Intracranial MRA

Wl, Davis; Warnock, SH; Hr, Harnsberger; Dl, Parker; Chen, CX

doi:10.1097/00004728-199301000-00002

Cited by 39 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A multi‐slab 4D‐flow (MS‐FLOW) sequence was developed that employed sequential excitation of thin overlapping slabs, as in 3D‐TOF 31 . A minimum‐phase Shinnar‐Le Roux pulse with a flat excitation profile was used for a highly selective excitation of each slab.…”

Section: Methodsmentioning

confidence: 99%

“…3D time-of-flight, 4D-flow, magnetization transfer, MOTSA, phase contrast slabs, as in 3D-TOF. 31 A minimum-phase Shinnar-Le Roux pulse with a flat excitation profile was used for a highly selective excitation of each slab. Each slab was acquired with undersampled, distributed spiral trajectories 32 in which spiral arms were distributed equidistantly along the slice phase-encoding direction and rotated by the golden angle between adjacent arms.…”

Section: Acquisition Overviewmentioning

confidence: 99%

See 1 more Smart Citation

Simultaneous 3D‐TOF angiography and 4D‐flow MRI with enhanced flow signal using multiple overlapping thin slab acquisition and magnetization transfer

Kim

Eisenmenger

Turski

et al. 2021

Magnetic Resonance in Med

View full text Add to dashboard Cite

Purpose: To investigate the fusion of 3D time-of-flight principles into 4D-flow MRI to enhance vessel contrast and signal without an exogenous contrast agent, enabling simultaneous in-flow based angiograms. Methods: A 4D-flow MRI technique was developed consisting of multiple overlapping slabs with intermittent magnetization transfer preparation. The scan time penalty associated with multiple slab acquisitions was mitigated by using undersampled distributed spiral trajectories and compressed sensing reconstruction. A flow phantom was used to characterize in-flow enhancement, velocity noise improvement, and flow rate measurements against the single-slab 4D-flow MRI. In a patient-volunteer cohort (n = 15), magnitude-based angiograms were radiologically evaluated against 3D time-of-flight, and velocity measurements were compared pixel-wise against single-slab and contrast-enhanced 4D-flow MRI.Results: Multiple-slab acquisitions, together with magnetization transfer preparation, substantially improved vessel signal, contrast, and vessel conspicuity in magnitude angiograms. Both clinical 3D time-of-flight and the proposed technique produced equivalent vessel depictions with no statistically significant difference (p < .1). Both techniques also produced clear depictions of brain aneurysms in all patients; however, very small vessels tended to show reduced conspicuity in the proposed technique. Velocity measurements agreed with contrast-enhanced and single-slab scans with high correlations (R 2 = 0.941-0.974) and agreements (slopes = 0.994-1.071). Slab boundary and magnetization transfer-related artifacts were not observed in velocity measurements, and velocity noise was reduced with in-flow enhancement over single-slab scans (phantom). Conclusion:The vessel signal and contrast can be improved in 4D-flow MRI without exogenous contrast agents by utilizing in-flow enhancement, efficient sampling, and compressed sensing. The in-flow enhancement also enables simultaneous 3D time-of-flight angiograms useful for flow quantification and diagnosis.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Acquisition Overviewmentioning

confidence: 99%

Simultaneous 3D‐TOF angiography and 4D‐flow MRI with enhanced flow signal using multiple overlapping thin slab acquisition and magnetization transfer

Kim

Eisenmenger

Turski

et al. 2021

Magnetic Resonance in Med

View full text Add to dashboard Cite

show abstract

“…There are two MRI techniques available for this purpose, with each performing slightly less sensitively than the gold standard, digital subtraction angiography. Three-dimensional time-of-flight angiography (3DTOF) (Davis et al, 1993) provides a non-invasive method of assessing the intracranial circulation. The technique is based on the fact that if RF pulses are applied rapidly in succession, there is little time for T1 recovery of longitudinal magnetization.…”

Section: Mri Of Acute Strokementioning

confidence: 99%

Magnetic Resonance Imaging to Visualize Stroke and Characterize Stroke Recovery: A Review

MacIntosh¹,

Graham²

2013

Front. Neurol.

View full text Add to dashboard Cite

The global burden of stroke continues to grow. Although stroke prevention strategies (e.g., medications, diet, and exercise) can contribute to risk reduction, options for acute interventions (e.g., thrombolytic therapy for ischemic stroke) are limited to the minority of patients. The remaining patients are often left with profound neurological disabilities that substantially impact quality of life, economic productivity, and increase caregiver burden. In the last decade, however, the future outlook for such patients has been tempered by movement toward the view that the brain is capable of reorganizing after injury. Many now view brain recovery after stroke as an area of scientific research with large potential for therapeutic advances, far into the future (Broderick and William, 2004). As a probe of brain anatomy, function and physiology, magnetic resonance imaging (MRI) is a non-invasive and highly versatile modality that promises to play a particularly important role in such research. Here we provide a basic review of MRI physical principles and applications for assessing stroke, looking toward the future role MRI may play in improving stroke rehabilitation methods and stroke recovery.

show abstract

“…34 Second, the RF excitation in 3D TOF is typically a ramped RF pulse to maximize vessel contrast, particularly for slower flowing vessels, 35,36 as opposed to a flat RF profile used in SWI/QSM. Third, to further improve inflow, 3D TOF is typically performed with MOTSA, 37 while SWI/QSM methods tend to use one large slab. Previous papers [35][36][37] have discussed features such as ramped RF and MOTSA being beneficial for TOF imaging by limiting arterial blood saturation through the use of only thin slabs and ramping the RF across the slab.…”

Section: Introductionmentioning

confidence: 99%

“…Third, to further improve inflow, 3D TOF is typically performed with MOTSA, 37 while SWI/QSM methods tend to use one large slab. Previous papers [35][36][37] have discussed features such as ramped RF and MOTSA being beneficial for TOF imaging by limiting arterial blood saturation through the use of only thin slabs and ramping the RF across the slab. However, the number of slices per slab also strongly affects the available signal-to-noise ratio (SNR), because SNR depends on ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi number of slices p for static tissues.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous time‐of‐flight MR angiography and quantitative susceptibility mapping with key time‐of‐flight features

De,

Grenier,

Wilman

2023

NMR in Biomedicine

View full text Add to dashboard Cite

A technique for combined time‐of‐flight (TOF) MR angiography (MRA) and quantitative susceptibility mapping (QSM) was developed with key features of standard three‐dimensional (3D) TOF acquisitions, including multiple overlapping thin slab acquisition (MOTSA), ramped RF excitation, and venous saturation. The developed triple‐echo 3D TOF‐QSM sequence enabled TOF‐MRA, susceptibility‐weighted imaging (SWI), QSM, and R2* mapping. The effects of ramped RF, resolution, flip angle, venous saturation, and MOTSA were studied on QSM. Six volunteers were scanned at 3 T with the developed sequence, conventional TOF‐MRA, and conventional SWI. Quantitative comparison of susceptibility values on QSM and normalized arterial and venous vessel‐to‐background contrasts on TOF and SWI were performed. The ramped RF excitation created an inherent phase variation in the raw phase. A generic correction factor was computed to remove the phase variation to obtain QSM without artifacts from the TOF‐QSM sequence. No statistically significant difference was observed between the developed and standard QSM sequence for susceptibility values. However, maintaining standard TOF features led to compromises in signal‐to‐noise ratio for QSM and SWI, arising from the use of MOTSA rather than one large 3D slab, higher TOF spatial resolution, increased TOF background suppression due to larger flip angles, and reduced venous signal from venous saturation. In terms of vessel contrast, veins showed higher normalized contrast on SWI derived from TOF‐QSM than the standard SWI sequence. While fast flowing arteries had reduced contrast compared with standard TOF‐MRA, no statistical difference was observed for slow flowing arteries. Arterial contrast differences largely arise from the longer TR used in TOF‐QSM over standard TOF‐MRA to accommodate additional later echoes for SWI. In conclusion, although the sequence has a longer TR and slightly lower arterial contrast, provided an adequate correction is made for ramped RF excitation effects on phase, QSM may be performed from a multiecho sequence that includes all key TOF features, thus enabling simultaneous TOF‐MRA, SWI, QSM, and R2* map computation.

show abstract

Intracranial MRA

Cited by 39 publications

References 0 publications

Simultaneous 3D‐TOF angiography and 4D‐flow MRI with enhanced flow signal using multiple overlapping thin slab acquisition and magnetization transfer

Simultaneous 3D‐TOF angiography and 4D‐flow MRI with enhanced flow signal using multiple overlapping thin slab acquisition and magnetization transfer

Magnetic Resonance Imaging to Visualize Stroke and Characterize Stroke Recovery: A Review

Simultaneous time‐of‐flight MR angiography and quantitative susceptibility mapping with key time‐of‐flight features

Contact Info

Product

Resources

About