Magnetic Resonance Imaging Angiography Research Articles

Cerebrovascular disease in patients with antiphospholipid antibody syndrome: a transcranial Doppler and magnetic resonance imaging study

Abstract Objective Transcranial Doppler (TCD) and brain MRI (Magnetic Resonance Imaging) may be useful in evaluating patients with antiphospholipid syndrome (APS), helping to stratify the risk of cerebrovascular ischemic events in this population. This study aimed to assess the frequency of brain MRI abnormalities in patients with primary antiphospholipid syndrome (PAPS), secondary antiphospholipid syndrome (SAPS), and systemic lupus erythematosus (SLE) and correlate to TCD findings. Methods The study, conducted over four years at two autoimmune disease referral centers, included 22 PAPS patients, 24 SAPS patients, 27 SLE patients without APS, and 21 healthy controls. All participants underwent TCD to assess cerebral hemodynamics, detect microembolic signals, and evaluate right-to-left shunts, followed by brain MRI and magnetic resonance angiography. MRI scans were reviewed for acute microembolism, localized cortical infarctions, border infarctions, lacunar infarctions, ischemic lesions, white matter hyperintensity, micro and macro hemorrhages, and arterial stenosis ≥50% of the cervical carotid artery, by two neuroradiologists blinded to the clinical data. Results Brain MRI findings were similar between the groups, except for lacunar infarction, more frequent in patients with SAPS (p = 0.022). Patients with intracranial stenosis detected by TCD had a higher frequency of territorial infarction (40% vs.s 7.5%, p = 0.02), lacunar (40% vs.s 11.3%, p = 0.075), and borderzone infarcts (20% vs.s 1.9%, p = 0.034). Conclusions Patients with intracranial stenosis presented a higher frequency of territorial, lacunar, and borderzone infarcts, suggesting that evaluating the intracranial vasculature should not be neglected in patients with APS and stroke.

Facile Synthesis of Rigid Binuclear Manganese Complexes for Magnetic Resonance Angiography and SLC39A14-Mediated Hepatic Imaging.

Manganese(II)-based contrast agents (MBCAs) are potential candidates for gadolinium-free enhanced magnetic resonance imaging (MRI). In this work, a rigid binuclear MBCA (Mn2-PhDTA2) with a zero-length linker was developed via facile synthetic routes, while the other dimer (Mn2-TPA-PhDTA2) with a longer rigid linker was also synthesized via more complex steps. Although the molecular weight of Mn2-PhDTA2 is lower than that of Mn2-TPA-PhDTA2, their T1 relaxivities are similar, being increased by over 71% compared to the mononuclear Mn-PhDTA. In the presence of serum albumin, the relaxivity of Mn2-PhDTA2 was slightly lower than that of Mn2-TPA-PhDTA2, possibly due to the lower affinity constant. The transmetalation reaction with copper(II) ions confirmed that Mn2-PhDTA2 has an ideal kinetic inertness with a dissociation half-life of approximately 10.4 h under physiological conditions. In the variable-temperature 17O NMR study, both Mn-PhDTA and Mn2-PhDTA2 demonstrated a similar estimated q close to 1, indicating the formation of monohydrated complexes with each manganese(II) ion. In addition, Mn2-PhDTA2 demonstrated a superior contrast enhancement to Mn-PhDTA in in vivo vascular and hepatic MRI and can be rapidly cleared through a dual hepatic and renal excretion pattern. The hepatic uptake mechanism of Mn2-PhDTA2 mediated by SLC39A14 was validated in cellular uptake studies.

Cerebral Venous Thrombosis Indicative of Polycythemia Vera: Case Report

Polycythemia vera, a myeloproliferative disorder, seldom leads to cerebral venous thrombosis, making this association a rare occurrence. Here, we present the case of a 62-year-old patient without significant medical history, who was admitted due to a one-month history of intracranial hypertension syndrome. Upon admission, papillary edema (stage II) was observed, along with a lack of focal neurological signs. MRI angiography revealed thrombosis in the right lateral sinus. Further diagnostic investigation confirmed the presence of polycythemia vera. The patient was initiated on anti-edematous and anticoagulant therapy, followed by bloodlettings and cyto-reduction treatment, resulting in a favorable clinical outcome.

SurLym trial: study protocol for a multicentre pragmatic randomised controlled trial on the added value of reconstructive lymphatic surgery to decongestive lymphatic therapy for the treatment of lymphoedema

IntroductionLymphoedema is a chronic condition caused by lymphatic insufficiency. It leads to swelling of the limb/midline region and an increased risk of infection. Lymphoedema is often associated with mental and...

Cognitive impairment in asymptomatic carotid artery stenosis is associated with abnormal segments in the Circle of Willis

Our group has previously demonstrated that patients with asymptomatic carotid artery stenosis (ACAS) demonstrate cognitive impairment. One proposed mechanism for cognitive impairment in patients with ACAS is cerebral hypoperfusion due to flow-restriction. We tested whether the combination of a high-grade carotid stenosis and inadequate cross-collateralization in the Circle of Willis (CoW) resulted in worsened cognitive impairment. Twenty-four patients with high-grade (≥70% diameter-reducing) ACAS underwent carotid duplex ultrasound, cognitive assessment, and 3D time-of-flight magnetic resonance angiography (MRA). The cognitive battery consisted of nine neuropsychological tests assessing four cognitive domains: learning and recall, attention and working memory, motor and processing speed, and executive function. Raw cognitive scores were converted into standardized T-scores. A structured interpretation of the MRA images was performed with each segment of the CoW categorized as being either normal or abnormal. Abnormal segments of the CoW were defined as segments characterized as narrowed or occluded due to congenital aplasia or hypoplasia, or acquired atherosclerotic stenosis or occlusion. Linear regression was used to estimate the association between the number of abnormal segments in the CoW, and individual cognitive domain scores. Significance was set to p<0.05. The mean age of the patients was 66.1 + 9.6 (mean + SD) years and 79.2% (n=19) were male. A significant negative association was found between the number of abnormal segments in the CoW and cognitive scores in the learning and recall (β = -6.5, p = 0.01), and attention and working memory (β = -7.0, p = 0.02) domains. There was a trend suggesting a negative association in the motor and processing speed (β = -2.4, p = 0.35) and executive function (β = -4.5, p = 0.06) domains that did not reach significance. In patients with high-grade ACAS, the concomitant presence of increasing occlusive disease in the CoW correlates with worse cognitive function. This association was significant in the learning and recall and attention and working memory domains. While motor and processing speed and executive function also declined numerically with increasing abnormal segments in the CoW, the relationship was not significant. Since flow restriction at a carotid stenosis compounded by inadequate collateral compensation across a diseased CoW worsens cerebral perfusion, our findings support the hypothesis that cerebral hypoperfusion underlies the observed cognitive impairment in patients with ACAS.

Left posterior cerebral artery occlusion following minor head trauma: a case report

A 17-year-old male patient who received a punch behind the left ear 2 days ago, was admitted to the emergency room with a headache and dizziness. His neurological examination was normal. Brain CT images demonstrated diffuse hypodense areas and sulcus deletion in the left occipital lobe. On MR images, diffusion restriction for acute ischemia in the left PCA watershed area was determined, and hospitalization was recommended. However, he and his relatives left the hospital. Through the electronic information system called “e-nabız”, it was learned that the patient was hospitalized in an external center and treated with antiplatelet and anticoagulant regimens for ten days due to an acute thrombus at the left PCA P1 distal-P2 level observed on the brain CT and MR angiography images. In our clinic, his neurological examination was completely normal thirty days later. Still, a visual field examination revealed a total quadrianopsy in the upper temporal pole on the right and left eyes. An encephalomalacia in the left PCA watershed area was observed on CT images. The findings of this case showed that minor head trauma in children can cause large vessel occlusion and therefore close follow-up of these children for a certain time would be appropriate.

Intensity Score of Vessel Wall Contrast Enhancement in MRI Allows Prediction of Disease Progression in Moyamoya Angiopathy.

The underlying pathophysiological cause of moyamoya angiopathy (MMA) is still unclear. High-resolution vessel wall imaging has become a useful tool. The aim was to study vessel wall contrast-enhancement (VW-CE) as an imaging marker to predict disease progression in MMA. Patients with MMA, who had undergone serial contrast-enhanced high-resolution MRI with concomitant and follow-up digital subtraction angiography, were analyzed retrospectively. VW-CE was semiquantified by measurement of the signal intensity of the vessel wall in in contrast-enhanced high-resolution MRI. A comparative quotient with the contrast-intensity of the pituitary stalk was calculated and graded accordingly from grade 1 to 5. VW-CE status was correlated with disease status, stroke, cerebrovascular reactivity in CO2-triggered blood-oxygen level-dependent MRI, angiographic disease progression, revascularization surgery, and follow-up imaging. Forty eight patients met the inclusion criteria. N = 56 MRI and digital subtraction angiography time-intervals were evaluated for 12 vessel sections per hemisphere each (N = 1344). N = 38 (79%) patients showed VW-CE and N = 10 (21%) did not. VW-CE was only observed in the terminal internal carotid artery and the proximal circle of Willis (N = 96/1344). Notably, patients with VW-CE significantly more often presented with acute infarction in the concomitant MRI. The incidence of angiographically proven disease progression was significantly associated with the incidence of VW-CE, and time to disease progression was earlier in higher grades of VW-CE compared with lower grades. VW-CE is a semiquantifiable marker for disease activity in patients with MMA and associated with disease progression and increased risk of stroke. VW-CE analysis can be routinely performed in patients with MMA to estimate the risk for disease progression and stroke.

[Automatic detection method of intracranial aneurysms on maximum intensity projection images based on SE-CaraNet].

Conventional maximum intensity projection (MIP) images tend to ignore some morphological features in the detection of intracranial aneurysms, resulting in missed detection and misdetection. To solve this problem, a new method for intracranial aneurysm detection based on omni-directional MIP image is proposed in this paper. Firstly, the three-dimensional magnetic resonance angiography (MRA) images were projected with the maximum density in all directions to obtain the MIP images. Then, the region of intracranial aneurysm was prepositioned by matching filter. Finally, the Squeeze and Excitation (SE) module was used to improve the CaraNet model. Excitation and the improved model were used to detect the predetermined location in the omni-directional MIP image to determine whether there was intracranial aneurysm. In this paper, 245 cases of images were collected to test the proposed method. The results showed that the accuracy and specificity of the proposed method could reach 93.75% and 93.86%, respectively, significantly improved the detection performance of intracranial aneurysms in MIP images.

ACCURACY OF SUSCEPTIBILITY WEIGHTED IMAGING AND 3D-TOF MRA IN DETECTION AND PRE-TREATMENT EVALUATION OF INTRACRANIAL DURAL ARTERIOVENOUS FISTULAS

Background: Dural arteriovenous fistulas (DAVFs) are abnormal connections between meningeal arteries and dural venous sinuses or cortical veins. A cerebral angiogram is the gold standard for diagnosing and treating DAVFs. Still, non-invasive techniques such as three-dimensional time-offlight magnetic resonance angiography (3D-TOF MRA) and susceptibility-weighted imaging (SWI) are also helpful in evaluating the location and severity of the fistulas, including cortical venous reflux (CVR) and cortical venous ectasia (CVE). This study aimed to compare the efficacy in detecting and pretreating DAVFs evaluating SWI and 3D-TOF MRA with cerebral angiography. Methods: The retrospective study included 35 patients with 41 DAVFs who underwent pre-treatment MR imaging and cerebral angiogram. The fistulous point at convexity and cavernous locations, arterial feeders, venous drainers, CVR, and CVE were evaluated. Results: SWI and 3D-TOF MRA showed high sensitivity and excellent specificity in detecting DAVFs Cognard II-IV at convexity location and high sensitivity in evaluating CVR. For DAVFs at cavernous sinus locations, arterial feeders and venous drainers were significantly identified in 3D-TOF MRA (p &lt; 0.001). SWI exhibited superior sensitivity (87.5%) in detecting CVE at convexity locations (p &lt; 0.001). Slow flow or low-grade fistulas in cavernous sinus locations (n = 2, 4.8%, Cognard I) were not identified using MR imaging. Conclusion: SWI and 3D-TOF MRA are helpful tools for evaluating high-flow DAVFs (Cognard II-IV). SWI is superior in detecting CVE in convexity locations but is limited in assessing the fistulous point in cavernous sinus locations. Thus, combining findings from both SWI and 3D-TOF MRA exhibited high accuracy in detecting and pretreating high-flow DAVFs.

Intracranial aneurysm detection: an object detection perspective.

Intracranial aneurysm detection from 3D Time-Of-Flight Magnetic Resonance Angiography images is a problem of increasing clinical importance. Recently, a streak of methods have shown promising performance by using segmentation neural networks. However, these methods may be less relevant in a clinical settings where diagnostic decisions rely on detecting objects rather than their segmentation. We introduce a 3D single-stage object detection method tailored for small object detection such as aneurysms. Our anchor-free method incorporates fast data annotation, adapted data sampling and generation to address class imbalance problem, and spherical representations for improved detection. A comprehensive evaluation was conducted, comparing our method with the state-of-the-art SCPM-Net, nnDetection and nnUNet baselines, using two datasets comprising 402 subjects. The evaluation used adapted object detection metrics. Our method exhibited comparable or superior performance, with an average precision of 78.96%, sensitivity of 86.78%, and 0.53 false positives per case. Our method significantly reduces the detection complexity compared to existing methods and highlights the advantages of object detection over segmentation-based approaches for aneurysm detection. It also holds potential for application to other small object detection problems.

Performance changes due to differences among annotating radiologists for training data in computerized lesion detection.

The quality and bias of annotations by annotators (e.g., radiologists) affect the performance changes in computer-aided detection (CAD) software using machine learning. We hypothesized that the difference in the years of experience in image interpretation among radiologists contributes to annotation variability. In this study, we focused on how the performance of CAD software changes with retraining by incorporating cases annotated by radiologists with varying experience. We used two types of CAD software for lung nodule detection in chest computed tomography images and cerebral aneurysm detection in magnetic resonance angiography images. Twelve radiologists with different years of experience independently annotated the lesions, and the performance changes were investigated by repeating the retraining of the CAD software twice, with the addition of cases annotated by each radiologist. Additionally, we investigated the effects of retraining using integrated annotations from multiple radiologists. The performance of the CAD software after retraining differed among annotating radiologists. In some cases, the performance was degraded compared to that of the initial software. Retraining using integrated annotations showed different performance trends depending on the target CAD software, notably in cerebral aneurysm detection, where the performance decreased compared to using annotations from a single radiologist. Although the performance of the CAD software after retraining varied among the annotating radiologists, no direct correlation with their experience was found. The performance trends differed according to the type of CAD software used when integrated annotations from multiple radiologists were used.

A Computational Pipeline to Investigate Longitudinal Blood Flow Changes in the Circle of Willis of Patients with Stable and Growing Aneurysms.

Changes in cerebral blood flow are often associated with the initiation and development of different life-threatening medical conditions including aneurysm rupture and ischemic stroke. Nevertheless, it is not fully clear how haemodynamic changes in time across the Circle of Willis (CoW) are related with intracranial aneurysm (IA) growth. In this work, we introduced a novel reduced-order modelling strategy for the systematic quantification of longitudinal blood flow changes across the whole CoW in patients with stable and unstable/growing aneurysm. Magnetic Resonance Angiography (MRA) images were converted into one-dimensional (1-D) vessel networks through a semi-automated procedure, with a level of geometric reconstruction accuracy controlled by user-dependent parameters. The proposed pipeline was used to systematically analyse longitudinal haemodynamic changes in seven different clinical cases. Our preliminary simulation results indicate that growing aneurysms are not necessarily associated with significant changes in mean flow over time. A concise sensitivity analysis also shed light on which modelling aspects need to be further characterized to have reliable patient-specific predictions. This study poses the basis for investigating how time-dependent changes in the vasculature affect the haemodynamics across the whole CoW in patients with stable and growing aneurysms.

Preoperatively determining renal perfusion and visualizing renal arteries and any abnormalities in potential living kidney donors using non-contrast-enhanced magnetic resonance imaging techniques at 1.5 Tesla

Abstract Background The aim of this work was to create and evaluate a preoperative non-contrast-enhanced (CE) magnetic resonance imaging (MRI)/angiography (MRA) protocol to assess renal function and visualize renal arteries and any abnormalities in potential living kidney donors. Methods In total, 28 subjects were examined using scintigraphy to determine renal function. In addition, 3D-pseudocontinuous arterial spin labeling (pCASL), a 2D-non-CE electrocardiogram triggered radial quiescent interval slice-selective (QISS-MRA), and 4D-CE time-resolved angiography with interleaved stochastic trajectories (CE-MRA) were performed to assess renal perfusion, visualize renal arteries, and detect any abnormalities. Two glomerular filtration rates (described by Gates, GFRG, and according to the Chronic Kidney Disease Epidemiology Collaboration formula, GFRCKD-EPI). The renal volumes were determined using both MRA techniques. Results The mean value of regional renal blood flow (rRBF) on the right side was significantly higher than that on the left. The agreements between QISS-MRA and CE-MRA concerning the assessment of absence or presence of an aberrant artery and renal arterial stenosis were perfect. The mean renal volumes measured in the right kidney with QISS-MRA were lower than the corresponding values of CE-MRA. In contrast, the mean renal volumes measured in the left kidney with both MRA techniques were similar. The correlation between the GFRG and rRBF was compared in the same manner as that between GFRCKD-EPI and rRBF. Conclusion The combination of pCASL and QISS-MRA constitute a reliable preoperative protocol with a total measurement time of less than 10 min without the potential side effects of gadolinium-based contrast agents or radiation exposure.

In silico analysis of embolism in cerebral arteries using fluid-structure interaction method

Ischemic stroke, particularly embolic stroke, stands as a significant global contributor to mortality and long-term disabilities. This paper presents a comprehensive simulation of emboli motion through the middle cerebral artery (MCA), a prevalent site for embolic stroke. Our patient-specific computational model integrates major branches of the middle cerebral artery reconstructed from magnetic resonance angiography images, pulsatile flow dynamics, and emboli of varying geometries, sizes, and material properties. The fluid-structure interactions method is employed to simulate deformable emboli motion through the middle cerebral artery, allowing observation of hemodynamic changes in artery branches upon embolus entry. We investigated the impact of embolus presence on shear stress magnitude on artery walls, analyzed the effects of embolus material properties and geometries on embolus trajectory and motion dynamics within the middle cerebral artery. Additionally, we evaluated the non-Newtonian behavior of blood, comparing it with Newtonian blood behavior. Our findings highlight that embolus geometry significantly influences trajectory, motion patterns, and hemodynamics within middle cerebral artery branches. Emboli with visco-hyperelastic material properties experienced higher stresses upon collision with artery walls compared to those with hyperelastic properties. Furthermore, considering blood as a non-Newtonian fluid had notable effects on emboli stresses and trajectories within the artery, particularly during collisions. Notably, the maximum von Mises stress experienced in our study was 21.83 kPa, suggesting a very low probability of emboli breaking during movement, impact, and after coming to a stop. However, in certain situations, the magnitude of shear stress on them exceeded 1 kPa, increasing the likelihood of cracking and disintegration. These results serve as an initial step in anticipating critical clinical conditions arising from arterial embolism in the middle cerebral artery. They provide insights into the biomechanical parameters influencing embolism, contributing to improved clinical decision-making for stroke management.

Turbo spin-echo-based enhanced acceleration-selective arterial spin labeling without electrocardiography or peripheral pulse unit triggering and contrast enhancement for lower extremity MRA

PurposeLower extremity magnetic resonance angiography (MRA) without electrocardiography (ECG) or peripheral pulse unit (PPU) triggering and contrast enhancement is beneficial for diagnosing peripheral arterial disease (PAD) while avoiding synchronization failure and nephrogenic systemic fibrosis. This study aimed to compare the diagnostic performance of turbo spin-echo-based enhanced acceleration-selective arterial spin labeling (eAccASL) (TSE-Acc) of the lower extremities with that of turbo field-echo-based eAccASL (TFE-Acc) and triggered angiography non-contrast enhanced (TRANCE). MethodsNine healthy volunteers and a patient with PAD were examined on a 3.0 Tesla magnetic resonance imaging (MRI) system. The artery-to-muscle signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) were calculated. The arterial visibility (1: poor, 4: excellent) and artifact contamination (1: severe, 4: no) were independently assessed by two radiologists. Phase-contrast MRI and digital subtraction angiography were referenced in a patient with PAD. Friedman's test and a post-hoc test according to the Bonferroni-adjusted Wilcoxon signed-rank test were used for the SIR, CNR, and visual assessment. p < 0.05 was considered statistically significant. ResultsNo significant differences in nearly all the SIRs were observed among the three MRA methods. Higher CNRs were observed with TSE-Acc than those with TFE-Acc (anterior tibial artery, p = 0.014; peroneal artery, p = 0.029; and posterior tibial artery, p = 0.014) in distal arterial segments; however, no significant differences were observed upon comparison with TRANCE (all p > 0.05). The arterial visibility scores exhibited similar trends as the CNRs. The artifact contamination scores with TSE-Acc were significantly lower (but within an acceptable level) compared to those with TFE-Acc. In the patient with PAD, the sluggish peripheral arteries were better visualized using TSE-Acc than those using TFE-Acc, and the collateral and stenosis arteries were better visualized using TSE-Acc than those using TRANCE. ConclusionPeripheral arterial visualization was better with TSE-Acc than that with TFE-Acc in lower extremity MRA without ECG or PPU triggering and contrast enhancement, which was comparable with TRANCE as the reference standard. Furthermore, TSE-Acc may propose satisfactory diagnostic performance for diagnosing PAD in patients with arrhythmia and chronic kidney disease.

Сapabilities of Dynamic Infrared Thermography for Planning and Monitoring of Perforating Flaps

Background. Free perforating flaps are the most optimal for reconstruction of both upper and lower extremities. However, along with the obvious advantages of these flaps, there are also a number of difficulties associated with their more complex vascular anatomy and, as a consequence, more time-consuming dissection. This determines the need for a more thorough preoperative planning, including the mapping of perforating vessels and development of flap design. At the same time, the problems with intraoperative assessment of perfusion of perforating flaps and their monitoring in the postoperative period have not been solved. For these purposes, several instrumental methods of examination such as MRI and CT angiography, Doppler sonography, ICG and dynamic infrared thermography are used.&#x0D; Aim of the study — to evaluate the capabilities of dynamic infrared thermography (DIT) for mapping of perforating vessels when planning the design of perforating flaps, as well as for assessing their intra- and postoperative perfusion.&#x0D; Methods. We have analyzed the results of using DIT along with CT-angiography and Doppler sonography for preliminary mapping of perforating vessels in the design of 18 perforating flaps (ALT flap — 10, SCIP flap — 8) transplanted in 15 patients from 01.01.2022 to 30.07.2022. DIT was also used in all cases for intraoperative instrumental confirmation of flap perfusion and for its monitoring in the postoperative period.&#x0D; Results. A total of 39 perforating vessels were detected by CT angiography at the point of origin from the main arteries. DIT was used to detect the distal portions of 37 perforating vessels in 15 patients at the marking of 18 flaps. On average, 2.5 per ALT flap and 1.4 per SCIP flap. Thermographic examination time was approximately 10 minutes. Localization of all perforating vessels detected by DIT were first confirmed by Doppler sonography and then visualized intraoperatively during flap dissection. Intraoperatively, perfusion of all transplanted flaps was clearly confirmed by DIT. In the postoperative period, perfusion problems were clinically detected in 3 (16%) flaps and confirmed by DIT: venous stasis — 2 cases, arterial insufficiency — 1 case. In two patients (13%) with a body mass index of more than 35 (corresponding to class 2–3 obesity), the location of perforating vessels could not be determined by thermography and Doppler sonography. Also, in these patients DIT was ineffective for confirmation of flap perfusion intraoperatively and in the postoperative period.&#x0D; Conclusion. This study confirms that CT angiography, Doppler sonography and infrared thermography are complementary methods that allow to detect and visualize perforating arteries from their origin from a main artery to the site of their passage through the deep fascia (CT-angiography), as well as to determine their more accurate projection on the skin surface (DIT and Doppler sonography). DIT is also an auxiliary method for flap monitoring in the intraoperative and postoperative periods, which allows to engage nursing staff in postoperative monitoring.

Deep learning-based 3D cerebrovascular segmentation workflow on bright and black blood sequences magnetic resonance angiography

BackgroundCerebrovascular diseases have emerged as significant threats to human life and health. Effectively segmenting brain blood vessels has become a crucial scientific challenge. We aimed to develop a fully automated deep learning workflow that achieves accurate 3D segmentation of cerebral blood vessels by incorporating classic convolutional neural networks (CNNs) and transformer models.MethodsWe used a public cerebrovascular segmentation dataset (CSD) containing 45 volumes of 1.5 T time-of-flight magnetic resonance angiography images. We collected data from another private middle cerebral artery (MCA) with lenticulostriate artery (LSA) segmentation dataset (MLD), which encompassed 3.0 T three-dimensional T1-weighted sequences of volumetric isotropic turbo spin echo acquisition MRI images of 107 patients aged 62 ± 11 years (42 females). The workflow includes data analysis, preprocessing, augmentation, model training with validation, and postprocessing techniques. Brain vessels were segmented using the U-Net, V-Net, UNETR, and SwinUNETR models. The model performances were evaluated using the dice similarity coefficient (DSC), average surface distance (ASD), precision (PRE), sensitivity (SEN), and specificity (SPE).ResultsDuring 4-fold cross-validation, SwinUNETR obtained the highest DSC in each fold. On the CSD test set, SwinUNETR achieved the best DSC (0.853), PRE (0.848), SEN (0.860), and SPE (0.9996), while V-Net achieved the best ASD (0.99). On the MLD test set, SwinUNETR demonstrated good MCA segmentation performance and had the best DSC, ASD, PRE, and SPE for segmenting the LSA.ConclusionsThe workflow demonstrated excellent performance on different sequences of MRI images for vessels of varying sizes. This method allows doctors to visualize cerebrovascular structures.Critical relevance statementA deep learning-based 3D cerebrovascular segmentation workflow is feasible and promising for visualizing cerebrovascular structures and monitoring cerebral small vessels, such as lenticulostriate arteries.Key points• The proposed deep learning-based workflow performs well in cerebrovascular segmentation tasks.• Among comparison models, SwinUNETR achieved the best DSC, ASD, PRE, and SPE values in lenticulostriate artery segmentation.• The proposed workflow can be used for different MR sequences, such as bright and black blood imaging.Graphical

Detection of femoropopliteal arterial steno-occlusion at MR angiography: initial experience with artificial intelligence

BackgroundThis study evaluated a deep learning (DL) algorithm for detecting vessel steno-occlusions in patients with peripheral arterial disease (PAD). It utilised a private dataset, which was acquired and annotated by the authors through their institution and subsequently validated by two blinded readers.MethodsA single-centre retrospective study analysed 105 magnetic resonance angiography (MRA) images using an EfficientNet B0 DL model. Initially, inter-reader variability was assessed using the complete dataset. For a subset of these images (29 from the left side and 35 from the right side) where digital subtraction angiography (DSA) data was available as the ground truth, the model’s accuracy and the area under the curve at receiver operating characteristics analysis (ROC-AUC) were evaluated.ResultsA total of 105 patient examinations (mean age, 75 years ±12 [mean ± standard deviation], 61 men) were evaluated. Radiologist-DL model agreement had a quadratic weighted Cohen κ ≥ 0.72 (left side) and ≥ 0.66 (right side). Radiologist inter-reader agreement was ≥ 0.90 (left side) and ≥ 0.87 (right side). The DL model achieved a 0.897 accuracy and a 0.913 ROC-AUC (left side) and 0.743 and 0.830 (right side). Radiologists achieved 0.931 and 0.862 accuracies, with 0.930 and 0.861 ROC-AUCs (left side), and 0.800 and 0.799 accuracies, with 0.771 ROC-AUCs (right side).ConclusionThe DL model provided valid results in identifying arterial steno-occlusion in the superficial femoral and popliteal arteries on MRA among PAD patients. However, it did not reach the inter-reader agreement of two radiologists.Relevance statementThe tested DL model is a promising tool for assisting in the detection of arterial steno-occlusion in patients with PAD, but further optimisation is necessary to provide radiologists with useful support in their daily routine diagnostics.Key points• This study focused on the application of DL for arterial steno-occlusion detection in lower extremities on MRA.• A previously developed DL model was tested for accuracy and inter-reader agreement.• While the model showed promising results, it does not yet replace human expertise in detecting arterial steno-occlusion on MRA.Graphical

[A New Preoperative Simulation Using Magnetic Resonance Imaging Bone-Like Imaging with Zero-Echo-Time Sequence].

This study aimed to evaluate the clinical usefulness of zero-echo time(ZTE)-based magnetic resonance imaging(MRI)in planning an optimal surgical approach and applying ZTE for anatomical guidance during transcranial surgery. P atients who underwent transcranial surgery and carotid endarterectomy and for whom ZTE-based MRI and magnetic resonance angiography(MRA)data were obtained, were analyzed by creating ZTE/MRA fusion images and 3D-ZTE-based MRI models. We examined whether these images and models could be substituted for computed tomography imaging during neurosurgical procedures. Furthermore, the clinical usability of the 3D-ZTE-based MRI model was evaluated by comparing it with actual surgical views. ZTE/MRA fusion images and 3D-ZTE-based MRI models clearly illustrated the cranial and intracranial morphology without radiation exposure or the use of an iodinated contrast medium. The models allowed the determination of the optimum surgical approach for cerebral aneurysms, brain tumors near the brain surface, and cervical internal carotid artery stenosis by visualizing the relationship between the lesions and adjacent bone structures. However, ZTE-based MRI did not provide useful information for surgery for skull base lesions, such as vestibular schwannoma, because bone structures of the skull base often include air components, which cause signal disturbances in MRI. ZTE sequences on MRI allowed distinct visualization of not only the bone but also the vital structures around the lesion. This technology is minimally invasive and useful for preoperative planning and guidance of the optimum approach during surgery in a subset of neurosurgical diseases.

New Vessel Extraction Method by Using Skew Normal Distribution for MRA Images

Vascular-related diseases pose significant public health challenges and are a leading cause of mortality and disability. Understanding the complex structure of the vascular system and its processes is crucial for addressing these issues. Recent advancements in medical imaging technology have enabled the generation of high-resolution 3D images of vascular structures, leading to a diverse array of methods for vascular extraction. While previous research has often assumed a normal distribution of image data, this paper introduces a novel vessel extraction method that utilizes the skew normal distribution for more accurate probability distribution modeling. The proposed method begins with a preprocessing step to enhance vessel structures and reduce noise in Magnetic Resonance Angiography (MRA) images. The skew normal distribution, known for its ability to model skewed data, is then employed to characterize the intensity distribution of vessels. By estimating the parameters of the skew normal distribution using the Expectation-Maximization (EM) algorithm, the method effectively separates vessel pixels from the background and non-vessel regions. To extract vessels, a thresholding technique is applied based on the estimated skew normal distribution parameters. This segmentation process enables accurate vessel extraction, particularly in detecting thin vessels and enhancing the delineation of vascular edges with low contrast. Experimental evaluations on a diverse set of MRA images demonstrate the superior performance of the proposed method compared to previous approaches in terms of accuracy and computational efficiency. The presented vessel extraction method holds promise for improving the diagnosis and treatment of vascular-related diseases. By leveraging the skew normal distribution, it provides accurate and efficient vessel segmentation, contributing to the advancement of vascular imaging in the field of medical image analysis.