Discussion
Diagnosis With Brief Discussion
- Diagnosis
- SVC obstruction due to non-small cell lung cancer
- Radiologic Findings
- On contrast-enhance CT scan, there is wedge-shaped enhancement in anterior liver.
There is dense enhancement of many superficial collateral veins, the azygos and hemiazygos vein.
Contrast-enhanced CT scan at level of carina shows narrowing and encasement of both the SVC and right main bronchus by a large right upper lobe mass with mediastinal extension.
Also note the dense enhancement of the internal mammary and lateral thoracic vein.
- Brief Review
- The pattern and direction of collateral flow in the azygos system vary with the site of SVC obstruction relative to the azygos arch.
If the SVC is obstructed proximal to the azygos arch and is patent distally, blood flows via chest wall collateral vessels and superior intercostal veins into the accessory hemiazygos and azygos veins, where it then flows forward into the right atrium via the distal SVC.
If the SVC obstruction is distal to azygos arch, there is a retrograde flow from the proximal SVC into the azygos arch and vein.
This is manifested on CT scans by dense enhancement of the azygos vein during bolus intravenous administration of contrast medium.
Blood may be diverted to the periumbilical veins and subsequently to the left portal vein along the ligamentum teres by superficial thoracoabdominal and epigastric veins, accounting for the wedge-shaped region of increased density within the anterior aspect of the left lobe of the liver (1, 2).
Focal areas of increased activity on hepatic scintigraphy in SVC obstruction have also been well documented (3).
- References
- 1. Ishikawa T, Clark RA, Tokuda M, et al. Focal enhancement on hepatic CT in superior vena caval and brachiocephalic vein obstruction. AJR 1983; 140:337-338.
2. Bashist B, Parisi A, Frager DH, Suster B. Abdominal CT findings when the superior vena cava, brachiocephalic vein, or subclavian vein is obstructed. AJR 1996;167:1457-1463.
3. Tetalman MR, Kusumi R, Gaughran G, Baba N. Radionuclide liver spots; indicator of liver disease of blood flow phenomenon. AJR 1978;130:291-296.
- Keywords
- Lung, Mediastinum, Malignant tumor,