[Infected aneurysm of abdominal aorta: early CT finding]. / Anévrisme infectieux de l'aorte abdominale: un aspect TDM précoce.

Infected abdominal aortic aneurysm is an uncommon but life-threatening disease, especially in case of salmonella infection. Early CT findings should be well known in order to allow immediate diagnosis and accurate management. The authors present an early CT finding of a salmonella infected aneurysm of abdominal aorta in an HIV-infected patient. This pattern consists in a slight-enhancing focal densification of periaortic soft-tissue, while aorta remains of normal size. Within two weeks, infection progressed to the constitution of an infected aneurysm. This CT finding seems to be initial to previously described signs.

Evaluation of retroperitoneal and pelvic lymph node metastases with MRI and MR lymphangiography.

Local, regional lymph node involvement is an essential prognostic factor and an important determinant of treatment choices for patients with retroperitoneal and pelvic cancer. Current cross-sectional imaging modalities, including computed tomography and magnetic resonance (MR) imaging, use the nonspecific criterion of size and are limited in their ability to differentiate benign from malignant lymph nodes. MR lymphography is a promising imaging modality in differentiating benign from metastatic lymph nodes and provides information on lymph node morphology and function. Ultrasmall superparamagnetic iron oxide (USPIO) particles with a long plasma circulation time are suitable as an MR contrast agent for intravenous MR lymphography. They are taken up by macrophages in normally functioning nodes and reduce the signal intensity of tissue in which they accumulate because of T2 and susceptibility effects of iron oxide. In metastatic nodes, macrophages are replaced by cancer cells, which lack reticuloendothelial activity and cannot take up USPIO. The main mechanisms that might explain a heterogeneous node appearance after USPIO injection are discussed. In published reports, USPIO has shown high degrees of sensitivity and specificity for characterizing lymph nodes in cancer patients. We review the development of USPIO compounds, their imaging characteristics, and our clinical experience.