39. Radioisotope diagnostics of pulmonary embolism (perfusion and inhalation). Radioisotope methods in pulmonary malignancies.

From greek.doctor
  • Pulmonary ventilation/perfusion (V/Q) scan for PE
    • Not so much used anymore – CT pulmonary angiography is more used for diagnosing PE
    • V/Q scan used if CT-PA is not available or if there is contraindication to it
    • X-ray should be performed first to rule out other diseases of the lungs and heart
    • Perfusion and ventilation are studied separately
    • Perfusion study
      • Radiopharmaceutical used: 99mTc – macroaggregated albumin
        • Imaging begins immediately after IV injection
      • Uptake should be visible throughout the lungs
        • Less around the hila and heart
      • If perfusion study shows perfusion defects, a ventilation scan is performed
    • Ventilation study
      • Radiopharmaceutical used: aerosol labeled 99mTc -> patient inhales it
      • The radiotracer should wash into the lungs homogeneously
    • Pulmonary embolism
      • Ventilation will be normal but perfusion will be absent in an area
  • Radioisotope methods in pulmonary malignancies
    • Neuroendocrine (carcinoid) lung tumors express somatostatin receptors -> radiopharmaceuticals will bind to these receptors
      • Lung carcinoid and adenocarcinomas
      • Radiopharmaceuticals which bind to SST receptors
        • 111In-octreotide – indium-111-octreotide
        • 99mTc-depreotide
    • PET/CT
      • For lung cancer and metastases
      • 18F-FDG
        • Increased glucose metabolism in tumor