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RD6.1 | Patient Preparation for Imaging — Graded Quiz
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A 70-year-old man with chronic kidney disease (eGFR 22 mL/min/1.73m²) is referred for a contrast-enhanced MRI requiring gadolinium-based contrast. What is the principal patient-safety concern that should prompt the clinician to discuss the request with radiology before proceeding?
Correct. Gadolinium-based contrast carries a risk of nephrogenic systemic fibrosis (NSF) when eGFR is severely reduced (caution at eGFR <30), so the request should be reviewed and the lowest-risk agent/dose considered.
Gadolinium + eGFR <30: caution for nephrogenic systemic fibrosis (NSF) — review the request and consider the lowest-risk agent/dose.
The specific hazard of gadolinium in severe renal impairment (eGFR <30) is nephrogenic systemic fibrosis (NSF). Lactic acidosis is a metformin/iodinated-contrast issue; MRI uses no ionising radiation, so foetal radiation is not the concern.
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A 26-year-old woman is booked for a TRANSVAGINAL pelvic ultrasound to assess early pregnancy. What bladder instruction should appear on her preparation sheet?
Correct. For transvaginal scanning the bladder should be empty — the probe is close to the pelvic organs and a full bladder pushes them away and causes discomfort. (A full bladder is needed only for the transabdominal approach.)
Transvaginal US = empty bladder; transabdominal pelvic/obstetric US = full bladder.
Transvaginal ultrasound requires an EMPTY bladder; the close-range probe images the pelvic organs directly, and a full bladder displaces them and causes discomfort. A full bladder is required only for transabdominal pelvic/obstetric scanning.
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A clinician is reviewing renal function before iodinated contrast for a CT urogram. At which eGFR threshold is the risk of contrast-associated acute kidney injury (CA-AKI) considered high enough to warrant particular caution, hydration measures and radiology discussion?
Correct. The main caution for contrast-associated AKI with iodinated contrast applies at eGFR <30, where prophylactic hydration and radiology discussion are warranted. (Note the separate metformin rule, which uses an eGFR <60 cut-off.)
Iodinated contrast CA-AKI caution at eGFR <30; metformin is withheld at eGFR <60 — two different thresholds.
Iodinated-contrast CA-AKI caution is centred on eGFR <30 (hydration, radiology discussion). Do not confuse this with the metformin-withholding threshold of eGFR <60, which is a different precaution against lactic acidosis.
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During pre-MRI screening, a metalworker reports a previous high-velocity injury where a metal fragment may have entered his eye, never formally removed. What is the correct action before MRI?
Correct. A possible intra-ocular metallic foreign body is a key MRI screening flag — the magnetic field can move a ferromagnetic fragment and damage the eye, so exclude it with orbital radiographs/CT before MRI.
Suspected intra-ocular metallic foreign body before MRI: exclude with orbital imaging first — the field can move the fragment and damage the eye.
A suspected intra-ocular metallic foreign body must be excluded (orbital radiographs/CT) before MRI, because the magnetic field can displace a ferromagnetic fragment and injure the eye. Fasting, laxatives and contrast are irrelevant safety steps here.
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A clinician needs a contrast-enhanced study in a pregnant patient with a strong clinical indication. Which statement best guides counselling and preparation about contrast use in pregnancy?
Correct. Gadolinium is generally avoided in pregnancy unless essential, whereas iodinated contrast may be used when clearly indicated; either way the decision needs informed discussion, documented justification and radiology input.
In pregnancy: avoid gadolinium unless essential; iodinated contrast may be used when clearly indicated — always with informed discussion and radiology input.
Contrast in pregnancy is a risk–benefit decision, not an absolute ban. Gadolinium is generally avoided unless essential; iodinated contrast may be used when clearly indicated. The decision requires informed counselling and radiology input — gadolinium is not the default just because MRI lacks radiation.
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A patient telephones, anxious that 'fasting' for an upper-abdominal ultrasound means absolutely nothing by mouth, including her morning antihypertensive. What is the most appropriate verbal instruction to give?
Correct. Fasting for upper-abdominal ultrasound means avoiding food for 4–6 hours so the gallbladder stays distended; small sips of water and essential regular medication are generally permitted. Verbal counselling lets you clarify exactly this kind of misunderstanding.
US fasting = no food 4–6 h for gallbladder distension; small water sips and essential medication are usually allowed — use verbal counselling/teach-back to correct misunderstanding.
Fasting for upper-abdominal/gallbladder ultrasound means no food for 4–6 hours (to keep the gallbladder distended); small sips of water and essential medicines are usually allowed. Patients should not stop essential drugs, and a full bladder is not needed for this scan.
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