Pulmonary Flashcards
Mostly used to detect
Pulmonary embolism
Indications
Detection of PE, follow up after treatment, quantitative lung function before lung resection
evaluation of lung transplants, CF, cause of pulmonary hypertension, cardiac shunts
Contraindications
Pregnant, breast feeding, recent NM
Active wheezing - can cause false positive
Pt prep
No prep except focused Hx and recent chest x-ray or chest ct scan
- within 4 hours of scan and acceptable up to 24 hours before scan
What blood work is important to include in Hx
Results of D-dimer test
What is D-dimer
A test that measures protein fragments in the blood that release when a blood clot dissolves
Can indicate a blood clotting disorder
perfusion RP
99mTc MAA
Perfusion RP dose
MAA 1 mCi (1-4 mCi)
Normal amount of particles for perfusion
200,000-700,000 particles
Reduced particles amount
100,000-200,000 particles
Who needs reduced particles
Peds, chronic severe pulmonary hypertension, right to left shunts, or pneumonectomy
If aerosol is performed before perfusion study, the 2nd study must be _____ times the count rate of the 1st study
2nd study must be 3-4x count rate of the 1st study
Injection to imaging time
Immediately
Perfusion pt position during imaging
Upright for single head to increase the size of the chest cavity
Supine for dual head
Perfusion views
All 8 - planar
Perfusion matrix
256x256
Planar counts per view
500k - 1 million
Pt position for perfusion injection and why
Supine to allow for uniform distribution all the way to the apices (top) - if upright, the particles will settle at the bottom due to gravity
Important things to remember when injecting MAA
Gentle agitate vial before injection
Have to cough and take deep breaths before injection
Inject MAA over 3-5 respiratory cycles
MAA adheres to plastic tubing
Do not draw back blood
Lung quantification - place ROIs where
Place 3 equal ROIs top, middle, and bottom, of each lung
Determine total activity for each lung in addition to the activity in all 6 regions of interest
Normal right to left lung ratio
55:45
Pt with chronic obstructive lung disease or signs of reactive airways (wheezing) may use _____ before study
Bronchodilator
Perfusion scan shows visualization of kidneys and brain means
Right to left shunt
Need to scan head
Aerosol ventilation RP
99mTc DTPA
Or
99mTc Sulfur Colloid
Aerosol ventilation RP dose
25 mCi (25-35)
For both DTPA and SC
Aerosol ventilation administration to imaging time
Acquisition started on completion of inhalation
Of the aerosol dose, only how much is actually delivered to the lungs?
0.5-1 mCi
Aerosol ventilation projections and acquisition type
Planar for 8 views
Pt position during ventilation
Upright is preferred
But supine if necessary
Inhalation process of aerosol
Pt breathes through an oxygen-agitated nebulizer until approximately 100,000 counts into the lungs
Gas ventilation RP
133 xenon
Gas ventilation RP dose
Xenon 5 mCi
(5-30 mCi)
Gas ventilation administration to imaging time
Acquisition started AT first breath
Acquisition type and number of views for each phase in gas ventilation
Dynamic
First breath: 1
Equilibrium: 4
Washout: 5-20
Time/view for each phase of gas ventilation
First breath: as long as patient can hold their initial breath
Equilibrium: 45 seconds
Washout: 15-60 seconds
Pt position for gas ventilation
Erect is preferred
Describe what happens during each phase of gas ventilation
First breath: pt takes a breath of xenon and holds it
Equilibrium: have pt rebreathe xenon+O2 and take 4 dynamic images 45 seconds each
Wash out: have pt breath air+O2 while exhaling in xe trap and take serial dynamics for 5 mins
