scholarly journals Simultaneous Perfusion and Permeability Measurements Using Combined Spin- and Gradient-Echo MRI

2013 ◽  
Vol 33 (5) ◽  
pp. 732-743 ◽  
Author(s):  
Heiko Schmiedeskamp ◽  
Jalal B Andre ◽  
Matus Straka ◽  
Thomas Christen ◽  
Seema Nagpal ◽  
...  
Keyword(s):  
Cerebral Blood Volume ◽  
Spin Echo ◽  
Mean Transit Time ◽  
Brain Perfusion ◽  
Gradient Echo ◽  
Planar Imaging ◽  
Imaging Sequence ◽  
Tissue Characteristics ◽  
Echo Planar ◽  
Good Agreement

The purpose of this study was to estimate magnetic resonance imaging-based brain perfusion parameters from combined multiecho spin-echo and gradient-echo acquisitions, to correct them for T1-, T2-, and T∗2-related contrast agent (CA) extravasation effects, and to simultaneously determine vascular permeability. Perfusion data were acquired using a combined multiecho spin- and gradient-echo (SAGE) echo-planar imaging sequence, which was corrected for CA extravasation effects using pharmacokinetic modeling. The presented method was validated in simulations and brain tumor patients, and compared with uncorrected single-echo and multiecho data. In the presence of CA extravasation, uncorrected single-echo data resulted in underestimated CA concentrations, leading to underestimated single-echo cerebral blood volume ( CBV) and mean transit time ( MTT). In contrast, uncorrected multiecho data resulted in overestimations of CA concentrations, CBV, and MTT. The correction of CA extravasation effects resulted in CBV and MTT estimates that were more consistent with the underlying tissue characteristics. Spin-echo perfusion data showed reduced large-vessel blooming effects, facilitating better distinction between increased CBV due to active tumor progression and elevated CBV due to the presence of cortical vessels in tumor proximity. Furthermore, extracted permeability parameters were in good agreement with elevated T1-weighted postcontrast signal values.

scholarly journals Evaluation of Imaging Schemes for Pulsed Arterial Spin Labelling of the Human Kidney Cortex

2018 ◽  
Author(s):  
Charlotte E. Buchanan ◽  
Eleanor F. Cox ◽  
Susan T. Francis
Keyword(s):  
Spin Echo ◽  
Human Kidney ◽  
Echo Planar Imaging ◽  
Arterial Spin Labelling ◽  
Kidney Cortex ◽  
Gradient Echo ◽  
Planar Imaging ◽  
Spatial Coverage ◽  
Echo Planar ◽  
Spin Labelling

Purpose: A number of imaging readout schemes have been proposed for renal arterial spin labelling (ASL) to quantify kidney cortex perfusion, including gradient echo based methods of balanced fast field echo (bFFE) and gradient-echo echo-planar imaging (GE-EPI), or spin echo based schemes of spin-echo echo planar imaging (SE-EPI) and turbo spin-echo (TSE). Here, we compare these imaging schemes to evaluate the optimal imaging scheme for pulsed ASL (PASL) assessment of human kidney cortex perfusion at 3 T. Methods: Ten healthy volunteers with normal renal function were scanned using each 2D multislice imaging scheme, in combination with a respiratory triggered FAIR (flow-sensitive alternating inversion recovery) ASL scheme on a 3 T Philips Achieva scanner. All volunteers returned for a second identical scan session within two weeks of the first scan session. Comparisons were made between the imaging schemes in terms of perfusion weighted image (PWI) signal-to-noise ratio (SNR) and perfusion quantification, temporal SNR (tSNR), spatial coverage, and repeatability. Results: For each imaging scheme, renal cortex perfusion was calculated (bFFE: 276 ± 29 mL/100 g/min, GE-EPI: 222 ± 18 mL/100 g/min, SE-EPI: 201 ± 36 mL/100 g/min, TSE: 200 ± 20 mL/100 g/min). Perfusion was found to be higher for GE based readouts compared to SE based readouts, with significantly higher measured perfusion for the bFFE readout compared to all other schemes (P < 0.05), attributed to the greater vascular signal present. Despite the PWI-SNR being significantly lower for SE-EPI compared to all other schemes (P < 0.05), the SE-EPI readout gave the highest tSNR and was found to be the most reproducible scheme for the assessment of kidney cortex, with a CoV of 17.2%, whilst minimizing variability of the perfusion weighted signal across slices for whole kidney perfusion assessment. Conclusion: For the assessment of kidney cortex perfusion, SE-EPI provides optimal tSNR, minimal variability across slices and repeatable data acquired in a short scan time with low specific absorption rate. 

Spinal cord functional MRI at 3 T: Gradient echo echo-planar imaging versus turbo spin echo

NeuroImage ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 288-296 ◽  
Author(s):  
C.J.C. Bouwman ◽  
J.T. Wilmink ◽  
W.H. Mess ◽  
W.H. Backes
Keyword(s):  
Spinal Cord ◽  
Functional Mri ◽  
Spin Echo ◽  
Echo Planar Imaging ◽  
Turbo Spin Echo ◽  
Gradient Echo ◽  
Planar Imaging ◽  
Turbo Spin ◽  
Echo Planar
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