Venous aneurysms: MR diagnosis with the "layered gadolinium" sign.

OBJECTIVE Our goal was to present MR findings in venous aneurysms and introduce the "layered gadolinium" sign as an ancillary diagnostic finding. METHOD Gadolinium-enhanced MR images of three patients with retroperitoneal venous aneurysms were retrospectively reviewed. Prior to MRI, venous aneurysm had been suspected clinically in only one patient. Surgical correlation was available in one patient. A phantom was constructed and imaged to investigate the cause of the layered gadolinium sign. RESULTS A gradation of signal intensity, the layered gadolinium sign, was observed in three patients with venous aneurysms on postcontrast T1-weighted images. The anterior portion of the aneurysms demonstrated high signal intensity separated by a sharp interface from the low signal intensity posterior region. Unenhanced time-of-flight MR venography, color Doppler, and duplex sonography failed to demonstrate flow in the patient with surgical proof. CONCLUSION The layered gadolinium sign may be helpful in the diagnosis of venous aneurysm and in differentiating these masses from solid neoplasms.