cardiac blood pool scan

A multi-gated (MUGA) cardiac blood pool scan (sometimes just called a MUGA scan) is a common study performed in patients who are receiving potentially cardiotoxic chemotherapy.

Indications

• acute myocardial infarction (AMI)
• coronary artery disease (CAD)
• evaluation after coronary artery bypass graft surgery
• cardiomyopathy/myocarditis
• assessment of drug therapy
• pulmonary disease
  • right ventricular (RV) enlargement
  • cor pulmonale
  • normal left ventricular (LV) ejection fraction, wall motion and chamber size strongly suggests a pulmonary etiology

Tracer dose and route of administration

• technetium-99m-labeled red blood cells (RBCs)

Technique

• patient in normal sinus rhythm
• IV administration of Tc-99m-labeled RBCs
• ECG gated – with R wave gating
• minimum of 16 frames/cardiac cycle
• at rest and exercise

First pass study

This is obtained by injecting a compact bolus of suitable radiopharmaceutical intravenously.

• major advantage: data collected rapidly over very few cardiac cycles allows measurement of ventricular function at peak stress during exercise ventriculography

• major disadvantage: counting statistics are low and only a limited number of views are possible

Analysis

• qualitative analysis
• quantitative analysis
• functional parameters
  • wall motion assessment (regional and global)
  • end-diastolic (ED) and end-systolic (ES) ventricular volumes
  • stroke volume
  • cardiac output
  • ejection fraction (LV and RV)
  • regurgitant fraction (stroke index ratio)
  • ventricular filling and emptying rates
  • cardiac shunt quantitation
    • left to right shunts: evaluated using the first transit technique (not equilibrium)
    • right to left shunts: evaluated using Tc-99m labeled macroaggregated albumin and comparing ratio of tracer in the lung to tracer gaining access to the systemic circulation