Normal Anatomical Features and Variations of the Vertebrobasilar Circulation and Its Branches: An Analysis with 64‐Detector Row CT and 3T MR Angiographies

Abstract

Purpose. To determine the normal anatomical features and variations of the vertebrobasilar circulation and its branches in patients who underwent multidetector computed tomography (CT) or magnetic resonance (MR) angiographies of the brain. Methods. 135 patients (male, 83 and female, 52; mean age, 50.1 years) who underwent CT (n = 71) or MR (n = 64) angiographies of the vertebrobasilar vasculature for various reasons were analyzed retrospectively. The right and left distal vertebral arteries (VAs), posterior inferior cerebellar arteries (PICAs), anterior inferior cerebellar arteries (AICAs), superior cerebellar arteries (SCAs), posterior cerebral arteries (PCAs), and posterior communicating arteries (PCoAs) were analyzed individually. Results. In 24.4% of the cases (33/135) right PICA, in 19.3% of the cases (26/135) left PICA, in 17.8% of the cases (24/135) right AICA, and in 18.5% of the cases (25/135) left AICA were absent. In cases without PICA or AICA, there was a statistically significant, moderately or well-developed AICA or PICA on the same side, respectively (P < 0.001). The most common variation was isolated absence of right PICA and was seen in 17.8% of the cases. Conclusions. The anatomic features of the branches of the vertebrobasilar circulation may be different from well-known normal anatomy. CT and MR angiographies allow a precise and detailed evaluation of vertebrobasilar circulation.

Differential distribution patterns in cerebellar irrigation. A study with autopsy material

“…In our study, the AICA had a caliber of 1.02 mm, i.e., near to the lower limit of the 1-1.37 mm range reported by other authors [1,5,7,15], whereas the caliber of the PICA of 1.45 mm measured in our series is in the middle segment of the de 1.2-1.84 mm range reported in previous studies [1,7,8,15]. Agenesis of the AICA is an anatomical expression reported in a significant number of specimens both in our work (16.1%) and in previous studies; for the AICA a figure of 2-36.1% has been reported [1,5,15,16,17]. The agenesis of the PICA observed in the present study (7.5%) is slightly lower than what has been reported in other population groups, within a range of 9.6-38.4% [1,5,15,16,17,20].…”

“…The caliber of the SCA reported in previous studies within a range of 1.5-1.67 mm [1,5,7,15] is larger than what is found in the present study (1.46 mm). In our study, the AICA had a caliber of 1.02 mm, i.e., near to the lower limit of the 1-1.37 mm range reported by other authors [1,5,7,15], whereas the caliber of the PICA of 1.45 mm measured in our series is in the middle segment of the de 1.2-1.84 mm range reported in previous studies [1,7,8,15].…”

“…Agenesis of the AICA is an anatomical expression reported in a significant number of specimens both in our work (16.1%) and in previous studies; for the AICA a figure of 2-36.1% has been reported [1,5,15,16,17]. The agenesis of the PICA observed in the present study (7.5%) is slightly lower than what has been reported in other population groups, within a range of 9.6-38.4% [1,5,15,16,17,20]. The variations of the cerebellar irrigation related to arterial origins, agenesis, duplication, calibers, distribution of irrigated territories, have been reported previously [1,16] in 65.2-88.3%.…”

“…The agenesis of the PICA observed in the present study (7.5%) is slightly lower than what has been reported in other population groups, within a range of 9.6-38.4% [1,5,15,16,17,20]. The variations of the cerebellar irrigation related to arterial origins, agenesis, duplication, calibers, distribution of irrigated territories, have been reported previously [1,16] in 65.2-88.3%. In our series, this variability was observed in 52.7%.…”

“…However, qualitative and quantitative information on the global distribution patterns of cerebellar artery variants is scarce [3]. These morphological characteristics must be taken into account for diagnostic imaging, for surgical approaches, and for the interpretation and management of clinical events involving these structures [1,15,16,17].…”