Magnetic Resonance Angiography Research Articles

Anterior Labrum Periosteal Sleeve Avulsion Lesions of the Shoulder: A Scoping Review.

Anterior labrum periosteal sleeve avulsion (ALPSA) lesion of the shoulder is defined as a labral avulsion with an intact periosteum of the glenoid neck resulting in medial malattachment of the labrum, which is both nonanatomic and nonfunctional. It is relatively rare compared with Bankart lesions, and its results are usually reported in combination with other anterior labroligamentous lesions in the literature. To (1) assess the size and scope of the literature on ALPSA lesions, (2) highlight the importance of this lesion, and (3) distinguish between ALPSA and Bankart lesions in diagnostic and treatment strategies. Scoping review; Level of evidence, 4. The PubMed, Scopus, Embase, and Google Scholar databases were searched with the keywords "ALPSA,""anterior labrum periosteal sleeve avulsion,""anterior labral periosteal sleeve avulsion," and "anterior labroligamentous periosteal sleeve avulsion" lesion. Duplicate articles and those that did not meet the inclusion criteria were excluded, resulting in the identification of 42 relevant articles. Their references were analyzed for further data curation. This scoping review demonstrated that ALPSA lesions are difficult to clinically identify. Magnetic resonance angiography in the adduction internal rotation position is the most sensitive and specific imaging modality for identification. Optimal views are the anterosuperior portal for accurate identification and the anteroinferior portal for surgical repair during arthroscopy. Treatment begins with correctly identifying the labrum, in contradistinction to dense reactive fibrous tissue, and reattaching the labrum to the correct anatomic glenoid footprint. Chronic lesions with bone loss require either bone block or soft tissue augmentation procedures. There is paucity of exclusive literature on ALPSA lesions. It is important to distinguish this lesion from the Bankart lesion as it is associated with worse outcomes. The higher failure rates of ALPSA lesion repair indicate that the current repair techniques require further refinement to improve the outcomes to the standard of Bankart lesions.

Susceptibility weighted imaging for detection of thrombus in acute ischemic stroke: A cross-sectional study.

Susceptibility-weighted imaging (SWI) can help in the diagnosis of thrombus within the vessel in acute ischemic stroke, known as susceptibility vessel sign (SVS), and detection of SVS within the vessel can predict treatment modality and outcome. In this study, the purpose is to correlate the SVS on SWI with different parameters of stroke. This prospective cross-sectional study enrolled consecutive stroke patients with vessel occlusion on magnetic resonance angiography (MRA) over 1 year. The relationship between SVS on SWI with risk factors, territory involved, and length of thrombus was correlated with the National Institutes of Health Stroke Scale (NIHSS). A total of 105patients were enrolled in this study. Sixty-two percent (66 out of 105) of patients showed SVS on SWI with MRA-positive occlusion. A positive correlation was observed between SVS on SWI and the risk factor (p = 0.003, chi-square test), with 86% of patients with heart disease and 47% with hypertension exhibiting SVS. Additionally, a positive correlation was observed between SVS on SWI and territorial occlusion (p = 0.000, chi-square test). A moderate positive correlation was observed between the NIHSS and thrombus length (p = 0.002, Pearson's correlation coefficient), with a Pearson's coefficient of 0.367. SWI can be useful in identifying the location of the thrombus, and NIHSS can determine the thrombus length in acute stroke. A higher incidence of SVS can be associated with risk factors, and it also depends upon the site of occlusion of the vessel.

Hemodynamic evaluation of intracranial arteriovenous malformations: Pre- and post-treatment 2D phase-contrast MRI measurements.

Hemodynamic changes are seen in the feeding arteries of arteriovenous malformations (AVMs). Phase-contrast MRI (PC-MRI) enables the acquisition of hemodynamic information from blood vessels. There is insufficient knowledge on which flow or velocity parameter best discriminates AVMs from healthy subjects. To evaluate PC-MRI-measured flow and velocity in feeding arteries of AVMs before and, when possible, also after treatment and to compare these measurements to corresponding measurements in healthy controls. Highest flow (HF), lowest flow (LF), mean flow (MF), peak systolic velocity (PSV), end-diastolic velocity (EDV), and mean velocity (MV) were measured in feeding arteries in patients with intracranial AVMs using 2D PC-MRI at 3 T. Measurements were compared to previously reported values in healthy individuals. Values in patients above the 95th percentile in the healthy cohort were categorized as pathological. Nidus volume was measured using 3D time-of-flight MR angiography. Ten patients with diagnosed AVMs were examined with PC-MRI. Among these, three patients also underwent follow-up PC-MRI after treatment. Pathological velocities (PSV, EDV, and MV) were seen in all five subjects with a nidus larger or equal to 5.7cm3, whereas pathological flow values were not seen in all, that is, pathologic HF in three, pathologic LF in two, and pathologic MF in two. After treatment, there was a decrease in flow and velocity (all measured parameters). After treatment, velocities (PSV, EDV, and MV) were no longer abnormal compared to healthy controls. Patients with a large AVM nidus show pathological velocities, but less consistent flow increases. Following treatment, velocities normalize.

Venous malformations in children: comparison between magnetic resonance imaging and histopathological findings.

Among low-flow vascular malformations, venous malformations are relatively frequent. The pathological patterns vary in severity and are generally characterized by dilated vessels and low-flow blood that over time can organize into phleboliths. Sometimes small capillary and/or lymphatic vessels may be associated, micro- and/or macro-shunts may form alone or in different combinations, and finally adipose tissue may be interposed between the malformed vessels. Magnetic resonance imaging (MRI) is a crucial examination for confirming venous malformations because it can accurately identify different features of the lesions. The aim of our study was to compare MRI and histopathological findings of venous malformations in childrento assess thepossibilities and limitationsof MRI. In a retrospective study, two observers independently evaluated the contrast-enhanced MRI of 26 children with venous malformations. Several radiological parameters were considered and compared with histopathological findings. The agreement between the interobserver radiological evaluation and between histopathological and radiological diagnosis was verified using Cohen's kappa. MRI interobserver agreement was excellent for micro-shunts and good for the remaining findings. The radiological-pathological agreement was perfect for the presence/absence of phleboliths and of macro-shunts and almost perfect for the presence of intralesional adipose tissue, lymphatic component, and micro-shunts. MRI in venous malformations can detect the presence of phleboliths, adipose tissue, and lymphatic components with excellent accuracyand good to excellent interobserver agreement. Furthermore, MR angiography can detect micro-shunts in simple and combined venous malformations with substantial agreement with histopathological findings.

Staged cerebral and brachiocephalic bypass in a patient with MCA and brachiocephalic steno-occlusion.

Background: Brachiocephalic steal is a rare phenomenon that may lead to hemodynamic abnormalities in the ipsilateral vertebral and carotid arteries. Current treatment includes management of vascular risk factors, endovascular stenting, and surgical management depending on the severity of symptoms. Case Information: We describe a patient with multiple vascular risk factors who presented with mild neurological symptoms and chronic right arm weakness associated with concurrent brachiocephalic steal and right MCA M1 stenosis on neuroimaging. Use of right superficial temporal artery to middle cerebral artery bypass and aorta-right subclavian bypass resulted in improved flow to the right hemisphere on quantitative magnetic resonance angiography and single-photon emission computed tomography, significantly lowering the risk of catastrophic ischemic stroke. Conclusion: Complex steal phenomena increase stroke risk. In cases of high-grade occlusion or advanced symptoms, endovascular or surgical management should be considered for optimal stroke prevention.

Clinical Features of 17 Patients With Primary Angiitis of the Central Nervous System Confirmed by Brain Biopsy

Objective To analyze the clinical features of 17 patients with primary angiitis of the central nervous system (PACNS) and thus facilitate the early diagnosis and treatment,reduce the recurrence and mortality,and improve the prognoses of this disease. Methods We collected the data of patients with PACNS diagnosed by brain biopsy from January 2009 to June 2023 and analyzed their clinical presentations,laboratory and imaging manifestations,electrophysiological and pathological changes,and treatment regimens and prognosis. Results The 17 patients diagnosed with PACNS via brain biopsy included one child and 16 adults.The subtyping results showed that 10,2,3,2,1,and 1 patients had tumorous,spinal cord-involved,angiography-positive,rapidly progressive,hemorrhagic,and amyloid β-related PACNS,respectively.Eleven (64.7%) of the patients were complicated with secondary epilepsy.All the patients exhibited abnormal manifestations in head MRI,with 94.1% showing lesions with uneven enhancement around the lesions or in the leptomeninges. Magnetic resonance angiography revealed large vessel abnormalities in 3 patients,and spinal cord involvement was observed in 2 patients.Histopathological typing revealed 7 (43.7%) patients with lymphocytic vasculitis and 5 (31.2%) patients with necrotizing vasculitis.Eleven patients were treated with glucocorticoids and cyclophosphamide,which resulted in partial lesion disappearance and symptom amelioration in 6 patients upon reevaluation with head MRI after 3 months of maintenance therapy.Two,1,and 3 patients experienced rapid disease progression,death,and recurrence within 1 year,respectively.Three patients showed insensitivity to hormonotherapy and residual disabilities.Two patients received rituximab after relapse and remained clinically stable during a follow-up period of 0.5-1 year. Conclusion Tumorous PACNS was more prone to epilepsy,mainly occurring in males.The most common histopathological type was necrotizing vasculitis,which responded to hormonotherapy and had favorable outcomes.Therefore,for the young patients with epilepsy and intracranial tumorous lesions,the possibility of PACNS should be considered.Spinal cord involvement in PACNS was often located in the thoracic and cervical cords,suggesting a poorer prognosis.Electromyography commonly revealed neural conduction abnormalities in the anterior horn or roots,providing clues for differential diagnosis.For suspected spinal cord involvement,comprehensive electromyography is recommended.Rapidly progressive PACNS often presented infratentorial lesions,such as lesions in the pons and medulla,with a higher mortality rate.Hemorrhagic PACNS was rare,and a multifocal hemorrhagic lesion with enhancement in the intracranial region,particularly in young patients,should raise suspicion.For the patients with recurrent or progressive disease,rituximab is a recommended therapeutic option.

Flow capacity of a superficial temporal artery as a donor in a consecutive series of 100 patients with superficial temporal artery-middle cerebral artery bypass.

A superficial temporal artery-middle cerebral artery (STA-MCA) bypass is classically considered a low-flow bypass. It is known that the flow in the flow augmentation STA-MCA bypass is influenced by flow demand of the revascularized territory and can reach significantly higher values. The authors report their intraoperative flow measurement data in a consecutive series of 100 STA-MCA bypasses performed at their institution. Moreover, in a subanalysis, they show the postoperative bypass flow measured with quantitative MR angiography (qMRA) noninvasive optimal vessel analysis (NOVA). Between January 2013 and October 2023, 100 patients with acute, subacute, or chronic large-vessel occlusion (LVO) or moyamoya disease underwent a flow augmentation STA-MCA bypass revascularization at the authors' department with intraoperative bypass flow measurement. Patients with atherosclerotic LVO who underwent bypass surgery within a 6-week period following the onset of ischemic stroke symptoms were categorized into the acute bypass group, encompassing both acute and subacute LVO cases. Conversely, those who underwent bypass surgery > 6 weeks after the last occurrence of ischemic stroke were classified as the chronic group. Since May 2019, a consecutive subgroup of 37 patients received a postoperative (before discharge) bypass flow measurement with the qMRA-NOVA imaging tool. The mean ± SD intraoperative bypass flow in this consecutive series of 100 STA-MCA bypasses was 53.5 ± 28.8 ml/min (range 14-145 ml/min). In the subanalysis, there was no difference in the intraoperative flow capacity between the acute and chronic groups and between the moyamoya and acute groups. Patients in the moyamoya group showed a significantly higher flow rate in the STA-MCA bypass compared with the chronic group (63.0 ± 30.2 ml/min vs 48.4 ± 26.5 ml/min, p = 0.03). In a consecutive subanalysis of 37 STA-MCA bypass cases, postoperative flow measurements were also performed using qMRA-NOVA, showing a significant increase in the flow of STA-MCA bypasses after surgery compared with intraoperative flow measurements (mean intraoperative bypass flow rate vs qMRA-NOVA postoperative bypass flow rate: 73.4 ± 29.9 ml/min vs 111.3 ± 51.4 ml/min, p = 0.005). Using intraoperative and postoperative quantitative flow measurements of the STA, the data confirm that the flow in the flow augmentation STA-MCA bypass is influenced by the flow demand of the revascularized territory and can reach high values if needed. Moreover, the significant flow increase in the postoperative flow measurement using qMRA-NOVA demonstrates that the bypass can increase its flow over time.

Diagnostic Accuracy of Non-Contrast-Enhanced Time-Resolved MR Angiography to Assess Angioarchitectural Classification Features of Brain Arteriovenous Malformations.

This study aims to assess the diagnostic accuracy of non-contrast-enhanced 4D MR angiography (NCE-4D-MRA) compared to contrast-enhanced 4D MR angiography (CE-4D-MRA) for the detection and angioarchitectural characterisation of brain arteriovenous malformations (bAVMs). Utilising a retrospective design, we examined 54 MRA pairs from 43 patients with bAVMs, using digital subtraction angiography (DSA) as the reference standard. Both NCE-4D-MRA and CE-4D-MRA were performed using a 3-T MR imaging system. The primary objectives were to evaluate the diagnostic performance of NCE-4D-MRA against CE-4D-MRA and DSA and to assess concordance between imaging modalities in grading bAVMs according to four main scales: Spetzler-Martin, Buffalo, AVM embocure score (AVMES), and R2eDAVM. Our results demonstrated that NCE-4D-MRA had a higher accuracy and specificity compared to CE-4D-MRA (0.85 vs. 0.83 and 95% vs. 85%, respectively) and similar agreement, with DSA detecting shunts in bAVMs or residuals. Concordance in grading bAVMs was substantial between NCE-4D-MRA and DSA, particularly for the Spetzler-Martin and Buffalo scales, with CE-4D-MRA showing slightly higher kappa values for interobserver agreement. The study highlights the potential of NCE-4D-MRA as a diagnostic tool for bAVMs, offering comparable accuracy to CE-4D-MRA while avoiding the risks associated with gadolinium-based contrast agents. The safety profile of imaging techniques is a significant concern in the long-term follow up of bAVMs, and further prospective research should focus on NCE-4D-MRA protocol improvement for clinical use.

Variable-density velocity-selective magnetization preparation for non-contrast-enhanced peripheral MR angiography.

Velocity-selective (VS) magnetization preparation has shown great promise for non-contrast-enhanced (NCE) magnetic resonance angiography (MRA) with the ability to generate positive angiographic contrast directly using a single 3D acquisition. However, existing VS-MRA methods have an issue of aliased saturation around a certain velocity, known as velocity field-of-view (vFOV), which can cause undesired signal loss in arteries. This study aimed to develop a new version of the VS preparation pulse sequence that overcomes the aliased saturation problem in conventional VS preparation. Utilizing the fact that an excitation profile is the Fourier transform of excitation k-space sampling, we sampled the k-space in a non-uniform fashion by scaling gradient pulses accordingly to have aliased excitation diffused over velocity. The variable density sampling function was numerically optimized to maximize the average of the velocity passband signal while minimizing its variance. The optimized variable density VS magnetization was validated through Bloch simulations and applied to peripheral NCE MRA in healthy subjects. The in-vivo experiments showed that the proposed variable density VS-MRA significantly lowered arterial signal loss observed in conventional VS-MRA, as evidenced by a higher arterial signal-to-noise ratio (58.50 ± 14.29 vs. 55.54 ± 12.32; p < 0.05) and improved artery-to-background contrast-to-noise ratio (22.75 ± 7.57 vs. 20.60 ± 6.51; p < 0.05).

BOLD Cerebrovascular Reactivity and NOVA Quantitative MR Angiography in Adult Patients with Moyamoya Vasculopathy Undergoing Cerebral Bypass Surgery.

Revascularization surgery for the symptomatic hemisphere with hemodynamic impairment is effective for Moyamoya vasculopathy patients. However, careful patient selection is crucial and ideally supported by advanced quantitative hemodynamic imaging. Recently, blood oxygenation level-dependent cerebrovascular reactivity (BOLD-CVR) and quantitative magnetic resonance angiography with non-invasive optimal vessel analysis (qMRA-NOVA) have gained prominence in assessing these patients. This study aims to present the results of BOLD-CVR and qMRA-NOVA imaging along with the changes in cerebral hemodynamics and flow status following flow augmentation with superficial temporal artery-middle cerebral artery (STA-MCA) bypass in our Moyamoya vasculopathy patient cohort. Symptomatic patients with Moyamoya vasculopathy treated at the Clinical Neuroscience Center of the University Hospital Zurich who underwent hemodynamic and flow imaging (BOLD-CVR and qMRA-NOVA) before and after bypass were included in the analysis. Reduced hemispheric volume flow rates, as well as impaired BOLD-CVR, were measured in all 12 patients with Moyamoya vasculopathy before STA-MCA bypass surgery. Following the surgical procedure, post-operative BOLD-CVR demonstrated a non-significant increase in BOLD-CVR values within the revascularized, symptomatic middle cerebral artery territory and cerebral hemisphere. The results of the statistical tests should be viewed as indicative due to the small sample size. Additionally, post-operative qMRA-NOVA revealed a significant improvement in the hemispheric volume flow rate of the affected hemisphere due to the additional bypass flow rate. Our findings affirm the presence of hemodynamic and flow impairments in the symptomatic hemisphere of the Moyamoya vasculopathy patients. Bypass surgery proves effective in improving both BOLD-CVR impairment and the hemispheric volume flow rate in our patient cohort.

Superficial temporal artery aneurysm misdiagnosed in a patient with long-term migraine headache treatment: a case report

BackgroundSuperficial temporal artery aneurysm is a rare vascular abnormality without specific clinical symptoms. In this case report, we present the case of a patient with superficial temporal artery aneurysm who was diagnosed with migraine headache at first.Case presentationA 60-year-old Iranian man with a previous history of headaches, who did not respond properly to the treatments following the initial diagnosis of migraine, presented with a painless lump in the left temporal region, and he was diagnosed with superficial temporal artery aneurysm via Doppler ultrasound. Finally, surgical removal of the left superficial temporal artery aneurysm was performed.ConclusionsThis case shows the importance of vascular causes in the approach to headache etiologies, especially when the headache is prolonged without proper responses to treatment. Computed tomography angiography and magnetic resonance angiography are appropriate diagnostic methods for aneurysm detection that should be considered in future studies.

Optimal Catheter Selection for Patients with Acute Stroke with Type III Aortic Arch Based on Magnetic Resonance Angiography Road Mapping of the Para-Aortic Transfemoral Access Route Before Mechanical Thrombectomy

Although mechanical thrombectomy for acute ischemic stroke has a high recanalization rate, procedurally challenging lesions remain in approximately 10% of the cases. Type III aortic arches, due to their anatomical configuration, are a fundamental problem impacting this procedure. This study aimed to determine whether optimal catheter selection for type III aortic arches, using magnetic resonance angiography (MRA)-based road mapping of the para-aortic transfemoral access route, reduces the time required for mechanical thrombectomy. We retrospectively evaluated 203 consecutive patients who underwent mechanical thrombectomy at multiple centers between April 2018 and July 2022. 23 patients were diagnosed with a type III aortic arch using MRA-based road mapping performed to visualize the para-aortic access route before neuro-interventional procedures. Among the 23 patients with type III aortic arches, 10 received a Simmons-type catheter (initial Simmons group) and 13 received a JB-2-type catheter (initial JB-2 group) as their first inner catheter. The time required for mechanical thrombectomy was compared between the groups. Compared with the initial JB-2 group, the initial Simmons group exhibited a significantly shorter "puncture-to-recanalization time" (105 vs. 53minutes, P=0.009) and "door-to-recanalization time" (164 vs. 129minutes, P=0.032). Optimal catheter selection by identifying the aortic arch before mechanical thrombectomy using MRA-based road mapping effectively reduced the mechanical thrombectomy time. This suggests that even in type III aorta cases, appropriate catheter selection may shorten the mechanical thrombectomy time and improve acute ischemic stroke prognosis.

Investigation of distributed learning for automated lesion detection in head MR images

In this study, we investigated the application of distributed learning, including federated learning and cyclical weight transfer, in the development of computer-aided detection (CADe) software for (1) cerebral aneurysm detection in magnetic resonance (MR) angiography images and (2) brain metastasis detection in brain contrast-enhanced MR images. We used datasets collected from various institutions, scanner vendors, and magnetic field strengths for each target CADe software. We compared the performance of multiple strategies, including a centralized strategy, in which software development is conducted at a development institution after collecting de-identified data from multiple institutions. Our results showed that the performance of CADe software trained through distributed learning was equal to or better than that trained through the centralized strategy. However, the distributed learning strategies that achieved the highest performance depend on the target CADe software. Hence, distributed learning can become one of the strategies for CADe software development using data collected from multiple institutions.

Hippocampus infarct following a posterior cerebral artery occlusion.

A 64-year-old gentleman, presented for subacute onset of short-term memory problem, preceded by headache, right arm numbness and visual disturbances. On neurological exam, he had anterograde amnesia, decreased pinprick sensation on his right arm and right homonymous hemianopsia. Brain Magnetic Resonance imaging (MRI) and Magnetic Resonance Angiography (MRA) showed subacute ischemic lesions in the left occipital lobe, hippocampus and thalamus, caused by a distal occlusion of the left Posterior Cerebral Artery (PCA). A distal occlusion of the PCA led to multiple infarcts in different anatomical structures, causing a constellation of variant neurological signs. Our case demonstrates an anterior hippocampus predominantly irrigated by the PCA.

Dural venous sinus angioplasty and stenting for treatment of idiopathic intracranial hypertension: a single-center experience with 20 consecutive cases

Background: Dural venous sinus stenosis has been shown to be a potential cause or aggravating factor of idiopathic intracranial hypertension (IIH). Endovascular therapy for angioplasty of venous sinus stenosis is emerging as a potential alternative to treat IIH. Objective: This article aims to present the results of a cases series representing the experience of a single center in treating this disease. Materials and Methods: We retrospectively reviewed the angiographic and manometric data of patients undergoing angioplasty and stenting for the treatment of IIH with venous sinus stenosis on magnetic resonance angiography. All patients had failed conventional medical treatment. Data on demographic features, clinical and radiologic presentation, and outcomes were collected retrospectively. Results: 20 female patients, with persistent headache and papilledema, underwent venous sinus angioplasty and stenting. Mean age was 35.9 (SD, 10) years. Eighteen patients (90%) had clinical improvement after the procedure. Of these, all showed resolution (17 patients, 94%) or partial improvement (1 patient, 6%) of papilledema within 6 months. Two patients had persistent moderate-to-severe headache (intensity &gt; 6 on a 10-point pain scale), with continued papilledema despite stable visual acuity on visual field testing. The mean pre-procedure lumbar puncture opening pressure was 30.1 (SD, 4) mm Hg, decreasing to 16.2 (SD, 4) mm Hg after the procedure. Only 4 patients experienced complications directly or indirectly related to the procedure, with no impact on outcome. Conclusion: Angioplasty and stenting of the stenotic segment may effectively and safely treat IIH associated with focal venous sinus stenosis, with a high technical success rate and an acceptable complication rate.

Robust data-driven segmentation of pulsatile cerebral vessels using functional magnetic resonance imaging.

Functional magnetic resonance imaging (fMRI) captures rich physiological and neuronal information that can offer insights into neurofluid dynamics, vascular health, and waste clearance function. The availability of cerebral vessel segmentation could facilitate fluid dynamics research in fMRI. However, without magnetic resonance angiography scans, cerebral vessel segmentation is challenging and time-consuming. This study leverages cardiac-induced pulsatile fMRI signal to develop a data-driven, automatic segmentation of large cerebral arteries and the superior sagittal sinus (SSS). The method was validated in a local dataset by comparing it to ground truth cerebral artery and SSS segmentations. Using the Human Connectome Project (HCP) aging dataset, the method's reproducibility was tested on 422 participants aged 36 to 100 years, each with four repeated fMRI scans. The method demonstrated high reproducibility, with an intraclass correlation coefficient > 0.7 in both cerebral artery and SSS segmentation volumes. This study demonstrates that the large cerebral arteries and SSS can be reproducibly and automatically segmented in fMRI datasets, facilitating the investigation of fluid dynamics in these regions.

Ultra-low-field magnetic resonance angiography at 0.05 T: A preliminary study.

We aim to explore the feasibility of head and neck time-of-flight (TOF) magnetic resonance angiography (MRA) at ultra-low-field (ULF). TOF MRA was conducted on a highly simplified 0.05 T MRI scanner with no radiofrequency (RF) and magnetic shielding. A flow-compensated three-dimensional (3D)gradient echo (GRE) sequence with a tilt-optimized nonsaturated excitation RF pulse, and a flow-compensated multislice two-dimensional (2D) GRE sequence, were implemented for cerebral artery and vein imaging, respectively. For carotid artery and jugular vein imaging, flow-compensated 2D GRE sequences were utilized with venous and arterial blood presaturation, respectively. MRA was performed on young healthy subjects. Vessel-to-background contrast was experimentally observed with strong blood inflow effect and background tissue suppression. The large primary cerebral arteries and veins, carotid arteries, jugular veins, and artery bifurcations could be identified in both raw GRE images and maximum intensity projections. The primary brain and neck arteries were found to be reproducible among multiple examination sessions. These preliminary experimental results demonstrated the possibility of artery TOF MRA on low-cost 0.05 T scanners for the first time, despite the extremely low MR signal. We expect to improve the quality of ULF TOF MRA in the near future through sequence development and optimization, ongoing advances in ULF hardware and image formation, and the use of vascular T1 contrast agents.

Current Opinion on Diagnosis of Peripheral Artery Disease in Diabetic Patients.

Peripheral arterial disease (PAD) prevalence and diabetes mellitus (DM) prevalence are continuously increasing worldwide. The strong relationship between DM and PAD is highlighted by recent evidence. PAD diagnosis in diabetic patients is very important, particularly in patients with diabetic foot disease (DFD); however, it is often made difficult by the characteristics of such diseases. Diagnosing PAD makes it possible to identify patients at a very high cardiovascular risk who require intensive treatment in terms of risk factor modification and medical therapy. The purpose of this review is to discuss the diagnostic methods that allow for a diagnosis of PAD in diabetic patients. Non-invasive tests that address PAD diagnosis will be discussed, such as the ankle-brachial index (ABI), toe pressure (TP), and transcutaneous oxygen pressure (TcPO2). Furthermore, imaging methods, such as duplex ultrasound (DUS), computed tomography angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA), are described because they allow for diagnosing the anatomical localization and severity of artery stenosis or occlusion in PAD. Non-invasive tests will also be discussed in terms of their ability to assess foot perfusion. Foot perfusion assessment is crucial in the diagnosis of critical limb ischemia (CLI), the most advanced PAD stage, particularly in DFD patients. The impacts of PAD diagnosis and CLI identification in diabetic patients are clinically relevant to prevent amputation and mortality.

High Resolution TOF-MRA Using Compressed Sensing-based Deep Learning Image Reconstruction for the Visualization of Lenticulostriate Arteries: A Preliminary Study.

To investigate the visibility of the lenticulostriate arteries (LSAs) in time-of-flight (TOF)-MR angiography (MRA) using compressed sensing (CS)-based deep learning (DL) image reconstruction by comparing its image quality with that obtained by the conventional CS algorithm. Five healthy volunteers were included. High-resolution TOF-MRA images with the reduction (R)-factor of 1 were acquired as full-sampling data. Images with R-factors of 2, 4, and 6 were then reconstructed using CS-DL and conventional CS (the combination of CS and sensitivity conceding; CS-SENSE) reconstruction, respectively. In the quantitative assessment, the number of visible LSAs (identified by two radiologists), length of each depicted LSA (evaluated by one radiological technologist), and normalized mean squared error (NMSE) value were assessed. In the qualitative assessment, the overall image quality and the visibility of the peripheral LSA were visually evaluated by two radiologists. In the quantitative assessment of the DL-CS images, the number of visible LSAs was significantly higher than those obtained with CS-SENSE in the R-factors of 4 and 6 (Reader 1) and in the R-factor of 6 (Reader 2). The length of the depicted LSAs in the DL-CS images was significantly longer in the R-factor 6 compared to the CS-SENSE result. The NMSE value in CS-DL was significantly lower than in CS-SENSE for R-factors of 4 and 6. In the qualitative assessment of DL-CS images, the overall image quality was significantly higher than that obtained with CS-SENSE in the R-factors 4 and 6 (Reader 1) and in the R-factor 4 (Reader 2). The visibility of the peripheral LSA was significantly higher than that shown by CS-SENSE in all R-factors (Reader 1) and in the R-factors 2 and 4 (Reader 2). CS-DL reconstruction demonstrated preserved image quality for the depiction of LSAs compared to the conventional CS-SENSE when the R-factor is elevated.

Non-contrast MR angiography: physical principles and clinical applications in chest, abdomen and pelvis imaging.

This review article focuses on the advancements in non-contrast magnetic resonance angiography (NC-MRA) and its increasing importance in body imaging, especially for patients with renal complications, pregnant women, and children. It highlights the relevance of NC-MRA in chest, abdominal, and pelvis imaging and details various bright-blood NC-MRA techniques like cardiac-gated 3D Fast Spin Echo (FSE), balanced Steady-State Free Precession (bSSFP), Arterial Spin Labeling (ASL), and 4D flow methods. The article explains the operational principles of these techniques, their clinical applications, and their advantages over traditional contrast-enhanced methods. Special attention is given to the utility of these techniques in diverse imaging scenarios, including liver, renal, and pelvic imaging. The article underscores the growing importance of NC-MRA in medical diagnostics, offering insights into current practices and potential future developments. This comprehensive review is a valuable resource for radiologists and clinicians, emphasizing NC-MRA's role in enhancing patient care and diagnostic accuracy across various medical conditions.