Relationship between the Tortuosity of the Extracranial Internal Carotid and Vertebral Arteries on Magnetic Resonance Imaging/Angiography and Vascular Risk Factors in a Japanese Population

Objective We aimed to investigate the relationship between tortuosity of the extracranial internal carotid artery (ICA) or vertebral artery (VA) and vascular risk factors among residents of Asahikawa, northeast Japan. Methods We retrospectively surveyed participants of "brain dock" medical brain checkups, which involved magnetic resonance imaging and angiography. We measured the tortuosity of the ICA and VA, and evaluated vascular risk factors based on medical interviews, questionnaires, and medical records. Results A total of 218 participants were enrolled in the study. ICA tortuosity (right and left) was significantly correlated with age [odds ratio (OR): 2.452, 95% confidence interval (CI): 1.695-3.548, p<0.001]. A more pronounced correlation was observed in females than in males (OR: 1.678, 95% CI: 1.004-2.807, p=0.048). VA tortuosity (right and left) was significantly correlated with age (OR: 1.786, 95% CI: 1.250-2.550, p=0.001) and smoking history (OR: 2.140, 95% CI: 1.235-3.707, p=0.007), and was more pronounced in females than in males (OR: 1.864, 95% CI: 1.107-3.137, p=0.019). Conclusion ICA tortuosity was correlated with age, while VA tortuosity was correlated with age and smoking history. ICA and VA tortuosity were more pronounced in females than in males.

Arterial tortuosity in pediatric Loeys-Dietz syndrome patients

Loeys-Dietz syndrome (LDS) is an autosomal connective tissue disorder commonly presenting with hypertelorism, bifid uvula, aortic aneurysms, and arterial tortuosity. The aim of the present study was to investigate differences in tortuosity index (TI) between genotypes of LDS, possible progression over time and its use as an adjunctive prognostic tool alongside aortic dimensions to aid timely surgical planning in pediatric patients. A retrospective observational study of pediatric LDS patients referred to our center (November 2012-February 2021) was conducted. Using magnetic resonance angiography (MRA) with 3D maximum intensity projection volume-rendered angiogram, arterial TI was measured. Twenty three patients had genetically confirmed LDS with at least one head and neck MRA and 19 had no less than one follow-up MRA available. All patients presented arterial tortuosity. Patients with TGFBR2 variants had greater values of TI compared to patients with TGFB2 variants (p = 0.041). For patients who did not undergo surgery (n = 18), z-scores at the level of the sinus of Valsalva showed a significant correlation with vertebral TI (rs  = 0.547). There was one death during follow-up. This study demonstrates that patients with LDS and TGFBR2 variants have greater values of TI than patients with TGFB2 variants and that greatest values of TI are associated with increased aortic root z-scores. Furthermore, as TI decreases over time, less frequent neuroimaging follow-up can be considered. Nevertheless, additional studies are needed to better define more accurate risk stratification and long-term surveillance in these patients.

MRA for Preoperative Planning and Postoperative Management of Perforator Flap Surgeries: A Review

Perforator flap magnetic resonance angiography (MRA) has emerged as a widely accepted and preferred modality for perforator flap mapping at several institutions. Autologous perforator flaps are a type of reconstructive microsurgical technique that involves transferring skin and fat from one part of the patient's body to another to replace tissue lost due to trauma, cancer resection, or other reasons. Autologous perforator flaps are based on a specific perforating blood vessel perfusing the transferred tissue. Hence, the surgery relies on the precise identification and mapping of perforating vessels to ensure successful outcomes. With its superior soft tissue contrast and multiplanar imaging capabilities, MRA has shown great potential in providing accurate and detailed visualization of perforator anatomy, size, and course. This review article summarizes the current literature on perforator flap MRA, including its technical considerations, imaging protocols, postprocessing, and reporting, specifically for autologous breast reconstructions. The advantages and limitations of MRA in evaluating perforator flaps are discussed, including its role in preoperative planning, intraoperative guidance, and postoperative assessment. Anatomy, brief surgical technique, specific technical modifications, and reporting of most commonly performed autologous breast flaps are described. Recent advancements in Perforator flap surgery and MRA techniques are discussed. Additionally, we examine the emerging role of artificial intelligence and machine learning in improving the accuracy and efficiency of perforator flap MRA interpretation. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 5.

Vertebral artery dissection caused by atlantoaxial dislocation in a patient with Marfan syndrome

A small number of case reports have documented a link between atlantoaxial dislocation (AAD) and vertebral artery dissection (VAD), but this association has never been described in patients with hereditary connective tissue disorders. We present a case of an 18-year-old female patient, diagnosed with Marfan syndrome since the age of one, who underwent brain MRA for intracranial aneurysm screening revealing tortuosity of the internal carotid and vertebral arteries as well as atlantoaxial dislocation. Since the patient was asymptomatic, a wait-and-see approach was chosen, but a follow-up MRA after 18 months showed the appearance of a dissecting pseudoaneurysm of the V3 segment of the left vertebral artery. Despite the patient being still asymptomatic, it was decided to proceed with C1-C2 stabilization to prevent further vascular complications. Follow-up imaging showed realignment of the atlantoaxial joint and reduction of the dissecting pseudoaneurysm of the left vertebral artery. In our patient, screening MRA has led to the discovery of asymptomatic arterial and skeletal abnormalities which, if left untreated, might have led to severe cerebrovascular complications. Therefore, AAD correction or close monitoring with MRA should be provided to MFS patients with this craniovertebral junction anomaly, even if asymptomatic.

Cerebral Aneurysm Characteristics and Surgical Outcomes: An In-Depth Analysis of 346 Cases Operated Using Microsurgical Clipping

This comprehensive study analyzes 346 surgically treated intracranial aneurysms, emphasizing the importance of understanding risk factors and prevalent characteristics in patients. Intracranial aneurysms, primarily of the saccular or berry type, significantly contribute to nontraumatic subarachnoid hemorrhages and demonstrate a rising incidence due to advances in imaging techniques. The study highlights a gender discrepancy in aneurysm occurrence and a higher prevalence in individuals over 30 years old. The research delves into various aspects, including aneurysm localization, diameter, neck dimensions, and rupture status, with a focus on the anterior communicating artery and middle communicating artery as predominant locations. Significant findings include the prevalence of ruptured aneurysms and the impact of arterial hypertension, atherosclerosis, obesity, and diabetes on aneurysm epidemiology. The study also investigates the occurrence of vasospasm, a significant factor in delayed morbidity and mortality in aneurysmal subarachnoid hemorrhage. The utilization of the Glasgow Outcome Scale and other quantification scales aids in understanding the severity and postoperative outcomes of intracranial aneurysms. Challenges such as the incidence of reopenings and postoperative osteomyelitis are addressed, underlining the need for refined protocols and multidisciplinary approaches in treatment. The study's results contribute to the existing knowledge base on intracranial aneurysms, emphasizing the importance of ongoing research and tailored treatment strategies. The comprehensive nature of this analysis, covering preoperative, intraoperative, and postoperative factors, provides valuable insights into the complex interplay of risk factors and clinical outcomes in patients with intracranial aneurysms.

Evaluating the diagnostic accuracy of 3D contrast-enhanced magnetic resonance angiography versus digital subtraction angiography in spinal dural arteriovenous fistulas

OBJECTIVE

Spinal dural arteriovenous fistulas (SDAVFs) often go undiagnosed, leading to irreversible spinal cord dysfunction. Although digital subtraction angiography (DSA) is the gold standard for diagnosing SDAVF, DSA is invasive and operator dependent, with associated risks. MR angiography (MRA) is a promising alternative. This study aimed to evaluate the performance of MRA as an equal alternative to DSA in investigating, diagnosing, and localizing SDAVF.

METHODS

Prospectively collected data from a single neurosurgeon at a large tertiary academic center were searched for SDAVFs. Eligibility criteria included any patient with a surgically proven SDAVF in whom preoperative DSA, MRA, or both had been obtained. The eligible patients formed a consecutive series, in which they were divided into DSA and MRA groups. DSA and MRA were the index tests that were compared to the surgical SDAVF outcome, which was the reference standard. Accurate diagnosis was considered to have occurred when the imaging report matched the operative diagnosis to the correct spinal level. Comparisons used a two-sample t-test for continuous variables and Fisher-Freeman-Halton's exact test for categorical variables, with p < 0.05 specifying significance. Univariate, bivariate, and multivariate analyses were conducted to investigate group associations with DSA and MRA accuracy. Positive predictive value, sensitivity, and accuracy were calculated.

RESULTS

A total of 27 patients with a mean age of 63 years underwent surgery for SDAVF. There were 19 male (70.4%) and 8 female (29.6%) patients, and the mean duration of symptoms at the time of surgery was 14 months (range 2-48 months). Seventeen patients (63%) presented with bowel or bladder incontinence. Bivariate analysis of the DSA and MRA groups further revealed no significant relationships between the characteristics and accuracy of SDAVF diagnosis. MRA was found to be more sensitive and accurate (100% and 73.3%) than DSA (85.7% and 69.2%), with a subanalysis of the patients with both preoperative MRA and DSA showing that MRA had a greater positive predictive value (78.6 vs 72.7), sensitivity (100 vs 72.7), and accuracy (78.6 vs 57.1) than DSA.

CONCLUSIONS

In surgically proven cases of SDAVFs, the authors determined that MRA was more accurate than DSA for SDAVF diagnosis and localization to the corresponding vertebral level. Incomplete catheterization at each vertebral level may result in the failure of DSA to detect SDAVF.

Amorphous Albumin Gadolinium-Based Nanoparticles for Ultrahigh-Resolution Magnetic Resonance Angiography

Magnetic resonance angiography (MRA) contrast agents are extensively utilized in clinical practice due to their capability of improving the image resolution and sensitivity. However, the clinically approved MRA contrast agents have the disadvantages of a limited acquisition time window and high dose administration for effective imaging. Herein, albumin-coated gadolinium-based nanoparticles (BSA-Gd) were meticulously developed for in vivo ultrahigh-resolution MRA. Compared to Gd-DTPA, BSA-Gd exhibits a significantly higher longitudinal relaxivity (r1 = 76.7 mM-1 s-1), nearly 16-fold greater than that of Gd-DTPA, and an extended blood circulation time (t1/2 = 40 min), enabling a dramatically enhanced high-resolution imaging of microvessels (sub-200 μm) and low dose imaging (about 1/16 that of Gd-DTPA). Furthermore, the clinically significant fine vessels were successfully mapped in large mammals, including a circle of Willis, kidney and liver vascular branches, tumor vessels, and differentiated arteries from veins using dynamic contrast-enhanced MRA BSA-Gd, and have superior imaging capability and biocompatibility, and their clinical applications hold substantial promise.

Detection Rates and Trends of Asymptomatic Unruptured Intracranial Aneurysms From 2005 to 2019

BACKGROUND AND OBJECTIVES

The trend in detection rates of asymptomatic unruptured intracranial aneurysms (UIAs) on brain computed tomography angiography/magnetic resonance angiography (CTA/MRA) is not well established. Our objective was to evaluate time trends in asymptomatic UIA detection rates on brain CTA/MRA between 2005 and 2019.

METHODS

We conducted a retrospective study of all brain computed tomography/magnetic resonance scans (n = 288 336 scans in 130 621 patients) performed between January 2005 and December 2019 at a tertiary referral hospital. Patients who underwent brain CTA/MRA examinations were included (n = 81 261 scans in 48 037 patients). The annual detection rate of new UIA cases was calculated based on the first brain CTA/MRA imaging. Detection rates were compared between three periods and across different age groups.

RESULTS

The number of first CTA/MRA examinations increased significantly from 2005 to 2009 (n = 12 190 patients) to 2010-2014 (n = 14 969 patients) and 2015-2019 (n = 20 878 patients) ( P < .001). The UIA detection rate also increased significantly from 1.7% in 2005-2009 to 2.5% in 2010-2014 and 3.4% in 2015-2019 ( P < .001). The UIA detection rate increased significantly from 2010-2014 to 2015-2019 (relative risk [RR], 1.33; 95% CI, 1.17-1.51), particularly in patients aged 60-69 years (RR, 1.29; 95% CI, 1.01-1.63), 70-79 years (RR, 1.71; 95% CI, 1.30-2.25), and >79 years (RR, 2.33; 95% CI, 1.56-3.47). Furthermore, the detection rate of <5-mm UIAs increased from 2010-2014 to 2015-2019 (RR, 1.51; 95% CI, 1.28-1.77).

CONCLUSION

The detection rate of asymptomatic UIAs, particularly in elderly patients, has increased significantly over the past 15 years, coinciding with the increased use of CTA/MRA imaging. Furthermore, the size of the identified UIAs has decreased. These findings raise concerns about the management strategies for UIAs, indicating the need for further research.

Preoperative Evaluation for Carotid Endarterectomy Using CT and MRI Fusion Images Without Contrast Media

The usefulness of carotid endarterectomy (CEA) for carotid artery stenosis has been established even in the era of endovascular treatment. Digital subtraction angiography (DSA) and three-dimensional computed tomography angiography (3D-CTA) are used for preoperative evaluation of CEA; however, contrast agents cannot be used in patients with renal dysfunction or contrast agent allergy. Since the introduction of a three-dimensional image analysis software, SYNAPSE VINCENT (Fujifilm, Tokyo, Japan) in February 2016, we initially fused cervical CT, carotid three-dimensional time-of-flight magnetic resonance angiography, and carotid plaque imaging using 1.5 T magnetic resonance imaging to evaluate carotid artery stenosis in patients with renal dysfunction. Since then, we have gradually accumulated several cases, and at present, this fusion imaging is our first choice for preoperative evaluation of CEA instead of DSA or 3D-CTA. This evaluation method has many advantages over DSA and 3D-CTA, including the fact that it does not require contrast media. We report its usefulness, limitations, and cautions.

Anatomical variations in the circle of Willis on magnetic resonance angiography in a south Trinidad population

Objectives

This article seeks to determine the prevalence of a complete circle of Willis (CoW) and its common morphological variations in a south Trinidad population, while also investigating the influence of gender, age, and ethnicity on CoW morphology.

Methods

A prospective, descriptive, cross-sectional study was done on the magnetic resonance images for consecutive patients who had a brain MRI/magnetic resonance angiography at a tertiary health institution in south Trinidad between October 2019 and September 2020. Patients with significant cerebrovascular disease and/or a history of prior neurosurgical intervention were excluded.

Results

A complete CoW was seen in 24.3%, with more complete circles observed in younger participants (≤45 years) and Afro-Trinidadians. No gender predilection for a complete CoW was demonstrated. The most common variations in the anterior and posterior parts of the circle were a hypoplastic anterior communicating artery (8.6%, n = 13) and bilateral aplastic posterior communicating arteries (18.4%, n = 28), respectively.

Conclusions

Significant variations exist in the CoW of a south Trinidad population with a frequency of complete in 24.3%, and more complete circles in younger patients and Afro-Trinidadians. Gender did not influence CoW morphology.

Advances in knowledge

Structural abnormalities in the CoW may be linked to future incidence of cerebrovascular diseases and should therefore be communicated to the referring physician in the written radiology report. Knowledge of variant anatomy and its frequency for a particular populations is also required by neurosurgeons and neuro-interventional radiologists to help with preprocedural planning and to minimize complications.

Anatomical and Three-Dimensional Study of the Female Feline Abdominal and Pelvic Vascular System Using Dissections, Computed Tomography Angiography and Magnetic Resonance Angiography

This study describes the anatomical characteristics of the abdominal and pelvic vascular system of two healthy mature female cats via three-dimensional contrast enhanced computed tomography angiography, non-contrast enhanced magnetic resonance angiography and three-dimensional printing. Volume-rendering computed tomography angiography images were acquired from the ventral aspect using RadiAnt, Amira and OsiriX MD Dicom three-dimensional formats, and three-dimensional printing was obtained and compared with the corresponding computed tomography angiography images. Non-contrast enhanced magnetic resonance angiography was made using the time-of-flight imaging in ventral, oblique and lateral views. In addition, three cadavers with colored latex injection were dissected to facilitate the identification of the vascular structures. Three-dimensional computed tomography angiography showed the main vascular structures, whereas with the time-of-flight blood appeared with a high signal intensity compared with associated abdominal and pelvic tissues. Three-dimensional computed tomography angiography images and time-of-flight sequences provided adequate anatomical details of the main arteries and veins that could be used for future feline anatomical and clinical vascular studies of the abdomen and pelvis.

A Case Report of a Giant Basilar Artery Aneurysm

Intracranial aneurysms, characterized by the localized dilation of cerebral arteries, pose a substantial risk of rupture, leading to severe consequences. Basilar artery aneurysms, in particular, present unique challenges due to their location and potential impact on vital brainstem structures. Advanced diagnostic imaging has improved the chances of early identification of the condition, enabling timely intervention. We discuss the case of a 54-year-old female with controlled hypertension, who presented with persistent severe headaches and neurological symptoms. Diagnostic investigations revealed a large saccular basilar artery aneurysm measuring 4.7 cm. The aneurysm exerted pressure on the brainstem. After comprehensive discussions, the patient underwent successful flow-diverter stent placement, which led to the gradual resolution of symptoms. The multidisciplinary team closely monitored the patient in the neurointensive care unit. Managing giant basilar artery aneurysms poses significant challenges due to the potentially life-threatening complications associated with it. The success in treating the presented case underscores the importance of a multidisciplinary approach involving neurosurgery, interventional radiology, and critical care in managing these patients.

VEGFR2 Expression Correlates with Postnatal Development of Brain Arteriovenous Malformations in a Mouse Model of Type I Hereditary Hemorrhagic Telangiectasia

Brain arteriovenous malformations (BAVMs) are a critical concern in hereditary hemorrhagic telangiectasia (HHT) patients, carrying the risk of life-threatening intracranial hemorrhage. While traditionally seen as congenital, the debate continues due to documented de novo cases. Our primary goal was to identify the precise postnatal window in which deletion of the HHT gene Endoglin (Eng) triggers BAVM development. We employed SclCreER(+);Eng2f/2f mice, enabling timed Eng gene deletion in endothelial cells via tamoxifen. Tamoxifen was given during four postnatal periods: P1-3, P8-10, P15-17, and P22-24. BAVM development was assessed at 2-3 months using latex dye perfusion. We examined the angiogenic activity by assessing vascular endothelial growth factor receptor 2 (VEGFR2) expression via Western blotting and Flk1-LacZ reporter mice. Longitudinal magnetic resonance angiography (MRA) was conducted up to 9 months. BAVMs emerged in 88% (P1-3), 86% (P8-10), and 55% (P15-17) of cases, with varying localization. Notably, the P22-24 group did not develop BAVMs but exhibited skin AVMs. VEGFR2 expression peaked in the initial 2 postnatal weeks, coinciding with BAVM onset. These findings support the "second hit" theory, highlighting the role of early postnatal angiogenesis in initiating BAVM development in HHT type I mice.

Vertebral artery dissection aneurysm in a pediatric patient: A rare case with unusual clinical manifestations, diagnostic, and management challenges

Vertebral artery aneurysm is a rare condition with diverse clinical manifestations in pediatric patients. We present the case of a 12-year-old male who presented with diplopia, vomiting, ataxia, and severe headache. Diagnostic evaluation revealed an extracranial vertebral artery dissection with an associated aneurysm at the C3-C4 level. Despite the absence of recurrent ischemic strokes, the aneurysm posed challenges in differentiating the symptoms from other inflammatory demyelinating disorders, particularly internuclear ophthalmoplegia. Diagnosis relied on a thorough history, physical examination, and imaging studies. Magnetic resonance imaging with magnetic resonance angiography confirmed the diagnosis and played a crucial role in assessing the size, location, and extent of the aneurysm. Additionally, the imaging findings helped guide treatment decisions and determine the need for anticoagulation therapy. Regular follow-up imaging was initiated to monitor for late complications and evaluate the effectiveness of the management approach. This case highlights the atypical presentation of vertebral artery aneurysm in a pediatric patient, underscoring the importance of clinical suspicion and the role of advanced imaging techniques in facilitating accurate diagnosis and guiding appropriate management. Prompt diagnosis and optimal utilization of imaging modalities are essential in preventing severe morbidity and mortality. Further research is warranted to enhance our understanding of this condition and refine imaging and management protocols in pediatric population.

Visualizing Cerebral Small Vessel Degeneration During Aging and Diseases Using Magnetic Resonance Imaging

Cerebral small vessel disease is a major contributor to brain disorders in older adults. It is associated with a much higher risk of stroke and dementia. Due to a lack of clinical and fluid biomarkers, diagnosing and grading small vessel disease are highly dependent on magnetic resonance imaging. In the past, researchers mostly used brain parenchymal imaging markers to represent small vessel damage, but the relationships between these surrogate markers and small vessel pathologies are complex. Recent progress in high-resolution magnetic resonance imaging methods, including time-of-flight MR angiography, phase-contrast MR angiography, black blood vessel wall imaging, susceptibility-weighted imaging, and contrast-enhanced methods, allow for direct visualization of cerebral small vessel structures. They could be powerful tools for understanding aging-related small vessel degeneration and improving disease diagnosis and treatment. This article will review progress in these imaging techniques and their application in aging and disease studies. Some challenges and future directions are also discussed. EVIDENCE LEVEL: 4. TECHNICAL EFFICACY: 3.

Assessing Machine Learning Models for Predicting Age with Intracranial Vessel Tortuosity and Thickness Information

This study aimed to develop and validate machine learning (ML) models that predict age using intracranial vessels' tortuosity and diameter features derived from magnetic resonance angiography (MRA) data. A total of 171 subjects' three-dimensional (3D) time-of-flight MRA image data were considered for analysis. After annotations of two endpoints in each arterial segment, tortuosity features such as the sum of the angle metrics, triangular index, relative length, and product of the angle distance, as well as the vessels' diameter features, were extracted and used to train and validate the ML models for age prediction. Features extracted from the right and left internal carotid arteries (ICA) and basilar arteries were considered as the inputs to train and validate six ML regression models with a four-fold cross validation. The random forest regression model resulted in the lowest root mean square error of 14.9 years and the highest average coefficient of determination of 0.186. The linear regression model showed the lowest average mean absolute percentage error (MAPE) and the highest average Pearson correlation coefficient (0.532). The mean diameter of the right ICA vessel segment was the most important feature contributing to prediction of age in two out of the four regression models considered. An ML of tortuosity descriptors and diameter features extracted from MRA data showed a modest correlation between real age and ML-predicted age. Further studies are warranted for the assessment of the model's age predictions in patients with intracranial vessel diseases.

Volumetric surveillance of brain aneurysms: Pitfalls of MRA

INTRODUCTION

Untreated brain aneurysms are usually surveilled with serial MR imaging and evaluated with 2D multiplanar measurements. The assessment of aneurysm growth may be more accurate with volumetric analysis. We evaluated the accuracy of a magnetic resonance angiography (MRA) segmentation pipeline for aneurysm volume measurement and surveillance.

METHODS

A pipeline to determine aneurysm volume was developed and tested on two aneurysm phantoms imaged with time-of flight (TOF) MRA and 3D rotational angiography (3DRA). The accuracy of the pipeline was then evaluated by reconstructing 10 aneurysms imaged with contrast enhanced-MRA (CE-MRA) and 3DRA. This calibrated and refined post-processing pipeline was subsequently used to analyse aneurysms from our prospectively acquired database. Volume changes above the threshold of error were considered true volume changes. The accuracy of these measurements was analysed.

RESULTS

TOF-MRA reconstructions were not as accurate as CE-MRA reconstructions. When compared to 3DRA, CE-MRA underestimated aneurysm volume by 7.8% and did not accurately register the presence of blebs. Eighteen aneurysms (13 saccular and 5 fusiform) were analysed with the optimized 3D volume reconstruction pipeline, with a mean follow-up time of 11 months. Artifact accounted for 10.2% error in volume measurements using serial CE-MRA. When this margin of error was used to assess aneurysms volume in serial imaging with CE-MRA, only two fusiform aneurysms changed in volume. The variations in volume of these two fusiform aneurysms were caused by intra-mural and intrasaccular thrombosis.

CONCLUSIONS

CE-MRA and TOF-MRA 3D volume reconstructions may not register minor morphological changes such as the appearance of blebs. CE-MRA underestimates volume by 7.8% compared to 3DRA. Serial CE-MRA volume measurements had a larger margin of error of approximately 10.2%. MRA-based volumetric measurements may not be appropriate for aneurysm surveillance.

Joint two-stage convolutional neural networks for intracranial aneurysms detection on 3D TOF-MRA

Objective. This study aims to develop a three-dimensional convolutional neural network utilizing computer-aided diagnostic technology to facilitate the detection of intracranial aneurysms and automatically assess their location and extent, thereby enhancing the efficiency of radiologists, and streamlining clinical workflows.Approach. A retrospective study was conducted, proposing a joint segmentation and classification network (JSCD-Net) that employs 3D time-of-flight magnetic resonance angiography images for preliminary detection of aneurysms and the minimization of false positives. Specifically, the U-Net++ network was utilized for pre-detection of aneurysms. This was followed by the creation of a multi-path network, co-trained with U-Net++ to correct the results of the first stage to further reduce the rate of false positives. Model effectiveness and robustness were evaluated using sensitivity and false positive analyses on internal and external datasets. A cross-validated free-response receiver operating characteristic curve was also plotted.Main results. JSCD-Net demonstrated a sensitivity of 91.2% (31 of 34; 95% CI: 77.0, 97.0) with an average of 3.55 false positives per scan on the internal test set. For the external test set, it identified 97.2% (70 of 72; 95% CI: 90.4, 99.2) of aneurysms with an average of 2.7 false positives per scan.Significance. When compared with the existing studies, the proposed model shows high sensitivity in detecting intracranial aneurysms with a reasonable number of false positives per case. This result emphasizes the model's potential as a valuable tool in aiding clinical diagnoses.

A Case Report of Migraine With Hypoplasia of the Internal Carotid Artery

Migraine, a widespread and incapacitating neurological disorder, affects numerous individuals worldwide, causing severe headaches and impairing their quality of life. The interplay of genetic, environmental, and neurovascular factors underlies the pathophysiology of migraine. This report highlights the case of a 25-year-old woman with recurrent, severe headaches, predominantly in the right frontal and temporal regions. She was diagnosed with migraine with aura, a diagnosis supported by her family history. No previous history of seizures was reported. A comprehensive work-up, including neuroimaging, revealed left internal carotid artery hypoplasia with compensatory collateral circulation. The coexistence of severe migraines and left internal carotid artery hypoplasia underscores the complex interrelationship between cerebrovascular anomalies and neurological symptoms. The rarity of this vascular variation emphasizes the need for attentive clinical evaluation and consideration of anatomical deviations in migraine patients. As medical knowledge progresses, further research is essential to unravel the mechanisms connecting vascular anomalies and neurological disorders, ultimately leading to personalized interventions for improved patient outcomes.

Super-giant fusiform basilar artery aneurysm

Intracranial aneurysms are focal pathological dilatation of the arteries with a prevalence of 3.2%. Fusiform aneurysms are rare and mainly due to dissection or atherosclerosis. They may manifestas as stroke, cranial nerve palsies, brainstem compression and Sub-arachnoid hemorrhage. A diameter greater than 10 mm is a risk factor for rupture and warrants early intervention.

Non-Contrast-Enhanced MR Arteriography of Potential Living-Related Liver Donor: Using Contrast Enhanced CT Arteriography as Standard Reference

BACKGROUND

Contrast-enhanced computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are the primary modalities to assess donors' vessels before transplant surgery. Radiation and contrast medium are potentially harmful to donors.

PURPOSE

To compare the image quality and visualization scores of hepatic arteries on CTA and balanced steady-state free-precession (bSSFP) non-contrast-enhanced MRA (NC-MRA), and to evaluate if bSSFP NC-MRA can potentially be a substitute for CTA.

STUDY TYPE

Prospective.

POPULATION

Fifty-six consecutive potential living-related liver donors (30.9 ± 8.4 years; 31 men).

FIELD STRENGTH/SEQUENCE

1.5T; four bSSFP NC-MRA sequences: respiratory-triggered (Inhance inflow inversion recovery [IFIR]) and three breath-hold (BH); and CTA.

ASSESSMENT

The artery-to-liver contrast (Ca-l) was quantified. Three radiologists independently assigned visualization scores using a four-point scale to potential origins, segments, and branches of the hepatic arteries, determined the anatomical variants based on Hiatt's classification, and assessed the image quality of NC-MRA sequences.

STATISTICAL TESTS

Fleiss' kappa to evaluate the readers' agreement. Repeat measured ANOVA or Friedman test to compare Ca-l of each NC-MRA. Friedman test to compare overall image quality and visualization scores; post hoc analysis using Wilcoxon signed-rank test. P-value <0.05 was considered statistically significant.

RESULTS

Inhance IFIR Ca-l was significantly higher than all BH bSSFP Ca-l (0.56 [0.45-0.64] vs. 0.37 [0.29-0.47] to 0.41 [0.23-0.51]). Overall image quality score of BH bSSFP TI1200 was significantly higher than other NC-MRA (4 [4-4] vs. 4 [3 to 4-4]). The median visualization scores of almost all arteries on CTA were significantly higher than on NC-MRA (4 [3 to 4-4] vs. 1 [1-2] to 4 [4-4]). The median visualization scores were all 4 [4-4 ] on Inhance IFIR with >92.3% observed scores ≥3, except the segment 4 branch (3 [1-4], 53.6%). The identification rates of arterial variants were 92.9%-97% on Inhance IFIR.

DATA CONCLUSIONS

Although CTA is superior to the NC-MRA, all NC-MRA depict the donor arterial anatomy well. Inhance IFIR can potentially be an alternative image modality for CTA to evaluate the arterial variants of living donors.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Report from the society of magnetic resonance angiography: clinical applications of 7T neurovascular MR in the assessment of intracranial vascular disease

In recent years, ultra-high-field magnetic resonance imaging (MRI) applications have been rapidly increasing in both clinical research and practice. Indeed, 7-Tesla (7T) MRI allows improved depiction of smaller structures with high signal-to-noise ratio, and, therefore, may improve lesion visualization, diagnostic capabilities, and thus potentially affect treatment decision-making. Incremental evidence emerging from research over the past two decades has provided a promising prospect of 7T magnetic resonance angiography (MRA) in the evaluation of intracranial vasculature. The ultra-high resolution and excellent image quality of 7T MRA allow us to explore detailed morphological and hemodynamic information, detect subtle pathological changes in early stages, and provide new insights allowing for deeper understanding of pathological mechanisms of various cerebrovascular diseases. However, along with the benefits of ultra-high field strength, some challenges and concerns exist. Despite these, ongoing technical developments and clinical oriented research will facilitate the widespread clinical application of 7T MRA in the near future. In this review article, we summarize technical aspects, clinical applications, and recent advances of 7T MRA in the evaluation of intracranial vascular disease. The aim of this review is to provide a clinical perspective for the potential application of 7T MRA for the assessment of intracranial vascular disease, and to explore possible future research directions implementing this technique.

Effects of Path-Finding Algorithms on the Labeling of the Centerlines of Circle of Willis Arteries

Quantitative analysis of intracranial vessel segments typically requires the identification of the vessels' centerlines, and a path-finding algorithm can be used to automatically detect vessel segments' centerlines. This study compared the performance of path-finding algorithms for vessel labeling. Three-dimensional (3D) time-of-flight magnetic resonance angiography (MRA) images from the publicly available dataset were considered for this study. After manual annotations of the endpoints of each vessel segment, three path-finding methods were compared: (Method 1) depth-first search algorithm, (Method 2) Dijkstra's algorithm, and (Method 3) A* algorithm. The rate of correctly found paths was quantified and compared among the three methods in each segment of the circle of Willis arteries. In the analysis of 840 vessel segments, Method 2 showed the highest accuracy (97.1%) of correctly found paths, while Method 1 and 3 showed an accuracy of 83.5% and 96.1%, respectively. The AComm artery was highly inaccurately identified in Method 1, with an accuracy of 43.2%. Incorrect paths by Method 2 were noted in the R-ICA, L-ICA, and R-PCA-P1 segments. The Dijkstra and A* algorithms showed similar accuracy in path-finding, and they were comparable in the speed of path-finding in the circle of Willis arterial segments.

Rapid MR Angiography Using 3D Gradient-echo Imaging and the Two-point Dixon Method to Evaluate Carotid Plaque

Liver acquisition with volume acceleration-flex (LAVA-Flex) acquires out-of-phase and in-phase echo images and automatically generates water-only and fat-only images from one single acquisition. The scan time of carotid MR angiography (MRA) using LAVA-Flex (LAVA MRA) is about one-fifth that of conventional time-of-flight MRA (cTOF MRA). We aimed to investigate whether LAVA MRA could provide useful information for the diagnosis of carotid plaque by utilizing the ability to acquire multiple sequences simultaneously. Comparing LAVA MRA and cTOF MRA images for carotid plaque, low-intensity plaques were more clearly identified in the in-phase images, and high-intensity plaques were more clearly identified in the water-only or out-of-phase images. None of the plaques exhibited superior visualization with the cTOF sequence. We concluded that LAVA MRA can provide more useful information on plaque evaluation using multiple sequences than cTOF MRA.

Prevalence and Clinical Implications of Incidental Aortic Arch Abnormalities on Contrast-Enhanced Neck MR Angiography: A Single-Center Experience

Background and Objectives: Vascular abnormalities within the anatomical coverage are frequently encountered in imaging studies. The aortic arch is often overlooked as an anatomical blind spot, especially in neck magnetic resonance (MR) angiography. This study investigated the prevalence of incidental aortic arch abnormalities. We also estimated the potential clinical significance of aortic arch abnormalities as blind spots detected on contrast-enhanced neck MR angiography. Materials and Methods: Between February 2016 and March 2023, 348 patients were identified based on contrast-enhanced neck MR angiography reports. The clinical and radiological characteristics of the patients and the presence of additional imaging studies were assessed. The aortic arch abnormalities and coexisting non-aortic arterial abnormalities were classified into two categories according to their clinical significance. We performed the χ² test and Fisher's exact test for group comparisons. Results: Of the 348 study patients, only 29 (8.3%) had clinically significant incidental aortic arch abnormalities. Among these 348 patients, 250 (71.8%) and 136 (39%) had intracranial and extracranial abnormalities, respectively; the clinically significant intracranial abnormalities in the two groups were 130 lesions (52.0%) and 38 lesions (27.9%), respectively. In addition, there was a significantly higher tendency of clinically significant aortic arch abnormalities (13/29, 44.8%) in the patients who had clinically significant coexisting non-aortic arterial abnormalities than in the other group (87/319, 27.3%) (p = 0.044). The patient groups with clinically significant intracranial or extracranial arterial abnormalities had higher rates of clinically significant aortic abnormalities (31.0% and 17.2%), but there was no statistical significance (p = 0.136). Conclusions: The incidence of clinically significant aortic arch abnormalities was 8.3% on neck MR angiography, with a significant association between aortic and coexisting non-aortic arterial abnormalities. The findings of this study could improve the understanding of incidental aortic arch lesions on neck MR angiography, which is of crucial clinical importance for radiologists to achieve accurate diagnoses and management.

Prevalence of unruptured intracranial aneurysms in patients with Marfan syndrome: A cross-sectional study and meta-analysis

INTRODUCTION

Marfan syndrome (MFS) is the most common inherited connective tissue disorder and its association with intracranial aneurysms (ICAs) has been debated for more than two decades. Here, we report the prevalence of ICAs at screening neuroimaging in a population of genetically confirmed MFS patients and present the results of a meta-analysis including our cohort of patients and those of previous studies.

PATIENTS AND METHODS

We enrolled 100 consecutive MFS patients, who underwent screening with brain magnetic resonance angiography at our tertiary center between August 2018 and May 2022. We did a PubMed and Web of Science search to retrieve all studies on the prevalence of ICAs in patients with MFS published before November, 2022.

RESULTS

Of the 100 patients included in this study (94% Caucasians, 40% females, mean age 38.6 ± 14.6 years), three had an ICA. We pooled the current study with five previously published studies, including a total of 465 patients, 43 of which harbored at least one unruptured ICA, leading to an overall ICA prevalence of 8.9% (95% CI 5.8%-13.3%).

DISCUSSION AND CONCLUSION

In our cohort of genetically confirmed MFS patients, the prevalence of ICAs was 3%, which is substantially lower compared to previous studies based on neuroimaging. The high frequency of ICA found in previous studies could be explained by selection bias and lack of genetic testing, which may have led to the inclusion of patients with different connective tissue disorders. Further studies, including several centers and a large number of patients with genetically confirmed MFS, are needed to confirm our results.

Beta-Thalassemia Presenting as Moyamoya Syndrome With a Review of Skeletal Manifestations

Moyamoya angiopathy (MMA) is a progressive vasculopathy characterized by slowly progressive stenosis involving the proximal portions of the major intracranial arteries, resulting in strokes and intracranial hemorrhages. If it occurs secondary to a known cause, it is called Moyamoya syndrome (MMS). Here, we describe the case of a five-year-old male child who presented to us with symptoms of stroke and, upon evaluation, revealed Moyamoya angiopathy. He was further evaluated, and it was found that MMA occurred as a complication of undetected beta-thalassemia. Thalassemia is an autosomal recessive blood disorder where there is a defect in hemoglobin production. It affects 100 to 150 thousand children in the Indian subcontinent. It is classified into two main types: alpha thalassemia and beta thalassemia, depending on which globin chain is affected. It primarily presents with symptoms of anemia such as easy fatiguability, dizziness, jaundice, or breathlessness. The occurrence of Moyamoya syndrome in beta-thalassemia is extremely rare, and it is extremely important to identify MMS at the earliest as it can cause long-term disabilities. We describe the imaging findings in MMS and the various classical skeletal radiographic findings in thalassemia that were seen in our patient.

Primary Central Nervous System Vasculitis: A Rare Cause of Stroke

Primary central nervous system vasculitis (PCNSV) is a rare cause of ischemic stroke and is considered idiopathic in most cases. PCNSV can present with a wide variety of neurological manifestations and should be considered in the differential diagnosis of ischemic stroke, particularly if the neurological deficit cannot be explained by the affected vascular area or when it is multifocal. The diagnosis of PCNSV is relevant because the required therapy differs from the treatments commonly used for frequent ischemic strokes. We report the case of a 64-year-old woman admitted for an ischemic stroke with a right frontal cortico-subcortical ischemic lesion. The etiological investigation documented multiple intracranial arterial stenoses. Secondary causes of central nervous system vasculitis were excluded. The patient refused a brain biopsy, and corticosteroid therapy was initiated due to high suspicion of PCNSV, supported by findings from transcranial Doppler ultrasound and brain magnetic resonance angiography. The patient had a positive clinical outcome and did not have any recurrences while under therapy. This case raises awareness of the importance of considering PCNSV in the differential diagnosis of ischemic stroke. It emphasizes the importance of promptly initiating therapy to minimize PCNSV-associated complications.

Gadolinium(III) Complex-Backboned Branched Polymers as Imaging Probes for Contrast-Enhanced Magnetic Resonance Angiography

Compared to traditional branched polymers with Gd(III) chelates conjugated on their surface, branched polymers with Gd(III) chelates as the internal skeleton are considered to be a reasonable strategy for preparing efficient magnetic resonance imaging contrast agents. Herein, the Gd(III) ligand DOTA was chosen as the internal skeleton; four different molecular weights (3.5, 5.3, 8.6, and 13.1 kDa) and degrees of branching poly-DOTA branched polymers (P1, P2, P3, and P4) were synthesized by a simple "A₂ + B₄"-type one-pot polymerization. The Gd(III) chelates of these poly-DOTA branched polymers (P1-Gd, P2-Gd, P3-Gd, and P4-Gd) display excellent kinetic stability, which is significantly higher than those of linear Gd-DTPA and cyclic Gd-DOTA-butrol and slightly lower than that of cyclic Gd-DOTA. The T₁ relaxivities of P1-Gd, P2-Gd, P3-Gd, and P4-Gd are 29.4, 38.7, 44.0, and 47.9 Gd mM^-1 s^-1, respectively, at 0.5 T, which are about 6-11 times higher than that of Gd-DOTA (4.4 Gd mM^-1 s^-1). P4-Gd was selected for in vivo magnetic resonance angiography (MRA) because of its high kinetic stability, T₁ relaxivity, and good biosafety. The results showed excellent MRA effect, sensitive detection of vascular stenosis, and prolonged observation window as compared to Gd-DOTA. Overall, Gd(III) chelates of poly-DOTA branched polymers are good candidates of MRI probes, providing a unique design strategy in which Gd chelation can occur at both the interior and surface of the poly-DOTA branched polymers, resulting in excellent relaxivity enhancement. In vivo animal MRA studies of the probe provide possibilities in discovering small vascular pathologies.

Use of Non-Contrast-Enhanced MR Angiography to Assess Recanalization after Uterine Artery Embolization

The purpose of this study was to examine the use of non-contrast-enhanced MR angiography (MRA) for assessing recanalization of uterine arteries (UAs) after uterine artery embolization (UAE) for symptomatic fibroids. Pre-procedural and follow-up unenhanced MRA images of 30 patients were reviewed, and the extent to which the UAs could be visualized was classified on a 4-point scale. An increase in the score between consecutive time points indicates that a previously inconspicuous segment of the UA became visible on follow-up images. Patients were divided into two groups according to the presence (or absence) of recanalization. The median UA visualization score at each follow-up was significantly lower than that at baseline (p < 0.01), but there was no significant difference between the scores of the follow-up images. Recanalization was detected in 63% (19/30) of patients. In these patients, the mean decrease in uterine and largest fibroid volume at 12 months after UAE was inferior to the mean decrease in patients for whom recanalization was not detected. Based on MRA assessment, recanalization after UAE occurred in 63% of patients but did not compromise the reduction in uterine and dominant fibroid volumes within 12 months after UAE.

Cerebral Venous Reflux and Cerebral Amyloid Angiopathy: An Magnetic Resonance Imaging/Positron Emission Tomography Study

BACKGROUND

Cerebral venous outflow alterations contribute to central nervous system pathology in aging and neurodegenerative disorders and are potentially linked to underlying cerebral microangiopathy. We investigated whether cerebral venous reflux (CVR) is more closely associated with cerebral amyloid angiopathy (CAA) than hypertensive microangiopathy in intracerebral hemorrhage (ICH) survivors.

METHODS

This cross-sectional study included 122 patients of spontaneous ICH with magnetic resonance and positron emission tomography imaging studies (2014-2022) in Taiwan. The presence of CVR was defined as abnormal signal intensity in the dural venous sinus or internal jugular vein on magnetic resonance angiography. Cerebral amyloid load was measured using the Pittsburgh compound B standardized uptake value ratio. Clinical and imaging characteristics associated with CVR were evaluated in univariable and multivariable analyses. In the subset of patients with CAA, we applied univariable and multivariable linear regression analyses to evaluate the association between CVR and cerebral amyloid retention.

RESULTS

Compared with patients without CVR (n=84, 64.5±12.1 years), patients with CVR (n=38, 69.4±11.5 years) were significantly more likely to have CAA-ICH (53.7% versus 19.8%; P<0.001) and had a higher cerebral amyloid load (standardized uptake value ratio [interquartile range], 1.28 [1.12-1.60] versus 1.06 [1.00-1.14]; P<0.001). In a multivariable model, CVR was independently associated with CAA-ICH (odds ratio, 4.81 [95% CI, 1.74-13.27]; P=0.002) after adjustment for age, sex and conventional small vessel disease markers. In CAA-ICH, higher PiB retention was observed in patients with CVR than patients without CVR (standardized uptake value ratio [interquartile range], 1.34 [1.08-1.56] versus 1.09 [1.01-1.26]; P<0.001). In multivariable analysis after adjustment for potential confounders, the presence of CVR was independently associated with a higher amyloid load (standardized β=0.40; P=0.001).

CONCLUSIONS

In spontaneous ICH, CVR is associated with CAA and a higher amyloid burden. Our results suggest venous drainage dysfunction potentially plays a role in CAA and cerebral amyloid deposition.

Poor inter-observer agreement in anatomical classifications of infrapopliteal arterial disease due to mandatory selection of only one target artery

BACKGROUND

Established anatomical classifications of infrapopliteal arterial lesion severity are based on assessment of only one target artery, not including all infrapopliteal arteries although multivessel revascularization is common.

PURPOSE

To investigate the reproducibility of one of these classifications and a new aggregated score.

MATERIAL AND METHODS

A total of 68 patients undergoing endovascular infrapopliteal revascularization at Sahlgrenska University Hospital during 2008-2016 were included. Preoperative magnetic resonance angiographies (MRA) and digital subtraction angiographies (DSA) were evaluated by three blinded observers in random order, using the infrapopliteal TransAtlantic Inter-Society Consensus (TASC) II classification. An aggregated score, the Infrapopliteal Total Atherosclerotic Burden (I-TAB) score, including all infrapopliteal arteries, was constructed and used for comparison.

RESULTS

Inter-observer agreement on lesion severity for each evaluated artery was good; Krippendorff's α for MRA 0.64-0.79 and DSA 0.66-0.84. Inter-observer agreement on TASC II grade, based on the selected target artery as stipulated, was poor; Krippendorff's α 0.14 (95% confidence interval [CI]=-0.05 to 0.30) for MRA and 0.48 (95% CI=0.33-0.61) for DSA. Inter-observer agreement for the new I-TAB score was good; Krippendorff's α 0.76 (95% CI=0.70-0.81) for MRA and 0.79 (95% CI=0.74-0.84) for DSA.

CONCLUSION

Reproducible assessment of infrapopliteal lesion severity can be achieved for separate arteries with both MRA and DSA using the TASC II definitions. However, poor inter-observer agreement in selecting the target artery results in low reproducibility of the overall infrapopliteal TASC II grade. An aggregated score, such as I-TAB, results in less variability and may provide a more robust evaluation tool of atherosclerotic disease severity.

Unilateral renal atrophy 4 years after renal sympathetic denervation: a case report

Renal sympathetic denervation (RDN) carries a low risk of renal artery stenosis, and most cases occur within the first year. However, limited data are available on long-term incidence. Here, we present a case of a 68-year-old woman who underwent radiofrequency RDN for resistant hypertension. Ambulatory blood pressure improved following RDN and uptitration of antihypertensive drugs. Between year 3 and 4 after RDN, eGFR reduced from 87 to 50 ml/min per 1.73 m 2 . Ultrasound imaging revealed left renal atrophy, while subsequent magnetic resonance angiography showed a haemodynamically significant stenosis of the left renal artery. The patient remained in good clinical condition with stable blood pressure, while eGFR mildly deteriorated during a 6-year follow-up period. This case of renal artery stenosis occurred in a patient with multiple risk factors. A causal relationship to the RDN procedure cannot be confirmed nor ruled out. Long-term surveillance for adverse events should be considered in all RDN patients.

Feasibility of 3.0 T balanced fast field echo non-contrast-enhanced whole-heart coronary magnetic resonance angiography

Background

Coronary artery disease (CAD) is one of the most common diseases seriously harmful to human health caused by atherosclerosis. Besides coronary computed tomography angiography (CCTA) and invasive coronary angiography (ICA), coronary magnetic resonance angiography (CMRA) has become an alternative examination. The purpose of this study was to prospectively evaluate the feasibility of 3.0 T free-breathing whole-heart non-contrast-enhanced coronary magnetic resonance angiography (NCE-CMRA).

Methods

After Institutional Review Board approval, the NCE-CMRA data sets of 29 patients acquired successfully at 3.0 T were evaluated independently by two blinded readers for visualization and image quality of coronary arteries using the subjective quality grade. The acquisition times were recorded in the meantime. A part of the patients had undergone CCTA, we represented stenosis by scores and used the Kappa to evaluate the consistency between CCTA and NCE-CMRA.

Results

Six patients did not get diagnostic image quality because of severe artifacts. The image quality score assessed by both radiologists is 3.2±0.7, which means the NCE-CMRA can show the coronary arteries excellently. The main vessels of the coronary artery on NCE-CMRA images are considered reliably assessable. The acquisition time of NCE-CMRA, is 8.8±1.2 min. The Kappa of CCTA and NCE-CMRA on detecting stenosis is 0.842 (P<0.001).

Conclusions

The NCE-CMRA results in reliable image quality and visualization parameters of coronary arteries within a short scan time. The NCE-CMRA and CCTA have a good agreement for detecting stenosis.

Stress perfusion cardiovascular magnetic resonance imaging: a guide for the general cardiologist

Stress cardiovascular magnetic resonance (CMR) is an emerging non-invasive imaging technique for the assessment of known or suspected ischaemic heart disease (IHD). Stress CMR provides information on myocardial perfusion, wall motion, ventricular dimensions and volumes, as well as late gadolinium enhancement (LGE) scar imaging in a single test without ionising radiation. Data from numerous multicentre randomised studies show high diagnostic and prognostic utility, its efficacy as a gatekeeper to invasive coronary angiography and use for guiding coronary revascularisation decisions. Stress CMR is cost-effective across multiple healthcare settings, yet its uptake and usage varies worldwide and is an underutilised technology. New developments include rapid acquisition protocols, automated quantification of perfusion and myocardial blood flow, and artificial intelligence-aided automated analysis and reporting. Stress CMR is becoming more accessible and standardised around the globe and is ready for 'prime time' use in the non-invasive assessment of patients with suspected IHD.

Usefulness of Pointwise Encoding Time Reduction with Radial Acquisition-Magnetic Resonance Angiography after Endovascular Treatment for Intracranial Aneurysms

PURPOSE

Imaging follow-up after endovascular treatment is important; however, time-of-flight magnetic resonance angiography (TOF-MRA) has limitations associated with magnetic susceptibility and radiofrequency shielding caused by the stent and coils. We evaluated the diagnostic performance of pointwise encoding time reduction with radial acquisition (PETRA)-MRA after endovascular treatment for intracranial aneurysms.

MATERIAL AND METHODS

A total of 186 patients with 211 aneurysms who underwent both pointwise encoding time reduction with radial acquisition- and time-of-flight magnetic resonance angiography in the same imaging session for follow-up after endovascular treatment. We subjectively graded the overall image quality, visualization of treated sites, and occlusion status.

RESULTS

Although the overall image quality scores of pointwise encoding time reduction with radial acquisition-magnetic resonance angiography were significantly lower than those of time-of-flight magnetic resonance angiography for both observers (4.04 ± 0.81 vs. 4.85 ± 0.35 [observer 1], 4.60 ± 0.69 vs. 4.94 ± 0.24 [observer 2]) (both P < .001), the visibility of treated sites using pointwise encoding time reduction with radial acquisition-magnetic resonance angiography was significantly better than that of time-of-flight magnetic resonance angiography overall (4.27 ± 0.97 vs. 3.42 ± 1.01; P < .001), in the distal internal carotid artery (4.46 ± 0.79 vs. 3.40 ± 1.00; P < .001), and in the middle cerebral artery (4.19 ± 0.93 vs. 3.08 ± 0.53, P = 0.007). Pointwise encoding time reduction with radial acquisition-magnetic resonance angiography showed a higher area under the curve than time-of-flight magnetic resonance angiography for the evaluation of treated aneurysm occlusion, except for posterior circulation aneurysms.

CONCLUSIONS

Pointwise encoding time reduction with radial acquisition-magnetic resonance angiography showed better visualization of treated sites and better diagnostic performance than time-of-flight magnetic resonance angiography for anterior circulation aneurysms. However, Pointwise encoding time reduction with radial acquisition-magnetic resonance angiography showed limitations in the follow-up evaluation of posterior circulation aneurysms.

Cystic Adventitial Disease of the Popliteal Vein: A Case Report

Venous cystic adventitial disease (VCAD) is a rare vascular anomaly located in the common femoral vein in most cases. We describe the case of a 59-year-old female patient with right leg edema who was misdiagnosed with deep vein thrombosis of the lower extremity at another hospital. Magnetic resonance angiography revealed a round mass in the popliteal vein, with a narrow lumen. Considering the location of the lesion, absence of a history of deep venous thrombosis and trauma, and clinical manifestations, the diagnosis is likely a popliteal vein adventitial cyst. Segmental popliteal vein resection and reconstruction were performed using a cylindrical great saphenous vein graft. No joint connection was found during the operation, and the postoperative pathology confirmed VCAD.

Impact of magnetic resonance angiography parameters on stroke prevention therapy in pediatric patients with sickle cell anemia

BACKGROUND

Degree of cerebrovascular stenosis in pediatric patients with sickle cell anemia (SCA) informs need for chronic transfusion therapy, which has significant risks. Flow artifact, intrinsic to magnetic resonance angiography (MRA), is dependent on technical parameters and can lead to overinterpretation of stenosis. The primary objective of this study was to document any change in stroke prevention therapy that could be attributed to the implementation of a standardized MRA scanning protocol for patients with SCA.

METHODS

A standardized MRA scanning protocol with an echo time of less than 5 ms was implemented at Montefiore Medical Center (MMC), NY in May 2016. Retrospective chart review identified 21 pediatric patients with SCA, with an MRA head both pre- and post-May 2016. Arterial stenosis on MRA, machine parameters, and treatment plans were compared pre- and post-implementation.

RESULTS

Ten of the 21 patients met inclusion criteria. Previously seen stenosis was re-classified to a lower degree in six of the 10 patients, leading to discontinuation of transfusions in five patients. No patients required escalation of therapy to chronic transfusions.

CONCLUSION

Optimizing flow artifact by decreasing echo time to less than 5 ms can improve accurate interpretation of cerebrovascular disease, and ensure appropriate treatment plans are in place for stroke prevention. This is especially important for implementing "TCD With Transfusions Changing to Hydroxyurea (TWiTCH)" clinical trial results in the real-world setting.

Experience of 500 cardiovascular magnetic resonance imaging and systematic analysis of cases

OBJECTIVE

Cardiovascular magnetic resonance imaging (MRI) is a widely accepted reference imaging technique in routine cardiology clinics in many centers due to its advantages in providing preferable functional, morphologic information. However, there is little information about national experience in clinical application and findings of cardiovascular MRI. The objective of this study was to demonstrate the clinical and demographic characteristics of patients admitted to our cardiac imaging department.

METHODS

A total of 500 cardiovascular MRI examinations performed between 2016 and 2019 were enrolled in this retrospective study. Clinical indications, demographic, and cardiovascular MRI findings of the patients were retrospectively evaluated.

RESULTS

Five hundred patients (M/F=301/199) were included in this retrospective, single center study. The majority of the examinations were performed for the assessment of congenital heart disease (n=254, 50.8%). The other indications were for myocardial disease (n=160, 32%), cardiac mass (n=44, 8.8%), valvular heart disease (n=20, 4%), magnetic resonance angiography (n=12, 2.4% for aorta and pulmonary artery [n=9, 1.8%] and for coronary arteries [n=3, 0.6%]), and vasculitis (n=7, 1.7%), pericardial disease (n=3, 0.6%). Minor complication was seen during the contrast agent injection in three patients (0.06%).

CONCLUSION

Cardiovascular MRI is a reliable and accurate imaging tool in identifying the various cardiac pathology with widely accepted use in the clinical area. Our single-center experience of 500 cases demonstrates the varieties of clinical indications in daily practice that may contribute to the national data pool.

To Cross or Not to Cross: Using MRI-Histology to Characterize Dense Collagenous Plaque in Critical Limb Ischemia

Peripheral artery disease (PAD) is caused by atherosclerotic buildup in the lower extremities, leading to obstruction and inadequate perfusion to the peripheral vasculature. Impenetrable plaques initially treated with percutaneous vascular intervention (PVI) have led to worse secondary bypass outcomes and amputation in patients. In this case report, we discuss the importance of using magnetic resonance imaging (MRI) histology in PVI planning in a patient with critical limb ischemia. PVI attempts to recanalize the limb failed because of an impenetrable occlusion in the popliteal artery that was not identified on routine preoperative imaging. Subsequent bypass occluded multiple times eventually requiring an above-knee amputation. An MRI-histology protocol-using ultrashort echo time (UTE) and T2-weighted (T2W) sequences-that was performed prior to the index PVI identified the occlusion as a dense collagen plaque. Histology analysis of the amputated specimen confirmed the MRI finding. This imaging modality offers a novel approach to characterize plaque composition and morphology, thereby identifying lesions at greatest risk of PVI failure and potentially playing an important role in selecting the right candidates for an endovascular-first approach.

Multimodal brain age prediction fusing morphometric and imaging data and association with cardiovascular risk factors

Introduction

The difference between the chronological and biological brain age, called the brain age gap (BAG), has been identified as a promising biomarker to detect deviation from normal brain aging and to indicate the presence of neurodegenerative diseases. Moreover, the BAG has been shown to encode biological information about general health, which can be measured through cardiovascular risk factors. Current approaches for biological brain age estimation, and therefore BAG estimation, either depend on hand-crafted, morphological measurements extracted from brain magnetic resonance imaging (MRI) or on direct analysis of brain MRI images. The former can be processed with traditional machine learning models while the latter is commonly processed with convolutional neural networks (CNNs). Using a multimodal setting, this study aims to compare both approaches in terms of biological brain age prediction accuracy and biological information captured in the BAG.

Methods

T1-weighted MRI, containing brain tissue information, and magnetic resonance angiography (MRA), providing information about brain arteries, from 1,658 predominantly healthy adults were used. The volumes, surface areas, and cortical thickness of brain structures were extracted from the T1-weighted MRI data, while artery density and thickness within the major blood flow territories and thickness of the major arteries were extracted from MRA data. Independent multilayer perceptron and CNN models were trained to estimate the brain age from the hand-crafted features and image data, respectively. Next, both approaches were fused to assess the benefits of combining image data and hand-crafted features for brain age prediction.

Results

The combined model achieved a mean absolute error of 4 years between the chronological and predicted biological brain age. Among the independent models, the lowest mean absolute error was observed for the CNN using T1-weighted MRI data (4.2 years). When evaluating the BAGs obtained using the different approaches and imaging modalities, diverging associations between cardiovascular risk factors were found. For example, BAGs obtained from the CNN models showed an association with systolic blood pressure, while BAGs obtained from hand-crafted measurements showed greater associations with obesity markers.

Discussion

In conclusion, the use of more diverse sources of data can improve brain age estimation modeling and capture more diverse biological deviations from normal aging.

Gadofosveset-Trinatrium-Enhanced MR Angiography and MR Venography in the Diagnosis of Venous Thromboembolic Disease: A Single-Center Cohort Study

BACKGROUND

The aim of this single-center combined prospective/retrospective cohort study was to analyze Gadolinium (Gd)-enhanced MRA (magnetic resonance angiography) and MRV (MR venography) for the diagnosis of pulmonary artery embolism and deep venous thrombosis. The gold standard methods result in major exposure to radiation and a high amount of nephrotoxic iodinated contrast media. This is the first larger contrast-enhanced MR imaging study of acute and chronic venous thromboembolic disease of various stages.

METHODS

We prospectively examined 88 patients presenting clinical signs of deep vein thrombosis and/or pulmonary artery embolism. A single-session, one-stop shop Gd-enhanced MRA/MRV at 1.5 Tesla, using gradient echo sequences with very short repetition and echo times as well as low flip angles with subtraction and three-dimensional reconstruction, was performed. A diagnosis was made with the consensus of two experienced radiologists.

RESULTS

We observed excellent MRA image quality in 87% and even higher diagnostic image quality of MRV in 90% of our examinations. Pulmonary artery embolism occurred with deep vein thrombosis in 22%.

CONCLUSIONS

Gd-enhanced MRA/MRV provided excellent image quality for the diagnosis of venous thromboembolic disease in the majority of cases. It may be particularly useful to plan and follow-up filter implantation and retrieval in the inferior caval vein.

Redefining the Koizumi model of mouse cerebral ischemia: A comparative longitudinal study of cerebral and retinal ischemia in the Koizumi and Longa middle cerebral artery occlusion models

Cerebral and retinal ischemia share similar pathogenesis and epidemiology, each carrying both acute and prolonged risk of the other and often co-occurring. The most used preclinical stroke models, the Koizumi and Longa middle cerebral artery occlusion (MCAO) methods, have reported retinal damage with great variability, leaving the disruption of retinal blood supply via MCAO poorly investigated, even providing conflicting assumptions on the origin of the ophthalmic artery in rodents. The aim of our study was to use longitudinal in vivo magnetic resonance assessment of cerebral and retinal vascular perfusion after the ischemic injury to clarify whether and how the Koizumi and Longa methods induce retinal ischemia and how they differ in terms of cerebral and retinal lesion evolution. We provided anatomical evidence of the origin of the ophthalmic artery in mice from the pterygopalatine artery. Following the Koizumi surgery, retinal responses to ischemia overlapped with those in the brain, resulting in permanent damage. In contrast, the Longa method produced only extensive cerebral lesions, with greater tissue loss than in the Koizumi method. Additionally, our data suggests the Koizumi method should be redefined as a model of ischemia with chronic hypoperfusion rather than of ischemia and reperfusion.

Successful technical note—Identification of the Adamkievicz artery with 1.5 Tesla MR angiography in a 14-month-old child

Posterior mediastinal tumors surgery may be complicated by their proximity to the artery of Adamkiewicz (AKA) and its segmental supplier, increasing the risk of ischemia of the spinal cord. We describe a case of preoperative identification of the AKA with magnetic resonance angiography (MRA) in a 14-month-old boy diagnosed with a thoracic neuroblastoma, thus allowing an accurate surgical planning in order to avoid injury to those vessels. Given the relatively high incidence of posterior mediastinal tumors in the pediatric age, MRA may establish itself as a viable alternative for this purpose, even in young children.

Synthetic Time of Flight Magnetic Resonance Angiography Generation Model Based on Cycle-Consistent Generative Adversarial Network Using PETRA-MRA in the Patients With Treated Intracranial Aneurysm

BACKGROUND

Pointwise encoding time reduction with radial acquisition (PETRA) magnetic resonance angiography (MRA) is useful for evaluating intracranial aneurysm recurrence, but the problem of severe background noise and low peripheral signal-to-noise ratio (SNR) remain. Deep learning could reduce noise using high- and low-quality images.

PURPOSE

To develop a cycle-consistent generative adversarial network (cycleGAN)-based deep learning model to generate synthetic TOF (synTOF) using PETRA.

STUDY TYPE

Retrospective.

POPULATION

A total of 377 patients (mean age: 60 ± 11; 293 females) with treated intracranial aneurysms who underwent both PETRA and TOF from October 2017 to January 2021. Data were randomly divided into training (49.9%, 188/377) and validation (50.1%, 189/377) groups.

FIELD STRENGTH/SEQUENCE

Ultra-short echo time and TOF-MRA on a 3-T MR system.

ASSESSMENT

For the cycleGAN model, the peak SNR (PSNR) and structural similarity (SSIM) were evaluated. Image quality was compared qualitatively (5-point Likert scale) and quantitatively (SNR). A multireader diagnostic optimality evaluation was performed with 17 radiologists (experience of 1-18 years).

STATISTICAL TESTS

Generalized estimating equation analysis, Friedman's test, McNemar test, and Spearman's rank correlation. P < 0.05 indicated statistical significance.

RESULTS

The PSNR and SSIM between synTOF and TOF were 17.51 [16.76; 18.31] dB and 0.71 ± 0.02. The median values of overall image quality, noise, sharpness, and vascular conspicuity were significantly higher for synTOF than for PETRA (4.00 [4.00; 5.00] vs. 4.00 [3.00; 4.00]; 5.00 [4.00; 5.00] vs. 3.00 [2.00; 4.00]; 4.00 [4.00; 4.00] vs. 4.00 [3.00; 4.00]; 3.00 [3.00; 4.00] vs. 3.00 [2.00; 3.00]). The SNRs of the middle cerebral arteries were the highest for synTOF (synTOF vs. TOF vs. PETRA; 63.67 [43.25; 105.00] vs. 52.42 [32.88; 74.67] vs. 21.05 [12.34; 37.88]). In the multireader evaluation, there was no significant difference in diagnostic optimality or preference between synTOF and TOF (19.00 [18.00; 19.00] vs. 20.00 [18.00; 20.00], P = 0.510; 8.00 [6.00; 11.00] vs. 11.00 [9.00, 14.00], P = 1.000).

DATA CONCLUSION

The cycleGAN-based deep learning model provided synTOF free from background artifact. The synTOF could be a versatile alternative to TOF in patients who have undergone PETRA for evaluating treated aneurysms.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: Stage 1.

Modification of cerebrovascular morphologies during different stages of life

To expand previous understanding of age-related vascular changes, we examined the association between aging and characteristics of cerebral arteries among 1133 participants aged 35 to 75 years recruited from Shanghai, China. Characteristics of the cerebral vessels including arterial branch density, mean radius, and mean tortuosity were quantified using MR angiography. The radius, tortuosity, and length of the basilar artery (BA) and the M1 segment of middle cerebral artery (MCA) were also accessed. Linear regression model was used to examine the association between age and vasculature features. The sample was divided into four subgroups by age and the association was analyzed in each subgroup. Age was found to be a significant predictor for cerebrovascular modifications after adjusting for vascular risk factors. Further analysis in subgroup revealed that the associations were due to the predominate effect of the vascular modifications happened during the younger years (35-54 years). The radius of either BA or MCA was associated with aging only in subjects aged 45-54 years. In conclusion, rapid alterations in all three morphological features assessed have been noticed to be associated with aging in the 45-54 subgroup, suggesting the potential importance of the 5th decade for early preservation method for vascular aging.