MPI Flashcards
coronary artery disease
- decrease in blood flow to heart due to atherosclerotic plaque, or occlusive thrombus/embolism
where is plaque likely to form?
in a bend or bifurcation in the coronary artery
- where there are more blood turbulence occurring
what contributes to CAD?
- HTN, hyperlipidemia, diabetes, smoking, obesity, diabetes, sedentary lifestyle, family hx, gender
how does plaque formation occur?
- injury - damage to inner lining of blood vessels
- healing
- localization of macrophages and smooth muscles
- plaque progresses
how does plaque progression occur?
- fibrous tissue deposition (fibrous cap)
- calcium deposition
how do drugs reduce the size of plaque?
- by reducing lipids in plaque
- increasing lipids out of the plaque
- limit number of macrophages present
what drugs are used for plaque reduction?
statins
Lipitor, Crestor, Zocor
which wall will be seen to have more uptake?
lateral > ant or inf
normal LHR when using 201Tl
<0.5:1
normal TID
stress:rest
~1
normal summed stress score (SSS)
normal summed rest score (SRS)
<4
<4
normal LVEF
> 50%
stress/rest matched with NO defects
normal
but watch out for triple vessel disease
stress/rest mismatched defects
stressed induced reversible myocardial ischemia
stress/rest matched defects
chronic hibernating myocardium
/ myocardial infarction
what is triple vessel disease?
stenosis in all major coronary arteries = overall decreased perfusion making it look normal
what pathological conditions will make it easier to see the ischemic myocardium?
when one vessel is affected significantly more than the others
when does sensitivity increase for ischemic myocardium?
when two obstructed vessels “watersheds” affect the same portion of myocardium
TID >1.4
multi-vessel disease
polar plots
semi-quantitative method of analyzing regional perfusion
- data obtained is compared to a large database of normal
increase Rt:Lt ventricular uptake ratio to indicate CAD
> 0.42
summed stress score indicating mild risk
4-8
summed stress score indicating moderate risk
9-13
summed stress score indicating severe risk
> 13
low SDS is due to…
matched SSS and SRS
what does low SDS indicate?
irreversible
large SDS =?
mismatched SSS and SRS
SSS scoring is created by…
infarcts or stress induced ischemia
SDS scoring is created by…
fixed perfusion defects or hibernating myocardium caused by chronic ischemia
stunned myocardium
acute + temporary
- after acute ischemic event
tissue viable but function and contractility is diminished
what does a stunned myocardium look like on a NM scan?
normal perfusion but poor ventricular contraction
how do you treat stunned myocardium?
it should spontaneously resolve after a few weeks!
hibernating myocardium
chronic ischemia caused by severe coronary artery stenosis
no perf on rest, fill in on redistribution images
201Tl perf
stress: normal
redistribution: normal
24hr delay: n/a
interpretation?
neg for cad
201Tl perf
stress: abnormal
redistribution: normal
24hr delay: n/a
interpretation?
ischemia
201Tl perf
stress: abnormal
redistribution: abnormal
24hr delay: normal
interpretation?
chronic ischemia/hibernating myocardium
201Tl perf
stress: abnormal
redistribution: abnormal
24hr delay: abnormal
interpretation?
non-viable/infarct/scar
201Tl viability
rest: normal
redistribution: n/a
interpretation?
viable myocardium
201Tl viability
rest: abnormal
redistribution: normal
interpretation?
viable/hibernating myocardium
201Tl viability
rest: abnormal
redistribution: abnormal
interpretation?
non-viable myocardium
