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Magnetic resonance imaging.
Magnetic resonance
imaging (MRI) is also used extensively in the diagnosis
of SVCS, and this test is often very important in deter-
mining the cause of SVCS. Although the collateral circu-
lation is easier to detect by CT scan, MRI, by virtue of its
multidimensional capabilities, shows the relationships of
vessels, lymph nodes, and other mediastinal structures
better than the information provided by CT scanning.
2–7
Diagnostic surgery.
When all other diagnostic proce-
dures fail to provide information about the cause of
SVCS, surgery may be the last alternative. Exploratory
thoracotomy is successful in obtaining diagnostic tissue in
patients with SVCS in virtually every case. A surgical
approach has several advantages—surgery allows direct
visualization of the underlying disease process, assess-
ment of the extent of disease involvement, and accessibil-
ity for tissue biopsy. However, compared to the previously
described diagnostic methods, this procedure is the most
invasive and is associated with increased risks.
2–10
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