Simultaneous Luminal and Hemodynamic Evaluation of the Cervical Arteries Using Nonenhanced 3D Quantitative Quiescent-Interval Slice-Selective Magnetic Resonance Angiography.

Background: Luminal and hemodynamic evaluations of the cervical arteries inform the diagnosis and management of patients with cervical arterial disease.

Purpose: To demonstrate a 3D nonenhanced quantitative quiescent interval slice-selective (qQISS) magnetic resonance angiographic (MRA) strategy that provides simultaneous hemodynamic and luminal evaluation of the cervical arteries.

Study Type: Prospective.

Equilibrium phase contrast-enhanced magnetic resonance angiography of the thoracic aorta and heart using balanced T1 relaxation-enhanced steady-state.

Background: Three-dimensional (3D) contrast-enhanced magnetic resonance angiography (CEMRA) is routinely used for vascular evaluation. With existing techniques for CEMRA, diagnostic image quality is only obtained during the first pass of the contrast agent or shortly thereafter, whereas angiographic quality tends to be poor when imaging is delayed to the equilibrium phase. We hypothesized that prolonged blood pool contrast enhancement could be obtained by imaging with a balanced T1 relaxation-enhanced steady-state (bT1RESS) pulse sequence, which combines 3D balanced steady-state free precession (bSSFP) with a saturation recovery magnetization preparation to impart T1 weighting and suppress background tissues.

Efficacy and immunogenicity following dengue virus-1 human challenge after a tetravalent prime-boost dengue vaccine regimen: an open-label, phase 1 trial.

Background: Dengue human infection models (DHIMs) are important tools to down-select dengue vaccine candidates and establish tetravalent efficacy before advanced clinical field trials. We aimed to provide data for the safety and immunogenicity of DHIM and evaluate dengue vaccine efficacy.

Methods: We performed an open-label, phase 1 trial at the University of Maryland (Baltimore, MD, USA).

Quantitative Time-of-Flight Head Magnetic Resonance Angiography of Cerebrovascular Disease.

Background: Standard Cartesian time-of-flight (TOF) head magnetic resonance angiography (MRA) is routinely used to evaluate the intracranial arteries, but does not provide quantitative hemodynamic information that is useful for patient risk stratification as well as for monitoring treatment and tracking changes in blood flow over time. Quantitative TOF (qTOF) MRA represents a new and efficient method for simultaneous evaluating the intracranial arteries and quantifying blood flow velocity, but it has not yet been evaluated in patients with cerebrovascular disease.

Purpose: To evaluate qTOF for simultaneously evaluating the intracranial arteries and quantifying intracranial blood flow velocity in patients with cerebrovascular disease, without the need for a phase contrast (PC) scan.

Dark Blood Contrast-Enhanced Brain MRI Using Echo-uTRESS.

Background: The widely used magnetization-prepared rapid gradient-echo (MPRAGE) sequence makes enhancing lesions and blood vessels appear bright after gadolinium administration. However, dark blood imaging using T1-weighted Sampling Perfection with Application optimized Contrast using different flip angle Evolution (T1 SPACE) can be advantageous since it improves the conspicuity of small metastases and leptomeningeal disease. As a potential alternative to T1 SPACE, we evaluated a new dark blood sequence called echo-uTRESS (unbalanced T1 Relaxation-Enhanced Steady-State).

Evaluation of Lower Leg Arteries and Fibular Perforators before Microsurgical Fibular Transfer Using Noncontrast-Enhanced Quiescent-Interval Slice-Selective (QISS) Magnetic Resonance Angiography.

(1) Background: Preoperative imaging of the lower leg arteries is essential for planning fibular grafting. The aim of this study was to evaluate the feasibility and clinical value of non-contrast-enhanced (CE) Quiescent-Interval Slice-Selective (QISS)-magnetic resonance angiography (MRA) for reliably visualizing the anatomy and patency of the lower leg arteries and for preoperatively determining the presence, number, and location of fibular perforators. (2) Methods: The anatomy and stenoses of the lower leg arteries and the presence, number, and location of fibular perforators were determined in fifty patients with oral and maxillofacial tumors.

Improved Brain Tumor Conspicuity at 3 T Using Dark Blood, Fat-Suppressed, Dixon Unbalanced T1 Relaxation-Enhanced Steady-State MRI.

Objectives: Contrast-enhanced magnetic resonance imaging (MRI) is the cornerstone for brain tumor diagnosis and treatment planning. We have developed a novel dual-echo volumetric dark blood pulse sequence called Dixon unbalanced T1 relaxation-enhanced steady-state (uT 1 RESS) that improves the visibility of contrast-enhancing lesions while suppressing the tissue signals from blood vessels and fat. The purpose of this study was to test the hypothesis that Dixon uT 1 RESS would significantly improve the conspicuity of brain tumors compared with magnetization-prepared rapid gradient echo (MPRAGE), as well as to determine potential limitations of the technique.

Clinical Evaluation of Non-Contrast-Enhanced Radial Quiescent-Interval Slice-Selective (QISS) Magnetic Resonance Angiography in Comparison to Contrast-Enhanced Computed Tomography Angiography for the Evaluation of Endoleaks after Abdominal Endovascular Aneurysm Repair.

Purpose: Contrast-enhanced (CE) angiographic techniques, such as computed tomographic angiography (CE-CTA), are most commonly used for follow-up imaging after endovascular aneurysm repair. In this study, CE-CTA and non-CE QISS-MRA were compared for the first time for assessing endoleaks and aneurysms at follow-up after abdominal EVAR.

Methods: Our study included 20 patients (17 male, median age 79.

Dark blood cardiovascular magnetic resonance of the heart, great vessels, and lungs using electrocardiographic-gated three-dimensional unbalanced steady-state free precession.

Background: Recently, we reported a novel neuroimaging technique, unbalanced T1 Relaxation-Enhanced Steady-State (uTRESS), which uses a tailored 3D unbalanced steady-state free precession (3D uSSFP) acquisition to suppress the blood pool signal while minimizing bulk motion sensitivity. In the present work, we hypothesized that 3D uSSFP might also be useful for dark blood imaging of the chest. To test the feasibility of this approach, we performed a pilot study in healthy subjects and patients undergoing cardiovascular magnetic resonance (CMR).

Evaluation of Renal Allograft Vasculature Using Non-contrast 3D Inversion Recovery Balanced Steady-state Free Precession MRA and 2D Quiescent-interval Slice-selective MRA.

Background And Objectives: Renal transplant patients often require periodic imaging to evaluate the transplant vessel anastomosis for potential vascular complications. The use of non-contrast enhanced magnetic resonance angiography (NCE-MRA) techniques is encouraged in these patients because they are at increased risk of nephrogenic systemic fibrosis (NSF) due to their renal insufficiency. This study aimed to evaluate the performance of two NCE-MRA techniques (three-dimensional [3D] balanced steady-state free precession [bSSFP] with inversion recovery and quiescent-interval slice-selective [QISS]) for the evaluation of renal allograft vasculature in patients with clinical suspicion, or Doppler ultrasound, or both of arterial anastomotic stenosis.

MR Angiography Series: Fundamentals of Non-Contrast-enhanced MR Angiography.

Unlike CT angiography, which requires the use of contrast medium, MR angiography (MRA) can be performed without the use of contrast agents. This subfield of MRA is referred to as non-contrast-enhanced MRA (NC-MRA). While NC-MRA can be performed in many patients, it is especially useful in the imaging of pediatric and pregnant patients, as well as in patients with renal impairment.

Quantitative time-of-flight MR angiography for simultaneous luminal and hemodynamic evaluation of the intracranial arteries.

Purpose: To report a quantitative time-of-flight (qTOF) MRA technique for simultaneous luminal and hemodynamic evaluation of the intracranial arteries.

Methods: Implemented using a thin overlapping slab 3D stack-of-stars based 3-echo FLASH readout, qTOF was tested in a flow phantom and for imaging the intracranial arteries of 10 human subjects at 3 Tesla. Display of the intracranial arteries with qTOF was compared to resolution-matched and scan time-matched standard Cartesian 3D time-of-flight (TOF) MRA, whereas quantification of mean blood flow velocity with qTOF, done using a computer vision-based inter-echo image analysis procedure, was compared to 3D phase contrast MRA.

Quiescent-Interval Slice-Selective MRA Accurately Estimates Intravascular Stent Dimensions Prior to Intervention in Patients With Peripheral Artery Disease.

Background: Quiescent-interval slice-selective (QISS) magnetic resonance angiography (MRA) is a non-contrast alternative for the pre-procedural assessment of patients with peripheral artery disease (PAD). However, the feasibility of pre-procedural stent size estimation using QISS MRA would merit investigation.

Purpose: To evaluate the feasibility of QISS MRA for pre-procedural stent size estimation in PAD patients compared to computed tomography angiography (CTA).

Cardiovascular magnetic resonance for the detection of descending thoracic aorta calcification in patients with end-stage renal disease.

Background: Vascular calcification is an independent predictor of cardiovascular disease in patients with chronic kidney disease. Computed tomography (CT) is the gold-standard for detecting vascular calcification. Radial volumetric-interpolated breath-hold examination (radial-VIBE), a free-breathing gradient-echo cardiovascular magnetic resonance (CMR) sequence, has advantages over CT as it is ionising radiation-free.

Updates in Magnetic Resonance Venous Imaging.

For years, magnetic resonance angiography (MRA) has been a leading imaging modality in the assessment of venous disease involving the pelvis and lower extremities. Current advancement in noncontrast MRA techniques enables imaging of a larger subset of patients previously excluded due to allergy or renal insufficiency, allowing for preintervention assessment and planning. In this article, the current status of MR venography, with a focus on current advancements, will be presented.

Comparison of 2D and 3D quiescent-interval slice-selective non-contrast MR angiography in patients with peripheral artery disease.

Objective: To evaluate the potential clinical benefit of the superior spatial resolution of 3D prototype thin-slab stack-of-stars (tsSOS) quiescent-interval slice-selective (QISS) MRA over standard 2D-QISS MRA for the detection peripheral artery disease (PAD), using computed tomography angiography (CTA) as reference.

Materials And Methods: Twenty-three patients (70 ± 8 years, 18 men) with PAD who had previously undergone run-off CTA were prospectively enrolled. Patients underwent non-contrast MRA using 2D-QISS and tsSOS-QISS at 1.

Super-resolution head and neck MRA using deep machine learning.

Purpose: To probe the feasibility of deep learning-based super-resolution (SR) reconstruction applied to nonenhanced MR angiography (MRA) of the head and neck.

Methods: High-resolution 3D thin-slab stack-of-stars quiescent interval slice-selective (QISS) MRA of the head and neck was obtained in eight subjects (seven healthy volunteers, one patient) at 3T. The spatial resolution of high-resolution ground-truth MRA data in the slice-encoding direction was reduced by factors of 2 to 6.

High-resolution, non-contrast-enhanced magnetic resonance angiography of the wrist, hand and digital arteries using optimized implementation of Cartesian quiescent interval slice selective (QISS) at 1.5 T.

Purpose: Non-contrast-enhanced (CE) magnetic resonance angiography (MRA) techniques are of considerable interest for diagnosing vascular diseases in the upper extremities owing to the possibility of repeated examinations, sufficient coverage of the measurement volume, and because possible side effects of administering iodine- or gadolinium-based contrast agents and radiation exposure can be avoided. The aim of this study was to investigate the feasibility of an optimized electrocardiogram (ECG) triggered Cartesian quiescent interval slice selective (QISS) technique for MRA of hand arteries.

Material And Methods: Both hands of 20 healthy volunteers (HVs) were examined using an optimized QISS-MRA pulse sequence at 1.

Radial-based acquisition strategies for pre-procedural non-contrast cardiovascular magnetic resonance angiography of the pulmonary veins.

Background: Computed tomography angiography (CTA) or contrast-enhanced (CE) cardiovascular magnetic resonance angiography (CMRA) is often obtained in patients with atrial fibrillation undergoing evaluation prior to pulmonary vein (PV) isolation. Drawbacks of CTA include radiation exposure and potential risks from iodinated contrast agent administration. Free-breathing 3D balanced steady-state free precession (bSSFP) Non-contrast CMRA is a potential imaging option, but vascular detail can be suboptimal due to ghost artifacts and blurring that tend to occur with a Cartesian k-space trajectory or, in some cases, inconsistent respiratory gating.

Twofold improved tumor-to-brain contrast using a novel T1 relaxation-enhanced steady-state (TRESS) MRI technique.

A technique that provides more accurate cancer detection would be of great value. Toward this end, we developed T1 relaxation-enhanced steady-state (TRESS), a novel magnetic resonance imaging (MRI) pulse sequence that enables the flexible modulation of T1 weighting and provides the unique feature that intravascular signals can be toggled on and off in contrast-enhanced scans. TRESS makes it possible to effectively use an MRI technique with improved signal-to-noise ratio efficiency for cancer imaging.

Diagnostic accuracy of non-contrast quiescent-interval slice-selective (QISS) MRA combined with MRI-based vascular calcification visualization for the assessment of arterial stenosis in patients with lower extremity peripheral artery disease.

Objectives: The proton density-weighted, in-phase stack-of-stars (PDIP-SOS) MRI technique provides calcification visualization in peripheral artery disease (PAD). This study sought to investigate the diagnostic accuracy of a combined non-contrast quiescent-interval slice-selective (QISS) MRA and PDIP-SOS MRI protocol for the detection of PAD, in comparison with CTA and digital subtraction angiography (DSA).

Methods: Twenty-six prospectively enrolled PAD patients (70 ± 8 years) underwent lower extremity CTA and 1.