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Collateral score as a prognostic marker in acute anterior circulation stroke: A multiphase computed tomography angiography analysis
, Aravind Shanmugam2, Anupama Maheswaran2, Virag Shethna1, Karthik Thamarai Kannan3, Parvathy Giridas3, Janarthanan Maniyarasu4, Jagadeesan Dhanasekaran1,
*Corresponding author: Jagadeesan Dhanasekaran, Department of Interventional Radiology, G. Kuppuswamy Naidu Memorial Hospital, Coimbatore, Tamil Nadu, India. drdjagadeesan@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Padhi R, Shanmugam A, Maheswaran A, Shethna V, Kannan KT, Giridas P, et al. Collateral score as a prognostic marker in acute anterior circulation stroke: A multiphase computed tomography angiography analysis. J Neurosci Rural Pract. 2025:16:256-63. doi: 10.25259/JNRP_435_2024
Abstract
Objectives:
Cerebral collateral circulation is the main compensatory phenomenon that maintains the ischemic penumbra viable. Early and fast imaging of collaterals plays a major role in aiding revascularisation therapies. Recent studies showed the advantage of multiphasic computed tomographic angiography (mCTA) over single-phase computed tomographic angiography in an acute ischemic stroke (AIS) patient. In our study, collateral status is evaluated prospectively and assessed for its association with the outcome of the patient. The objectives of this study were to evaluate the cerebral collaterals using the mCTA collateral scoring system in AIS patients with large-vessel occlusion (LVO) involving the anterior circulation for determining clinical and radiological outcomes.
Materials and Methods:
Prospectively, 56 patients with anterior circulation LVO were included in this study; all were subjected to mCTA, and collateral scoring was done. Each patient’s treatment was categorized based on inclusion criteria. The early clinical outcome (National Institutes of Health Stroke Scale [NIHSS] at discharge), late clinical outcome (modified Rankin scale [mRS] at 3-month follow-up), and radiological outcome (Alberta Stroke Program Early CT Score [ASPECTS] and hemorrhagic transformation [HT] at 24 h) were collected. Our primary analysis is intended to the association between collateral score and the clinical outcome.
Results:
Collateral score is having a statistically significant association (P = 0.0001) with primary functional clinical outcomes (NIHSS at discharge, mRS at 3-month follow-up) and 24 h radiological follow-up (ASPECTS at 24 h; P = 0.0001 and HT at 24 h; P = 0.003).
Conclusion:
Our study prospectively demonstrates that the mCTA collateral score can be used as a standalone parameter in predicting a better functional outcome of anterior circulation ischemic stroke patients. Further, more inclusive LVO studies are needed in an extended window period (>24 h) and low NIHSS (<6) thrombectomy.
Keywords
Acute stroke
Clinical Outcome
Collateral score
Multiphasic computed tomographic angiography
INTRODUCTION
Stroke is the second leading cause of death after ischemic heart disease and the third leading cause of combined death and disability (DALYs).[1] The World Stroke Organization reports a significant rise in stroke burden from 1990 to 2019, with a 70% increase in incidence, 43% in mortality, and 143% in DALYs, particularly in developing nations like India. This underscores the need for early diagnosis and timely interventions such as revascularization.[2] In specialized stroke centers, prompt recognition and emergency treatments, supported by neuroimaging, are crucial for reducing stroke burden and identifying treatable ischemic strokes.[3]
In acute stroke care, non-contrast computed tomography (CT) is the initial imaging tool, followed by CT angiography (CTA), to rule out hemorrhage, detect infarcts, and assess vessel occlusion. This protocol is widely recommended due to its speed, availability, and high resolution, aiding in treatment decisions and revascularization success. In ischemic stroke, collateral circulation plays a key role in maintaining tissue viability when primary arteries are blocked.[4] Strong collaterals are hypothesized to improve clinical outcomes and recovery. Various imaging techniques, including CT,[5] magnetic resonance imaging,[6] angiography,[7] and transcranial Doppler (TCD),[8] have been used to evaluate collaterals. CT perfusion (CTP) imaging is increasingly being used for assessing not only tissue perfusion but also collateral circulation, which is a critical factor in the management of acute ischemic stroke (AIS) or other vascular conditions. CTP aids functional correlation by showing normal perfusion in the region of good collateral supply despite the presence of arterial occlusion, hence guiding treatment options of thrombectomy or thrombolysis.
Recent advancements highlight multiphasic CT angiography (mCTA) as superior to single-phase CTA for assessing collateral status, particularly leptomeningeal collaterals.[9] While many studies have linked collateral status to outcomes in anterior circulation stroke, most are retrospective. Our study prospectively evaluates collateral status and its association with functional and radiological outcomes.
MATERIALS AND METHODS
This prospective observational study, approved by the Scientific Research Committee and Institutional Ethics Committee (GKNH/Admin/DNB 2020 TP), included 56 patients from February 2021 to June 2022. Participants aged over 18 years, presenting within 8 h of stroke symptoms, underwent plain CT brain followed by mCTA. A neurologist or emergency physician with over 3 years of experience assessed baseline National Institutes of Health Stroke Scale (NIHSS) and modified Rankin scale (mRs) scores. Patient history, clinical details (age, sex, risk factors such as hypertension, diabetes, coronary heart disease, atrial fibrillation, smoking, and dyslipidemia), and written informed consent were documented.
The study focused on AIS patients with anterior circulation large-vessel occlusion (LVO) in the internal carotid artery, M1, M2 middle cerebral artery (MCA), or A1 anterior cerebral artery, identified through mCTA. Experienced radiologists evaluated initial Alberta Stroke Program Early CT Score (ASPECTS) (0–10) and mCTA collateral scores (0– 5). Radiological outcomes were assessed at 24 h using follow-up CT brain ASPECTS, with hemorrhagic transformation (HT) (European cooperative acute stroke study [ECASS] grading) indicating poor outcomes. Clinical outcomes were measured at discharge using NIHSS and at 3 months using mRs, where scores of 0–2 indicated good outcomes, 3–5 poor outcomes, and 6 denoted death.
Imaging protocol
Imaging was performed with the patient in a supine position. A standardized protocol was followed to obtain CT brain plain and CTA images.
CT brain plain
The study utilized a 256-slice CT scanner (Philips Brilliance ICT). Patients meeting the inclusion criteria first underwent standard unenhanced CT. Continuous axial slices, parallel to the orbitomeatal line, were acquired with 2 mm thickness and 2 mm intervals from the skull base to the vertex at 120 kVp and 250 mAs. These images were reconstructed to a 0.6 mm thickness. The ASPECTS score was calculated for each patient from the plain CT, with a score of <6 indicating a large core infarct.
mCTA
Scanning was initiated using bolus tracking, with the region of interest placed in the descending thoracic aorta and a trigger threshold set at 150 HU. A total of 50 mL of non-ionic, low-osmolar contrast agent (Iohexol, 350 mg/mL) was injected through a peripheral vein (preferably antecubital) at 5 mL/sec, followed by a 30 mL saline chase. Three phases of cerebral angiograms were acquired: The first phase covered the aortic arch to the vertex during the peak arterial phase, completing the single-phase CT angiography (sCTA). For mCTA, two additional venous phases were acquired from the skull base to the vertex during peak and late venous phases, respectively. The total scanning duration averaged 30 s, with images acquired at 120 kVp, 425 mAs, and 2 mm slice thickness/interval. Axial source images, reconstructed at 0.6 mm overlapping sections, were reformatted using Multi-Planar Reconstruction, Maximum Intensity Projections (MIP), and volume rendering (VR) techniques. Thick-section axial MIP (8 mm thickness) was used to assess vessel occlusion and collateral grading.
Collateral grading on mCTA followed a 6-point scale (0–5) by Menon et al.,[10] categorizing collateral supply as poor (grades 0–1), intermediate (grades 2–3), or good (grades 4–5) based on the extent and prominence of vascular enhancement in the occluded territory compared to the contralateral side [Figures 1 and 2]. Unlike sCTA, mCTA considers grade 3 as intermediate rather than good. The mCTA acquisition and interpretation process was consistent throughout the study, and no LVO patients were excluded based on mCTA phase B or C for mechanical thrombectomy (MT).
- Multiphasic maximum intensity projection computed tomography angiogram in a patient with large-vessel occlusion showing left middle cerebral artery territory infarct and good collaterals in all 3 phases - (a) peak arterial, (b) early venous, and (c) late venous with multiphase computed tomography angiography collateral score of 5/5.
- Multiphasic maximum intensity projection computed tomography angiogram in another patient with large-vessel occlusion showing left middle cerebral artery territory infarct and poor collaterals in all 3 phases - (a) peak arterial, (b) early venous, and (c) late venous with multiphase computed tomography angiography collateral score of 1/5.
RESULTS
The study included 56 patients (38 men, 18 women) with a mean age of 55.9 years (range: 27–87 years) [Table 1]. Most patients presented with limb weakness (hemiplegia/hemiparesis) and a high mean NIHSS score of 15. The average time from symptom onset to initial imaging was 242 min (range: 75–470 min). Hypertension (55.4%) and diabetes (39.3%) were the most common risk factors [Table 2]. Despite low ASPECTS scores (<6) on initial plain CT, MT was performed in patients with good collaterals. Acute MCA territory involvement was observed in 87.5% of patients, while combined MCA and ACA territory involvement was seen in 12.5% [Table 3]. Isolated MCA occlusion was present in 80.4% of cases. Of the 56 patients, 22 (39.3%) opted for conservative management, 9 (16.1%) received IV thrombolysis, and 25 (44.7%) underwent MT. Patients excluded from MT primarily presented beyond the 8-h window or had low NIHSS scores (<6). All MT patients achieved successful revascularization, with modified thrombolysis in cerebral infarction (mTICI) scores of 2c (14 patients) and 3 (11 patients) [Figure 3].
![A 42-year-old male patient with sudden-onset right-sided limb weakness, slurring of speech. (a) 3-dimensional virtual reality computed tomography angiography image and (b) sagittal digital subtraction angiography image revealed occlusion of left distal cervical internal carotid artery with smooth tapering [thin blue arrow in (a) and thick blue arrow in (b)]. (c) Post-thrombectomy sagittal digital subtraction angiography image of the same patient showing revascularization with modified thrombolysis in cerebral infarction 3 flow. Red arrow indicates stenting of long dissected segment of left distal cervical internal carotid artery.](/content/150/2025/16/2/img/JNRP-16-256-g003.png)
- A 42-year-old male patient with sudden-onset right-sided limb weakness, slurring of speech. (a) 3-dimensional virtual reality computed tomography angiography image and (b) sagittal digital subtraction angiography image revealed occlusion of left distal cervical internal carotid artery with smooth tapering [thin blue arrow in (a) and thick blue arrow in (b)]. (c) Post-thrombectomy sagittal digital subtraction angiography image of the same patient showing revascularization with modified thrombolysis in cerebral infarction 3 flow. Red arrow indicates stenting of long dissected segment of left distal cervical internal carotid artery.
| Characteristics (N=56) | N (%) | Multiphase CT collateral score | P-value** | ||
|---|---|---|---|---|---|
| Poor (%) | Good (%) | ||||
| Age (in years) | Mean±SD | 55.95±13.45 | 58.85±14.02 | 51.78±11.63 | 0.052† |
| <30 years | 2 (3.6%) | 1 (3%) | 1 (4.3%) | ||
| 31-40 years | 3 (5.3%) | 1 (3%) | 2 (8.7%) | ||
| 41-50 years | 14 (25%) | 6 (18.2%) | 8 (34.8%) | ||
| 51-60 years | 17 (30.4%) | 10 (30.3%) | 7 (30.4%) | ||
| 61-70 years | 11 (19.6%) | 8 (24.2%) | 3 (13%) | ||
| >70 years | 9 (16.1%) | 7 (21.2%) | 2 (8.7%) | 0.46 | |
| Gender | Male | 38 (67.86) | 23 (69.70) | 15 (65.22) | |
| Female | 18 (32.14) | 10 (30.30) | 8 (34.78) | 0.72* | |
| Hemiplegia/Hemiparesis | 54 (96.43) | 32 (96.97) | 22 (95.65) | 1 | |
| Aphasia/Dysarthria | 38 (67.86) | 20 (60.61) | 18 (78.26) | 0.16* | |
| Poor GCS/Drowsy | 11 (19.64) | 9 (27.27) | 2 (8.70) | 0.1 | |
| Facial weakness | 17 (30.36) | 9 (27.27) | 8 (34.78) | 0.55* | |
| NIHSS score at admission | Mean±SD | 16.16±2.96 | 17.24±2.91 | 14.61±2.33 | <0.001† |
| 06 to 14 | 17 (30.36) | 6 (18.18) | 11 (47.83) | ||
| 15 to 19 | 31 (55.36) | 20 (60.61) | 11 (47.83) | ||
| 20 to 24 | 7 (12.50) | 6 (18.18) | 1 (4.35) | ||
| >24 | 1 (1.79) | 1 (3.03) | 0 | 0.07 | |
| mRs score at admission | Mean±SD | 4.09±0.67 | 4.30±0.64 | 3.78±0.60 | 0.003† |
| 3 | 10 (17.86) | 3 (9.09) | 7 (30.43) | ||
| 4-5 | 46 (82.14) | 30 (90.91) | 16 (69.57) | 0.07 | |
| Time since onset of symptoms (in minutes) | |||||
| CT findings at admission | Mean±SD | 242.65±109.66 | 296.39±113.89 | 205±92.96 | 0.03† |
| Acute Left MCA territory infarct | 26 (46.43) | 13 (39.39) | 13 (56.52) | ||
| Acute Right MCA territory infarct | 23 (41.07) | 14 (42.42) | 9 (39.13) | ||
| Large infarct involving MCA and ACA territory | 6 (10.71) | 6 (18.18) | 0 | ||
| Acute right/left ACA territory infarct | 1 (1.79) | 0 | 1 (4.35) | 0.06 | |
| CT plain aspects score | Mean±SD | 5.39±2.56 | 4.03±2.21 | 7.35±1.58 | <0.001† |
| 0 to 04 | 20 (35.71) | 19 (57.58) | 1 (4.35) | ||
| 05 to 07 | 23 (41.07) | 12 (36.36) | 11 (47.83) | ||
| 08 to 10 | 13 (23.21) | 2 (6.06) | 11 (47.83) | <0.001 | |
| Characteristics (N = 56) | Multiphase CT collateral score | P-value* | |
|---|---|---|---|
| Poor (%) | Good (%) | ||
| Hypertension | 17 (51.52) | 14 (60.87) | 0.49 |
| Smoking | 7 (21.21) | 4 (17.39) | 1** |
| Diabetes mellitus | 10 (30.30) | 12 (52.17) | 0.1 |
| Coronary heart disease | 15 (45.45) | 6 (26.09) | 0.14 |
| Atrial fibrillation | 5 (15.15) | 1 (4.35) | 0.38** |
| Dyslipidemia | 13 (39.39) | 8 (34.78) | 0.73 |
| Characteristics (N=56) | N (%) | Multiphase CT collateral score | P-value* | |
|---|---|---|---|---|
| Poor (%) | Good (%) | |||
| M1 MCA | 38 (67.86) | 22 (66.67) | 16 (69.57) | 0.82 |
| M2 MCA | 14 (25) | 8 (24.24) | 6 (26.09) | 0.88 |
| ACA | 4 (7.14) | 3 (9.09) | 1 (4.35) | 0.64 |
| ICA | 10 (17.86) | 9 (27.27) | 1 (4.35) | 0.04** |
On 24-h follow-up CT, 14 patients (25%) showed HT, including three post-MT cases. The majority exhibited Parenchymal Hematoma (PH) type 1 and PH type 2 ECASS grades (5 patients each) [Table 4 and Figure 4]. Hypertension and diabetes were associated with poorer mCTA collaterals, though not statistically significant. No significant relationship was found between collaterals and atrial fibrillation, dyslipidemia, coronary artery disease, or smoking. Males had less collateral formation compared to females.
| Characteristics (N=56) | N (%) | Multiphase CT collateral score | P-value** | ||
|---|---|---|---|---|---|
| Poor (%) | Good (%) | ||||
| Thrombolysis | 19 (33.93) | 9 (27.27) | 10 (43.48) | 0.21* | |
| Thrombectomy | 25 (44.64) | 6 (18.18) | 19 (82.61) | <0.001 | |
| Conservative | 22 (39.29) | 20 (60.61) | 2 (8.70) | <0.001 | |
| mTICI grading (N=25) | 2C | 14 (56) | 6 (100) | 8 (42.11) | |
| 3 | 11 (44) | 0 | 11 (57.89) | 0.02 | |
| Post treatment imaging 24 hours CT plain aspects score | Mean±SD | 4.68±3.06 | 3±2.40 | 7.09±2.19 | <0.001† |
| Hemorrhagic transformation | 14 (25) | 13 (39.39) | 1 (4.35) | 0.004 | |
| ECASS II grading (N=14) | HI type 1 | 1 (7.14) | 1 (7.69) | 0 | |
| HI type 2 | 3 (21.43) | 3 (23.08) | 0 | ||
| PH type 1 | 5 (35.71) | 5 (38.46) | 0 | ||
| PH type 2 | 5 (35.71) | 4 (30.77) | 1 (100) | 1 | |
| mRs score at 3 months | Median (IQR) | 2 (0, 3) | 3 (2, 4) | 0 | <0.001‡ |
| 0 to 2 | 34 (60.71) | 12 (36.36) | 22 (95.65) | ||
| 3 | 9 (16.07) | 9 (27.27) | 0 | ||
| 4 to 5 | 8 (14.29) | 8 (24.24) | 0 | ||
| 6 | 5 (8.93) | 4 (12.12) | 1 (4.35) | <0.001 | |
![Axial sections of follow-up computed tomography brain in three different patients with different grades of hemorrhagic transformation 24 h post-treatment. (a) European Cooperative Acute Stroke Study II (ECASS-II) Hemorrhagic Infarction (HI) type 1 grade with small isolated petechial hemorrhages at the infarcted margin (left middle cerebral artery [MCA] territory). (b) ECASS II HI type 2 grade showing confluent petechiae within infarcted area without any midline shift (right MCA territory). (c) ECASS II subtype 3 showing parenchymal hematoma type 1 involving ≤30% of the infarcted area with mild midline shift (right MCA territory).](/content/150/2025/16/2/img/JNRP-16-256-g004.png)
- Axial sections of follow-up computed tomography brain in three different patients with different grades of hemorrhagic transformation 24 h post-treatment. (a) European Cooperative Acute Stroke Study II (ECASS-II) Hemorrhagic Infarction (HI) type 1 grade with small isolated petechial hemorrhages at the infarcted margin (left middle cerebral artery [MCA] territory). (b) ECASS II HI type 2 grade showing confluent petechiae within infarcted area without any midline shift (right MCA territory). (c) ECASS II subtype 3 showing parenchymal hematoma type 1 involving ≤30% of the infarcted area with mild midline shift (right MCA territory).
Patients with good mCTA collateral scores (4–5) had better clinical outcomes at 3-month follow-up (mRs 0–2). The median mRs score improved from 4 (Interquartile range [IQR] 4–5) at admission to 2 (IQR 0–3) at follow-up. Among those achieving functional independence (60%), 65% had good collaterals, while only 35% with poor collaterals (0–3) achieved similar outcomes. A significant negative correlation was found between mCTA collateral scores and 3-month mRs outcomes (correlation coefficient = −0.597, P < 0.001). Similarly, collateral scores negatively correlated with NIHSS at discharge (correlation coefficient = −0.631, P < 0.001), indicating a statistically significant association.
Significant associations were also observed between mCTA collateral scores and ASPECTS at admission (P < 0.001), 24-h follow-up ASPECTS (P < 0.001), and time from symptom onset to imaging (P = 0.03). Poor collaterals were significantly linked to HT (P = 0.004).
DISCUSSION
Collateral vasculature in ischemic territories is a strong predictor of recovery. Among imaging methods such as CTA, Magnetic Resonance Angiography, Digital subtraction angiography, and TCD, CTA is preferred due to its availability, cost-effectiveness, and efficiency. At our institution, mCTA is routinely performed at 3 time points, with collateral grading based on the Menon et al. method.[10] mCTA is favored over sCTA as it assesses contrast arrival and washout delays without extra contrast, offers better interobserver reliability for detecting LVO, and provides precise thrombus length measurement, final infarct volume (FIV), and clinical outcome correlations.
The MR CLEAN-LATE trial[11] highlighted the role of CTA collaterals in selecting late-window MT candidates, offering an alternative to perfusion imaging used in DAWN and DEFUSE-3 trials. In LVO stroke, collateral status is a key radiological marker for predicting clinical outcomes.[12-14] Strong collaterals correlate with smaller initial infarcts,[15] larger ischemic penumbra, higher recanalization rates post-revascularization,[16] and improved clinical outcomes.[17,18] Even without reperfusion, robust collaterals can limit infarct expansion.[19] Thus, evaluating collateral circulation is crucial for triaging stroke patients and guiding treatment decisions.[20]
Collaterals and 3-month follow-up mRs clinical outcome score
The association between mCTA collateral scores and 3-month mRs clinical outcomes is statistically significant (P < 0.001), consistent with findings by Conrad et al.[21] However, Conrad et al. assessed mRs at discharge, which may be influenced by factors such as age, gender, risk factors, hospital-acquired infections, and discharge timing.[21] In contrast, evaluating mRs at 3 months provides a more accurate measure of long-term functional independence, reflecting pre-stroke activity levels rather than specific task performance.
Seker et al.[22] also found a significant association (P = 0.021) between mCTA collateral scores and 3-month mRs outcomes, though with a weaker correlation (coefficient = −0.22). They emphasized that collateral scores should be considered alongside other factors, such as initial infarct size, rather than as standalone predictors. Our study, however, demonstrated a stronger correlation (coefficient = −0.597), suggesting that collateral status may independently predict functional outcomes.
A retrospective study by Nigron et al.[23] further supports this, showing a significant independent association between collateral status and 3-month outcomes in both univariate and multivariate analyses, even after adjusting for confounders such as age, treatment, and time to imaging. While our study aligns with these findings, it was limited to univariate analysis, leaving room for other factors-such as initial infarct size, risk factors, treatment modality, and time to treat. Thus, while collateral status is a robust predictor, its interpretation should be integrated with additional clinical and radiological parameters for comprehensive stroke management.
Collateral status and NIHSS clinical score
Collateral flow scores showed a statistically significant association with NIHSS at discharge as a secondary clinical outcome, consistent with findings by Nigron et al.[23] (P < 0.001). However, their study assessed NIHSS at 24 h, which can be influenced by post-treatment complications, such as those from MT, whereas our study evaluated NIHSS at discharge. A higher NIHSS score at admission indicates greater stroke severity. Collateral flow scores were negatively correlated with NIHSS at admission (correlation coefficient = −0.354) and had a statistically significant association (P = 0.007), as good collateral status helps maintain ischemic region viability, resulting in lower NIHSS scores.
Collateral status and ASPECTS score
Patients with good collaterals exhibited higher initial CT ASPECTS, with collateral scores positively correlated with ASPECTS at admission (correlation coefficient = 0.618) and at 24 h (correlation coefficient = 0.684). The association between admission ASPECTS and mCTA collateral score was statistically significant (P < 0.001), as good collaterals enhance perfusion in the ischemic penumbra, resulting in a smaller initial infarct core and higher ASPECTS. In contrast, Tong et al.[24] found no significant association between admission ASPECTS and collateral status (P = 0.416), likely due to delayed patient presentations, which reduce penumbra size and lower ASPECTS despite good collaterals. The link between collateral status and 24-h ASPECTS was significant (P < 0.001), attributed to sustained perfusion by leptomeningeal collaterals. Sallustio et al.[25] also reported a significant association between collateral status and radiological outcomes (P = 0.001).
Collateral status and HT
Previous studies suggest that good collateral status reduces the risk of symptomatic intracerebral HT. Although HT can arise from multiple factors, no significant association was found with independent risk factors such as diabetes mellitus, systemic hypertension, antiplatelet/anticoagulation use, overweight, old age, or leukoaraiosis. In our study, 14 out of 56 patients (25%) experienced HT, with only 1 (7%) having good collateral status, while the remaining 13 (93%) had poor collaterals. Poor collateral status was significantly associated with HT (P = 0.004). Failed autoregulation in ischemic areas leads to maximal vasodilation (reactive hyperemia) and collateral recruitment in adjacent regions, creating a steal-like phenomenon that expands the ischemic core. These processes collectively increase hyperperfusion-related damage and the likelihood of bleeding.
Collateral status and time since onset of symptoms to initial imaging
The mean time from symptom onset to initial imaging was 242 min, with a statistically significant association between this time and collateral status (P = 0.03). Similarly, Nannoni et al.[26] found a significant link, reporting a mean time of 180 min. Collateral recruitment is dynamic, particularly in the early hours post-stroke, where transient collaterals are gradually replaced by permanent ones. Earlier imaging and treatment improve perfusion of ischemic areas through these transient collaterals.
Collateral status and various risk factors
The study found no significant link between major stroke risk factors (hypertension, diabetes, atrial fibrillation, dyslipidemia, coronary artery disease, and smoking) and intracranial collateral status. However, a larger study by Nannoni et al.[26] involving 857 patients, identified a significant association between dyslipidemia and collateral status, contrasting with our findings, likely due to our smaller sample size of 56 patients. Although our study was prospective and included consecutive cases of acute anterior circulation ischemic stroke, its limitations include the small patient cohort, potential outcome bias from varied treatments (conservative, thrombolysis, and thrombectomy), and the lack of multivariate analysis, which requires a larger dataset to minimize standard errors.
CONCLUSION
mCTA-based collateral scoring system being simple to interpret, with the advantage of rapid performance on most standard CT platforms, with no additional contrast, can be used as a valuable tool for predicting the clinical outcome of anterior circulation LVO stroke patients. Patients with good collaterals, even in the extended window period, show better functional recovery, while poor collateral scores are associated with worse outcomes and higher hemorrhage risk.
Ethical approval:
The research/study approved by the Institutional Review Board at G. KUPPUSWAMY NAIDU MEMORIAL HOSPITAL, number DNB 2020 TP, dated February 25, 2021.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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