𝔖 Bobbio Scriptorium
✦   LIBER   ✦

The effects of linearly increasing flip angles on 3D inflow MR angiography

✍ Scribed by Thomas Nägele; Uwe Klose; Wolfgang Grodd; Dirk Petersen; Jaroslav Tintera

Publisher
John Wiley and Sons
Year
1994
Tongue
English
Weight
601 KB
Volume
31
Category
Article
ISSN
0740-3194

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

As recently demonstrated, spin saturation effects in 3D time‐of‐flight (TOF) MR angiography (MRA) can be reduced by using RF pulses with linearly increasing flip angles (ramp pulses) in the main direction of flow. We developed a model for calculating the signal distribution of proton flow within the excitation volume (slab) for different ramp slopes and compared the results with the measured distribution for the lower‐leg arteries. The ramp pulses were generated using the Fourier transformation of the desired excitation profiles. With a bandwidth of 6 kHz and a pulse length of 2.56 ms satisfactory ramps with variable slopes were generated and applied in a standard flow‐compensated 3D FISP sequence. The effects on the signal distribution in the resulting angiograms of the lower limbs revealed a considerable reduction of saturation losses in agreement with the calculations. Calculated optimal ramp slopes are provided for flow velocities ranging from 5 to 50 cm/s and excitation volumes ranging from 5 to 25 cm.

📜 SIMILAR VOLUMES

Effects of cardiac motion on 3D contrast
Effects of cardiac motion on 3D contrast-enhanced MR angiography of the carotid arteries
✍ Dean Jeffery; Derek J. Emery; Alan H. Wilman 📂 Article 📅 2011 🏛 John Wiley and Sons 🌐 English ⚖ 328 KB 👁 1 views

## Abstract ## Purpose: To determine the effect of cardiac‐related carotid artery motion on the image quality of 3D contrast‐enhanced MR angiography (CEMRA) in patients presenting with suspected carotid artery disease. ## Materials and Methods: Twenty patients with suspected carotid artery disea

Evaluation of the effects of intravascul
Evaluation of the effects of intravascular MR contrast media (gadolinium dendrimer) on 3D time of flight magnetic resonance angiography of the body
✍ Michael W. Bourne; Larry Margerun; Nola Hylton; Brian Campion; Jan-Ji Lai; Nikit 📂 Article 📅 1996 🏛 John Wiley and Sons 🌐 English ⚖ 785 KB

## Abstract The aims of this preliminary study were to establish the efficacy and minimum effective dose of TG~5~(FdDO3A)~52~ gadolinium dendrimer for contrast‐enhanced, three‐dimensional (3D) time of flight (TOF) magnetic resonance angiography (MRA) of the body. In a dose ranging study in eight ra

Effects of RF inhomogeneity at 3.0T on r
Effects of RF inhomogeneity at 3.0T on ramped RF excitation: Application to 3D time-of-flight MR angiography of the intracranial arteries
✍ Amir M. Eissa; Alan H. Wilman 📂 Article 📅 2007 🏛 John Wiley and Sons 🌐 English ⚖ 463 KB

## Abstract ## Purpose To demonstrate the effects of inherent RF inhomogeneity on ramped RF excitation at 3.0T, and to introduce a simple correction for improving visualization of distal intracranial arteries in three‐dimensional time‐of‐flight MR angiography (3D‐TOF‐MRA). ## Materials and Method

The effect of blood inflow and B1-field
The effect of blood inflow and B1-field inhomogeneity on measurement of the arterial input function in axial 3D spoiled gradient echo dynamic contrast-enhanced MRI
✍ Caleb Roberts; Ross Little; Yvonne Watson; Sha Zhao; David L. Buckley; Geoff J. 📂 Article 📅 2010 🏛 John Wiley and Sons 🌐 English ⚖ 812 KB

## Abstract A major potential confound in axial 3D dynamic contrast‐enhanced magnetic resonance imaging studies is the blood inflow effect; therefore, the choice of slice location for arterial input function measurement within the imaging volume must be considered carefully. The objective of this s