RadioGraphics 2010; 30:111-125
Satoru Morita, MD,PhD , Eiko Ueno, MD, PhD .Ai Masukawa, MD Kazufumi Suzuki, MD , Haruhiko Machida, MD, PhD , Mikihiko Fujimura, MD, PhD
When a vascular disease is suspected, the focus is usually on morpho¬logic features seen at contrast material-enhanced multidetector com¬puted tomography (CT). However, unenhanced CT also plays an im¬portant role in revealing so-called hyperattenuating signs, which represent a slight increase in the focal attenuation of a vessel. Hyper¬attenuating signs are occasionally observed when an acute clot has formed in a vessel and can be seen in various vascular diseases, in¬cluding acute arterial occlusion, acute arterial dissection, aneurysm rupture, and acute venous thrombosis. The attenuation of these signs tends to increase because the concentration of hemoglobin increases as water content decreases. Hyperattenuating signs are a transient phe¬nomenon, as the attenuation gradually decreases. Therefore, they can serve as unique findings indicating an acute state. Although hyperat¬tenuating signs are not well understood, recognition of these signs is important because they can help reveal serious acute vascular diseases even at unenhanced CT.
