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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 in people ===Low renal function==={{Main|CT with a risk of IV contrast-induced nephropathy are:in low renal function}}*'''Adjustment''' Decreased renal function and several other conditions increase the risk of the radiocontrast dose*Using '''no intravenous contrast-induced nephropathy''' for , which is a potentially lethal renal injury to the investigation.*Switching to '''another modality''' such as [[ultrasonography]] or [[MRI]]*'''Treating or mitigating risk factors''':*'''Hydration''' by drinking or kidney following intravenous volume expander, either before or after contract administration, decreases the risk of contrast-induced nephropathyradiocontrast.<ref name="YangHiremath2013RudnickFeldman2008">{{cite journal|last1=YangRudnick|first1=XiaomingM.|last2=HiremathFeldman|first2=Swapnil|last3=Akbari|first3=Ayub|last4=Shabana|first4=Wael|last5=Fergusson|first5=Dean A.|last6=Knoll|first6=Greg AH.|title=Prevention of Contrast-Induced Acute Kidney InjuryNephropathy: Is Simple Oral Hydration Similar To IntravenousWhat Are the True Clinical Consequences? A Systematic Review of the Evidence|journal=PLoS ONEClinical Journal of the American Society of Nephrology|volume=83|issue=31|year=20132008|pages=e60009263–272|issn=19321555-62039041|doi=10.13712215/journal.poneCJN.006000903690907}}</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 [[File:Intramuscular site of adrenaline.jpg|150px|thumb]]{{Main|Contrast medium reaction}}In a ratio of grams of iodine to glomerular filtration rate (Imore severe reaction:<subref name=SURF>gram<Unless otherwise specified in lists and table: {{cite web|url=http://www.mastcellssjukdom.se/wp-content/uploads/sub> 2015/ GFR<sub>ml12/minNationella_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}}</subref>*'''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 maximum of 1glucocorticoid, preferably starting 12 or 13 hours before contrast administration.<ref name="KeaneyHannon2013">{{cite journalweb|last1url=Keaney|first1=Jhttps://www.acr. Jorg/-/media/ACR/Files/Clinical-Resources/Contrast_Media.|last2pdf#page=Hannon11|first2title=C. M.Page 9 in: ACR Manual On Contrast Media|last3website=MurrayAmerican College of Radiology, Committee on Drugs and Contrast Media|first3accessdate=P2018-08-25}} Version 10. T3.|title2018. ACR </ref> ===Hyperthyroidism===ContrastPatients at risk for contrast-induced acute kidney injury: how much hyperthyroidism are mainly those with diagnosed yet untreated hyperthyroidism, which may motivate contrast is safe?|journal-free alternatives such as using a different modality.<ref name=Nephrology Dialysis TransplantationUpToDate-thyr>{{cite web|volumeurl=28https://www.uptodate.com/contents/iodine-induced-thyroid-dysfunction|issuetitle=6Iodine-induced thyroid dysfunction|yearauthor=2013|pages=1376–1383|issn=0931-0509Martin I Surks, MD|doiwebsite=10.1093/ndt/gfs602UpToDate}}This topic last updated: Apr 02, 2019.</ref> The local practice at NU Hospital Group has a I_gram/GFR ratio of maximum 0.7 in  In older patients with GFR ≥45 ml/min. It recommends multinodular goiter and borderline low or subnormal TSH concentrations, a ratio suggested measure is measurement of maximum 0thyroid function tests three to four weeks after contrast administration.5 if GFR is lower, <ref name=UpToDate-thyr/> Limited evidence suggests that antithyroid agents before the investigation may blunt or in the presence of risk factorsprevent hyperthyroidism.<ref name=UpToDate-thyr/> {|class="wikitable" align="center"=Pregnancy===|+ Volume for various IIodinated contrast in pregnancy, when orally administered, is harmless.<subref name=acog>gram<{{cite web|url=https://sub> www.acog.org/ GFR_{mlResources-And-Publications/min<Committee-Opinions/sub> ratios! Iodine<br>concentration !! 1 !! 0.7 !! 0.5|Committee-on-Obstetric-| 240 mgPractice/ml Guidelines-for-Diagnostic-Imaging-During-Pregnancy-and-Lactation|title=Guidelines for Diagnostic Imaging During Pregnancy and Lactation| 4.2 ml *GFRwebsite=[[American Congress of Obstetricians and Gynecologists]]}} February 2016<sub/ref>ml/minIntravenous 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/sub> || 2but 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:/min} || 2www.acr.1 ml *GFR<sub>mlorg/~/min<media/sub>37D84428BF1D4E1B9A3A2918DA9E27A3.pdf|-title=ACR Manual on Contrast Media. Version 10.3| 350 mg/ml year=2017|website=American College of Radiology| 2.9 ml *GFR_ml/min publisher=American College of Radiology Committee on Drugs and Contrast Media|| 2 ml *GFRaccessdate=2017-07-30}}<sub>ml/min</subref> || 1Nevertheless, 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.4 ml *GFR<sub>ml/min<ref name=acog/sub>|}

====How much contrast is needed=Breastfeeding===This depends on the issue at hand. Examples are:*Liver: In males at 30 years American College of age, there Radiology guidelines state that iodinated contrast administration to a breastfeeding mother is an estimated 0.027 HU of liver parenchymal enhancement per kilogram of body weight considered safe for both the mother and per gram of iodine, when injected at 4 ml per secondchild.<ref name="Bae2010"yale>{{cite journalweb|last1url=Bae|first1=Kyongtae Thttps://medicine.yale.edu/diagnosticradiology/patientcare/policies/breastfeeding.aspx|title=Intravenous Contrast Medium Administration and Scan Timing at CT: Considerations and Approaches|journal=Diagnostic RadiologyProcedures on Breastfeeding Patients|volumewebsite=256[[Yale School of Medicine]]|issueaccessdate=1|year=2010|pages=32–61|issn=00332019-07-8419|doi=10.1148/radiol.1009090808}}</ref> For exampleStill, a body weight mothers who remain concerned about any potential adverse effects to the child are recommended to have the option 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 abstaining from breastfeeding for 24 hours, with risk factors, dual energy CTA (continued milk extraction such as 90/150SnkVp) is feasible even at iodine doses of 6g (such as 15 ml of 370 mg/ml of iodine)by a breast pump during that period.<ref name="LeroyerMeier2016"yale/>{{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 ScoreMothers that opt for this for non-Matched Study|journal=PLOS ONE|volume=11|issue=12|year=2016|pages=e0167214|issn=1932emergent exams may also use a breast pump to obtain milk before the exam in order to feed the child during the 24-6203|doi=10hour abstinence period.1371/journal.pone.0167214}}<ref name=yale/ref> :*Other diseases of the thorax, such as parenchymal changes, can often be evaluated adequately without the use of intravenous contrast.

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}}