Objective  To explore the reason of the streaks in low density in arteria carotis interna and arteria vertebralis of the skull base which are manifestationed by 64-ultislice spiral computed tomography (MSCT)

and investigate the clinical values of the display.   Methods  CT angiography (CTA) was performed in 270 non-rauma patients admitted in our hospital from September 14 to October 15

2009 by a GE LightSpeed 64-lice MSCT scanner. Postprocessing images were obtained by ADW 4.4

then transmitted with the row date to a picture archiving and communication system (PACS). The number of arteria basilaris and arteria carotis interna having streaks in low density in the lumen of blood vessel were calculated

and the computerized tomography value and the diameters of arteria carotis interna and arteria basilaris were measured and statistically analyzed.   Results  There were 40 patients having no streak in low density

and 230 patients having such streaks (85%). The streaks in low density were divided into 3 types according to what were displayed in cross shaft images. Type I was 440 strips which displayed one streak in low density in lumen of blood vessel

type II was 64 strips with two streaks in low density (like “harpoon”)

and type Ⅲ was 137 strips with three streaks in low density (like “stellate”). As for the location of streaks in low density

there were 108 strips in arteria basilaris

341 strips in arteria carotis interna siphonage

23 strips in segment anterior to carotid foramen

143 strips in carotid foramen

19 strips in arteria ophthalmica

and 7 strips in cavernous internal carotid artery

Our data showed that streaks in low density were more common in the arteria basilaris and arteria carotis interna siphonage. The CT value of the blood vessel with streak in low density (421.68±65.26 Hu) were higher than that having no streak (390.81±73.78 Hu). The diameter of arteria basilaris having no streak in low density was smaller than that of the vessel having. But for the arteria carotis interna

the diameter of left vessel having no streak was larger than that of the vessel having (P0.01). However

there was no significance for the right arteria carotis interna (P0.05).   Conclusion  The streak in low density in the MSCT image has a relationship with CT value of blood vessel

blood anatomy and artifact

but has no relationship with blood vessel diameter. It has a very considerable significance in identifying the endomembrane laceration.