T2-prepared segmented 3D-gradient-echo for fast T2-weighted high-resolution three-dimensional imaging of the carotid artery wall at 3T: a feasibility study.

Background: The multi-contrast assessment of the carotid artery wall has become an important diagnostic tool for the characterization of atherosclerotic plaque and vessel wall thickening. For providing the required T1-, T2-, and proton density weighted contrast, multi-slice turbo spin echo (TSE) techniques are normally applied. The straightforward extension of the TSE techniques to volumetric imaging of large sections of the carotid arteries is limited by the resulting long acquisition times.

Two-point magnitude MRI for rapid mapping of brown adipose tissue and its application to the R6/2 mouse model of Huntington disease.

The recent discovery of active brown fat in human adults has led to renewed interest in the role of this key metabolic tissue. This is particularly true for neurodegenerative conditions like Huntington disease (HD), an adult-onset heritable disorder with a prominent energy deficit phenotype. Current methods for imaging brown adipose tissue (BAT) are in limited use because they are equipment-wise demanding and often prohibitively expensive.

Medial meniscal displacement and strain in three dimensions under compressive loads: MR assessment.

Purpose: To investigate the 3D displacement and the local strain of the medial meniscus and its attachments under compressive loading.

Materials And Methods: Magnetic resonance imaging (MRI) scans of six porcine knee joints were performed under unloaded and loaded conditions (100% and 200% body weight [BW]). Volumes were registered to obtain a 3D displacement field of the medial meniscus and its attachments, which were divided into five anatomic compartments.

Volumetric motion quantification by 3D tissue phase mapped CMR.

Background: The objective of this study was the quantification of myocardial motion from 3D tissue phase mapped (TPM) CMR. Recent work on myocardial motion quantification by TPM has been focussed on multi-slice 2D acquisitions thus excluding motion information from large regions of the left ventricle. Volumetric motion assessment appears an important next step towards the understanding of the volumetric myocardial motion and hence may further improve diagnosis and treatments in patients with myocardial motion abnormalities.

Combination of tagging and tissue phase mapping to accelerate myocardial motion measurements in three directions.

Object: Until now, a three-directional velocity field has mostly been obtained by velocity encoding in three directions, which is very time-consuming and hence not usually used in clinical routine. We show the feasibility of combining in-plane tagging with through-plane tissue phase mapping (TPM) to encode a three-directional velocity field at 3 T with reduced overall acquisition time.

Materials And Methods: Assessment of a three-directional velocity field was performed for 10 healthy volunteers.

Acceleration of tissue phase mapping with sensitivity encoding at 3T.

Background: The objective of this study was to investigate the impact of sensitivity encoding on the quantitative assessment of cardiac motion in black blood cine tissue phase mapping (TPM) sequences. Up to now whole volume coverage of the heart is still limited by the long acquisition times. Therefore, a significant increase in imaging speed without deterioration of quantitative motion information is indispensable.

Feasibility of ultra-short echo time (UTE) magnetic resonance imaging for identification of carious lesions.

The objective of this study was to investigate the potential of ultra short echo time imaging for the assessment of caries lesions and early demineralization. 12 patients with suspected caries lesions underwent a dental magnetic resonance imaging investigation comprising ultra short echo time imaging (echo time=50 μs) and spin echo imaging. Before the dental magnetic resonance imaging, all patients underwent a conventional clinical dental investigation including visual assessment of the teeth as well as dental x-ray imaging.

MRI assessment of thoracic stent grafts after emergency implantation in multi trauma patients: a feasibility study.

Purpose: To evaluate the feasibility of MRI for static and dynamic assessment of the deployment of thoracic aortic stent grafts after emergency implantation in trauma patients.

Methods: Twenty patients initially presenting with a rupture of the thoracic aorta were enrolled in this study. All patients underwent thoracic endovascular aortic repair (TEVAR).

SAR reduced black-blood cine TPM for increased temporal resolution at 3T.

Object: The objective was to improve the temporal resolution in black-blood CINE tissue phase mapping sequences at high field MR systems. The temporal resolution is limited due to SAR constraints causing idle times into the sequence. The aim was to avoid these idle times and therefore providing an increased number of heart phases.

Acceleration of tissue phase mapping by k-t BLAST: a detailed analysis of the influence of k-t-BLAST for the quantification of myocardial motion at 3T.

Background: The assessment of myocardial motion with tissue phase mapping (TPM) provides high spatiotemporal resolution and quantitative motion information in three directions. Today, whole volume coverage of the heart by TPM encoding at high spatial and temporal resolution is limited by long data acquisition times. Therefore, a significant increase in imaging speed without deterioration of the quantitative motion information is required.

Assessment of the coronary venous system in heart failure patients by blood pool agent enhanced whole-heart MRI.

Objective: To investigate the feasibility of MRI for non-invasive assessment of the coronary sinus (CS) and the number and course of its major tributaries in heart failure patients.

Methods: Fourteen non-ischaemic heart failure patients scheduled for cardiac resynchronisation therapy (CRT) underwent additional whole-heart coronary venography. MRI was performed 1 day before device implantation.

Dynamic visualization of arachnoid adhesions in a patient with idiopathic syringomyelia using high-resolution cine magnetic resonance imaging at 3T.

A 39-year-old female patient with thoracic syringomyelia underwent routine magnetic resonance imaging (MRI) and 3 T MRI to investigate the value of retrospectively cardiac-gated cine steady-state free precession (SSFP) MRI in the preoperative and postoperative diagnosis of arachnoid membranes in the spinal subarachnoid space. Therefore, 3T MRI included sagittal and transverse retrospectively cardiac-gated cine balanced fast-field echo (balanced-FFE) sequences both preoperatively and after microsurgical lysis of arachnoid adhesions and expansive duraplasty. Arachnoid membranes were detected and this result was correlated with intraoperative findings and the results of routine cardiac-gated phase-contrast cerebrospinal fluid (CSF) flow MRI.

Quantification of calcifications in endarterectomy samples by means of high-resolution ultra-short echo time imaging.

Objective: Magnetic resonance imaging (MRI) has proven its value for noninvasive assessment and classification of atherosclerotic lesions. MRI provides excellent access to soft tissue information, but its capability for assessing calcified segments of the lesion remains limited. The aim of this study was to investigate the ultra-short echo time (UTE) sequence for accurate quantification of the plaque volumes and qualitative assessment of the calcium density.

Dual stack black blood carotid artery CMR at 3T: application to wall thickness visualization.

Background: The increasing understanding of atherosclerosis as an important risk factor for the development of acute ischemic events like ischemic stroke has stimulated increasing interest in non-invasive assessment of the structure, composition and burden of plaque depositions in the carotid artery wall. Vessel wall imaging by means of cardiovascular magnetic resonance (CMR) is conventionally done by 2D dual inversion recovery (DIR) techniques, which often fail in covering large volumes of interest as required in plaque burden assessment. Although the technique has been extended to 2D multislice imaging, its straight extension to 3D protocols is still limited by the prolonged acquisition times and incomplete blood suppression.

Blood oxygen level-dependent magnetic resonance imaging using T2-prepared steady-state free-precession imaging in comparison to contrast-enhanced myocardial perfusion imaging.

Background: Diagnosis of inducible myocardial ischemia is important for deciding further diagnosis and therapy in coronary artery disease (CAD). Blood oxygen level-dependent (BOLD) cardiac magnetic resonance imaging (CMR) is a potential method to evaluate myocardial perfusion reserve alternatively to first-pass perfusion using contrast agents.

Methods And Results: We imaged 46 patients with suspected CAD on a 1.

Cardiac phase-specific shimming (CPSS) for SSFP MR cine imaging at 3 T.

The application of steady-state-free-precession (SSFP) techniques at 3 T systems is still limited by their sensitivity to magnetic field inhomogeneities. Especially during imaging of the heart, the arising signal voids and distortions in the myocardium currently often limit the diagnostic value of the resulting images. Dedicated shim systems providing higher order shimming capabilities have been applied to improve the field homogeneity across the heart.

Strain-encoded MRI to evaluate normal left ventricular function and timing of contraction at 3.0 Tesla.

Purpose: To define the reproducibility of strain-encoded (SENC) magnetic resonance imaging (MRI) for assessment of regional left ventricular myocardial strain and timing of contraction in a 3T MRI system.

Materials And Methods: The study population consisted of 16 healthy subjects. SENC measurements were performed in three short-axis (SA) slices (apical, mid, and basal) and three long-axis (LA) views (two-, three-, and four-chamber) for assessment of maximal transmural systolic strain and time to peak strain.

Local excitation black blood imaging at 3T: application to the carotid artery wall.

A novel approach for imaging large sections of the carotid artery wall at isotropic spatial resolution is presented. Local excitation by means of 2D excitation pulses was combined with a diffusion-prepared segmented steady-state black-blood gradient echo technique enabling the assessment of the carotid arterial wall over a range of up to 15 cm. The carotid arteries of five healthy volunteers were imaged with the proposed technique.

Variable resolution reconstruction for Cartesian data acquired with nonconstant sampling density in phase-encoding direction.

The variable-kernel extent technique is applied for providing local high-resolution images from k-space data sampled on a Cartesian sampling grid with gradually decreasing sampling density in the phase-encoding direction. The approach is based on a variable spatial resolution reconstruction technique providing gradually decreasing resolution in the phase-encoding direction with increasing distance to the image center, while preserving full spatial resolution in a narrow slab centered in spatial domain. Reconstruction is performed by a variable convolution kernel gridding technique.

MR myocardial perfusion imaging with k-space and time broad-use linear acquisition speed-up technique: feasibility study.

Unlabelled: The purpose of this study was to prospectively evaluate the diagnostic accuracy of a cardiovascular magnetic resonance (MR) k-space and time (k-t) broad-use linear acquisition speed-up technique (BLAST) accelerated perfusion sequence for depicting clinically relevant coronary artery disease (CAD), with use of coronary angiography as the reference standard. The local ethics committee approved this study, and informed consent was obtained from 40 patients (28 men, 12 women; mean age, 61 years +/- 8 [standard deviation]) scheduled for coronary catheterization. A balanced steady-state free precession pulse sequence (2.

Four-dimensional single breathhold magnetic resonance imaging using kt-BLAST enables reliable assessment of left- and right-ventricular volumes and mass.

Purpose: To prospectively determine the accuracy of four-dimensional (4D) kt-broad-use linear acquisition speed-up technique (BLAST) accelerated MRI (kt-BLAST) for the assessment of left-ventricular (LV) volumes and mass as well as right-ventricular (RV) volumes in comparison to standard multiple breathhold cine imaging.

Materials And Methods: A total of 40 patients with suspected or known coronary artery disease (CAD) underwent cardiac MRI. In each patient a standard multislice cine steady-state free precession (SSFP) sequence was performed with complete ventricular coverage during multiple breathholds.

Accelerated 4D dobutamine stress MR imaging with k-t BLAST: feasibility and diagnostic performance.

Purpose: To prospectively determine feasibility and diagnostic performance (with angiography as reference standard) of k-space and time (k-t) broad-use linear acquisition speed-up technique (k-t BLAST) cine imaging during dobutamine stress for identification of inducible cardiac wall motion abnormalities.

Materials And Methods: The study was conducted according to standards of the Charité and Virchow-Klinikum Ethics Committee. Patients gave written consent.

The impact of different positions and thoracial restrains on respiratory induced cardiac motion.

One of the limiting factors for high resolution magnetic resonance coronary angiography (MRCA) is the motion of the heart during breathing. Current approaches use mainly motion correction in one dimension. We aimed to determine the relation between diaphragmatic motion and cardiac motion as well as the potential influence from external restraints reducing thoracical anterior posterior (AP) motion.

Magnetic resonance imaging-guided balloon angioplasty of coarctation of the aorta: a pilot study.

Background: MRI guidance of percutaneous transluminal balloon angioplasty (PTA) of aortic coarctation (CoA) would be desirable for continuous visualization of anatomy and to eliminate x-ray exposure. The aim of this study was (1) to determine the suitability of MRI-controlled PTA using the iron oxide-based contrast medium Resovist (ferucarbotran) for catheter visualization and (2) to subsequently apply this technique in a pilot study with patients with CoA.

Methods And Results: The MRI contrast-to-noise ratio and artifact behavior of Resovist-treated balloon catheters was optimized in in vitro and animal experiments (pigs).

On the heating of inductively coupled resonators (stents) during MRI examinations.

Stents that have been implanted to preserve the results of vascular dilatation are frequently affected by in-stent restenosis, which ideally should be followed up by a noninvasive diagnostic modality. Active MRI stents can enable this kind of follow-up, while normal metallic stents can not. The prototype stents investigated in this study were designed as electric resonating circuits without a direct connection to the MR imager, and function as inductively coupled transmit coils.