Continuous inversion angiography

Roberts, D. A.; Bolinger, Lizann; Detre, J.; Insko, Erik K.; Bergey, Philip; Leigh, Jr Js

doi:10.1002/mrm.1910290508

Cited by 15 publications

(16 citation statements)

References 17 publications

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“…The instantaneous velocity, calculated from band displacement, never fell below 10 cm/sec, and inversion was observed during every phase of the cardiac cycle. As we use a single coil to apply the inversion and observation pulses, the off-resonance effects of the inversion pulse represent a potential source of error in the measurement (21). The labeling pulse affects magnetization in the image plane directly or via cross-relaxation phenomena (22,23).…”

Section: Resultsmentioning

confidence: 99%

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Quantitative magnetic resonance imaging of human brain perfusion at 1.5 T using steady-state inversion of arterial water.

Roberts

Detre

Bolinger

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

166

106

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We report our experience using a noninvasive magnetic resonance technique for quantitative imaging of human brain perfusion at 1.5 T. This technique uses magneticafy inverted arterial water as a freely diffusible blood flow tracer. A perfusion image is calculated from magnetic resonance images acquired with and without arterial blood inversion and from an image of the apparent spin-lattice relaxation time. Single-slice perfusion maps were obtained from nine volunteers with approximately 1 x 2 x 5-mm resolution in an acquisition time of 15 min. Analysis yielded average perfusion rates of 93 + 16 ml 100 g-l-min'1 for gray matter, 38 ± 10 ml 100 g'i.min-1 for white matter, and 52 ± 8 ml 100 g'l min-I for whole brain. Significant changes in perfusion were observed during hyperventilation and breath holding. This technique may be used for quantitative measurement of perfusion in human brain without the risks and expense of methods which use exogenous tracers.

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Section: Resultsmentioning

confidence: 99%

“…1 has been shown to be valid even under partially relaxed conditions (11). We use the principle of transport-induced adiabatic fast passage (18)(19)(20)(21) to continuously invert blood entering the brain. In this approach, constant low-amplitude irradiation is applied off-resonance in the presence of a magnetic field gradient.…”

Section: Methodsmentioning

confidence: 99%

Quantitative magnetic resonance imaging of human brain perfusion at 1.5 T using steady-state inversion of arterial water.

Roberts

Detre

Bolinger

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

166

106

View full text Add to dashboard Cite

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“…The subtraction has the advantage of completely removing the background tissue signal. ASL has been proposed for MR angiographic applications in the cerebral vasculature and renal arteries (16)(17)(18)(19)(20)(21)(22)(23)(24)(25). Furthermore, spin-labeling approaches have been used to assess hemodynamic function, including infl ow in the vessels and arrival times to the tissue ( 26 ).…”

Section: Methodsmentioning

confidence: 99%

Time-resolved Vessel-selective Digital Subtraction MR Angiography of the Cerebral Vasculature with Arterial Spin Labeling

et al. 2010

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Purpose:To demonstrate an arterial spin-labeling (ASL) magnetic resonance (MR) angiographic technique that covers the entire cerebral vasculature and yields transparent-background, time-resolved hemodynamic, and vessel-specifi c information similar to that obtained with x-ray digital subtraction angiography (DSA) without the use of exogenous contrast agents. Materials and Methods:Prior institutional review board approval and written informed consent were obtained for this HIPAA-compliant study in which 12 healthy volunteers (fi ve women, seven men; age range, 21-62 years; average age, 28 years) underwent imaging. An ASL technique in which variable labeling durations are used to acquire hemodynamic infl ow information and a vessel-selective pulsed-continuous ASL technique were tested. Region-of-interest signal intensities in various vessel segments were averaged across subjects and used to quantitatively compare images. For comparison, a standard time of fl ight (TOF) acquisition was performed in the circle of Willis. Results:Infl ow temporal resolution of 200 msec was demonstrated, revealing arterial transit times of 750, 950, and 1100 msec to consecutive segments of the middle cerebral artery from distal to the circle of Willis to deep regions of the midbrain. Selective labeling resulted in an average of eightfold suppression of contralateral vessels relative to the labeled vessel. Signal-to-noise ratios and contrast-to-noise ratios on maximum intensity projection images obtained with 88-second volumetric acquisitions (60 6 15 [standard deviation] and 57 6 15, respectively) and 11-second single-projection acquisitions (19 6 5 and 17 6 5, respectively) were comparable with standard TOF acquisitions, in which a 2.7-fold longer imaging duration for a 2.6-fold lower pixel area was used. Normal variations of the vasculature were identifi ed with ASL angiography. Conclusion:ASL angiography can be used to acquire hemodynamic vessel-specifi c information similar to that obtained with x-ray DSA.q RSNA, 2010

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“…In perfusion experiments involving ASL, the perfusion flow rate is measured based on the difference of labeled and unlabeled (equilibrium or control) images acquired downstream from the inversion region (22). Under steady state conditions (with minimal transit delay and no magnetization transfer effects), the inversion efficiency can be measured within a flow ROI (e.g., arterial lumen) using:…”

Section: Measuring Inversion Efficiency With Mrimentioning

confidence: 99%

“…The errors associated with other losses (ϽBϾ) must be estimated after accounting for Ͻ␣Ͼ and ϽAϾ errors. The error contribution of variable a to function f is given by: fa f ϭ ‫ץ‬f ‫ץ‬a a f [22] where represents the standard deviation. Using the Zhernovoi model (Eq.…”

Section: Systematic Error Propagationmentioning

confidence: 99%

Quantitative analysis of adiabatic fast passage for steady laminar and turbulent flows

Gach

Kam

Reid

et al. 2002

Magnetic Resonance in Med

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Adiabatic fast passage (AFP) is used in noninvasive quantitative perfusion experiments to invert (or label) arterial spins. Continuous arterial spin labeling (CASL) experiments conducted in vivo often assume the inversion efficiency based on the labeling field and steady flow conditions, without direct verification. In practice, the labeling field used in CASL is often amplitude-and duty cycle-limited due to hardware or specific absorption rate constraints. In this study, the effects of the labeling field amplitude and duty cycle, and flow dynamics on the inversion efficiency of AFP were examined under steady flow conditions in a saline flow phantom. The experimental results were in general agreement with models based on Zhernovoi's theory except at high labeling field amplitudes, when the spin inversion times are at least half of the duration of the labeling pulse. The nonlinear relation observed between the inversion efficiency and the labeling duty cycle implies that the practice of linear derating the inversion efficiency with the labeling duty cycle may be prone to significant error. A secondary finding was that the Key words: arterial spin labeling; adiabatic fast passage; inversion efficiency; steady flow; labeling duty cycle During the last decade there has been a significant amount of development in noninvasive quantitative perfusion MRI using arterial spin labeling (ASL), with applications including the human brain (1-5) and kidney (6 -8). Continuous ASL (CASL) employs adiabatic fast passage (AFP) (9) to invert arterial spins (i.e., in blood) prior to their arrival at the tissue region of interest (ROI). The perfusion signal is directly proportional to the inversion (or labeling) efficiency of AFP within a finite inversion region and is attenuated by T 1 relaxation that occurs in transit from the inversion region to the imaging region (5,6,10). It is desirable to maximize the inversion efficiency (and, where possible, minimize T 1 relaxation in transit) since the perfusion signal is small in humans: approximately 1-2% of the image signal for gray matter (11) and 4 -6% in the renal cortex (6,7).Measurement of inversion efficiency in vivo is difficult since it may vary during the cardiac cycle (12) and the ability to synchronize the measurement with the spin labeling (or tagging) is challenging (6). Inversion efficiencies have been measured directly in the rat carotids (13) and rat descending aorta (14), human descending aorta (6) using gated acquisitions, and indirectly in the human brain (4,5,11,15,16) by varying the labeling field.However, the labeling fields and inversion efficiencies are not typically measured in every subject or study (3,17), since such measurements significantly extend the exam time and are prone to large errors. Instead, the inversion efficiency is assumed based on earlier experimental measurements or simulations. Sources of error include the assumptions of the spin hemodynamics (e.g., pulsatile vs. steady flow), relaxation times, labeling field amplitude, and the cycling of the ...

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Continuous inversion angiography

Cited by 15 publications

References 17 publications

Quantitative magnetic resonance imaging of human brain perfusion at 1.5 T using steady-state inversion of arterial water.

Quantitative magnetic resonance imaging of human brain perfusion at 1.5 T using steady-state inversion of arterial water.

Time-resolved Vessel-selective Digital Subtraction MR Angiography of the Cerebral Vasculature with Arterial Spin Labeling

Quantitative analysis of adiabatic fast passage for steady laminar and turbulent flows

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