Thoracic Imaging 2003 - Society of Thoracic Radiology

TUESDAY
144
as both entities may have identical clinical manifestations and
hemodynamic characteristics. The finding of a normal pericardium
on CT or MRI practically excludes the diagnosis of constrictive
pericarditis. CT and MRI findings in constrictive pericarditis
include pericardial thickening, external compression and
deformity of the right atrial or ventricular borders, and straightening
of the interventricular septum. Thickening of the pericardium
may or may not produce hemodynamic abnormalities
and this finding alone is insufficient to diagnose constrictive
pericarditis. Additional imaging findings that suggest hemodynamically
significant pericardial constriction include systemic
vein dilatation, hepatomegaly, ascites, and pleural effusions. It
should be emphasized that focal pericardial thickening or calcification,
sometimes quite large, may be present without clinical
findings of constrictive pericarditis. Encasement of large portions
of both ventricles is usually necessary to produce hemodynamic
consequences.
Neoplastic Pericardial Disease
Neoplastic cells can reach the pericardium by direct invasion
from an adjacent origin (carcinomas of the lung and breast are
the most frequent neoplasms involving the pericardium) and via
hematogenous or lymphatic spread. Associated mediastinal
lymph node enlargement may be present. Both CT and MRI are
useful in evaluating neoplastic involvement of the pericardium,
which most commonly manifests as an exudative effusion
although plaque-like thickening or nodular masses can also
occur along the pericardium.
Congenital Pericardial Cyst
Pericardial cysts are most often found in the cardiophrenic
angles and are usually thin-walled and sharply defined. On CT
they are typically of water attenuation, although high attenuation
cysts have been reported. They do not enhance after the
injection of contrast media. On MRI, these lesions are of low
signal intensity on short TR/TE images and of high signal intensity
on long TR/TE images.
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