Focal Hot Spots on Ventilation/Perfusion Scan

Focal hot spots on a V/Q scan represent areas of MAA aggregation. These may be caused by small, clinically insignificant, labeled blood clots that form if blood is introduced into the syringe during injection (e.g., for conforming intravenous location) and allowed to sit. MAA aggregates may also form if there is failure to properly suspend the MAA particles during preparation or if they are not re-suspended after sitting on the bench for a while prior to injection.

This Photoshopped image of a VQ scan simulates this appearance.

References

Mettler FA and Guiberteau MJ. Chapter 7: Respiratory System. In Essentials of Nuclear Medicine Imaging. Fifth Edition. Saunders, Philadelphia. 2006. pp 161-162.