First pass shunt

Question 1

Applications of first pass shunt

Answer 1

 Ventricular ejection fraction
 Stroke volume, ED volume, ES volume
 Cardiopulmonary circulation
 Pulmonary transit time
 Intracardiac shunts

Question 2

FIrst pass shunt protocol

Answer 2

 370 – 740 MBq 99mTcO4-in < 1 ml
 Compact bolus (< 2 sec)
 Collimation high sensitivity low resolution
 30% energy window
 Zoom 1.3 – 1.6
 370 – 740 MBq 99mTcO4-in < 1 ml
 Compact bolus (< 2 sec)
 Collimation high sensitivity low resolution
 30% energy window
 Zoom 1.3 – 1.6

Question 3

Describe first pass shunt analysis

Answer 3

 Select from cine frames to include in study
 Select range of R-R interval being accepted
 Differs if no gate

Question 4

Describe evaluation

Answer 4

 TAC of bolus
- > 2 sec bolus and study is not valid
 TAC of bolus through heart and lungs
- systemic recirculation occurs in 10 –15 secs
 RVEF & LVEF
- Normal = 50%

Question 5

Describe left-to-right shunt analysis

Answer 5

 TACs over heart and lungs
 Early pulmonary recirculation detected as small second
peak
 Normal lung to systemic circulation is 1
 > 1.2:1pulmonary to systemic L to R shunt

Question 6

Describe right-to-left shunt analysis

Answer 6

 Compare bolus thru left and right ventricles and
lungs.
 Some will go directly to left ventricle and not go to
lungs first
 Result early peak in left ventricle

Question 7

Pros of this imaging technique

Answer 7

 Temporal separation
 Rapid acquisition
 Combined imaging
techniques
 Cardiac cycle selection
 Arrhythmic

Question 8

Cons of this imaging technique

Answer 8

 Spatial resolution reduced
 One projection only
 Re-inject Increase Dose
 Large memory requirements
 Reconstruction time
 Low Counts
 Critical Nature Bolus