Which brain imaging methods and what they measure are correctly matched?

Which brain imaging methods and what they measure are correctly matched?

• A. fMRI measures blood flow and neural activity; PET measures metabolic activity; EEG measures electrical activity
• B. CT measures bone density; MRI measures calcium; fMRI measures wind speed
• C. Ultrasound measures blood flow; SPECT measures temperature; EEG measures sleep stages
• D. DTI measures diffusion; MEG measures magnetic fields; PET measures water content

Answer: (A)

Understanding what each brain imaging method actually measures helps you see why this match fits. fMRI looks at changes in blood flow in the brain—the hemodynamic response that accompanies neural activity. The idea is that when neurons are active, blood flow to that area increases, and the fMRI signal (the BOLD signal) tracks that. PET, on the other hand, uses radioactive tracers to measure metabolic activity, showing how much energy tissue is using. EEG records the brain’s electrical activity directly from the scalp, giving precise timing of neural firing. Put together, fMRI assesses blood flow related to activity, PET assesses metabolic activity, and EEG assesses electrical activity, which is exactly what this option states. Why the other options don’t fit: CT is about structural density (often used for bones), not bone density as a primary measure in the imaging sense, MRI isn’t about calcium in that sense and fMRI isn’t about wind speed. The ultrasound option is inconsistent with standard brain imaging in this context, SPECT measures blood flow rather than temperature, and EEG mainly reflects electrical activity (not sleep stages by itself). DTI indeed measures diffusion, MEG measures magnetic fields, but PET measures metabolic activity, not water content.

Understanding what each brain imaging method actually measures helps you see why this match fits. fMRI looks at changes in blood flow in the brain—the hemodynamic response that accompanies neural activity. The idea is that when neurons are active, blood flow to that area increases, and the fMRI signal (the BOLD signal) tracks that. PET, on the other hand, uses radioactive tracers to measure metabolic activity, showing how much energy tissue is using. EEG records the brain’s electrical activity directly from the scalp, giving precise timing of neural firing. Put together, fMRI assesses blood flow related to activity, PET assesses metabolic activity, and EEG assesses electrical activity, which is exactly what this option states.

Why the other options don’t fit: CT is about structural density (often used for bones), not bone density as a primary measure in the imaging sense, MRI isn’t about calcium in that sense and fMRI isn’t about wind speed. The ultrasound option is inconsistent with standard brain imaging in this context, SPECT measures blood flow rather than temperature, and EEG mainly reflects electrical activity (not sleep stages by itself). DTI indeed measures diffusion, MEG measures magnetic fields, but PET measures metabolic activity, not water content.