A 72-year-old gentleman underwent myocardial perfusion scintigraphy (MPS) for sinus
tachycardia of unknown cause. Baseline electrocardiography (ECG) showed sinus tachycardia
and electrical alternans. Thallium-201 stress-redistribution MPS was performed with
dipyridamole stress. On the raw projection images, a photopenic “halo” was noted surrounding
the heart. Reconstructed slices showed small left ventricle with no obvious perfusion
defect. Review of single-photon emission computed tomography/computed tomography images
showed suspected large pericardial effusion. The patient was admitted and Echocardiography
showed significant circumferential pericardial effusion with early tamponade effect.
Subsequent bedside pericardiocentesis aspirated 800 ml blood-stained fluid and the
cytology yielded metastatic adenocarcinoma with features suggestive of pulmonary primary.
Pericardial effusion is a rare finding in MPS. Finding of a “halo” around the heart
should raise suspicion on the presence of pericardial effusion and confirmatory investigation
such as ECG may be warranted.
Keywords
Halo - myocardial perfusion scintigraphy - pericardial effusion - tamponade - thallium-201
