Ag. Kane et al., REDUCED CALIBER OF THE INTERNAL CAROTID-ARTERY - A NORMAL FINDING WITH IPSILATERAL ABSENCE OR HYPOPLASIA OF THE A1 SEGMENT, American journal of neuroradiology, 17(7), 1996, pp. 1295-1301
Citations number
14
Categorie Soggetti
Clinical Neurology","Radiology,Nuclear Medicine & Medical Imaging
PURPOSE: To determine whether a relationship exists between normal var
iations in anatomy of the circle of Willis and the size of the interna
l carotid arteries (ICA). METHODS: MR angiograms and axial MR images o
f the brains of 104 patients were reviewed. Included were 10 patients
with unilateral absence of the A1 segment of the anterior cerebral art
ery, 10 with hypoplasia of one A1 segment, 28 with asymmetric A1 segme
nts, nine with isolated unilateral fetal origin of the posterior cereb
ral artery, and 47 with balanced circulation. RESULTS: The mean ICA di
ameter measurement for the total population was 4.62 +/- 0.68 mm. In p
atients with absent A1, the mean ipsilateral and contralateral ICA dia
meters were 3.63 +/- 0.41 mm and 5.25 +/- 0.52 mm, respectively. The m
ean percentages of the difference between the diameters of the right a
nd left ICA (31% in the group with absent A1 and 21% in the group with
hypoplastic A1) varied significantly from the differences in the ICA
diameters among the rest of the population. The diameter differences p
roduced by other common variations (unilateral small A1 segment or fet
al origin of the posterior cerebral artery) did not differ significant
ly from those of the 47 patients with balanced intracranial circulatio
n. CONCLUSIONS: There is an association of unilaterally absent or hypo
plastic A1 segments of the anterior cerebral artery with ipsilateral d
ecrease in ICA caliber, and this can be seen on MR angiograms.