Waleed Brinjikji1, Bong Jae Chung2, Carlos Jimenez3, Christopher Putman4, David F Kallmes1, Juan R Cebral2. 1. Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA. 2. Department of Bioengineering, Volgenau School of Engineering, George Mason University, Fairfax, Virginia, USA. 3. Department of Neurosurgery, University of Antioquia, Medellin, Colombia. 4. Department of Interventional Neuroradiology, Inova Fairfax Hospital, Falls Church, Virginia, USA.
Abstract
BACKGROUND: While clinical and angiographic risk factors for intracranial aneurysm instability are well established, it is reasonable to postulate that intra-aneurysmal hemodynamics also have a role in aneurysm instability. OBJECTIVE: To identify hemodynamic characteristics that differ between radiologically unstable and stable unruptured intracranial aneurysms. MATERIALS AND METHODS: 12 pairs of unruptured intracranial aneurysms with a 3D rotational angiographic set of images and followed up longitudinally without treatment were studied. Each pair consisted of one stable aneurysm (no change on serial imaging) and one unstable aneurysm (demonstrated growth of at least 1 mm diameter or ruptured during follow-up) of matching size (within 10%) and locations. Patient-specific computational fluid dynamics models were created and run under pulsatile flow conditions. Relevant hemodynamic and geometric variables were calculated and compared between groups using the paired Wilcoxon test. RESULTS: The area of the aneurysm under low wall shear stress (low shear stress area (LSA)) was 2.26 times larger in unstable aneurysms than in stable aneurysms (p=0.0499). The mean aneurysm vorticity was smaller by a factor of 0.57 in unstable aneurysms compared with stable aneurysms (p=0.0499). No statistically significant differences in geometric variables or shape indices were found. CONCLUSIONS: This pilot study suggests there may be hemodynamic differences between unstable and stable unruptured cerebral aneurysms. In particular, the area under low wall shear stress was larger in unstable aneurysms. These findings should be considered tentative until confirmed by future larger studies. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
BACKGROUND: While clinical and angiographic risk factors for intracranial aneurysm instability are well established, it is reasonable to postulate that intra-aneurysmal hemodynamics also have a role in aneurysm instability. OBJECTIVE: To identify hemodynamic characteristics that differ between radiologically unstable and stable unruptured intracranial aneurysms. MATERIALS AND METHODS: 12 pairs of unruptured intracranial aneurysms with a 3D rotational angiographic set of images and followed up longitudinally without treatment were studied. Each pair consisted of one stable aneurysm (no change on serial imaging) and one unstable aneurysm (demonstrated growth of at least 1 mm diameter or ruptured during follow-up) of matching size (within 10%) and locations. Patient-specific computational fluid dynamics models were created and run under pulsatile flow conditions. Relevant hemodynamic and geometric variables were calculated and compared between groups using the paired Wilcoxon test. RESULTS: The area of the aneurysm under low wall shear stress (low shear stress area (LSA)) was 2.26 times larger in unstable aneurysms than in stable aneurysms (p=0.0499). The mean aneurysm vorticity was smaller by a factor of 0.57 in unstable aneurysms compared with stable aneurysms (p=0.0499). No statistically significant differences in geometric variables or shape indices were found. CONCLUSIONS: This pilot study suggests there may be hemodynamic differences between unstable and stable unruptured cerebral aneurysms. In particular, the area under low wall shear stress was larger in unstable aneurysms. These findings should be considered tentative until confirmed by future larger studies. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
Authors: Paolo Machi; Rafik Ouared; Olivier Brina; Pierre Bouillot; Hasan Yilmaz; Maria I Vargas; Renato Gondar; Philippe Bijlenga; Karl O Lovblad; Zsolt Kulcsár Journal: Clin Neuroradiol Date: 2017-12-05 Impact factor: 3.649
Authors: B J Chung; F Mut; C M Putman; F Hamzei-Sichani; W Brinjikji; D Kallmes; C M Jimenez; J R Cebral Journal: AJNR Am J Neuroradiol Date: 2018-08-30 Impact factor: 3.825