Which imaging modality uses gamma-emitting isotopes to measure regional perfusion and activity in tissues?

Which imaging modality uses gamma-emitting isotopes to measure regional perfusion and activity in tissues?

• A. MRI
• B. Angiography
• C. Single Photon Emission Computed Tomography
• D. EEG

Answer: (C)

This question targets functional nuclear imaging that uses gamma-emitting radiotracers to map how blood flows through and how tissues are functioning in different regions. In this approach, a patient receives a tracer that releases gamma photons. A gamma camera detects these photons from multiple angles as the patient is rotated, and the data are reconstructed into a three-dimensional map of tracer distribution. That distribution reflects regional perfusion or metabolic/activity differences in tissues, allowing clinicians to see areas of reduced or enhanced activity. This is distinct from MRI, which relies on magnetic fields and radio waves to create anatomical or functional images without gamma emission. Angiography uses X-ray–visible contrast to image blood vessels rather than tissue perfusion via gamma signals. EEG records electrical activity directly from neurons on the scalp rather than producing tissue images.

This question targets functional nuclear imaging that uses gamma-emitting radiotracers to map how blood flows through and how tissues are functioning in different regions. In this approach, a patient receives a tracer that releases gamma photons. A gamma camera detects these photons from multiple angles as the patient is rotated, and the data are reconstructed into a three-dimensional map of tracer distribution. That distribution reflects regional perfusion or metabolic/activity differences in tissues, allowing clinicians to see areas of reduced or enhanced activity.

This is distinct from MRI, which relies on magnetic fields and radio waves to create anatomical or functional images without gamma emission. Angiography uses X-ray–visible contrast to image blood vessels rather than tissue perfusion via gamma signals. EEG records electrical activity directly from neurons on the scalp rather than producing tissue images.