Significance of diffuse cardiac activity on In-111 labeled leucocyte scans

Area of Science:

• Nuclear Medicine
• Cardiology
• Diagnostic Imaging

Background:

• Diffuse cardiac activity (DCA) on Indium-111 labeled leukocyte scans is an observed phenomenon requiring clinical significance assessment.
• Previous interpretations of DCA have varied, necessitating a review of its association with cardiac pathology.

Purpose of the Study:

• To evaluate the diagnostic significance of diffuse cardiac activity (DCA) detected on Indium-111 labeled leukocyte scintigraphy.
• To determine if DCA is a reliable marker for inflammatory cardiac conditions.

Main Methods:

• Retrospective review of 87 In-111 labeled leukocyte scans performed over a 4-year period.
• Comparison of the incidence of inflammatory cardiac conditions in patients with and without DCA.
• Analysis of the red blood cell (RBC) to white blood cell (WBC) ratio in leukocyte preparations.

Main Results:

• No significant difference in the frequency of inflammatory cardiac conditions was observed between patients with DCA (15%) and those without (7%, P = 0.3).
• A higher RBC:WBC ratio was noted in the leukocyte preparations of the false-positive DCA group compared to true-positive DCA and no DCA groups.
• False-positive DCA findings were strongly associated with residual blood pool activity.

Conclusions:

• Diffuse cardiac activity on In-111 labeled leukocyte scans is not a specific indicator of cardiac inflammation.
• Residual blood pool activity is the likely cause of false-positive DCA findings.
• Clinical interpretation of DCA on leukocyte scans should consider the potential for false positives due to blood pool activity.