Myocardial Perfusion Imaging Thallium

Question 1

describe how Tl-201 work in the myocardium cell?

Answer 1

Tl-201 is an analog of the element potassium (K). During the exercise, the demand of oxygen in myocardial cell increase -> blood flow increase, however, the vessel is narrow or atherosclerotic, that make blood flow is less to the ischemic area. Therefore, Tl-201 is less uptake in stress images shoed decreased activity. At rest, blood flow to the myocardial cell is adequate, Tl-201 pump in and out of the sodium potassium pump, Tl-201 redistribute to the ischemic area, so the ischemic can occur and is visualized on delayed images.

Question 2

what are indication for Tl-201 Cl imaging?

Answer 2

1. detection of coronary artery by way of classification of the left ventricular myocardium as normal, irreversibly ischemic, and reversibly ischemic
2. detection of hibernating myocardium
3. detection of myocardial perfusion abnormalities secondary to causes other than CAD
4. evaluation of the septum in the patients with left bundle branch block

Question 3

identify patient prep for Tl-201 Cl

Answer 3

1. discontinue all cardioactive medication
2. beta blockers 24hrs
3. calcium channel blocker
4. caffeine for 12hrs
5. perform ECG
6. NPO

Question 4

Dose of Tl-201 Cl?

Answer 4

2.5 -4 mCi for stress
1 -2 mCi for rest/redistribution

Question 5

Procedure for Tl-201

Answer 5

• patient supine, left arm above head.
• stress testing begin 10 post injection.
• rest done 3-4 hr after stress. image 20 min post inject

Question 6

why Tl-201 myocardial imaging patient cannot have fatty meal?

Answer 6

because glucose/carbohydrates speed up the rate Tl-201 leaving normal and ischemic areas

Question 7

why Tl-201 patient must be imaged within 5-10 min after stress

Answer 7

because at peak, myocardial oxygen demand may begin to fill in rapidly. After that duration, myocardial cell become redistribution, that lead to false-negative result

Question 8

what does Tallium viability used for?

Answer 8

identifying patient with viable myocardium and predicting which patients should demonstrate functional improvement after revascularization

Question 9

what is the dose for viability?

Answer 9

3-4mCi at rest

Question 10

imaging time for viability?

Answer 10

20 mins, 4 hr and 24 hrs

Question 11

how many percent of Tl-201 lost from the body?

Answer 11

10% over 10 days

Question 12

why Tl-201 stress studies need for early images?

Answer 12

because of redistributes
- Normal area redistributes faster than abnormal area