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