CM Risk Assessment

Flashcards about CM Risk Assessment

What is the time difference between an immediate and delayed reaction to iodinated contrast media?

Immediate reactions occur within 1 hour, while delayed reactions occur 1 hour to 1 week after administration.

What are the classifications of reactions to iodinated contrast media and their possible clinical signs?

Mild: Flushing, nausea, mild urticaria, pruritus, vomiting, headache. Moderate: Severe vomiting, marked urticaria, bronchospasm, facial/laryngeal oedema, vasovagal attacks. Severe: Hypovolemic shock, respiratory arrest, cardiac arrest, convulsions, anaphylaxis.

What is the basic purpose of a contrast media patient questionnaire?

To minimize the risk associated with iodinated contrast media administration.

What are the main questions covered in the iodinated contrast media patient questionnaire?

Pregnancy, breastfeeding, previous allergic reaction to CM or other allergies, contrast induced acute kidney injury (CI-AKI), diabetes, thyroid issues, Phx of cancer, paediatric considerations.

Why is pregnancy a concern when administering iodinated contrast media?

Concern for thyroid function in foetus and orgogenesis.

Why is it important to know if a patient suffers from asthma or topical iodine allergy when using CM?

Asthma - increased risk of bronchospasm.
Topical iodine allergy – no associated risk

What eGFR values indicate no risk, low risk, and severe risk regarding CI-AKI?

eGFR > 45 = no risk
eGFR 30-45 = low risk/no risk
eGFR < 45 = severe renal function impairment or actively deteriorating real function; weigh up risk vs benefit of iodinated CM

What is eGFR and how is it relevant to iodinated contrast media with regards to CI-AKI?

Estimation of actual glomerular filtration, based on serum creatinine level, age, sex, race.

Why is diabetes a concern when using CM?

Diabetics usually take Metformin – causes increased lactic acid production by intestines. lactic acidosis = too much lactic acid in body, can’t be metabolized

Why is history of cancer a concern when using CM?

Damage to veins due to frequent venous access OR toxicity of drugs given – difficult to gain venous access for administration of contrast. Could alter protocol -> known Phx of cancer always do pre and post CT scan because may be indicative of metastasis

What are the responsibilities of staff involved in the administration and use of iodinated contrast media?

Iodinated CM can only be administered when a radiologist or other medical officer is on site. Practitioners should be trained in recognition and treatment of CM reactions, resuscitation procedures, and be aware of relevant guidelines and equipment.

What are the steps to take if a patient has an iodinated CM reaction?

1. Stop injection. 2. Report changes to radiologist. 3. Breathing difficulties = code blue a. Emergency button b. 000 if private practice/no assistance c. Provide oxygen d. Emergency/crash cart e. Call emergency crash team f. Assist medical team g. Document adverse reactions + contrast manufacturer in patient notes Do not leave patient alone; reassure them

What strategies may be used for patients at risk of a contrast media reaction?

Avoid CM if possible, Premedication, Observe closely with IV in place for 30 mins following injection of contrast, Ensure emergency drugs and equipment for resuscitation are readily available, IV cannula kept in situ minimum of 15 mins post all IV admin examination

What is the preferred location for venous access for IVCM?

Superficial median of the median cubital vein, cephalic or basilic veins.

What are the advantages of power injectors compared to hand injection for contrast media administration?

Permit loading of contrast and saline (for saline chaser) onto same injector = improved ability to manage injector protocol data, patient safety and workflow efficiency. Inclusion of saline chaser in the image acquisition = ensures complete delivery of the contrast dose into the circulatory system and can reduce amount of iodine needed to achieve optimal imaging. Better bolus geometry + fewer artifacts

Explain the purpose of a saline chaser and the advantages of its use

pushes tail of injected CM bolus into central blood volume, makes use of contrast medium that would otherwise remain unused in injection tubing and peripheral veins

What is IVCM and the overview relating to enhancement phases?

Non-enhanced phase: Baseline status of patients anatomy/ Demonstrating already dense structures without contrast – calculi, calcifications. Early arterial phase: For certain arterial abnormalities (e.g. angiography + tummours)/ Contrast in arteries, aorta, tumours. Late arterial phase : For highly vascularised structures (e.g. liver, spleen, kidney)/Aorta still bright, but some return in IVC; highly vascularised structures e.g. liver, spleen, kidney - appear bright. Portal venous phase: Concentrated in mesenteric venous structures/ Mesenteric venous structures – portal vein is specific venous return from bowel (-> heads into liver)/ Some opacification in kidney cortex, some in aorta, some in IVC, particularly in IVC and PV structures in liver. Delayed phase: Wash out phase/equilibrium phase used to visualise lesions that retain contrast + delayed for urinary system/To demonstrate lesions specifically in liver; and delay in urinary system

Define TTP and PE level

Time to Peak (TTP) = time at which contrst concentration reaches its maximum/ Peak enhancement level (PE) = maximum level of contrast media enhancement achieved as measured in HU

How does cardiac output affect TTP and PE level?

As cardiac output reduces -> cardiovascular transit time increases -> increased TTP/ As cardiac input reduces -> PE (HU) also increases (due to slower clearance of IVCM from body – due to decreased output)

How does patient body weight affect TTP and PE level?

As body weight increases -> magnitude of PE level decreases;/ Larger patients have a larger blood volume in which to dilute the CM/ Heavier patients achieve less PE compared with smaller patients

How does Venous compression affect IVCM?

increases TTP and decreases contrast enhancement

How does the Valsalva manoeuvre affect IVCM?

Leads to more unopacified blood from IVC than opacified blood from SVC entering right atrium -> poor enhancement of pulmonary arteries

Describe the 3 techniques utilized for scan timing relating to IVCM administration including advantages and disadvantages

Fixed Delay: Simple, less contrast, less dose, time-efficient; cannot customize. Test Bolus: Picks up potential problems, customizable; additional radiation and contrast, increases exam time. Bolus Tracking: Customizable, no additional contrast, quick; potential problems not identified prior, relies on operator, ROI needs careful positioning.

Why is the brain parenchyma the ‘odd one out’ when it comes to IVCM uptake?

BBB restricts certain substances from entering brain/ IV contrast agents cross the BBB in disrupted areas (e.g. tumours, abcesses)/ normal brain parenchyma does not enhance with IV contrast/Breakdown of BBB -> IV contrast penetrates and is taken up by whatever pathology has caused breakdown in BBB/ IV contrast enhancement reflects breakdown of BBB rather than vascularity of pathology/ can take up to 5 minutes

What are potential reasons and outcomes for IVCM extravasation

IVCM extraversion = leakage of intravenously-administered CM from the normal intravascular compartment into surrounding soft tissues (aka tissuing)/ common complication of CE studies because nearly all CT studies require IVCM at high-flow, high volume fixed rates delivered under pressure by power injectors/ extraversion typically occurs during IVCM administration with IV cannula dislodges and punctures the vessel wall, causing leakage into extravascular tissue – the set CT protocol may be affected/ Higher % of leakage from venous access in back of hand, wrist, foot and ankle/ Usually cause minimal inflammation and erythema, further complications such as skin ulceration, tissue necrosis, and compartment syndrome can occur

What is the time difference between an immediate and delayed reaction to iodinated contrast media?

Occurs within 1 hour, while delayed reactions occur 1 hour to 1 week after administration.

What are the classifications of reactions to iodinated contrast media and their possible clinical signs?

Mild: Flushing, nausea, mild urticaria, pruritus, vomiting, headache.

Moderate: Severe vomiting, marked urticaria, bronchospasm, facial/laryngeal oedema, vasovagal attacks.

Severe: Hypovolemic shock, respiratory arrest, cardiac arrest, convulsions, anaphylaxis.

What is the basic purpose of a contrast media patient questionnaire?

To minimize the risk associated with iodinated contrast media administration.

What are the main questions covered in the iodinated contrast media patient questionnaire?

Pregnancy, breastfeeding, previous allergic reaction to CM or other allergies, contrast induced acute kidney injury (CI-AKI), diabetes, thyroid issues, Phx of cancer, paediatric considerations.

Why is pregnancy a concern when administering iodinated contrast media?

Concern for thyroid function in foetus and orgogenesis.

Why is it important to know if a patient suffers from asthma or topical iodine allergy when using CM?

Asthma - increased risk of bronchospasm.


Topical iodine allergy – no associated risk

What eGFR values indicate no risk, low risk, and severe risk regarding CI-AKI?

eGFR > 45 = no risk


eGFR 30-45 = low risk/no risk


eGFR < 45 = severe renal function impairment or actively deteriorating real function; weigh up risk vs benefit of iodinated CM

What is eGFR and how is it relevant to iodinated contrast media with regards to CI-AKI?

Estimation of actual glomerular filtration, based on serum creatinine level, age, sex, race.

Why is diabetes a concern when using CM?

Diabetics usually take Metformin – causes increased lactic acid production by intestines. lactic acidosis = too much lactic acid in body, can’t be metabolized

Why is history of cancer a concern when using CM?

Damage to veins due to frequent venous access OR toxicity of drugs given – difficult to gain venous access for administration of contrast. Could alter protocol -> known Phx of cancer always do pre and post CT scan because may be indicative of metastasis

What are the responsibilities of staff involved in the administration and use of iodinated contrast media?

Iodinated CM can only be administered when a radiologist or other medical officer is on site. Practitioners should be trained in recognition and treatment of CM reactions, resuscitation procedures, and be aware of relevant guidelines and equipment.

What are the steps to take if a patient has an iodinated CM reaction?

1. Stop injection. 2. Report changes to radiologist. 3. Breathing difficulties = code blue a. Emergency button b. 000 if private practice/no assistance c. Provide oxygen d. Emergency/crash cart e. Call emergency crash team f. Assist medical team g. Document adverse reactions + contrast manufacturer in patient notes Do not leave patient alone; reassure them

What strategies may be used for patients at risk of a contrast media reaction?

Avoid CM if possible, Premedication, Observe closely with IV in place for 30 mins following injection of contrast, Ensure emergency drugs and equipment for resuscitation are readily available, IV cannula kept in situ minimum of 15 mins post all IV admin examination

What is the preferred location for venous access for IVCM?

Superficial median of the median cubital vein, cephalic or basilic veins.

What are the advantages of power injectors compared to hand injection for contrast media administration?

Permit loading of contrast and saline (for saline chaser) onto same injector = improved ability to manage injector protocol data, patient safety and workflow efficiency. Inclusion of saline chaser in the image acquisition = ensures complete delivery of the contrast dose into the circulatory system and can reduce amount of iodine needed to achieve optimal imaging. Better bolus geometry + fewer artifacts

Explain the purpose of a saline chaser and the advantages of its use

pushes tail of injected CM bolus into central blood volume, makes use of contrast medium that would otherwise remain unused in injection tubing and peripheral veins

What is IVCM and the overview relating to enhancement phases?

Non-enhanced phase: Baseline status of patients anatomy/ Demonstrating already dense structures without contrast – calculi, calcifications. Early arterial phase: For certain arterial abnormalities (e.g. angiography + tummours)/ Contrast in arteries, aorta, tumours. Late arterial phase : For highly vascularised structures (e.g. liver, spleen, kidney)/Aorta still bright, but some return in IVC; highly vascularised structures e.g. liver, spleen, kidney - appear bright. Portal venous phase: Concentrated in mesenteric venous structures/ Mesenteric venous structures – portal vein is specific venous return from bowel (-> heads into liver)/ Some opacification in kidney cortex, some in aorta, some in IVC, particularly in IVC and PV structures in liver. Delayed phase: Wash out phase/equilibrium phase used to visualise lesions that retain contrast + delayed for urinary system/To demonstrate lesions specifically in liver; and delay in urinary system

Define TTP and PE level

Time to Peak (TTP) = time at which contrst concentration reaches its maximum/ Peak enhancement level (PE) = maximum level of contrast media enhancement achieved as measured in HU

How does cardiac output affect TTP and PE level?

As cardiac output reduces -> cardiovascular transit time increases -> increased TTP/ As cardiac input reduces -> PE (HU) also increases (due to slower clearance of IVCM from body – due to decreased output)

How does patient body weight affect TTP and PE level?

As body weight increases -> magnitude of PE level decreases;/ Larger patients have a larger blood volume in which to dilute the CM/ Heavier patients achieve less PE compared with smaller patients

How does Venous compression affect IVCM?

increases TTP and decreases contrast enhancement

How does the Valsalva manoeuvre affect IVCM?

Leads to more unopacified blood from IVC than opacified blood from SVC entering right atrium -> poor enhancement of pulmonary arteries

Describe the 3 techniques utilized for scan timing relating to IVCM administration including advantages and disadvantages

Fixed Delay: Simple, less contrast, less dose, time-efficient; cannot customize.
Test Bolus: Picks up potential problems, customizable; additional radiation and contrast, increases exam time.
Bolus Tracking: Customizable, no additional contrast, quick; potential problems not identified prior, relies on operator, ROI needs careful positioning.

Why is the brain parenchyma the ‘odd one out’ when it comes to IVCM uptake?

BBB restricts certain substances from entering brain/ IV contrast agents cross the BBB in disrupted areas (e.g. tumours, abcesses)/ normal brain parenchyma does not enhance with IV contrast/Breakdown of BBB -> IV contrast penetrates and is taken up by whatever pathology has caused breakdown in BBB/ IV contrast enhancement reflects breakdown of BBB rather than vascularity of pathology/ can take up to 5 minutes

What are potential reasons and outcomes for IVCM extravasation

IVCM extraversion = leakage of intravenously-administered CM from the normal intravascular compartment into surrounding soft tissues (aka tissuing)/ common complication of CE studies because nearly all CT studies require IVCM at high-flow, high volume fixed rates delivered under pressure by power injectors/ extraversion typically occurs during IVCM administration with IV cannula dislodges and punctures the vessel wall, causing leakage into extravascular tissue – the set CT protocol may be affected/ Higher % of leakage from venous access in back of hand, wrist, foot and ankle/ Usually cause minimal inflammation and erythema, further complications such as skin ulceration, tissue necrosis, and compartment syndrome can occur

What is the non-enhanced phase in IVCM imaging?

Baseline status of patient's anatomy; demonstrating already dense structures without contrast, such as calculi and calcifications

What is the early arterial phase in IVCM imaging?

Used for certain arterial abnormalities like angiography and tumors; contrast is visible in arteries, aorta, and tumors.

What is the late arterial phase in IVCM imaging?

Best for imaging highly vascularized structures such as the liver, spleen, and kidney; the aorta is still bright, with some return in the IVC, and these organs appear bright.

What is the portal venous phase in IVCM imaging?

Contrast is concentrated in mesenteric venous structures; specifically, the portal vein shows venous return from the bowel to the liver, with some opacification in the kidney cortex, aorta, and IVC.

What is the delayed phase in IVCM imaging?

Used to visualize lesions that retain contrast and for delayed imaging of the urinary system; also useful for demonstrating specific liver lesions.