OBJECTIVETo compare the feasibility of bone and calcified plaque subtracted dual-energy CT angiography (CTA) with time of flight magnetic resonance angiography (TOF MRA) in evaluation of internal carotid artery atherosclerosis.

METHODSTotally 32 patients received a dual-energy CTA scan, along with a cerebral TOF MRA scan before or after CTA examination from one day to one month. Dual-energy software was used for bone and calcified plaque subtraction. Five anatomical segments were described for each internal carotid artery according to Fischer (1938). Ratings were based on a 1-4 scale for the dual-energy CTA maximum intensity projection (MIP) image: 1 not diagnostic, 2 partially diagnostic, 3 diagnostic, and 4 excellent. Lesions were categorized as mild (0-29%), moderate (30%-69%), severe (70%-99%), or occluded (no flow detected). Stenosis of internal carotid artery was evaluated based on post-subtracted CTA images and TOF MRA images.

RESULTSIn 320 arterial segments, 99% of arterial segments were > or = 3 score. Grading of stenosis on dual-energy CTA agreed with grading of stenoses on MRA images in 98% of arteries. In the mild and occlusion group, the agreement was 100% respectively. In the moderate and severe group, dual-energy CTA showed more severe stenosis than MRA in 7 vessels and there was significant difference between the results from the two different modalities (Z = -3.071, P = 0.002).

CONCLUSIONDual-energy CTA can be used to assess the stenosis of internal arteries around skull base, but may exaggerate the severe stenosis of cerebral arteries compared with TOF MRA.