Clinical Nuclear Medicine Imaging Procedures
What the exam tests
Clinical procedure items test protocol selection, patient preparation, radiopharmaceutical choice, acquisition timing, and basic image interpretation across bone, cardiac, pulmonary, renal, thyroid, hepatobiliary, infection, and PET studies.
Core rules
- Match the radiopharmaceutical to the physiology: Tc-99m MDP for bone, sestamibi or tetrofosmin for myocardial perfusion, MAA for lung perfusion, MAG3 or DTPA for renal function, I-123 or pertechnetate for thyroid, mebrofenin for hepatobiliary, FDG for glucose metabolism.
- Patient preparation drives study validity: fasting and glucose control for FDG, caffeine avoidance before adenosine/regadenoson, hydration and voiding for bone and renal scans, thyroid blocking when indicated, and pregnancy/breastfeeding screening.
- Acquisition timing follows kinetics: bone scan 2–4 h after injection; FDG uptake about 60 min; renal Lasix timing depends on protocol; V/Q images are compared for mismatch.
- SPECT/CT adds localization and attenuation correction but also CT dose; use it when it changes management.
Worked example
A V/Q scan shows normal ventilation with multiple segmental perfusion defects. That pattern is a mismatch and raises pretest probability of pulmonary embolism; matched defects suggest airway disease. The reasoning links the physiologic tracer (MAA trapped in pulmonary capillaries) to the embolic obstruction, rather than relying on a visual impression alone. If the chest radiograph also shows a corresponding opacity, the probability estimate changes.
Traps that cost marks
- Scanning a patient without pregnancy or breastfeeding screening.
- Using the wrong collimator or energy window for the isotope.
- Ignoring recent exercise, insulin, or high glucose before FDG.
- Calling a matched V/Q defect a PE without considering COPD or pneumonia.