Encoding strategies for three‐direction phase‐contrast MR imaging of flow

Pelc, Norbert J.; Bernstein, Matt A.; Shimakawa, Ann; Glover, Gary H.

doi:10.1002/jmri.1880010404

Cited by 397 publications

(322 citation statements)

References 14 publications

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“…17 Total CBF was quantified by PC MRI, 8 a standard technique for measuring blood flow velocity in the SSS, from which CBF was calculated by multiplying average velocity in the vessel by the cross-sectional area. As the SSS is known to drain 45% of the total brain blood volume, 18,19 it is Figure 1.…”

Section: Magnetic Resonance Imaging Measurementsmentioning

confidence: 99%

Cerebral Oxygen Metabolism in Neonates with Congenital Heart Disease Quantified by MRI and Optics

Jain

Buckley

Licht

et al. 2013

J Cereb Blood Flow Metab

168

192

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Neonatal congenital heart disease (CHD) is associated with altered cerebral hemodynamics and increased risk of brain injury. Two novel noninvasive techniques, magnetic resonance imaging (MRI) and diffuse optical and correlation spectroscopies (diffuse optical spectroscopy (DOS), diffuse correlation spectroscopy (DCS)), were employed to quantify cerebral blood flow (CBF) and oxygen metabolism (CMRO 2 ) of 32 anesthetized CHD neonates at rest and during hypercapnia. Cerebral venous oxygen saturation (S v O 2 ) and CBF were measured simultaneously with MRI in the superior sagittal sinus, yielding global oxygen extraction fraction (OEF) and global CMRO 2 in physiologic units. In addition, microvascular tissue oxygenation (StO 2 ) and indices of microvascular CBF (BFI) and CMRO 2 (CMRO 2i ) in the frontal cortex were determined by DOS/DCS. Median resting-state MRI-measured OEF, CBF, and CMRO 2 were 0.38, 9.7 mL/minute per 100 g and 0.52 mL O 2 /minute per 100 g, respectively. These CBF and CMRO 2 values are lower than literature reports for healthy term neonates (which are sparse and quantified using different methods) and resemble values reported for premature infants. Keywords: cerebral blood flow; cerebral hemodynamics; diffuse optics; MRI; near-infrared spectroscopy; neonatal ischemia INTRODUCTION Congenital heart disease (CHD) affects B35,000 neonates each year in the United States. These patients suffer both short-and long-term neurologic sequelae. Periventricular leukomalacia is the most common cerebral injury found in this population. This type of injury is characterized by focal necrosis in the periventricular white matter, and it is associated with pyknotic glial nuclei and reactive gliosis. 1,2 During the early stages of brain development, the oligodendrocyte (brain glial cells) precursors are metabolically very active and highly susceptible to injury from reduced blood flow and oxygen delivery. Hence, hypoxiaischemia has been implicated as a major cause of this injury in CHD neonates.Periventricular leukomalacia leads to impaired myelination and has been linked to worse neurodevelopmental outcomes in premature infants and postulated to cause (at least in part) the impaired cognition and cerebral palsy commonly seen in this cohort of infants with CHD. 3,4 Quantification of the hemodynamic and metabolic state of these neonates via measurements of cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen consumption (CMRO 2 ) should provide valuable information toward understanding the interaction between cardiac pathophysiology and subsequent cerebral health. Potentially, such new knowledge could help predict and prevent adverse outcomes.

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Section: Magnetic Resonance Imaging Measurementsmentioning

confidence: 99%

Cerebral Oxygen Metabolism in Neonates with Congenital Heart Disease Quantified by MRI and Optics

Jain

Buckley

Licht

et al. 2013

J Cereb Blood Flow Metab

168

192

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“…The sequence used was a segmented 3D TFE (Turbo Field Echo) radiofrequency-and gradient-spoiled sequence with a Hadamard four-point velocity encoding strategy using a maximal gradient strength of 20 mT m -1 and a gradient slew rate of 100 mT m -1 ms -1 (29,30). Further sequence parameters were:…”

Section: Data Acquisitionmentioning

confidence: 99%

Accuracy of four-dimensional phase-contrast velocity mapping for blood flow visualizations: a phantom study

et al. 2013

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Background Time-resolved three-dimensional, three-directional phase-contrast magnetic resonance velocity mapping (4D PC-MRI) is a powerful technique to depict dynamic blood flow patterns in the human body. However, the impact of phase background effects on flow visualizations has not been thoroughly studied previously, and it has not yet been experimentally demonstrated to what degree phase offsets affect flow visualizations and create errors such as inaccurate particle traces. Purpose To quantify background phase offsets and their subsequent impact on particle trace visualizations in a 4D PC-MRI sequence. Additionally, we sought to investigate to what degree visualization errors are reduced by background phase correction. Material and Methods A rotating phantom with a known velocity field was used to quantify background phase of 4D PC-MRI sequences accelerated with SENSE as well as different k-t BLAST speed-up factors. The deviation in end positions between particle traces in the measured velocity fields were compared before and after the application of two different phase correction methods. Results Phantom measurements revealed background velocity offsets up to 7 cm/s (7% of velocity encoding sensitivity) in the central slice, increasing with distance from the center. Background offsets remained constant with increasing k-t BLAST speed-up factors. End deviations of up to 5.3 mm (1.8 voxels) in the direction perpendicular to the rotating disc were found between particle traces and the seeding plane of the traces. Phase correction by subtraction of the data from the stationary phantom reduced the average deviation by up to 56%, while correcting the data-set with a first-order polynomial fit to stationary regions decreased average deviation up to 78%. Conclusion Pathline visualizations can be significantly affected by background phase errors, highlighting the importance of dedicated and robust phase correction methods. Our results show that pathline deviation can be substantial if adequate phase background errors are not minimized.

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“…1): 1) the midsagittal slice to view the major CSF pathways; 2) an axial slice across the middle of the LV to investigate the LV volumetric change; 3) an axial slice across the junction between the AS and V4 to measure the CSF flow rate; 4) a midcoronal slice at V3 to measure the CSF flow rate; and 5) an axial slice nearly perpendicular to the basilar artery in the prepontine region to measure the blood flow rate. For the first two locations, velocities in all three directions were measured to investigate the flow dynamics based on the simple four-point method (11). Images at 16 equidistant time frames were reconstructed per cardiac cycle.…”

Section: Data Acquisition and Velocity Calculationmentioning

confidence: 99%

“…For the latter three locations, only the velocity perpendicular to the slice of interest was measured so that data could be collected with a higher temporal resolution. The simple two-point method was used to calculate the velocity (11). Images at 32 equidistant time frames were reconstructed per cardiac cycle.…”

Section: Data Acquisition and Velocity Calculationmentioning

confidence: 99%

Dynamics of lateral ventricle and cerebrospinal fluid in normal and hydrocephalic brains

Zhu

Xenos

Linninger

et al. 2006

Magnetic Resonance Imaging

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Purpose: To develop quantitative MRI techniques to measure, model, and visualize cerebrospinal fluid (CSF) hydrodynamics in normal subjects and hydrocephalic patients. Materials and Methods:Velocity information was obtained using time-resolved (CINE) phase-contrast imaging of different brain regions. A technique was developed to measure the change of lateral ventricle (LV) size. The temporal relationships between the LV size change, CSF movement, and blood flow could then be established. The data were incorporated into a first-principle CSF hydrodynamic model. The model was then used to generate specific predictions about CSF pressure relationships. To better-visualize the CSF flow, a color-coding technique based on linear transformations was developed that represents the magnitude and direction of the velocity in a single cinematic view. Results:The LV volume change of the eight normal subjects was 0.901 Ϯ 0.406%. Counterintuitively, the LV decreases as the choroid plexus expands, so that they act together to produce the CSF oscillatory flow. The amount of oscillatory flow volume is 21.7 Ϯ 10.6% of the volume change of the LV from its maximum to its minimum. Conclusion:The quantification and visualization techniques, together with the mathematical model, provide a unique approach to understanding CSF flow dynamics.

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Encoding strategies for three‐direction phase‐contrast MR imaging of flow

Cited by 397 publications

References 14 publications

Cerebral Oxygen Metabolism in Neonates with Congenital Heart Disease Quantified by MRI and Optics

Cerebral Oxygen Metabolism in Neonates with Congenital Heart Disease Quantified by MRI and Optics

Accuracy of four-dimensional phase-contrast velocity mapping for blood flow visualizations: a phantom study

Dynamics of lateral ventricle and cerebrospinal fluid in normal and hydrocephalic brains

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