Diffusion-weighted imaging for the diagnosis of bland versus tumor thrombosis in the portal and renal veins

Introduction Distinguishing bland from tumor thrombus within the portal and renal veins has important implications for tumor staging, treatment and prognosis. There is limited evaluation of diffusion-weighted imaging (DWI) for the detection and diagnosis of venous thrombosis, particularly outside the central nervous system [1, 2]. Thrombus conspicuity is potentially enhanced by the application of diffusion gradients which suppresses blood motion [3]. Since DWI does not require contrast, it can be utilized in patients in whom Nephrogenic Systemic Fibrosis is a concern [4]. Furthermore, no studies have evaluated the ability to separate bland from tumor thrombus using DWI. Previous reports have shown that hepatocellular carcinoma (HCC), metastatic disease and renal cell carcinoma (RCC) demonstrate restricted diffusion [5, 6]. Thus we hypothesize that tumor thrombus will also demonstrate restricted diffusion and enable its detection.