Scintigraphy & PET Scans

Nuclear Scintigraphy

• uses small amounts of radioisotopes

• diagnose dz involving bone, soft tissue, & vessels

• radionuclides injected or ingested

Scintigraphy Overview

• camera detects emission of radioactivity from patient

• nuclides carried to area with most active blood supply

  • localizing pathology or trauma site

Technetium-99

more attracted to bone

Iodine-131

more attracted to thyroid

Vascular Phase

• used if thrombosis suspected

• camera placed while injection given

Soft Tissue Phase

• 5-10 min after injection

• tendons & ligaments

Bone Phase

• 2-3hrs after injection

Scintigraphy Images

• demonstrate function, not anatomy

• plotted with dots

  • indicate radioactive bursts emitted from patient

• results can be displayed in color:

  • red: hot, high activity

  • blue: cold, low activity

Positron Emission Tomography - PET Scan

• paired with MRI or CT

• looks at metabolic activity not structure

• injection of radioisotope that emits gamma ray photons (positrons)

PET Unit

• series of scintillating sensors arranged in a ring

• images acquired & reconstructed like slices

• scanners detect photons & calculate their origin in body

Fludeoxyglucose - FDG

• most common isotope

• maps brain function & malignant tumors

• short half life

• produced near scanner