678-4.0]6}}</ref>*Age Estimated glomerular filtration rate (4 points if older than 75 years oldeGFR)*Anemia (3 points)*Use of an less than '''30 ml/min'''/1.73 m2 before intra-aortic balloon pump venous or intra-arterial radiocontrast administration with second-pass renal exposure (5 points)*eGFR 60 to 40 (2 points)*eGFR 40 to 20 (4 pointspassing lungs or other tissues before the kidneys).*eGFR of 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 (45 ml/min/1 point per 100 ml).73 m² before intra-arterial administration with first-pass renal exposure or in ICU patients*Congestive heart Known or suspected acute renal failure (5 points)*Diabetes (3 points).Large doses of radiocontrast given IA with first-pass renal exposureA risk score of less than 6 carries a risk of 7.5% to score more than 16 carries up to 57% risk.<ref name=Modi2017/>*Multiple radiocontrast injections within 48-72 h

===Adjustment [[File:Contrast CT in low GFR.png|thumb|260px|center|In case of dose===If and how low GFR, other risk factors need to adjust be checked. Subsequently, the dose procedure depends on supply and demand: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]]'' ====How much contrast can be given?=Allergy===Evidence suggests that contrast doses should be limited to a ratio of grams of iodine to glomerular filtration rate (I_gram / GFR_ml/min) [[File:Intramuscular site of adrenaline.jpg|150px|thumb]]{{Main|Contrast medium reaction}}In a maximum of 1.more severe reaction:<ref name="KeaneyHannon2013"SURF>Unless otherwise specified in lists and table: {{cite journalweb|last1url=Keaney|first1=Jhttp://www. Jmastcellssjukdom.|last2=Hannon|first2=C. M.|last3=Murray|first3=P. Tse/wp-content/uploads/2015/12/Nationella_rekommendationer_%C3%B6verk%C3%A4nslighetsreaktioner_kontrastmedel__PDF_2014-10-17.pdf|title=ContrastHypersensitivity reactions against contrast media -induced acute kidney injurySwedish Society of Uroradiology [Swedish: how much contrast is safe?|journal=Nephrology Dialysis Transplantation|volume=28|issue=6|year=2013|pages=1376–1383|issn=0931Överkänslighetsreaktioner mot kontrastmedel – SURFs kontrastmedelsgrupp] ], 2014-0509|doi=10.1093/ndt/gfs602-17}}</ref> The local practice at NU Hospital Group has a I_gram/GFR ratio of maximum *'''Adrenaline''' shot, 0.3-0.7 5mg in patients with GFR ≥45 ml/minadults, given intramuscularly. It recommends *Summon an '''anesthesiologist''' ;Prevention{{Main|Prevention of contrast medium reaction}}Before a ratio contrast CT of maximum 0.5 if GFR is lowera patient with known allergic-like or unknown-type of contrast reaction to the same class of contrast medium (such as iodinated), or in the presence American College of risk factorsof Radiology recommends premedication with a glucocorticoid, preferably starting 12 or 13 hours before contrast administration.<ref>{{cite web|classurl="wikitable" align="center"|+ Volume for various I<sub>gram<https:/sub> / GFR_ml/min ratios! Iodine<br>concentration !! 1 !! 0www.7 !! 0acr.5|org/-| 240 mg/ml || 4.2 ml *GFR<sub>mlmedia/ACR/Files/min<Clinical-Resources/sub> Contrast_Media.pdf#page=11|| 2.title=Page 9 ml *GFR_ml/min in: ACR Manual On Contrast Media|website=American College of Radiology, Committee on Drugs and Contrast Media| 2accessdate=2018-08-25}} Version 10.1 ml *GFR3. 2018. ACR _{ml/min</subref>|===Hyperthyroidism===Patients at risk for contrast-induced hyperthyroidism are mainly those with diagnosed yet untreated hyperthyroidism, which may motivate contrast-| 350 mg/ml || 2free alternatives such as using a different modality.9 ml *GFR<subref name=UpToDate-thyr>ml{{cite web|url=https:/min} || 2 ml *GFR<sub>mlwww.uptodate.com/min<contents/sub> iodine-induced-thyroid-dysfunction|title=Iodine-induced thyroid dysfunction|author=Martin I Surks, MD| 1website=UpToDate}} This topic last updated: Apr 02, 2019.4 ml *GFR<sub>ml/min</subref>|}

====How much contrast is needed====This depends on the issue at hand. Examples are:*Liver: In males at 30 years of ageolder patients with multinodular goiter and borderline low or subnormal TSH concentrations, there a suggested measure is an estimated 0.027 HU measurement of liver parenchymal enhancement per kilogram of body weight and per gram of iodine, when injected at 4 ml per secondthyroid function tests three to four weeks after contrast administration.<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=0033UpToDate-8419|doi=10.1148/radiol.10090908}}<thyr/ref> For example, a body weight of 70 kg and 125 ml of iodine at a concentration of 350 mg/ml confers an expected enhancement of 83 HU.*Thorax: :*For [[CT of pulmonary embolism]] in patients with risk factors, dual energy CTA (such as 90/150SnkVp) is feasible even at iodine doses of 6g (such as 15 ml of 370 mg/ml of iodine)Limited evidence suggests that antithyroid agents before the investigation may blunt or prevent hyperthyroidism.<ref name="LeroyerMeier2016">{{cite journal|last1=Leroyer|first1=Christophe|last2=Meier|first2=Andreas|last3=Higashigaito|first3=Kai|last4=Martini|first4=Katharina|last5=Wurnig|first5=Moritz|last6=Seifert|first6=Burkhardt|last7=Keller|first7=Dagmar|last8=Frauenfelder|first8=Thomas|last9=Alkadhi|first9=Hatem|title=Dual Energy CT Pulmonary Angiography with 6g Iodine—A Propensity ScoreUpToDate-Matched Study|journal=PLOS ONE|volume=11|issue=12|year=2016|pages=e0167214|issn=1932-6203|doi=10.1371/journal.pone.0167214}}<thyr/ref> :*Other diseases of the thorax, such as parenchymal changes, can often be evaluated adequately without the use of intravenous contrast.

===Treating risk factorsPregnancy===Risk factors Iodinated contrast in pregnancy, when orally administered, is harmless.<ref name=acog>{{cite web|url=https://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|website=[[American Congress of Obstetricians and Gynecologists]]}} February 2016</ref> Intravenous administration of iodinated radiocontrast agents can sometimes be treated cross the placenta and enter the fetal circulation, but animal studies have reported no teratogenic or at least mitigatedmutagenic effects from its use. There have been theoretical concerns about potential harm of free iodide on the fetal thyroid gland, especially if having suddenly appeared, such as <ref name=acog/> but multiple studies have shown that a single dose of intravenously administered iodinated contrast medium to a decreased renal pregnant mother has no effect on neonatal thyroid function when .<ref>{{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}}</ref> Nevertheless, it was previously normal. In such cases a common easily treated cause generally is dehydrationrecommended 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/>

'''Hydration''' by drinking or intravenous volume expander, either before or after contract ===Breastfeeding===American College of Radiology guidelines state that iodinated contrast administration, decreases to a breastfeeding mother is considered safe for both the risk of contrast-induced nephropathymother and child.<ref name="YangHiremath2013"yale>{{cite journalweb|last1url=Yang|first1=Xiaoming|last2=Hiremath|first2=Swapnil|last3=Akbari|first3=Ayub|last4=Shabana|first4=Wael|last5=Fergusson|first5=Dean Ahttps://medicine.yale.|last6=Knoll|first6=Greg Aedu/diagnosticradiology/patientcare/policies/breastfeeding.aspx|title=Prevention of Contrast-Induced Acute Kidney Injury: Is Simple Oral Hydration Similar To Intravenous? A Systematic Review of the Evidence|journal=PLoS ONEDiagnostic Radiology Procedures on Breastfeeding Patients|volumewebsite=8[[Yale School of Medicine]]|issueaccessdate=3|year=2013|pages=e60009|issn=19322019-07-6203|doi08}}</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=10.1371yale/journal> 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.pone.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}}