The evaluation value of intracranial magnetic resonance angiography combined with carotid ultrasound in cerebral infarction

Objective: To explore the evaluation value of intracranial magnetic resonance angiography (MRA) combined with carotid ultrasound (CU) in patients with cerebral infarction (CI). Methods: A retrospective analysis was conducted on 122 patients with CI who underwent intracranial MRA combined with CU examination in Shengzhou People’s Hospital from January 2021 to October 2022. Vascular stenosis rate and CU parameters of patients with different degrees of nerve damage (ND) and size of CI lesion were analyzed. Results: The rate of vascular stenosis and ultrasound parameters significantly varied between patients with different degrees of ND and different sizes of CI lesion. Spearman test showed a significant positive correlation between vascular stenosis, pulsatile index (PI), and resistance index (RI) with the degree of ND and the size of CI lesions in patients. There was a significant negative correlation between peak systolic velocity (PSV) and end-diastolic velocity (EDV) and the degree of ND and the size of CI lesions (P<0.05). Conclusions: Intracranial MRA combined with CU can clarify the vascular stenosis and hemodynamic characteristics of patients with CI, and the combined approach closely correlates with the characteristics of CI, which can be used for disease assessment.


INTRODUCTION
Cerebral infarction (CI), caused by acute interruption of cerebral arterial blood flow, is more prevalent in middleaged and elderly populations and is associated with high rates of disability and mortality. 12][3] Several imaging methods are currently used for CI diagnosis and assessment.Digital subtraction angiography (DSA) is considered the gold standard for the diagnosis of CI with high accuracy. 4However, DSA is costly and is associated with a certain degree of trauma, making it difficult to promote its application. 4,5as compared to Digital Subtraction Angiography (DSA Therefore, developing non-invasive CI diagnosis and assessment methods became a focus of research for decades. Intracranial magnetic resonance angiography (MRA) is a non-invasive imaging method commonly used in the diagnosis and evaluation of CI. 6 MRA has excellent correlation with cerebral angiography and can accurately show the number of diseased blood vessels, degree of stenosis, and specific location, as well as precisely reflect the degree of intracranial arteriosclerosis. 7Another method, carotid ultrasound (CU) is also an important non-invasive diagnostic technique for CI because of its simplicity and reproducibility, and is routinely used as a risk stratification tool for cerebral and cardiovascular events. 8][9] Studies have showed that a combination of MRA and CU may be highly efficient in providing accurate anatomical information and identifying lesions in patients with carotid diseases. 10,11Most studies focus on the vascular stenosis rate and inter-reader agreement, but few on the correlation between vascular stenosis, CU blood flow parameters, and the degree of nerve damage (ND) and lesion size.This retrospective study aimed to assess the value and effectiveness of intracranial MRA combined with CU for evaluating the characteristics of CI in patients with different degrees of ND and size of CI lesion.Intracranial MRA examination.The procedure was done using the GE Optima MR360 1.5 T MRA scanner (GE Healthcare, Beijing, China).Vertebral artery bifurcation to the top of the skull was scanned using a fast 3D FLASH sequence.Parameters were set as follows: Scanning time, 218 seconds; Field of view, 11 cm; Matrix, 220 mm×220 mm; Layer thickness, 1.2-1.4mm; Reverse angle, 70 º ; TE, 6.6 ms; TR, 19.5 ms; and Pixel size, 1 mm×1.07mm ×0.78 mm.The degree of stenosis of diseased blood vessels was evaluated based on the MRA images (Fig. 1): grade 0, normal; grade 1, complete visualization of distal vessels with a stenosis degree ≤ 50%; grade 2, distal vascular imaging with a stenosis degree>50%; grade 3, occlusion and no visualization of distal blood vessels.Grade 1-3 were considered as vascular stenosis. 13CU examination.Siemens ACUSON S2000™ (Siemens, Munich, Germany) ultrasound diagnostic equipment was selected for inspection.The probe frequency was

RESULTS
A total of 122 patients (69 males and 53 females) with CI were included in the analysis.The general information of the patients is shown in Table-I.The levels of vascular stenosis, PI, and RI in patients with mild to moderate ND or small to moderate lesions were significantly lower than in patients with severe or large lesions, and the lowest levels were observed in patients with mild or small lesions (P<0.05).PSV and EDV were significantly higher in patients with severe or large lesions, and the highest levels was observed in cases of mild or small lesions (P<0.05)(Table -

II).
Spearman test confirmed a significant positive correlation between vascular stenosis, PI, and RI and the degree of ND and the size of CI lesions in patients (P<0.05).There was a significant negative correlation between PSV, EDV, and the degree of ND and the size of CI lesions (P<0.05)(Table-III).

DISCUSSION
The study indicated that intracranial MRA combined with CU have high application value in the diagnosis of CI, and can effectively clarify vascular stenosis and hemodynamic characteristics of patients with CI.Wang et al. 16 98 normal subjects and 106 TIA patients who underwent MRI examination within 72 h after the last symptom onset including the DWI sequence to exclude acute cerebral infarction were enrolled.The blood flow of the cranial total, the area of the internal carotid artery and vertebral artery, the average velocity, and the average blood flow were obtained and compared in normal subjects and TIA group.Analysis of Variance (ANOVA found that MRA examination can effectively characterize cerebral hemodynamic status in patients Note: ND = nerve damage; CI =cerebral infarction; PSV = peak systolic velocity; EDV = end diastolic velocity; PI = pulsatile index; RI = resistance index. with cerebral ischemia.MRA allows to image arteries that are unreachable by a catheter approach, and the acquired images can be used to create specific cross-sectional views in the direction of choice.This method does not use radiation, is non-invasive and have demonstrated a strong reproducibility and high resolution for soft tissues.reported that there is still a certain risk of missed diagnosis and misdiagnosis when using MRA for diagnostics and evaluation of acute CI.It can be hypothesized that the accuracy of MRA as a diagnostic tool may be affected by the operator's skills.Additionally, plaque calcification at the examination site may also lead to unclear MRA imaging, thus affecting the examination results.These shortcomings may be resolved by combining MRA with other inspection methods.Zhao et al. 21showed that ultrasonic examination can improve the diagnostic efficacy of acute CI with high sensitivity and specificity and can evaluate the stability of atherosclerotic plaque.Yin et al. 22 demonstrated that CU can dynamically monitor atherosclerotic plaque, reflect changes in vascular wall, and determine the extent of lesions by measuring indexes such as EDV, PSV, etc.These observations are consistent with the results of our study.Our results also showed that patients with different characteristics (degree of DN, size of CI lesion) had different degrees of vascular stenosis which significantly correlated with the changes in PSV, EDV, PI, and RI.Our results suggested that combined MRA and CU examination can clarify the severity of the patient's condition, help guide clinical implementation of targeted treatment, and avoid improper or excessive treatment.
Psychogios et al. 23 pointed out that the main clinical manifestation of carotid artery stenosis is abnormal hemodynamic changes in the internal carotid artery.When the stenosis of the carotid artery occurs, arterial RI and PI increase abnormally, normal blood circulation in the body is obstructed, and the brain experiences varying degrees of ischemia and hypoperfusion, resulting in a slowdown in blood flow velocity. 24There is a significant correlation between the severity of the stenosis and the changes in the measured indexes.The more severe the carotid artery stenosis, the lower the EDV and PSV, and the higher the RI and PI are. 9,23CU clearly identifies the thickening of the intima media, plaque location, and volume of blood vessels, and can accurately measure the hemodynamic status of the carotid artery, providing a reference basis for evaluating the degree of carotid artery stenosis. 25Therefore, MRA combined with CU can comprehensively examine cerebral blood vessels and cervical arteries, comprehensively evaluate the patient's condition, and avoid missed diagnosis or misdiagnosis. 26mitations: First, it is a single-center retrospective study, which may be subject to selection bias due to incomplete medical records.Second, neither group was randomly assigned, and baseline information may be imbalanced and biased.The rate of vascular stenosis and ultrasound indicators may be influenced by human or technical factors.Finally, the prognostic evaluation value of the combined MRA/CU examination method was not analyzed.Further higher quality research is needed to validate our conclusions.

CONCLUSION
Intracranial MRA combined with CU can clarify the vascular stenosis and hemodynamic characteristics of patients with CI, and the combined approach closely correlates with the characteristics of CI, which can be used for disease assessment.

Fig. 1 :
Fig.1: Intracranial MRA imaging of patients with different infarct sizes.A-C: No abnormalities were found in the head MRA imaging and blood vessels of normal healthy individuals; D-F: Head MRA of patients with small area cerebral infarction, small acute infarction in the left basal ganglia area, mild stenosis of the right middle cerebral artery; G-I: Head MRA of patients with moderate area cerebral infarction, moderate acute cerebral infarction in the right basal ganglia, and moderate stenosis of the right middle cerebral artery; J-L: Head MRA of patients with extensive cerebral infarction, extensive cerebral infarction in the right basal ganglia, and severe stenosis of the right internal carotid artery.

Fig. 2 :
Fig.2: Neck vascular ultrasound of patients with different infarct sizes.A: Color Doppler ultrasound of normal and healthy neck blood vessels, no stenosis observed; B: Mild stenosis of the neck blood vessels can be seen on color Doppler ultrasound in patients with small area cerebral infarction; C: Moderate stenosis of the neck blood vessels can be seen on color Doppler ultrasound in patients with moderate area cerebral infarction; D: Severe stenosis of the neck blood vessels can be seen on color Doppler ultrasound in patients with extensive cerebral infarction.

Table - I
: General information of patients Note:ND=nerve damage; CI=cerebral infarction.One-way analysis of variance (ANOVA) was used to evaluate the statistical significance of continuous variable differences between different degrees of ND and different lesion sizes.Bonferroni post hoc test was used for paired comparison.Categorical variables were reported as frequency and percentage, and Chi-square tests were used to evaluate the differences between the groups, different degrees of ND, and different lesion sizes.Spearman test was used to analyze the correlation between vascular stenosis, PSV, EDV, PI, RI, and the degree of ND and lesion size in patients.A p-value less than 0.05 was considered statistically significant.All reported p-values were bilateral.

Table -
II: Baseline characteristics.Compared with mild cases, a P<0.05;Compared with moderate, b P<0.05;Compared with small lesions, Compared with medium lesions, d P<0.05.ND = nerve damage; S = second; PSV = peak systolic velocity; EDV = end diastolic velocity; PI = pulsatile index; RI = resistance index.Table-III: Analysis of the correlation between the combined MRA/CU and characteristics of CI.
c P<0.05; 18,1798 normal subjects and 106 TIA patients who underwent MRI examination within 72 h after the last symptom onset including the sequence to exclude acute cerebral infarction were enrolled.The blood flow of the cranial total, the area of the internal carotid artery and vertebral artery, the average velocity, and the average blood flow were obtained and compared in normal subjects and TIA group.Analysis of Variance (ANOVA Kim et al.18confirmed that MRA examination can effectively identify vascular stenosis in patients with acute CI, guide clinical targeted treatment, reduce the risk of symptomatic intracranial hemorrhage, and ensure favorable prognosis and outcome. Jaiswl et al.