Relation between Willis Polygon anatomy and interhemispheric asymmetries of cerebral blood flow: measured with 3'0 T MRI and Arterial Spin Labeling technique

This poster was previously presented in Spanish at the 2012 Congreso Nacional SERAM (Granada)

Congress:

ECR 2013

Poster Number:

C-0546

Type:

Scientific Exhibit

Keywords:

MR, Neuroradiology brain

Authors:

D. Armario Bel, A. Pla Esperanzi, D. Pareto, R. Mitjana Penella, C. Auger, A. Rovira Cañellas; Barcelona/ES

DOI:

10.1594/ecr2013/C-0546

DOI-Link:

https://dx.doi.org/10.1594/ecr2013/C-0546

Fig. 1: Scheme of anatomic variations of the Willis Polygon in 3 different...

Fig. 8: Three different situations with scheme of anatomical variant, angiography and...

Fig. 10: In normal conditions, blood pressure in interior carotid artery anb basilar...

Purpose

Correlate cerebral blood flow interhemispheric patterns observed with “arterial spin labeling” (ASL) technique with the presence of anatomic variants of Willis polygon (WP).

Methods and Materials

Patients: We have studied prospectively 76 patients, 46 women and 30 men, with mean age of 37’1 years (17-75 range), who underwent a cerebral MRI for different purposes, the most frequent in the following of Focal Epilepsy and Multiple Sclerosis. Those patients who presented vascular or tumoral pathology were excluded from the study. MRI Explorations were performed in a 3,0T MRI (Trio, Siemens) with the following parameters: - Anatomical MPRAGE: 128x240x256 (1,2x1x1mm3), TR=2300ms, TE=2ms. - Blood perfusion ASL: 64x64x18 (4x4x6,25mm3), TR=3000ms; TE=16ms; TI1=700ms; TI2=1800ms. Pulsatile...

Results

WP Anatomy Angiographic analysis showed anatomical variants of WP in: 21 patients (28%) in anterior circulation (Figure 4) 48 patients (67%) in posterior circulation (Figure 5) Afterwards 48 patients with variants in posterior circulation were classified in 3 groups depending on dominance: Symmetric: 25 Right dominance: 9 Left Dominance: 16 Interhemispheric asymmetries of flow with ASL Arterial spin labeling (ASL) is a non-invasive perfusion technique, which gives us quantitative information of cerebral blood flow. It’s been widely demonstrated its utility in different pathologies of nervous...

Conclusion

When evaluating maps of CBF obtained with ASL we should consider anatomy of Willis Polygon, since interhemispheric asymmetries in CBF maps which could suggest some kind of hemodynamic compromise are in fact produced by anatomical variants. Asymmetries are due essentially to a decreased CBF in posterior system irrigated from a fetal-type posterior cerebral artery.

References

1.Hartkamp M, Van der Grond J, Van Everdingen J et al.Circle of Willis Collateral Flow Investigated by Magnetic Resonance Angiography. Stroke1999; 30:2671-2678. 2. Jan van Laar, P, Van der Grond J, Hendrikse, J.Brain Perfusion Territory Imaging: Methods and Clinical Applications of Selective Arterial Spin-labeling MR Imaging.Radiology 2008; 246: 354-364. 3.Wentland A.L, Rowley H.A, VigenK.K.Fetal Origin of the Posterior Cerebral Artery Produces Left-Right Asymmetry on Perfusion Imaging. AJNR Am J Neuroradiol 2010 31:448–53. 4.Hendrikse J, Van Raamt F, Van der Graaf Y. Distribution of Cerebral Blood...