Card Set Information
Kowalski's lung lecture
What are the 2 main group of lung pharmaceutical agents?
1. Perfusion (labeled particles)
-Tc 99m Macroaggregated Albumin (MAA)
2. Ventilation Agents (gases and aerosols)
-Xenon 133 (gas)
- Tc 99m DTPA (aerosol)
How does the perfusion scan work?
1: MAA (20-60 microns) is trapped in smaller sized lung capillaries arterioles
: PE causes regions of absent radioactivity
: no perfusion defects (hot)
: obstructed perfusion (cold), ventilation confirms this
List some biological properties of MAA
1. Particle clearance by fragmentation
2. T 1/2 depends on size of particle and hardness (how hot temp is when making particles)
3. Cleared particles are phagocytosed in RES with proteolytic digestion in Kupffer's cell.
What is the relationship between time, MAA particles and activity?
#of MAA Particles
How big are MAA particles and how many are typically given to adult patients?
: 20-60 microns (too small, it goes to liver)
# of particles:300,000 (3mCi)
* Dilute if suspected pulmonary hypertension*
What's the purpose of Lung Ventilation Imaging
1. Assess lung ventilation
2. Differentiate PE from COPD
What are the 3 phases of Vent study?
: (inhales Xe 133 10mCi)
: pt re-breathes gas/O2 mixture (5min after inhalation)
: Pt inhales air, Xe-133 exhaled
What does COPD and PE look like on vent and perf images?
What 2 ways does MAA enter systemic circulation?
1. After fragmentation in lung (no risk)
2. Via right-to left cardiac shunt (VSD- ventricular septal defect)
-MAA bypassed lungs and ends up in kidney/brain.
*Max pt dose of 1mg MAA particles*