fluid in the pericardial sac. A large effusion inducing a
intrapericardial pressure causes cardiac compression and
tamponade. There are many aetologies for effusion
pericardial infection, pericardial tumours, postpericardiotomy
syndrome, radiation, collagen vascular diseases,
and myxoedema. The effusion may be loculated, especially
cardiac surgery. Chest X-ray suggests the diagnosis when
enlargement of the cardiac silhouette over a short time
especially in the absence of pulmonary venous hypertension
oedema. The lateral view may show the fat pad sign
separation of the parietal and epicardial fat layers by more
3 mm. Echocardiography
is usually employed for definitive diagnosis. Computed
and MRI are very sensitive techniques for demonstrating
Haemorrhagic effusions are characterized by high density on
high signal intensity on T1-weighted spin echo MRI (Fig.2).
of Medical Imaging Volume V:2
effusion, Fig. 1
spin-echo image shows a large pericardial effusion. This
transudative effusion has low signal intensity.
effusion, Fig. 2
spin-echo image demonstrates a loculated pericardial
haemorrhagic effusion has high signal intensity.