Positive susceptibility-based contrast imaging with dephased balanced steady-state free precession.

Purpose: Dephasing gradients can be introduced within a variety of gradient-echo pulse sequences to delineate local susceptibility changes ("White-Marker" phenomenon), e.g., for the visualization of metallic interventional devices which are otherwise difficult to display.

Feasibility of magnetic resonance imaging-guided cardiac catheterization, angioplasty, and stenting in a commercial wide-bore 0.55T scanner.

Background: Low-field (0.55T) magnetic resonance imaging (MRI) may allow MRI-guided interventions using available catheterization equipment, as radiofrequency-induced heating of interventional devices is reduced at low field. The purpose of this study was to test the feasibility of real-time MRI-guided right and left heart catheterization (R&LHC) as well as angioplasty and stenting of the inferior vena cava using a commercially available 0.

Rapid CNN-based needle localization for automatic slice alignment in MR-guided interventions using 3D undersampled radial white-marker imaging.

Background: In MR-guided in-bore percutaneous needle interventions, typically 2D interactive real-time imaging is used for navigating the needle into the target. Misaligned 2D imaging planes can result in losing visibility of the needle in the 2D images, which impedes successful targeting. Necessary iterative manual slice adjustment can prolong interventional workflows.

Performance of Image-navigated and Diaphragm-navigated 3D Late Gadolinium-enhanced Cardiac MRI for the Assessment of Atrial Fibrosis.

Purpose To perform a qualitative and quantitative evaluation of the novel image-navigated (iNAV) 3D late gadolinium enhancement (LGE) cardiac MRI imaging strategy in comparison with the conventional diaphragm-navigated (dNAV) 3D LGE cardiac MRI strategy for the assessment of left atrial fibrosis in atrial fibrillation (AF). Materials and Methods In this prospective study conducted between April and September 2022, 26 consecutive participants with AF (mean age, 61 ± 11 years; 19 male) underwent both iNAV and dNAV 3D LGE cardiac MRI, with equivalent spatial resolution and timing in the cardiac cycle. Participants were randomized in the acquisition order of iNAV and dNAV.

Interrelation Between Cerebrospinal Fluid Pressure, Intracranial Morphology and Venous Hemodynamics Studied by 4D Flow MRI.

Purpose: To quantify the effects of CSF pressure alterations on intracranial venous morphology and hemodynamics in idiopathic intracranial hypertension (IIH) and spontaneous intracranial hypotension (SIH) and assess reversibility when the underlying cause is resolved.

Methods: We prospectively examined venous volume, intracranial venous blood flow and velocity, including optic nerve sheath diameter (ONSD) as a noninvasive surrogate of CSF pressure changes in 11 patients with IIH, 11 age-matched and sex-matched healthy controls and 9 SIH patients, before and after neurosurgical closure of spinal dural leaks. We applied multiparametric MRI including 4D flow MRI, time-of-flight (TOF) and T2-weighted half-Fourier acquisition single-shot turbo-spin echo (HASTE).

Cardiac magnetic resonance for early atrial lesion visualization post atrial fibrillation radiofrequency catheter ablation.

Background: Incomplete atrial lesions resulting in pulmonary vein-left atrium reconnection after pulmonary vein antrum isolation (PVAI), are related to atrial fibrillation (AF) recurrence. Unfortunately, during the PVAI procedure, fluoroscopy and electroanatomic mapping cannot accurately determine the location and size of the ablation lesions in the atrial wall and this can result in incomplete PVAI lesions (PVAI-L) after radiofrequency catheter ablation (RFCA).

Aim: We seek to evaluate whether cardiac magnetic resonance (CMR), immediately after RFCA of AF, can identify PVAI-L by characterizing the left atrial tissue.

Spinal cord motion and CSF flow in the cervical spine of 70 healthy participants.

Pulsatile spinal cord and CSF velocities related to the cardiac cycle can be depicted by phase-contrast MRI. Among patients with spontaneous intracranial hypotension, we have recently described relevant differences compared with healthy controls in segment C2/C3. The method might be a promising tool to solve clinical and diagnostic ambiguities.

Magnetic resonance imaging-guided conventional catheter ablation of isthmus-dependent atrial flutter using active catheter imaging.

Background: Interventional cardiac magnetic resonance (iCMR) has been established as a radiation-free alternative compared to standard fluoroscopy-guided catheter ablation for cavotricuspid isthmus (CTI)-dependent atrial flutter to image anatomy, structural alterations, and further catheter guidance.

Objective: The purpose of this study was to explore the safety, feasibility, and efficacy of CTI ablations performed completely in the iCMR suite using active catheter imaging.

Methods: Consecutive patients underwent iCMR-guided catheter ablation for CTI-dependent atrial flutter.

Active Tracking-based cardiac triggering for MR-thermometry during radiofrequency ablation therapy in the left ventricle.

Cardiac MR thermometry shows promise for real-time guidance of radiofrequency ablation of cardiac arrhythmias. This technique uses ECG triggering, which can be unreliable in this situation. A prospective cardiac triggering method was developed for MR thermometry using the active tracking (AT) signal measured from catheter microcoils.

Carotid Geometry and Wall Shear Stress Independently Predict Increased Wall Thickness-A Longitudinal 3D MRI Study in High-Risk Patients.

Carotid geometry and wall shear stress (WSS) have been proposed as independent risk factors for the progression of carotid atherosclerosis, but this has not yet been demonstrated in larger longitudinal studies. Therefore, we investigated the impact of these biomarkers on carotid wall thickness in patients with high cardiovascular risk. Ninety-seven consecutive patients with hypertension, at least one additional cardiovascular risk factor and internal carotid artery (ICA) plaques (wall thickness ≥ 1.

Spinal Cord Motion in Degenerative Cervical Myelopathy: The Level of the Stenotic Segment and Gender Cause Altered Pathodynamics.

In degenerative cervical myelopathy (DCM), focally increased spinal cord motion has been observed for C5/C6, but whether stenoses at other cervical segments lead to similar pathodynamics and how severity of stenosis, age, and gender affect them is still unclear. We report a prospective matched-pair controlled trial on 65 DCM patients. A high-resolution 3D T2 sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) and a phase-contrast magnetic resonance imaging (MRI) sequence were performed and automatically segmented.

Intracranial vessel wall imaging framework - Data acquisition, processing, and visualization.

Objective: Assessment of vessel walls is an integral part in diagnosis and disease monitoring of vascular diseases such as vasculitis. Vessel wall imaging (VWI), in particular of intracranial arteries, is the domain of Magnetic Resonance Imaging (MRI) - but still remains a challenge. The tortuous anatomy of intracranial arteries and the need for high resolution within clinically acceptable scan times require special technical conditions regarding the hardware and software environments.

Focal cervical spinal stenosis causes mechanical strain on the entire cervical spinal cord tissue - A prospective controlled, matched-pair analysis based on phase-contrast MRI.

Background: Focally increased spinal cord motion at the level of cervical spinal stenosis has been revealed by phase-contrast MRI (PC-MRI).

Objective: To investigate spinal cord motion among patients suffering of degenerative cervical myelopathy (DCM) across the entire cervical spine applying automated segmentation and standardized PC-MRI post-processing protocols.

Methods: Prospective, matched-pair controlled trial on 29 patients with stenosis at C5/C6.

Parametric Sequential Method for MRI-Based Wall Shear Stress Quantification.

Wall shear stress (WSS) has been suggested as a potential biomarker in various cardiovascular diseases and it can be estimated from phase-contrast Magnetic Resonance Imaging (PC-MRI) velocity measurements. We present a parametric sequential method for MRI-based WSS quantification consisting of a geometry identification and a subsequent approximation of the velocity field. This work focuses on its validation, investigating well controlled high-resolution in vitro measurements of turbulent stationary flows and physiological pulsatile flows in phantoms.

Carotid geometry is an independent predictor of wall thickness - a 3D cardiovascular magnetic resonance study in patients with high cardiovascular risk.

Background: The posterior wall of the proximal internal carotid artery (ICA) is the predilection site for the development of stenosis. To optimally prevent stroke, identification of new risk factors for plaque progression is of high interest. Therefore, we studied the impact of carotid geometry and wall shear stress on cardiovascular magnetic resonance (CMR)-depicted wall thickness in the ICA of patients with high cardiovascular disease risk.

Analysis of accelerated 4D flow MRI in the murine aorta by radial acquisition and compressed sensing reconstruction.

Preclinical 4D flow MRI remains challenging and is restricted for parallel imaging acceleration due to the limited number of available receive channels. A radial acquisition with combined parallel imaging and temporal compressed sensing reconstruction was implemented to achieve accelerated preclinical 4D flow MRI. In order to increase the accuracy of the measured velocities, a quantitative evaluation of different temporal regularization weights for the compressed sensing reconstruction based on velocity instead of magnitude data is performed.

Passive needle guide tracking with radial acquisition and phase-only cross-correlation.

Purpose: Acceleration of a passive tracking sequence based on phase-only cross-correlation (POCC) using radial undersampling.

Methods: The phase-only cross-correlation (POCC) algorithm allows passive tracking of interventional instruments in real-time. In a POCC sequence, two cross-sectional images of a needle guide with a positive MR contrast are continuously acquired from which the instrument trajectory is calculated.

High-resolution Compressed-sensing T1 Black-blood MRI : A New Multipurpose Sequence in Vascular Neuroimaging?

Background And Purpose: In vasculopathies of the central nervous system, reliable and timely diagnosis is important against the background of significant morbidity and sequelae in cases of incorrect diagnosis or delayed treatment. Magnetic resonance imaging (MRI) plays a major role in the detection and monitoring of intracranial and extracranial vascular pathologies of different etiologies, in particular for evaluation of the vessel wall in addition to luminal information, thus allowing differentiation between various vasculopathies. Compressed-sensing black-blood MRI combines high image quality with relatively short acquisition time and offers promising potential in the context of neurovascular vessel wall imaging in clinical routine.

Publisher Correction: Real-time magnetic resonance imaging - guided coronary intervention in a porcine model.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Assessment of spinal cord motion as a new diagnostic MRI-parameter in cervical spinal canal stenosis: study protocol on a prospective longitudinal trial.

Background: Increased spinal cord motion has been proven to be a relevant finding within spinal canal stenosis disclosed by phase-contrast MRI (PC-MRI). Adapted PC-MRI is a suitable and reliable method within the well deliberated setting. As the decision between conservative and operative treatment can be challenging in some cases, further diagnostic marker would facilitate the diagnostic process.

Real-time magnetic resonance imaging - guided coronary intervention in a porcine model.

X-ray fluoroscopy is the gold standard for coronary diagnostics and intervention. Magnetic resonance imaging is a radiation-free alternative to x-ray with excellent soft tissue contrast in arbitrary slice orientation. Here, we assessed real-time MRI-guided coronary interventions from femoral access using newly designed MRI technologies.

MR-based wall shear stress measurements in fully developed turbulent flow using the Clauser plot method.

In arterial blood flow wall shear stress (WSS) quantifies the frictional force that flowing blood exerts on a vessel wall. WSS can be directly estimated from phase-contrast (PC) MR velocity measurements and has been suggested as a biomarker in cardio-vascular diseases. We present and investigate the application of the Clauser plot method for estimating WSS in fully developed turbulent stationary flow using PC velocity measurements.

Image-based assessment of uncertainty in quantification of carotid lumen.

Measurements of the vessel lumen diameter are often used to determine the degree of atherosclerotic disease in carotid arteries. However, quantification results vary with imaging technique and acquisition settings. We aim at providing a tool that quantifies the lumen diameter on different image datasets and gives an estimate of quantification uncertainties, so that they can be taken into consideration when evaluating and comparing measurements.

Autoregressive moving average modeling for hepatic iron quantification in the presence of fat.

Background: Measuring hepatic R2* by fitting a monoexponential model to the signal decay of a multigradient-echo (mGRE) sequence noninvasively determines hepatic iron content (HIC). Concurrent hepatic steatosis introduces signal oscillations and confounds R2* quantification with standard monoexponential models.

Purpose: To evaluate an autoregressive moving average (ARMA) model for accurate quantification of HIC in the presence of fat using biopsy as the reference.