Which modality is NOT listed among those that map a region of tissue?

• A. Ultrasound
• B. MRI
• C. CT
• D. Fluoro

Answer: (A)

The key idea is how each modality creates a spatial map of tissue. CT and MRI produce detailed anatomical maps by compiling cross-sectional slices across a region, giving a structured map of tissue densities and signals. Fluoroscopy provides real-time imaging of moving structures, effectively mapping how tissues and organs behave over time within a region. Ultrasound, while excellent for imaging specific structures, is usually used for targeted, real-time assessment of a limited area and does not generate a broad regional map in the same way as CT or MRI. It’s highly operator-dependent and has a smaller field of view, so it’s not treated as a modality that maps a region of tissue in the broader sense used here.