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Multiple Choices:
1. A 65-year-old patient with chronic kidney disease and an eGFR of 45 mL/min/1.73 m² requires a coronary
CTA. Which contrast protocol best minimizes the risk of contrast-induced nephropathy?
A. Use 120 mL of standard iodinated contrast at 350 mg I/mL
B. Administer low-iodine concentration at 270 mg I/mL with reduced volume and provide saline hydration
C. Perform the scan with a high-kV protocol and double the iodine dose
D. Use non-contrast calcium scoring only and defer coronary CTA
Answer: B
Rationale: Lower iodine concentration and reduced volume, combined with saline hydration, minimize
contrast-induced nephropathy in chronic kidney disease patients.
2. Which scanner architecture provides the highest spatial resolution for coronary artery imaging?
A. 64-slice single-source CT
B. Dual-source CT with 0.33 mm detector rows
C. Wide-detector 256-slice CT
D. Photon-counting CT
Answer: D
Rationale: Photon-counting detectors eliminate electronic noise and enable smaller detector elements,
delivering sub-0.3 mm isotropic resolution.
3. A patient with a heart rate of 55 bpm is undergoing a coronary CTA. Which dose-reduction technique is
most appropriate?
A. Retrospective ECG gating with full-dose acquisition
B. Prospective ECG-triggered step-and-shoot mode
C. High-pitch spiral acquisition with ECG-based tube current modulation
D. Increasing tube voltage to 140 kV
Answer: B
Rationale: At low heart rates, prospective step-and-shoot gating captures data in a narrow diastolic window,
dramatically reducing radiation dose.
4. A 62-year-old male undergoes non-contrast cardiac CT for calcium scoring. The Agatston calcium score
unit is defined as which of the following?
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,A. Area in mm² multiplied by peak Hounsfield unit and weighting factor
B. Volume in mm³ multiplied by mean HU and conversion factor
C. Number of calcified voxels multiplied by slice thickness
D. Total calcium mass in milligrams
Answer: A
Rationale: The Agatston score multiplies the lesion area by a factor based on the maximum HU, reflecting
both size and density of calcifications.
5. A 55-year-old patient with a contraindication to beta-blockers requires a coronary CTA. What is the most
appropriate pharmacologic preparation?
A. Intravenous diltiazem infusion
B. Oral atenolol 50 mg one hour before scan
C. Sublingual nitroglycerin only
D. No heart-rate control needed
Answer: A
Rationale: Calcium-channel blockers such as diltiazem can lower heart rate when beta-blockers are
contraindicated, improving image acquisition.
6. What does the term fractional flow reserve derived from CT refer to?
A. Direct measurement of pressure gradients during CT acquisition
B. Computational fluid dynamics applied to coronary CTA data to estimate lesion-specific ischemia
C. Contrast-enhanced perfusion imaging during adenosine stress
D. Measurement of coronary flow velocity using phase-contrast techniques
Answer: B
Rationale: FFR-CT applies computational fluid dynamics to coronary CTA data to estimate lesion-specific
ischemia without additional invasive procedures.
7. The primary determinant of temporal resolution in cardiac CT is which of the following?
A. Detector width
B. Tube current
C. Gantry rotation time
D. Slice thickness
Answer: C
Rationale: Temporal resolution is mainly determined by how fast the gantry rotates, especially in single-
source CT systems.
8. Dual-source CT improves temporal resolution by which mechanism?
A. Increasing tube voltage
B. Using two X-ray tubes simultaneously
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,C. Increasing detector rows
D. Using iterative reconstruction
Answer: B
Rationale: Two tubes at 90-degree offset halve temporal resolution requirements, improving motion-free
imaging.
9. The main advantage of iterative reconstruction is which of the following?
A. Increased scan time
B. Reduced radiation dose
C. Increased contrast volume
D. Increased motion artifacts
Answer: B
Rationale: Iterative reconstruction reduces image noise, allowing dose reduction while maintaining diagnostic
image quality.
10. Spatial resolution in cardiac CT is primarily influenced by which factor?
A. Heart rate
B. ECG gating
C. Detector element size
D. Contrast injection rate
Answer: C
Rationale: Smaller detector elements improve spatial resolution by allowing finer discrimination of small
structures.
11. Blooming artifact is most commonly caused by which of the following?
A. Low tube voltage
B. Partial volume averaging of high-density structures
C. Beam hardening
D. Low tube current
Answer: B
Rationale: High-density structures like calcium exaggerate size due to partial volume effects, causing
blooming artifact.
12. Prospective ECG gating is best described as which of the following?
A. Continuous data acquisition throughout the cardiac cycle
B. Data acquired only during predefined cardiac phases
C. Used only in arrhythmias
D. Higher radiation dose than retrospective gating
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, Answer: B
Rationale: Prospective gating acquires data only at selected phases, lowering radiation dose compared with
retrospective techniques.
13. Retrospective ECG gating is preferred when which of the following is required?
A. Heart rate below 55 bpm
B. Functional assessment is required
C. Calcium score only
D. Dose reduction is critical
Answer: B
Rationale: Retrospective gating allows functional and multiphase assessment, including ejection fraction and
wall motion evaluation.
14. Optimal heart rate for coronary CTA is which of the following?
A. Greater than 90 bpm
B. 75-85 bpm
C. Less than 60 bpm
D. Irrelevant with modern CT
Answer: C
Rationale: Lower heart rates reduce motion artifacts and improve diagnostic image quality for coronary
assessment.
15. A patient with atrial fibrillation undergoes coronary CTA. Which acquisition strategy is most appropriate?
A. Prospective ECG triggering with narrow padding
B. Retrospective gating with ECG editing and wider padding
C. High-pitch spiral acquisition
D. Non-gated axial acquisition
Answer: B
Rationale: Retrospective gating with ECG editing allows reconstruction at multiple phases to compensate for
irregular R-R intervals in atrial fibrillation.
16. Which of the following is the primary function of the pericardial sac?
A. Provides barrier protection from infection
B. Fixes the heart position within the mediastinum
C. Prevents excessive dilatation of the heart
D. Encloses the heart and proximal great vessels
Answer: B
Rationale: The pericardial sac fixes the heart position within the mediastinum and prevents excessive
dilatation.
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