Case 18-1 cont'd
History:
55 year old Female with dyspnea and EF:23% has been referred to rule out pulmonary embolism.
Description:
-Mild relative decreased perfusion in the posterior aspect of bilateral lungs more pronounced in posterior lower lobes.
In the transaxial perfusion SPECT images, perfusion is distributed to the non-dependent aspect of the lungs.
The ventilation scan is normal.
-Heart impression is enlarged.
Question1 . Is this pattern a reverse mismatch? No! A reversed mismatch defect pattern needs to have ventilation defect, while this case has mostly homogeneous ventilation.
Question2 . Is perfusion defect in the posterior in this case due to dependent atelectasis? Less likely! because dependent atelectasis is more a bandlike decreased activity and it's not as extensive as what we see in this case.