Computed Tomography and Advanced Imaging Questions and Answers Flashcards

In MRI, the term 'T1-weighted image' refers to a sequence that highlights contrast based on:

Answer: Spin-lattice (longitudinal) relaxation time differences between tissues

T1 weighting uses the longitudinal (spin-lattice) relaxation time (T1) to differentiate tissues; fat appears bright and fluid appears dark on T1 images.

Which contrast agent is most commonly used for MRI enhancement?

Answer: Gadolinium-based contrast agent (GBCA)

Gadolinium-based contrast agents (GBCAs) shorten T1 relaxation time, causing enhanced tissues to appear brighter on T1-weighted MRI sequences.

A patient with a pacemaker presents for an MRI examination. What is the most appropriate action?

Answer: Consult the ordering physician and check if the pacemaker is MR-conditional before proceeding

MR technologists must verify the pacemaker model, determine if it is MR-conditional, and consult the ordering physician and MRI physicist before proceeding.

In nuclear medicine, which radionuclide is most commonly used for bone scans?

Answer: Technetium-99m (Tc-99m)

Tc-99m labeled phosphonates (e.g., MDP) are the standard radiopharmaceuticals for bone scintigraphy due to their favorable physical properties and affinity for bone.

What does the term 'slice thickness' affect in CT image quality?

Answer: Z-axis resolution and partial volume averaging

Thinner slices improve z-axis (longitudinal) spatial resolution and reduce partial volume averaging, but increase image noise.

Which fluoroscopic technique reduces patient dose by pulsing the x-ray beam rather than continuous fluoroscopy?

Answer: Pulsed progressive fluoroscopy

Pulsed progressive fluoroscopy delivers x-ray pulses at lower frame rates, significantly reducing patient and staff dose compared to continuous fluoroscopy.