Increased tortuosity of ACA might be associated with increased risk of ACoA aneurysm development and less aneurysm dome size: a computer-aided analysis

Novel classification of brain vascular tortuosity measures: A systematic review

Given the absence of a standardized measure for evaluating tortuosity in cerebrovascular images, our investigation focuses on the methods used to estimate vascular tortuosity over the past decade. The main purpose is to create a useful, easily accessible guide to tortuosity estimation methods for brain researchers and clinicians. We conducted a systematic literature review in PUBMED and Scopus from 2013 to 2023 for tortuosity index (TI) analysis of human cerebrovascular images providing either quantitative or qualitative tortuosity measures. A total of 111 articles reporting TI measures were identified, in which 16 different TI were used to analyze 29 different diseases in Magnetic Resonance Angiography (MRA), Computed Tomography Angiography (CTA), Digital Subtraction Angiography (DSA), Ultrasound images (US), and other Magnetic Resonance Imaging (MRI) sequences. A novel categorization of tortuosity indices is suggested, based on the nature of the metrics. This classification comprises four categories: morphological-based, ratio distance-based, trigonometrical-based, and curvature-based methods. A TI Metric guide is proposed to facilitate the selection of the optimal TI for each use case. Our results show that Distance Metric (DM) is the most used, simple, and versatile method of capturing tortuous patterns, making it a preferred choice among researchers studying different disease contexts. Conversely, healthcare practitioners often prefer the Weibel and Fields tortuosity metric due to its categorical output, which offers a simplified and readily interpretable classification that complements clinical decision-making processes effectively.

The Influence of Embolization of Internal Carotid Artery Aneurysms on Arterial Tortuosity: A Prospective Cohort Study

PURPOSE

To measure changes in quantitative tortuosity descriptors of the internal carotid artery (ICA) after intracranial aneurysm embolization, and to determine possible factors associated with changes in tortuosity.

MATERIALS AND METHODS

An analysis of 52 patients with embolized intracranial aneurysms was performed. ICA tortuosity was assessed by digital subtraction angiograms obtained prior to the embolization and after the first follow-up examination. For each patient, tortuosity descriptors were calculated: relative length (RL), sum of angle metrics (SOAM), triangular index, product of angle distance (PAD), and inflection count metric (ICM). To represent changes in tortuosity for each descriptor, delta (Δ) value was defined as value of the descriptor prior to embolization minus value of the descriptor on follow-up examination.

RESULTS

In a median follow-up of 14 months, no statistically significant changes in tortuosity were observed on the nonembolized side. On the embolized side, SOAM (2.89 [SD ± 0.92] vs 2.38 [SD ± 0.94]; P < .001), PAD (5.01 [SD ± 1.83] vs 3.95 [SD ± 1.72]; P < .001), and ICM (12.18 [SD ± 4.55] vs 9.76 [SD ± 4.04]; P = .006) were significantly higher after embolization than before embolization. Median ΔRL (-0.02 [-0.045 to 0.002] vs -0.01 [-0.02 to 0.003]; P = .003), ΔPAD (0.84 [0.30-1.82] vs 0.10 [-0.001 to 1.10]; P < .001), and ΔICM (2.05 [0.42-3.50] vs 0.27 [0.02-2.16]; P = .004) were significantly higher on the embolized side. Tortuosity correlated with elapsed time after embolization.

CONCLUSIONS

Tortuosity of the ipsilateral ICA increased after intracranial aneurysm embolization.

Effect of Siphon Morphology on the Risk of C7 Segment Aneurysm Formation : A Case-control CFD Study

PURPOSE

Tortuosity of the internal carotid artery (ICA) is associated with intracranial aneurysms (IAs). The siphon is the most curved segment of the ICA, but its morphology has controversial effects on IAs. This study aimed to explore the morphometric features of the siphon and the potential hemodynamic mechanisms that may affect C7 aneurysm formation.

METHODS

In this study 32 patients with C7 aneurysms diagnosed at Xiangya Hospital between 2019 and 2021 and 32 control subjects were enrolled after propensity score matching. Computed tomography angiography (CTA) images were acquired to measure morphologic features, and then, by combining clinical data, simplified carotid siphon models were constructed, and computational fluid dynamics (CFD) analysis was performed.

RESULTS

The presence of C7 aneurysms was associated with the height of the C4-C6 curved arteries (odds ratio [OR] 0.028, 95% confidence interval [CI] 0.003-0.201; P < 0.001). The heights of the C4-C6 curved arteries in the aneurysm group were significantly shorter than those in the control group. The CFD analysis revealed that shorter C4-C6 bends led to greater blood velocity and pressure in the C7 segment arteries.

CONCLUSION

A shorter C4-C6 bend was associated with distal C7 aneurysm formation, and an elaborate hemodynamic mechanism may underlie this association.

Association of Arterial Tortuosity with Hemodynamic Parameters-A Computational Fluid Dynamics Study

BACKGROUND

Tortuosity of intracranial arteries has been proven to be associated with the risk of intracranial aneurysm development. We decided to analyze which aspects of tortuosity are correlated with hemodynamics parameters promoting intracranial aneurysm development.

METHODS

We constructed 73 idealized models of tortuous artery (length: 25 mm, diameter: 2.5 mm) with single bifurcation. For each model, on the course of segment before bifurcation, we placed 1-3 angles with measures 15, 30, 45, 60, or 75 degrees and arc lengths 2, 5, 7, 10, or 15 mm. We performed computational fluid dynamics analysis. Blood was modeled as Newtonian fluid. We have set velocity wave of 2 cardiac cycles. After performing simulation we calculated following hemodynamic parameters at the bifurcation: time average wall shear stress (TAWSS), time average wall shear stress gradient (TAWSSG), oscillatory shear index (OSI), and relative residence time (RRT).

RESULTS

We found a significant positive correlation with number of angles and TAWSS (R = 0.329; P < 0.01), TAWSSG (R = 0.317; P < 0.01), and negative with RRT (R = -0.335; P < 0.0.01). Similar results were obtained in terms of arcs lengths. On the other hand, mean angle measure was negatively correlated to TAWSS (R = -0.333; P < 0.01), TAWSSG (R = -0.473 P < 0.01), OSI (R = -0.463; P < 0.01), and positively to RRT (R = 0.332; P < 0.01). On the basis of the obtained results, we developed new tortuosity descriptor, which considered angle measures normalized to its arc length and distance from bifurcation. For such descriptor we found strong negative correlation with TAWSS (R = -0.701; P < 0.01), TAWSSG (R = 0.778; P < 0.01), OSI (R = -0.776; P < 0.01), and positive with RRT (R = 0.747; P < 0.01).

CONCLUSIONS

Hemodynamic parameters promoting aneurysm development are correlated with larger number of smaller angles located on larger arcs.

Unilateral cerebral arterial tortuosity: Associated with aneurysm occurrence, but potentially inversely associated with aneurysm rupture

PURPOSE

To investigate the association of tortuosity of the main cerebral arteries with intracranial aneurysm (IA) occurrence and rupture. To investigate the relationship between arterial tortuosity and aneurysm morphology as well as conventional risk factors of vascular diseases.

METHODS

Three subject groups were analyzed in this study: Patients with ruptured IAs, patients with unruptured IAs, and healthy subjects. The groups were matched by sex and age using tendency score matching. Their intracranial magnetic resonance angiography (MRA) images were collected retrospectively. The intracranial arterial structures were segmented from the MRA images. Arterial tortuosity was measured and statistically compared between the different subject groups and different vessels. Correlation analysis was conducted between arterial tortuosity and clinical risk factors as well as aneurysm morphology.

RESULTS

120 patients were included in the study (average age: 67.5 years; 60% female), 40 for each group after matching. The tortuosity of the aneurysm-bearing artery was significantly greater than that of the contralateral artery in both the ruptured and unruptured IA groups (p < 0.001). There was no significant association between clinical risk factors (history of hypertension, hyperlipidemia, diabetes, smoking, and alcohol use) and arterial tortuosity. There were significant negative correlations between aneurysm-bearing artery tortuosity and aneurysm morphological features such as maximal diameter (p = 0.0011), neck diameter (p < 0.0001), maximum height (p = 0.0024), and size ratio (p = 0.0269).

CONCLUSION

The occurrence of cerebral aneurysms correlates to increased unilateral arterial tortuosity, but the risk of aneurysm enlargement/rupturing decreases with greater arterial tortuosity. Abnormal tortuosity may be congenital as tortuosity has no clear connection with acquired common risk factors of vascular diseases.

Vascular tortuosity is related to reduced thalamic volume after middle cerebral artery occlusion

The mechanisms underlying secondary brain injury in remote areas remains unclear. This study aimed to investigate the relationship between vascular tortuosity and thalamic volume.

METHODS

In this study, we retrospectively analyzed sixty-five patients with unilateral middle cerebral artery occlusion (MCAO) who underwent magnetic resonance angiography. We compared the vascular tortuosity in patients with MCAO and controls, and analyzed the relationship between vascular tortuosity and thalamic volume.

RESULTS

Compared with controls, the MCAO group exhibited a significantly smaller thalamus volume on the affected side (5874 ± 183 mm³ vs. 5635 ± 383 mm³, p < 0.0001). The vascular tortuosity of the posterior cerebral artery (PCA) was higher in the MCAO group than in the controls (82.8 ± 17.3 vs. 76.7 ± 17.3, p = 0.040). Logistic regression analysis revealed that PCA tortuosity was an independent risk factor for reduced thalamic volume after MCAO (p = 0.034). In the subgroup analysis, only the 4-7-day group was not statistically different in thalamic volume between the MCAO and control groups. In the MCAO group, patients older than 60 years and female patients had a more tortuous PCA.

CONCLUSION

Reduced thalamic volume after MCAO was associated with a tortuous PCA. After MCAO, PCA tortuosity increased more significantly in patients aged >60 years and in female patients.

Subarachnoid Hemorrhage from Ruptured Internal Carotid Artery Aneurysm: Association with Arterial Tortuosity

OBJECTIVE

Many researchers have found a correlation between tortuous arteries and development of aneurysms in cerebral arteries. We decided to determine whether tortuosity of the internal carotid artery can be related to its aneurysm rupture.

METHODS

We retrospectively analyzed the internal carotid artery anatomy of 149 patients with internal carotid artery aneurysms. For each patient, we calculated relative length (RL), sum of angle metrics (SOAM), triangular index (TI), product of angle distance (PAD), and inflection count metrics (ICM).

RESULTS

A total of 33 patients (22.15%) had subarachnoid hemorrhage. These patients had significantly lower SOAM (0.31 ± 0.17 vs. 0.42 ± 0.21; P < 0.01), TI (0.27 ± 0.09 vs. 0.31 ± 0.11; P = 0.03) and ICM (0.25 ± 0.11 vs. 0.31 ± 0.17; P = 0.04). In multivariate logistic regression analysis, higher SOAM (odds ratio, 0.780; 95% confidence interval, 0.619-0.961; P = 0.025) remained independently associated with lower risk of internal carotid artery aneurysm rupture. In addition, we found significant positive correlation of aneurysm dome size with SOAM (R = 0.224; P = 0.013) and PAD (0.269; P < 0.01). Our study also showed that age (R = 0.252; P = 0.036), Glasgow Coma Scale score (R = -0.706; P < 0.01), and TI (R = -0.249; P = 0.042) were independently correlated with modified Rankin Scale score on discharge.

CONCLUSIONS

Lower tortuosity might be a protective factor against internal carotid artery aneurysm rupture and poor outcome after subarachnoid hemorrhage. Higher tortuosity is correlated with internal carotid artery aneurysm growth.

Coexistence of neurovascular compression syndrome and unruptured cerebral aneurysm

Unruptured cerebral aneurysms (UCAs) are usually asymptomatic and detected incidentally by intracranial examinations. The coexistence of neurovascular compression syndrome (NVCS) and UCAs has not been well described. The aim of this study was to clarify the characteristics of UCAs with the NVCS. A total of 103 cases that underwent microvascular decompression (MVD) for trigeminal neuralgia (TN) or hemifacial spasm (HFS) were assigned to the NVCS group. The prevalence of UCAs in the NVCS group was compared retrospectively to that in 110 control cases (a control group) by neuro-imaging. Overall treatment courses for NVCS and UCAs were investigated in the NVCS group. Sixteen (15.3%; TN 11 cases, HFS 5 cases) of 103 MVD cases had 19 UCAs, a significantly higher prevalence than the 3.6% in the control group. Binomial logistic regression showed that NVCS is a significant factor for predicting the presence of UCAs, with an odds ratio of 4.80. In the NVCS group, 18 UCAs (94.7%) were supratentorial aneurysms, and 17 UCAs (89.5%) were less than 5 mm in size. Nine UCAs were surgically treated with clipping or coiling. Of the surgical cases, 2 UCAs were treated before MVD for NVCS, whereas the other 7 UCAs were treated after MVD. No aneurysms ruptured during the treatment course. The NVCS occurred with UCAs at a significantly higher rate than in the control group. Most UCAs with the NVCS were supratentorial, small aneurysms that did not affect the surgical treatment of NVCS.

How Cerebral Vessel Tortuosity Affects Development and Recurrence of Aneurysm: Outer Curvature versus Bifurcation Type

Background and Purpose

Previous studies have assessed the relationship between cerebral vessel tortuosity and intracranial aneurysm (IA) based on two-dimensional brain image analysis. We evaluated the relationship between cerebral vessel tortuosity and IA according to the hemodynamic location using three-dimensional (3D) analysis and studied the effect of tortuosity on the recurrence of treated IA.

Methods

We collected clinical and imaging data from patients with IA and disease-free controls. IAs were categorized into outer curvature and bifurcation types. Computerized analysis of the images provided information on the length of the arterial segment and tortuosity of the cerebral arteries in 3D space.

Results

Data from 95 patients with IA and 95 controls were analyzed. Regarding parent vessel tortuosity index (TI; P<0.01), average TI (P<0.01), basilar artery (BA; P=0.02), left posterior cerebral artery (P=0.03), both vertebral arteries (VAs; P<0.01), and right internal carotid artery (P<0.01), there was a significant difference only in the outer curvature type compared with the control group. The outer curvature type was analyzed, and the occurrence of an IA was associated with increased TI of the parent vessel, average, BA, right middle cerebral artery, and both VAs in the logistic regression analysis. However, in all aneurysm cases, recanalization of the treated aneurysm was inversely associated with increased TI of the parent vessels.

Conclusions

TIs of intracranial arteries are associated with the occurrence of IA, especially in the outer curvature type. IAs with a high TI in the parent vessel showed good outcomes with endovascular treatment.

Increased Internal Carotid Artery Tortuosity is a Risk Factor for Spontaneous Cervicocerebral Artery Dissection

OBJECTIVE

Spontaneous cervicocerebral artery dissection (sCCD) is an important cause of ischaemic stroke that often occurs in young and middle aged patients. The purpose of this study was to investigate the correlation between tortuosity of the carotid artery and sCCD.

METHODS

Patients with confirmed sCCD who underwent computed tomography angiography (CTA) were reviewed retrospectively. Age and sex matched patients having CTA were used as controls. The tortuosity indices of the cervical arteries were measured from the CTA images. The carotid siphon and the extracranial internal carotid artery (ICA) were evaluated according to morphological classification. The carotid siphons were classified into five types. The extracranial ICA was categorised as simple tortuosity, coiling or kinking. Independent risk factors for sCCD were investigated using multivariable analysis.

RESULTS

The study included sixty-six patients with sCCD and 66 controls. There were no differences in vascular risk factors between the two groups. The internal carotid tortuosity index (ICTI) (25.24 ± 12.37 vs. 15.90 ± 8.55, respectively; p < .001) and vertebral tortuosity index (VTI) (median 11.28; interquartile range [IQR] 6.88, 18.80 vs. median 8.38; IQR 6.02, 12.20, respectively; p = .008) were higher in the patients with sCCD than in the controls. Type III and Type IV carotid siphons were more common in the patients with sCCD (p = .001 and p < .001, respectively). The prevalence of any vessel tortuosity, coiling and kinking of the extracranial ICA was higher in the patients with sCCD (p < .001, p = .018 and p = .006, respectively). ICTI (odds ratio [OR] 2.964; p = .026), VTI (OR 5.141; p = .009), and Type III carotid siphons (OR 4.654; p = .003) were independently associated with the risk of sCCD.

CONCLUSION

Arterial tortuosity is associated with sCCD, and greater tortuosity of the cervical artery may indicate an increased risk of arterial dissection.

Increased tortuosity of basilar artery might be associated with higher risk of aneurysm development

Objectives

We analysed tortuosity of basilar artery (BA) to determine its relationship with the presence of aneurysm.

Methods

We retrospectively analysed 71 patients with BA aneurysms along with 71 age- and risk factors-matched control patients without BA aneurysm. From patients’ medical records, we obtained their history including previous and current diseases and medications. For each patient, we calculated relative length (RL), sum of angle metrics (SOAM), triangular index (TI), product of angle distance (PAD) and inflexion count metrics (ICM). We used t-test and Mann-Whitney U test for continuous variables and χ² test for dichotomised variables. To find independent predictors of BA aneurysm, we employed logistic regression analysis.

Results

We found significant positive correlation between age and SOAM (R = 0.195, p = 0.02) and PAD (R = 0.199, p = 0.018). Our study also showed that patients with BA aneurysm had significantly higher SOAM (0.21 ± 0.16 vs. 0.11 ± 0.08; p < 0.01), PAD (0.30 ± 0.19 vs. 0.18 ± 0.11; p < 0.01), TI (0.23 ± 0.23 vs. 0.10 ± 0.16; p < 0.01) and ICM (0.20 ± 0.16 vs. 0.15 ± 0.11; p = 0.045). In multivariate logistic regression analysis, after adjustment for all possible confounders, SOAM (OR = 1.086; 95% CI 1.046–1.136; p < 0.01) and TI (OR = 1.004; 95%C: 1.002–1.006; p < 0.01) remained independently associated with higher risk of BA aneurysm.

Conclusions

Increased tortuosity of BA is associated with higher risk of its aneurysm development.

Key Points

• Basilar artery sum of angle metrics and product of angle distance are correlated with age.

• Basilar artery tortuosity is independently associated with higher risk of its aneurysm development.

• Basilar artery tortuosity is positively correlated with its diameter and bifurcation angle.