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Result : Searchterm 'Cine Sequence' found in 1 term [ ] and 1 definition [ ], (+ 17 Boolean[ ] results
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MRI Resources |
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| Cine Sequence |  |
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Cine sequences used in cardiovascular MRI are collection of images (usually at the same spatial location) covering of one full period of cardiac cycle or over several periods in order to obtain complete coverage.
The pulse sequence used, is either a standard gradient echo pulse sequence, a segmented data acquisition, a gradient echo EPI sequence or a gradient echo with balanced gradient waveform.
In cardiac gating studies it is possible to assign consecutive lines either to different images, yielding a multiphase sequence with as many images as lines, or the lines are grouped together into segments and assigned to the same image. The overall time to acquire such a segment has to be small compared to the RR-interval of the cardiac cycle, i. e. 50 ms, and hence contains typically 8 to 16 image lines.
This strategy is called segmented data acquisition, and has the advantage of reducing overall imaging time for cardiac images so that they can be acquired within a breath hold, but obviously decreasing the temporal resolution of each individual image.
This method shows dynamic processes, such as the ejection of blood out of the heart into the aorta, by means of fast imaging and displaying the resulting images in a sequential-loop, the impression of a real-time movie is generated. Ejection fractions and stroke volumes calculated from these cine MRI images in different cardiac axes have been shown to be more accurate than any other imaging modality.
See also Cardiac Gating.
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| Flow |  |
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Flow phenomena are intrinsic processes in the human body. Organs like the heart, the brain or the kidneys need large amounts of blood and the blood flow varies depending on their degree of activity. Magnetic resonance imaging has a high sensitivity to flow and offers accurate, reproducible, and noninvasive methods for the quantification of flow. MRI flow measurements yield information of blood supply of of various vessels and tissues as well as cerebro spinal fluid movement.
Flow can be measured and visualized with different pulse sequences (e.g. phase contrast sequence, cine sequence, time of flight angiography) or contrast enhanced MRI methods (e.g. perfusion imaging, arterial spin labeling).
The blood volume per time (flow) is measured in: cm3/s or ml/min. The blood flow-velocity decreases gradually dependend on the vessel diameter, from approximately 50 cm per second in arteries with a diameter of around 6 mm like the carotids, to 0.3 cm per second in the small arterioles.
Different flow types in human body:
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Behaves like stationary tissue, the signal intensity depends on T1, T2 and PD = Stagnant flow |
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Flow with consistent velocities across a vessel = Laminar flow |
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Laminar flow passes through a stricture or stenosis (in the center fast flow, near the walls the flow spirals) = Vortex flow |
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Flow at different velocities that fluctuates = Turbulent flow |
See also Flow Effects, Flow Artifact, Flow Quantification, Flow Related Enhancement, Flow Encoding, Flow Void, Cerebro Spinal Fluid Pulsation Artifact, Cardiovascular Imaging and Cardiac MRI.
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MRI Resources |
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| Delay Alternating with Nutation for Tailored Excitation |  |
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(DANTE) A technique used to place a saturation band over e.g. the myocardium. This technique includes spatial modulation of magnetization complementary and delays alternating with nutations for tailored excitation, followed by the application of a cine or real-time imaging. Because the saturated magnetization pattern moves with the atoms of the tissue, the cardiac motion shows up as deformations in the grid pattern in the resulting imaging sequence.
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| Myocardial Late Enhancement | |
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(LE) Myocardial late enhancement in contrast enhanced cardiac MRI has the ability to precisely delineate myocardial scar associated with coronary artery disease. Viability imaging implies evaluating infarcted myocardium to see whether there is enough viable tissue available for revascularization. The reversal of myocardial dysfunction is particularly relevant in patients with depressed ventricular function because revascularization improves long-term survival. In comparison to SPECT and PET imaging, myocardial late enhancement MRI demonstrates areas of delayed enhancement exactly in correlation with the infarcted region.
Viability on cardiac MRI (CMR) is based on the fact that all infarcts enhance vividly 10-15 minutes after the administration of intravenous paramagnetic contrast agents. This enhancement represents the accumulation of gadolinium in the extracellular space, due to the loss of membrane integrity in the infarcted tissue. This phenomenon of delayed hyperenhancement has been proven to correlate with the actual extent of the infarct.
MRI myocardial late enhancement can quantify the size, location and transmural extent of the infarct. If the transmural extent of the infarct (region of enhancement on MRI) is less than 50% of the wall thickness, there will be improved contractility in that segment following revascularization. In areas of hypokinesia, if there is a rim of "black" or non-infarcted myocardium that is not contracting well, it indicates the presence of hibernating myocardium, which is likely to improve after revascularization of the artery supplying that particular territory.
The total duration of a myocardial late enhancement MR imaging protocol for viability is approximately 30 minutes, including scout images, first-pass images, cine images in two planes, and delayed myocardial enhancement images. In order to assess viable myocardium, the gadolinium contrast agent is injected at a dose of 0.15 to 0.2 mmol/kg. After about 10 minutes, short axis and long axis views (see cardiac axes) of the heart are obtained using an inversion prepared ECG gated gradient echo sequence. The inversion pulse is adjusted to suppress normal myocardium. Areas of nonviable myocardium retain extremely high signal intensity, black areas show normal tissue.
For Ultrasound Imaging (USI) see Myocardial Contrast Echocardiography at US-TIP.com. |
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| Signa 3.0T™ | |
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(Signa VH/i 3.0T)
With GE Healthcare
leading-edge technology in ultra-high-field imaging. The 3 T VH/i provides a platform for advanced applications in radiology, cardiology, psychology and psychiatry. Real-time image processing lets you acquire multislice whole brain images and map brain functions for research or surgical planning. And the 3 T Signa VH/i is flexible enough to provide clinicians with high performance they require. It can provide not only outstanding features in brain scanning and neuro-system research, but also a wide range of use in scanning breasts, extremities, the spine and the cardiovascular systems.
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Device Information and Specification |
| CLINICAL APPLICATION |
Whole body
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| CONFIGURATION |
Cylindrical - high homogeneity |
| SURFACE COILS |
T/R quadrature head, T/R quadrature body, T/R phased array extremity (opt) |
| SPECTROSCOPY |
Single voxel & 2D CSI proton |
| SYNCHRONIZATION |
ECG/peripheral, respiratory gating |
| PULSE SEQUENCES |
SE, IR, 2D/3D GRE, FGRE, RF-spoiled GRE, FSE, Angiography: 2D/3D TOF, 2D/3D phase contrast vascular |
| IMAGING MODES |
Single, multislice, volume study, fast scan, multi slab, cine, localizer |
| SINGLE SLICE |
100 Images/sec with Reflex100 |
| MULTISLICE |
100 Images/sec with Reflex100 |
| FOV |
1 cm to 40 cm continuous |
| SLICE THICKNESS |
2D 0.5-100mm in 0.1mm incremental |
| DISPLAY MATRIX |
1280 x 1024 |
| MEASURING MATRIX |
128x512 steps 32 phase encode |
| PIXEL INTENSITY |
256 gray levels |
| SPATIAL RESOLUTION |
0.02mm |
| MAGNET TYPE |
Superconducting |
BORE DIAMETER
or W x H |
55cm |
| MAGNET WEIGHT |
15102 kg incl. cryogen's |
| H*W*D |
260cm x 238cm x 265cm |
| POWER REQUIREMENTS |
480 or 380/415, 3 phase ||
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| COOLING SYSTEM TYPE |
Closed-loop water-cooled grad. |
| CRYOGEN USE |
Less than 0.14 L/hr liquid He |
| FIELD STRENGTH |
3 T |
| STRENGTH |
40mT/m |
| 5-GAUSS FRINGE FIELD, radial/axial |
5.4 m x 3.2 m |
| SHIMMING |
Superconductive + hi order active |
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MRI Resources |
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