Bland and tumor thrombi in abdominal malignancies: magnetic resonance imaging assessment in a large oncologic patient population.

The purpose of this study was to examine the distribution of venous thrombi associated with primary or secondary abdominal malignancies on magnetic resonance (MR) imaging with respect to thrombus type (bland vs. tumor), tumor sites, tumor types, and veins involved in a large oncologic patient population. In a retrospective review of 10,908 oncologic patients, MR imaging studies identified 142 (1.3%) showing venous thrombi, of which 55 (0.5%) were bland and 87 (0.79%) were tumor thrombus. Bland thrombi were most commonly seen in liver (35%; 19/55) and retroperitoneal malignancies (24%; 13/55) and were most often located in the inferior vena cava (45%; 25/55) and the portal vein (22%; 12/55). Tumor thrombi were most commonly seen in renal (55%; 48/87) and liver (32%; 28/87) malignancies. The prevalence of tumor thrombi was 8.8% (48/545) in primary renal, 4.7% (6/126) in primary retroperitoneal, 2.9% (19/634) in primary liver, and 1.8% (9/479) in secondary liver malignancies. Tumor thrombi were most commonly located in the inferior vena cava (57%; 50/87), the renal vein (48%; 42/87), and the portal vein (29%; 25/87).