Shunt Study

Question 1

what is cardiac shunts?

Answer 1

movement of blood across the septum. most are congenital defect.

Question 2

what happen right to left shunts?

Answer 2

aorta show before the lungs and right ventricle may larger than the left ventricle.

Question 3

what happen left to right shunts?

Answer 3

blood will return prematurely to the pulmonary circulation

Question 4

what is Rp and dose for right to left shunt?

Answer 4

Tc99m-MAA 2-5 mCi

Question 5

which areas draw ROI in right to left shunt and how quantification MAA?

Answer 5

• Rt ventricle, lt ventricle and lungs.
• for quantification MAA may be used, image ANT/POST whole body, subtract lung ROI from WB ROI

Question 6

How confirm the right to left shunt?

Answer 6

the left ventricle spike at the same time as the lungs

Question 7

how to perform left to right shunt?

Answer 7

• evaluated by pulmonary time activity curve generated by a first pass
• entire chest image include lung and hear 0.5 sec/frame in 30sec
• ROI drawn one or both lungs, dont include hear or great vessels
• ROI around SVC to ensure a good bolus injection
• Peak SVC have FWHM in 3 secs or less

Question 8

what does normal pulmonary time activity curve should have?

Answer 8

• Large and single peak then small peak.

Question 9

What happen to the peak of the pulmonary time activity curve with left to right shunt?

Answer 9

a bump on its down slope