NCT 2026 Exam Prep: Nuclear Cardiology
Practice Questions with Answer Rationales
Myocardial Perfusion Stress Testing |
Cardiac Imaging | Radiopharmaceuticals |
Clinical Cases Review
SECTION 1: RADIOPHARMACEUTICALS (Questions 1–30)
1. Which radiopharmaceutical is most commonly used for SPECT myocardial
perfusion imaging due to its favorable 140 keV photon energy, 6-hour half-
life, and minimal redistribution?
A. Tl-201 thallous chloride
B. Tc-99m sestamibi
C. F-18 FDG
D. Rb-82 chloride
Rationale: Tc-99m sestamibi is the most commonly used radiopharmaceutical for
SPECT MPI. Its 140 keV photon energy is optimal for gamma camera detection,
the 6-hour half-life allows for flexible imaging protocols, and its minimal
redistribution permits separate stress and rest acquisitions.
2. Which radiopharmaceutical behaves as a potassium analog and enters
viable myocytes via the Na⁺-K⁺-ATPase pump?
A. Tl-201 thallous chloride
B. Tc-99m sestamibi
C. Tc-99m tetrofosmin
D. F-18 FDG
Rationale: Tl-201 is a potassium analog that enters viable myocardial cells via the
membrane Na⁺-K⁺-ATPase pump. Its initial uptake is proportional to blood flow,
and it redistributes over time, making it useful for viability assessment.
3. What is the physical half-life of Tc-99m?
,A. 6 hours
B. 13 hours
C. 73 hours
D. 75 seconds
Rationale: Tc-99m decays by isomeric transition with a physical half-life of
approximately 6 hours and a principal gamma emission of 140 keV.
4. Which PET perfusion tracer has the shortest half-life at approximately 75
seconds?
A. N-13 ammonia
B. O-15 water
C. Rb-82 chloride
D. F-18 flurpiridaz
Rationale: Rb-82 has an ultrashort half-life of 75 seconds, requiring generator
elution and immediate injection. It is taken up by myocardial cells via the Na⁺/K⁺-
ATPase pump.
5. Tc-99m sestamibi is taken up by myocardial cells and localizes primarily in
which intracellular organelle?
A. Nucleus
B. Mitochondria
C. Sarcoplasmic reticulum
D. Lysosomes
Rationale: Tc-99m sestamibi is a lipophilic cation that accumulates within the
inner mitochondrial matrix due to the strong negative transmembrane potential,
with approximately 92% of activity associated with mitochondria.
6. Which radiopharmaceutical is the gold standard for myocardial viability
assessment when combined with perfusion imaging?
A. Tl-201
B. Tc-99m sestamibi
C. F-18 FDG
D. Rb-82
,Rationale: F-18 FDG PET is considered the most accurate technique for detecting
viable myocardium. Viability is identified by a perfusion–metabolism mismatch
pattern where reduced perfusion is accompanied by preserved glucose uptake.
7. What is the mechanism of Tc-99m tetrofosmin uptake in myocardial cells?
A. Active transport via Na⁺-K⁺-ATPase
B. Passive diffusion followed by mitochondrial accumulation
C. Receptor-mediated endocytosis
D. Calcium channel-mediated influx
Rationale: Tc-99m tetrofosmin is a lipophilic cationic agent that enters myocardial
cells by passive diffusion and accumulates near mitochondria. Its uptake is
proportional to blood flow in the physiologic range.
8. Which radiopharmaceutical requires a 24-hour abstinence from caffeine
before pharmacologic stress testing?
A. Only Tl-201
B. Adenosine, dipyridamole, and regadenoson
C. Only F-18 FDG
D. Tc-99m sestamibi only
Rationale: Caffeine competitively antagonizes adenosine receptors and can reduce
the vasodilator effect of adenosine, dipyridamole, and regadenoson, potentially
producing false-positive or artifactual perfusion defects.
9. What is the primary mechanism of Tl-201 redistribution?
A. Immediate fixation in viable myocardium with no later change
B. Initial uptake proportional to flow followed by gradual washout from
viable cells
C. Uptake only in necrotic tissue
D. Direct binding to cellular DNA
Rationale: Tl-201 behaves like potassium, entering viable myocytes via Na⁺-K⁺-
ATPase. Over time (3–4 hours), it redistributes from areas of reduced perfusion to
areas of preserved viability, allowing differentiation of ischemic from scarred
myocardium.
10. Which radiopharmaceutical is used for Tc-99m pyrophosphate (PYP)
cardiac imaging to detect transthyretin cardiac amyloidosis?
, A. Tc-99m sestamibi
B. Tc-99m tetrofosmin
C. Tc-99m pyrophosphate (PYP)
D. Tc-99m MDP
Rationale: Tc-99m PYP scintigraphy is highly sensitive and specific for detecting
transthyretin cardiac amyloidosis (ATTR-CA) and differentiating it from light
chain (AL) amyloidosis.
11. What is the recommended dose range for Tc-99m sestamibi in a one-day
rest/stress protocol?
A. 5–10 mCi for each injection
B. 8–12 mCi at rest and 24–36 mCi at stress
C. 20–30 mCi for both injections
D. 1–3 mCi for each injection
Rationale: In a one-day protocol, a lower dose (8–12 mCi) is given at rest,
followed by a higher dose (24–36 mCi) at stress to overcome residual activity from
the first injection and ensure adequate count statistics.
12. Which radiopharmaceutical is a generator-produced PET perfusion
tracer?
A. N-13 ammonia
B. O-15 water
C. Rb-82 chloride
D. F-18 FDG
Rationale: Rb-82 is produced from a strontium-82/rubidium-82 generator,
allowing on-site production without a cyclotron. Its ultrashort half-life (75
seconds) requires immediate injection and dynamic acquisition.
13. In a two-day stress/rest Tc-99m sestamibi protocol, what is the typical
administered activity per injection?
A. 5–10 mCi
B. 8–12 mCi
C. 20–30 mCi
D. 40–50 mCi
Practice Questions with Answer Rationales
Myocardial Perfusion Stress Testing |
Cardiac Imaging | Radiopharmaceuticals |
Clinical Cases Review
SECTION 1: RADIOPHARMACEUTICALS (Questions 1–30)
1. Which radiopharmaceutical is most commonly used for SPECT myocardial
perfusion imaging due to its favorable 140 keV photon energy, 6-hour half-
life, and minimal redistribution?
A. Tl-201 thallous chloride
B. Tc-99m sestamibi
C. F-18 FDG
D. Rb-82 chloride
Rationale: Tc-99m sestamibi is the most commonly used radiopharmaceutical for
SPECT MPI. Its 140 keV photon energy is optimal for gamma camera detection,
the 6-hour half-life allows for flexible imaging protocols, and its minimal
redistribution permits separate stress and rest acquisitions.
2. Which radiopharmaceutical behaves as a potassium analog and enters
viable myocytes via the Na⁺-K⁺-ATPase pump?
A. Tl-201 thallous chloride
B. Tc-99m sestamibi
C. Tc-99m tetrofosmin
D. F-18 FDG
Rationale: Tl-201 is a potassium analog that enters viable myocardial cells via the
membrane Na⁺-K⁺-ATPase pump. Its initial uptake is proportional to blood flow,
and it redistributes over time, making it useful for viability assessment.
3. What is the physical half-life of Tc-99m?
,A. 6 hours
B. 13 hours
C. 73 hours
D. 75 seconds
Rationale: Tc-99m decays by isomeric transition with a physical half-life of
approximately 6 hours and a principal gamma emission of 140 keV.
4. Which PET perfusion tracer has the shortest half-life at approximately 75
seconds?
A. N-13 ammonia
B. O-15 water
C. Rb-82 chloride
D. F-18 flurpiridaz
Rationale: Rb-82 has an ultrashort half-life of 75 seconds, requiring generator
elution and immediate injection. It is taken up by myocardial cells via the Na⁺/K⁺-
ATPase pump.
5. Tc-99m sestamibi is taken up by myocardial cells and localizes primarily in
which intracellular organelle?
A. Nucleus
B. Mitochondria
C. Sarcoplasmic reticulum
D. Lysosomes
Rationale: Tc-99m sestamibi is a lipophilic cation that accumulates within the
inner mitochondrial matrix due to the strong negative transmembrane potential,
with approximately 92% of activity associated with mitochondria.
6. Which radiopharmaceutical is the gold standard for myocardial viability
assessment when combined with perfusion imaging?
A. Tl-201
B. Tc-99m sestamibi
C. F-18 FDG
D. Rb-82
,Rationale: F-18 FDG PET is considered the most accurate technique for detecting
viable myocardium. Viability is identified by a perfusion–metabolism mismatch
pattern where reduced perfusion is accompanied by preserved glucose uptake.
7. What is the mechanism of Tc-99m tetrofosmin uptake in myocardial cells?
A. Active transport via Na⁺-K⁺-ATPase
B. Passive diffusion followed by mitochondrial accumulation
C. Receptor-mediated endocytosis
D. Calcium channel-mediated influx
Rationale: Tc-99m tetrofosmin is a lipophilic cationic agent that enters myocardial
cells by passive diffusion and accumulates near mitochondria. Its uptake is
proportional to blood flow in the physiologic range.
8. Which radiopharmaceutical requires a 24-hour abstinence from caffeine
before pharmacologic stress testing?
A. Only Tl-201
B. Adenosine, dipyridamole, and regadenoson
C. Only F-18 FDG
D. Tc-99m sestamibi only
Rationale: Caffeine competitively antagonizes adenosine receptors and can reduce
the vasodilator effect of adenosine, dipyridamole, and regadenoson, potentially
producing false-positive or artifactual perfusion defects.
9. What is the primary mechanism of Tl-201 redistribution?
A. Immediate fixation in viable myocardium with no later change
B. Initial uptake proportional to flow followed by gradual washout from
viable cells
C. Uptake only in necrotic tissue
D. Direct binding to cellular DNA
Rationale: Tl-201 behaves like potassium, entering viable myocytes via Na⁺-K⁺-
ATPase. Over time (3–4 hours), it redistributes from areas of reduced perfusion to
areas of preserved viability, allowing differentiation of ischemic from scarred
myocardium.
10. Which radiopharmaceutical is used for Tc-99m pyrophosphate (PYP)
cardiac imaging to detect transthyretin cardiac amyloidosis?
, A. Tc-99m sestamibi
B. Tc-99m tetrofosmin
C. Tc-99m pyrophosphate (PYP)
D. Tc-99m MDP
Rationale: Tc-99m PYP scintigraphy is highly sensitive and specific for detecting
transthyretin cardiac amyloidosis (ATTR-CA) and differentiating it from light
chain (AL) amyloidosis.
11. What is the recommended dose range for Tc-99m sestamibi in a one-day
rest/stress protocol?
A. 5–10 mCi for each injection
B. 8–12 mCi at rest and 24–36 mCi at stress
C. 20–30 mCi for both injections
D. 1–3 mCi for each injection
Rationale: In a one-day protocol, a lower dose (8–12 mCi) is given at rest,
followed by a higher dose (24–36 mCi) at stress to overcome residual activity from
the first injection and ensure adequate count statistics.
12. Which radiopharmaceutical is a generator-produced PET perfusion
tracer?
A. N-13 ammonia
B. O-15 water
C. Rb-82 chloride
D. F-18 FDG
Rationale: Rb-82 is produced from a strontium-82/rubidium-82 generator,
allowing on-site production without a cyclotron. Its ultrashort half-life (75
seconds) requires immediate injection and dynamic acquisition.
13. In a two-day stress/rest Tc-99m sestamibi protocol, what is the typical
administered activity per injection?
A. 5–10 mCi
B. 8–12 mCi
C. 20–30 mCi
D. 40–50 mCi
