RESPIRATORY SYSTEM Flashcards
: What are the two main demonstrations involved in radionuclide lung imaging?
:
Pulmonary perfusion – by limited capillary blockade.
Assessment of ventilation – using radiolabeled gases or aerosols.
: What is the most common indication for nuclear medicine lung studies?
A: Diagnosis of pulmonary thromboembolism (PE).
ventilation Imaging
Radioactive gases: Krypton-81, Xenon-133.
Nanoparticles: 99mTc Technegas.
Radiolabeled aerosols: 99mTc DTPA.
Perfusion Imaging
Radiopharmaceutical: 99mTc Macroaggregated Albumin (MAA) (15-100 μm in diameter).
What is the primary clinical indication for lung perfusion imaging?
A: Diagnosis of pulmonary thromboembolism (PE).
What are the consequences of undiagnosed or misdiagnosed pulmonary thromboembolism?
Increased risk of fatal recurrence.
Development of chronic pulmonary hypertension.
Right heart failure (RHF).
Where do the majority of pulmonary thromboemboli originate?
A: From the deep veins of the lower limbs and pelvis (~90%).
Why does PE occur more frequently in the lower lobes of the lungs?
A: Due to preferential blood flow from gravity.
Other Sources of Pulmonary Emboli
Fat emboli: From long bone fractures or liposuction.
Air emboli: From cardiac and neurosurgeries.
Tumor emboli: From renal cell cancer invading the IVC.
Septic emboli: Infected thromboemboli.
onsequences of Pulmonary Embolism
onsequences of Pulmonary Embolism
Hypocapnia: Early bronchoconstriction.
Ischemia: Reduction in surfactant production causing dyspnea.
Pulmonary infarction: Leads to hemorrhage, hemoptysis, and chest pain.
Massive embolism: Causes acute pulmonary hypertension, RHF, and cardiac death.
SUMMARY
Pulmonary embolism is a potentially fatal condition.
Ventilation-perfusion scintigraphy is a sensitive, specific, and non-invasive method for diagnosing PE.
Radiolabeled gases, aerosols, or nanoparticles are used for ventilation imaging.
99mTc MAA is used for perfusion imaging.
Q: What is the most common type of pulmonary embolism?
A: Thromboembolism.
A: Thromboembolism.
Q: A sudden pulmonary embolism initially causes reduced ventilation in the affected area due to what?
A: Hypocapnia.
Q: Is pulmonary embolism seen as a ventilation-perfusion match or mismatch?
A: Ventilation-perfusion mismatch.
