Microflow imaging of contrast-enhanced ultrasound for evaluation of neovascularization in peripheral lung cancer

Differential Diagnosis of Pathological Type of Peripheral Lung Cancer with Multimodal Contrast-Enhanced Ultrasound

OBJECTIVE

The goal of the work described here was to investigate the role of multimodal contrast-enhanced ultrasound in the differential diagnosis of peripheral lung cancer.

METHODS

From April 2017 to July 2021, 109 patients with confirmed pulmonary malignant lesions who underwent CEUS examination were involved in our study. Seven patients were excluded because of the short duration of CEUS video or unsatisfactory imaging. Finally,102 patients with peripheral lung cancer were enrolled in this study. The maximum diameter of the lesions ranged from 1.6 to 13.0 cm (mean 6.2 ± 2.3 cm). On the basis of the pathological results, the patients were divided into the small cell lung cancer (SCLC) group and non-small cell lung cancer (NSCLC) group (including adenocarcinoma, lung squamous cell carcinoma and large cell neuroendocrine carcinoma). A Logiq E9 ultrasonic machine equipped with a 3.5 to 5.0 MHz C5-1 probe was used. Patient clinical information, CEUS features, CPI patterns and TIC parameters were analyzed and compared between different groups. Statistical analyses were performed with SPSS software and MedCalc software. The receiver operating characteristic curve was plotted.

RESULTS

In the differential diagnosis of SCLC and NSCLC, color parametric imaging indicated great performance. NSCLC exhibited a centripetal enhancement pattern more frequently (72.7%), while SCLC exhibited an eccentric enhancement pattern more frequently (92.9%) (p < 0.001). In the differential diagnosis of adenocarcinoma and squamous cell carcinoma, logistic regression analysis revealed that patient age of onset ≤60 y, difference in arrival time between lung and tumor ≤3.8 s, drop time of the time-intensity curve >23.2 s and absence of internal necrosis on CEUS were independent predictors for adenocarcinoma (area under the curve = 0.861).

CONCLUSION

In our study, multimodal contrast-enhanced ultrasound provided useful information in the differential diagnosis between small cell lung cancer and non-small cell lung cancer, especially between adenocarcinoma and squamous cell carcinoma.

Diagnosis of benign and malignant peripheral lung lesions based on a feature model constructed by the random forest algorithm for grayscale and contrast-enhanced ultrasound

Rationale and objectives

To construct a predictive model for benign and malignant peripheral pulmonary lesions (PPLs) using a random forest algorithm based on grayscale ultrasound and ultrasound contrast, and to evaluate its diagnostic value.

Materials and methods

We selected 254 patients with PPLs detected using chest lung computed tomography between October 2021 and July 2023, including 161 malignant and 93 benign lesions. Relevant variables for judging benign and malignant PPLs were screened using logistic regression analysis. A model was constructed using the random forest algorithm, and the test set was verified. Correlations between these relevant variables and the diagnosis of benign and malignant PPLs were evaluated.

Results

Age, lesion shape, size, angle between the lesion border and chest wall, boundary clarity, edge regularity, air bronchogram, vascular signs, enhancement patterns, enhancement intensity, homogeneity of enhancement, number of non-enhancing regions, non-enhancing region type, arrival time (AT) of the lesion, lesion-lung AT difference, AT difference ratio, and time to peak were the relevant variables for judging benign and malignant PPLs. Consequently, a model and receiver operating characteristic curve were constructed with an AUC of 0.92 and an accuracy of 88.2%. The test set results showed that the model had good predictive ability. The index with the highest correlation for judging benign and malignant PPLs was the AT difference ratio. Other important factors were lesion size, patient age, and lesion morphology.

Conclusion

The random forest algorithm model constructed based on clinical data and ultrasound imaging features has clinical application value for predicting benign and malignant PPLs.

The Role of Contrast-Enhanced Ultrasound Plus Color Parametric Imaging in the Differential Diagnosis of Subpleural Pulmonary Lesions

OBJECTIVES

To distinguish benign and malignant subpleural pulmonary lesions (SPLs) with contrast-enhanced ultrasound (CEUS) and color parametric imaging (CPI), and evaluate the role of CEUS plus CPI in the differential diagnosis of pathological types of SPLs.

METHODS

One hundred and thirty-six patients underwent CEUS with a Logiq E9 XD Clear ultrasonic machine equipped with a 3.5- to 5.0-MHz C5-1 transducer in our center were enrolled in our study, including 27 cases of benign lesions and 109 cases of malignant lesions. The ultrasound contrast agent used in this study was SonoVue. CEUS images and CPI of all cases were reviewed and analyzed by the resident and staff radiologist groups separately.

RESULTS

With CEUS alone, by both the two groups, the main enhancement pattern of benign SPLs was arborization (P < .001), while centripetal enhancement pattern occurred more frequently in malignant SPLs (P < .001). With CEUS plus CPI, by both the two groups, the main enhancement pattern of benign SPLs was arborization (P < .001), while those of malignant SPLs were centripetal (P < .001) and eccentric (P < .05). The diagnosis performance of CEUS plus CPI was significantly higher than that of CEUS alone in both the resident (area under the curve [AUC] = 0.857 vs 0.677, P < .001) and staff (AUC = 0.866 vs 0.681, P < .001) groups. Moreover, CPI offered remarkable inter-consistency improvements in the enhancement pattern determination between the two groups.

CONCLUSION

The CEUS enhancement patterns would provide information of blood perfusion patterns in the differential diagnosis of benign and malignant SPLs. The diagnosis performance could be significantly improved by CEUS plus CPI compared with CEUS alone.

Correlations between contrast-enhanced ultrasound and microvessel density in non-small cell lung cancer: A prospective study

Background

Immunohistochemical microvessel density (MVD) is an early indicator of angiogenesis and it could be used to evaluate the therapeutic efficacy of non-small cell lung cancer (NSCLC). We sought to identify the ability of contrast-enhanced ultrasound (CEUS) in evaluating MVD of subpleural NSCLC.

Methods

We prospectively collected CEUS data of NSCLC confirmed by ultrasound-guided transthoracic needle biopsy from October 2019 to February 2021, The MVD of NSCLC counted by CD34-positive vessels of immunohistochemical staining. Microflow enhancement (MFE) of CEUS was divided into "dead wood", "cotton", and "vascular" patterns. Pathology subgroup and MVD between different MFE patterns were analyzed, respectively. The arrival time, time to peak, peak intensity (PI), and area under curve (AUC) derivefrom time-intensity curve of CEUS with MVD in NSCLC and its pathological subgroups (adenocarcinoma and squamous cell carcinoma) were subjected to correlation analysis.

Results

A total of 87 patients were included in this study, consisting of 53 cases of adenocarcinoma and 34 cases of squamous cell carcinoma with a mean MVD of 27.8 ± 12.2 mm^-1. There was a significant statistical difference in MFE patterns between two pathological subgroups (p < 0.05). Besides, the MVD of "cotton" and "vascular" patterns were significantly higher than that of "dead wood" pattern (both of p < 0.05), whereas there was no significant difference in MVD between "cotton" pattern and "vascular" pattern. PI and AUC of CEUS were positively correlated with the MVD of NSCLC (r = 0.497, p < 0.001, and r = 0.367, p < 0.001, respectively). Besides, PI and AUC of CEUS were positively correlated with the MVD of squamous cell carcinoma (r = 0.802, and r = 0.663, respectively; both of p < 0.001). Only the PI was positively correlated with the MVD of lung adenocarcinoma (r = 0.288, p = 0.037).

Conclusions

MFE patterns and quantitative parameters of CEUS had good correlation with MVD of NSCLC, especially in squamous cell carcinoma.

Can Ultrasound and Contrast-Enhanced Ultrasound Help Differentiate between Subpleural Focal Organizing Pneumonia and Primary Lung Malignancy?

Background: Subpleural focal organizing pneumonia (FOP) and primary lung malignancy (PLM) are usually confused. The aim of this study was to explore the value of ultrasound (US) and contrast-enhanced ultrasound (CEUS) in the differential diagnosis of FOP and PLM. Methods: A total of 23 patients (mean age: 64.57 ± 11.86 years) with FOP and 100 (mean age: 66.29 ± 11.05 years) with subpleural lesions diagnosed as PLM, confirmed by pathological diagnosis and clinical follow-up, were retrospectively enrolled. The largest lesion diameter, angle between the lesion border and thoracic wall, air bronchial sign, internal blood supply, blood supply form, and pleural effusion examined using conventional US were retrospectively analyzed. The indicators of CEUS included the arrival time of contrast agent in the lesion, lesion−lung arrival time difference, degree of enhancement, distribution uniformity of contrast medium, presence of non-enhancing region, and arterial filling mode in the lesion. A p < 0.05 was considered statistically significant. Results: Presence of air bronchial sign (odds ratio [OR] = 6.18, p = 0.025), acute angle between the lesion border and thoracic wall (OR = 7.124, p = 0.033), and homogeneous enhancement (OR = 35.26, p = 0.01) showed predictive value for the diagnosis of FOP. According to the results of the logistic regression analysis, the area under the receiver operating curve of the above features combined was 0.960, and the sensitivity and specificity were 95.0% and 82.6%, respectively. Conclusions: US combined with CEUS has the potential to differentiate between FOP and PLM.

Application value of contrast-enhanced ultrasound in the diagnosis of peripheral pulmonary focal lesions

INTRODUCTION

Peripheral pulmonary lesions are encountered frequently in clinical practice. Accurate diagnosis of these lesions is of great importance for clinicians. Ultrasound-guided lung tissue puncture is a reliable method for diagnosing these lesions.

OBJECTIVES

To investigate the application value of contrast-enhanced ultrasound (CEUS) combined with rapid on-site evaluation (ROSE) in the diagnosis of peripheral pulmonary focal lesions.

METHODS

Eighty patients enrolled from July 2020 to June 2021 were divided into two groups: a conventional ultrasound group and a CEUS group. Both groups underwent diagnostic procedures guided by ROSE to improve the success rate of puncture sampling. The success rates and complications in both groups were compared. The results for lesion enhancement, time taken for the contrast agent to reach the lesions (AT) and lung tissues (L-AT), and the difference between these times (∆AT) were compared in the CEUS group.

RESULTS

The success rate of biopsy in the CEUS group was 97.62%, which was significantly higher than that in the conventional ultrasound group (84%; P < .05). Puncture complications did not occur in the CEUS group and occurred in 5.26% of the cases in the conventional ultrasound group, but the difference was not statistically significant (P > .05). A comparison of enhancement of benign lesions and malignant lesions in the CEUS group showed a statistically significant difference (P < .05). The difference between the AT and ∆AT of benign and malignant lesions was statistically significant (P <.05). The optimal threshold of ∆AT was 2.05 s.

CONCLUSION

CEUS combined with ROSE is a very important approach for biopsy in the diagnosis of peripheral pulmonary focal lesions. CEUS has definite clinical value in the diagnosis of benign and malignant lung lesions.

Application of Contrast-Enhanced Ultrasound in the Differential Diagnosis of Benign and Malignant Subpleural Pulmonary Lesions

OBJECTIVE

To explore the clinical value of contrast-enhanced ultrasound (CEUS) in the differential diagnosis of benign and malignant subpleural pulmonary lesions (SPLs).

METHODS

Among 959 patients with SPLs who were scheduled to undergo ultrasound-guided puncture in our department between January 2019 and June 2019, 506 patients were included and their B-mode ultrasound and CEUS features, including the lesion's location, size, margin, echo, perfusion pattern of ultrasound contrast agent, degree of enhancement, homogeneity, vascular signs, and necrosis, were retrospectively investigated. All malignant cases were diagnosed by pathology, while benign cases were diagnosed by two respiratory physicians after comprehensive analysis of pathology, etiology, imaging, and clinical symptoms. Statistical differences in these features between the benign and malignant groups were then analyzed.

RESULTS

There were 506 cases in this study, including 219 benign cases and 287 malignant cases. Among them, 351 were males and 155 were females, with an average age of 59 ± 16 years. There were statistically significant differences between benign and malignant groups in the perfusion pattern, the degree of enhancement, and vascular signs. The features of the malignant group included local-to-whole perfusion pattern, hypo-enhancement, and curly hair sign, while those of the benign group included a centrifugal perfusion pattern, iso-enhancement and hyper-enhancement, and dendritic sign. There was no statistically significant difference between the two groups in homogeneity and necrosis.

CONCLUSIONS

CEUS enhancement mode is different between benign and malignant SPLs, which can provide supplementary information for the differential diagnosis of SPLs in the existing imaging diagnosis.

Clinical Applications of Contrast-Enhanced Thoracic Ultrasound (CETUS) Compared to Standard Reference Tests: A Systematic Review

INTRODUCTION

 Contrast-enhanced ultrasound is utilized in an increasing array of medical fields, including thoracic medicine. However, the technique is still relatively new and only sporadically mentioned in current guidelines and recommendations. The aim of this systematic review is to provide a literature overview and to critically appraise the current clinical applications of contrast-enhanced thoracic ultrasound (CETUS).

MATERIALS AND METHODS

 A systematic literature search using major electronic databases and in accordance with PRISMA guidelines was performed. Studies with a primary focus on CETUS of thoracic disorders compared to a standard reference test were included. The QUADAS-2 tool was used for quality assessment of the studies.

RESULTS

 The search identified 43 articles: 1 randomized controlled study, 6 non-randomized controlled studies, 16 non-randomized non-controlled studies, 5 case series, 10 single case reports, and 5 animal studies. The overall risk of bias was judged to be high. Diagnostic accuracy measurements of noninvasive applications of CETUS were only reported in a few studies and they were too dissimilar for meta-analysis. Six studies compared CETUS-guided versus ultrasound-guided transthoracic needle biopsy of thoracic masses. They individually reported a significant increase in diagnostic accuracy in favor of CETUS guidance but were too heterogeneous for meta-analysis.

CONCLUSION

 The current literature on CETUS is overall heterogeneous with a few high evidence level studies, small study populations and a high risk of bias. CETUS-guided biopsy is the most frequent clinical application and increases diagnostic accuracy compared to ultrasound guidance by an average of 14.6 percentage points.

Value of Assessing Peripheral Vascularization with Micro-Flow Imaging, Resistive Index and Absent Hilum Sign as Predictor for Malignancy in Lymph Nodes in Head and Neck Squamous Cell Carcinoma

Simple Summary

Ultrasound-guided fine needle aspiration cytology (USgFNAC) is commonly used for N-staging in head and neck squamous cell carcinoma (HNSCC). The specificity of USgFNAC is always in the order of 100% as false positive cytology is rare. The difference in sensitivity is mainly attributable to selection of the lymph nodes to aspirate and aspiration technique. The aim of this study was to improve the selection criteria of lymph nodes to aspirate. Ultrasound features of nodes such as a short axis diameter, S/L ratio, loss of a fatty hilum sign, resistive index, and peripheral or mixed hilar and peripheral vascularization, obtained by Micro-flow imaging (MFI), which is a new technique to obtain micro-vascularization, were evaluated. To calculate the sensitivity and PPV of each feature, data of sonographic findings and cytological results of all aspirated nodes were statistically analyzed. We found that next to size, peripheral vascularisation obtained by MFI and absent hilum sign have a high predictive value for malignancy and should be added as selection criteria for fine needle aspiration in lymph nodes.

Abstract

Ultrasound-guided fine needle aspiration cytology (USgFNAC) is commonly used for nodal staging in head and neck squamous cell cancer (HNSCC). Peripheral vascularity is a described feature for node metastasis. Micro-flow imaging (MFI) is a new sensitive technique to evaluate micro-vascularization. Our goal is to assess the additional value of MFI to detect malignancy in lymph nodes. A total of 102 patients with HNSCC were included prospectively. USgFNAC was performed with the Philips eL18–4 transducer. Cytological results served as a reference standard to evaluate the prediction of cytological malignancy depending on ultrasound features such as resistive index (RI), absence of fatty hilum sign, and peripheral vascularization. Results were obtained for all US examinations and for the subgroup of clinically node-negative neck (cN0). USgFNAC was performed in 211 nodes. Peripheral vascularization had a positive predictive value (PPV) of 83% (cN0: 50%) and the absence of a fatty hilum had a PPV of 82% (cN0 50%) The combination of peripheral vascularization and absent fatty hilum had a PPV of 94% (cN0: 72%). RI (threshold: 0.705) had a PPV of 61% (cN0: RI-threshold 0.615, PPV 20%), whereas the PPV of short axis diameter (threshold of 6.5mm) was 59% for all patients and 19% in cN0 necks (threshold of 4 mm). Peripheral vascularization assessed by MFI and absent hilum has a high predictive value for cytological malignancy in neck metastases. Next to size, both features should be used as additional selection criteria for USgFNAC.

Development and Prospective Validation of an Ultrasound Prediction Model for the Differential Diagnosis of Benign and Malignant Subpleural Pulmonary Lesions: A Large Ambispective Cohort Study

OBJECTIVE

To develop and prospective validate an ultrasound (US) prediction model to differentiate between benign and malignant subpleural pulmonary lesions (SPLs).

METHODS

This study was conducted retrospectively from July 2017 to December 2018 (development cohort [DC], n = 592) and prospectively from January to April 2019 (validation cohort [VC], n = 220). A total of 18 parameters of B-mode US and contrast-enhanced US (CEUS) were acquired. Based on the DC, a model was developed using binary logistic regression. Then its discrimination and calibration were verified internally in the DC and externally in the VC, and its diagnostic performance was compared with those of the existing US diagnostic criteria in the two cohorts. The reference criteria were from the comprehensive diagnosis of clinical-radiological-pathological made by two senior respiratory physicians.

RESULTS

The model was eventually constructed with 6 parameters: the angle between lesion border and thoracic wall, basic intensity, lung-lesion arrival time difference, ratio of arrival time difference, vascular sign, and non-enhancing region type. In both internal and external validation, the model provided excellent discrimination of benign and malignant SPLs (C-statistic: 0.974 and 0.980 respectively), which is higher than that of "lesion-lung AT difference ≥ 2.5 s" (C-statistic: 0.842 and 0.777 respectively, P <0.001) and "AT ≥ 10 s" (C-statistic: 0.688 and 0.641 respectively, P <0.001) and the calibration curves of the model showed good agreement between actual and predictive malignancy probabilities. As for the diagnosis performance, the sensitivity and specificity of the model [sensitivity: 94.82% (DC) and 92.86% (VC); specificity: 92.42% (DC) and 92.59% (VC)] were higher than those of "lesion-lung AT difference ≥ 2.5 s" [sensitivity: 88.11% (DC) and 80.36% (VC); specificity: 80.30% (DC) and 75.00% (VC)] and "AT ≥ 10 s" [sensitivity: 64.94% (DC) and 61.61% (VC); specificity: 72.73% (DC) and 66.67% (VC)].

CONCLUSION

The prediction model integrating multiple parameters of B-mode US and CEUS can accurately predict the malignancy probability, so as to effectively differentiate between benign and malignant SPLs, and has better diagnostic performance than the existing US diagnostic criteria.

CLINICAL TRIAL REGISTRATION

www.chictr.org.cn, identifier ChiCTR1800019828.

The Adler grade by Doppler ultrasound is associated with clinical pathology of cervical cancer: Implication for clinical management

OBJECTIVE

To analyze the relationship of Adler grade by transvaginal color Doppler flow imaging (TV-CDFI) and the clinical pathological parameters of patients with cervical cancer, and to identify the value of Adler grade in the diagnosis and treatment of cervical cancer.

METHODS

Patients with cervical cancer diagnosed pathologically in our hospital from January 1, 2019 to December 31, 2019 were included, All patients underwent TV-CDFI examination, and the images were divided into 0 to III grades according to the Adler grades, and the correlations between the Adler classification and clinical pathological parameters (clinical stage, mass size, pathological type, squamous cell carcinoma subtype, CA125, CA199) were analyzed.

RESULTS

A total of 162 patients with cervical cancer were included. With the increase of Adler severity, the clinical stage of cervical cancer increased accordingly. the cancer size differed significantly in patients with different Adler grade (p = 0.004); There were significant differences in the level of CA125, CA199 between the squamous cell carcinoma and adenocarcinoma (all p<0.05). the Adler grade was positively related with the clinical stage, pathological type and squamous cell carcinoma subtypes of cervical cancer (all p<0.05), no correlations were found among the Adler grade and the cancer size, CA125, CA199 (all p>0.05). The area under ROC curve of the cervical squamous cell carcinoma predicted by Adler grade based on FIGO results and pathological results was 0.811and 0.762 respectively (all p<0.05).

CONCLUSIONS

Adler grades are closely associated with the clinical pathology of cervical cancer, which may be a convenient and effective approach for the assisting assessment of cervical cancer.

Ultrasound-guided intertumoral injection of contrast agents combined with human p53 gene for the treatment of breast cancer

The objective of this study was to investigate the effects of ultrasound-guided injection of ultrasound contrast agents (UCAs) and the p53 gene on the treatment of rats with breast cancer (BC). Assembly of the p53 expression vector as well as that of a rat model with BC consisted of 200 successfully modeled rats randomly divided into 5 groups: p53 gene introduction, p53 gene introduction + ultrasound irradiation, p53 gene introduction + UCAs, p53 gene introduction + UCA + ultrasound irradiation, and UCA + ultrasound irradiation groups. Expression of p53 was detected via quantitative real-time polymerase chain reaction (qRT-PCR), western blotting and immunohistochemical staining. In the p53 gene introduction + ultrasound irradiation group, we observed increased tumor volume with blood flow signals around and necrotic tumor tissues with an inhibition rate of 36.30%, as well as higher expression of p53 than that in the p53 gene introduction group and p53 gene introduction + UCA group. In the p53 gene introduction + UCA + ultrasound irradiation group, tumor volume increased slightly with reduced blood flow signals and massive degenerative necrosis of tumor cells was identified with inhibition rate of 62.62%, and expression of p53 was higher than that in the rest groups. Taken together, the key findings obtained from the present study elucidate that injection of p53 gene and UCA microbubbles guided by ultrasound could increase the expression of p53, thus inhibiting the tumor growth in rats with BC.

Ultrasonic diagnosis combined with targeted ultrasound contrast agent improves diagnostic sensitivity of ultrasonic for non-small cell lung cancer patients

Non-small cell lung cancer (NSCLC) is one of the most prevalent human cancers, which is known for local growth, easily migration, long-distance invasion and reoccurrence. Targeted ultrasound (US) contrast combined with ultrasound for lung cancer diagnosis has been applied in the clinic. In the present study, a novel targeted ultrasound contrast agent containing chistosan/Fe₃O₄-parceled bispecific antibody (TcBab) targeting carcino-embryonic antigen, vascular endothelial growth factor receptor was introduced, and the diagnostic accuracy and sensitivity was investigated in patients with NSCLC. A total of 384 patients with suspected NSCLC were recruited to investigate the accuracy of TcBab-ultrasound (TcBab-US) and ultrasound. Results demonstrated that TcBab-US improved sensitivity and may provide a novel protocol for diagnosing tumors in patients with suspected NSCLC at an early stage. Data analysis demonstrated that TcBab-US diagnosed 154 suspected patients with NSCLC, whereas ultrasound only diagnosed 84 suspected patients with NSCLC out of a total of 384 patients with suspected NSCLC (P<0.01). A dosage experiment revealed that the optimal dose of TcBab was 5 mg/kg for NSCLC patients. Pharmacodynamics analysis showed that TcBab may be metabolized within 16 h in serum of patients. Notably, early diagnosis determined by TcBab-US contributed to improvement of survival for NSCLC patients as determined by a comparison of the survival rate with the survival rate of patients who did not receive TcBab (P<0.05). In conclusion, these investigations suggested that TcBab improves the accuracy and diagnostic confidence of ultrasonic for the diagnosis of early-stage NSCLC, and may have potential application value in the clinic.

Evaluation of the thrombus of abdominal aortic aneurysms using contrast enhanced ultrasound - preliminary results

It is hypothesized that the degree of vascularization of the thrombus may have a significant impact on the rupture of aortic aneurysms. The presence of neovascularization of the vessel wall and mural thrombus has been confirmed only in histopathological studies. However, no non-invasive imaging technique of qualitative assessment of thrombus and neovascularization has been implemented so far. Contrast-enhanced ultrasound (CEUS) has been proposed as a feasible and minimally invasive technique for in vivo visualization of neovascularization in the evaluation of tumors and atherosclerotic plaques. The aim of this study was the evaluation of mural thrombus and AAAs wall with CEUS. CEUS was performed in a group of seventeen patients with AAAs. The mural thrombus enhancement was recognized in 12 cases, yet no significant correlation between the degree of contrast enhancement and AAAs diameter, thrombus width, and thrombus echogenicity was found. We observed a rise in AAAs thrombus heterogeneity with the increase in the aneurysm diameter (r = 0.62, p = 0.017). In conclusion CEUS can visualize small channels within AAAs thrombus, which could be a result of an ongoing angiogenesis. There is a need for further research to find out whether the degree of vascularization of the thrombus may have a significant impact on the rupture of aneurysms.