title: Re-circulation artefact at the carotid bulb can be differentiated from true stenosis.
abstract: Re-circulation artefact developing secondary to vortex flow at the bulb of the internal carotid artery is very difficult to distinguish from true stenotic defect on two-dimensional Fourier transformed time-of-flight magnetic resonance angiography (2D-FT TOF MRA). The purpose of our study is to identify appropriate distinguishing features of re-circulation artefact. We included 45 extracranial carotid arteries collected from 25 patients who underwent both 2D-FT TOF MRA and contrast medium based angiography. Review of the 45 vessels demonstrated re-circulation artefact in 21 vessels, true stenotic defect in 8 vessels, and no filling defect in 16 vessels on 2D-FT TOF MRA. We compared the findings of re-circulation artefact and true stenotic defect in 29 vessels excluding the 16 vessels without filling defect. The following were evaluated: (1) preservation of posterior wall contour; (2) marginal character of filling defect; (3) darkness of filling defect; (4) involvement of common carotid artery by filling defect; (5) size of filling defect. In four out of the five evaluated items, statistically significant difference was present between re-circulation artefact group and true stenotic defect group (p<0.01 in all four items, chi(2) analysis). Re-circulation artefact demonstrated the preservation of the posterior wall contour (19/21), ill-defined margin (19/21), less dark defect (18/21), and no involvement of the common carotid artery (19/21). On the contrary true stenotic defect demonstrated focal loss of posterior wall contour (8/8), sharp margin (8/8), dark defect (8/8), and involvement of common carotid artery (4/8). No significant difference was noted in the size of the defect between the two groups (p>0.05). The specificity of 2D-FT TOF MRA for carotid stenosis was markedly increased after application of above signs. These distinguishing signs are very helpful in differentiating re-circulation artefact from true stenotic defect.
authors.affiliation: Department of Radiology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: K J
authors.initials: KJ
authors.lastname: Ahn
authors.forename: W J
authors.initials: WJ
authors.lastname: You
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: B J
authors.initials: BJ
authors.lastname: Kang
authors.forename: Y J
authors.initials: YJ
authors.lastname: Kim
authors.forename: B S
authors.initials: BS
authors.lastname: Kim
authors.forename: S T
authors.initials: ST
authors.lastname: Hahn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D018056:Hemorheology; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012680:Sensitivity and Specificity