scholarly journals Mapping Brain Function Using a 30-Day Interval between Baseline and Activation: A Novel Arterial Spin Labeling fMRI Approach

2010 ◽  
Vol 30 (10) ◽  
pp. 1721-1733 ◽  
Author(s):  
Ajna Borogovac ◽  
Christian Habeck ◽  
Scott A Small ◽  
Iris Asllani
Keyword(s):  
Brain Function ◽  
Arterial Spin Labeling ◽  
Signal To Noise Ratio ◽  
Spin Labeling ◽  
Flow Density ◽  
Functional Changes ◽  
Young Subjects ◽  
Arterial Transit Time ◽  
Acute Changes

By comparing hemodynamic signals acquired immediately before and during activation, functional magnetic resonance imaging (fMRI) is well suited for mapping acute changes in brain function. However, it remains unclear whether fMRI can map functional changes over longer periods. Here, we address this issue by empirically testing the feasibility of arterial spin labeling (ASL) fMRI to detect changes in cerebral blood flow (CBF) with baseline and task separated by 1 month. To increase the sensitivity of the method, we applied an algorithm that yielded flow density (CBFd) images that were independent of tissue content. To increase the accuracy, we developed a technique that generated arterial transit time at each voxel, independently. Results showed that activation changes in CBFd during the same session were statistically the same as across 30 days. The activation CBFd on day-30 was 34% (motor) and 25% (visual) higher than the respective baselines of 83 and 107 mL/100 g/min obtained on day-1. Furthermore, the signal-to-noise ratio of the CBFd measurement was 2.1 and 2.9 times higher than that of the conventional CBF for within-subject and across-subjects comparisons, respectively ( n=9 healthy young subjects). Taken together, these results indicate that CBFd measure could be better suited than net CBF to map long-term changes in brain function.

Comparison of long-labeled pseudo-continuous arterial spin labeling (ASL) features between young and elderly adults: special reference to parameter selection

2016 ◽  
Vol 58 (1) ◽  
pp. 84-90 ◽  
Author(s):  
Yasuhiro Fujiwara ◽  
Tsuyoshi Matsuda ◽  
Masayuki Kanamoto ◽  
Tatsuro Tsuchida ◽  
Kazunobu Tsuji ◽  
...  
Keyword(s):  
Arterial Spin Labeling ◽  
Signal To Noise Ratio ◽  
The Elderly ◽  
Spin Labeling ◽  
In Vivo Studies ◽  
Cortical Region ◽  
Elderly Adult ◽  
Imaging Parameters ◽  
Arterial Transit Time

Background The signal intensity obtained by arterial spin labeling (ASL) depends not only on perfusion signal, but also on arterial transit time (ATT). Although ATT has a more significant effect on accurate regional cerebral blood flow (CBF) calculations, the multiple post-labeling delay (PLD) approach is difficult to use in routine examinations. Purpose To optimize imaging parameters for labeling duration (LD) and PLD and to confirm their validity in long-labeled pseudo-continuous ASL. Material and Methods The perfusion signal was simulated in four LDs and theoretical signal-to-noise ratio efficiency (SNReff) was calculated. In vivo studies were performed on a 3.0 T magnetic resonance imaging (MRI) scanner and 15 volunteers were categorized into either the young or elderly adult groups. We compared the differences in CBF values with or without ATT correction. Results Regarding signal simulation, perfusion signal increased with the length of LD. SNReff also improved with LD, but SNReff plateaued at an LD of 3.0 s. As for the in vivo study, SNR linearly increased along with the LD. The CBF differences with the correction of ATT were larger in the elderly adult group. This trend was most prominent in the longer ATT area in the occipital cortical region. Conclusion A combination of imaging settings of LD = 3.5 s and PLD = 2.0 s were suggested as optimal imaging parameters for allowing acceptable CBF quantification and sufficient SNR in both young and elderly individuals.

scholarly journals Mapping Long-Term Functional Changes in Cerebral Blood Flow by Arterial Spin Labeling

PLoS ONE ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. e0164112 ◽  
Author(s):  
Tracy Ssali ◽  
Udunna C. Anazodo ◽  
Yves Bureau ◽  
Bradley J. MacIntosh ◽  
Matthias Günther ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Spin Labeling ◽  
Spin Labeling ◽  
Functional Changes

scholarly journals Reliability and Reproducibility of Hadamard Encoded Pseudo-Continuous Arterial Spin Labeling in Healthy Elderly

2021 ◽  
Vol 15 ◽  
Author(s):  
Katja Neumann ◽  
Martin Schidlowski ◽  
Matthias Günther ◽  
Tony Stöcker ◽  
Emrah Düzel
Keyword(s):  
Arterial Spin Labeling ◽  
Signal To Noise Ratio ◽  
Brain Perfusion ◽  
Spin Labeling ◽  
Healthy Elderly ◽  
Perfusion Studies ◽  
Coefficients Of Variation ◽  
Arterial Transit Time ◽  
Magnetic Resonance Imaging Mri ◽  
Continuous Arterial Spin Labeling

The perfusion parameters cerebral blood flow (CBF) and arterial transit time (ATT) measured with arterial spin labeling (ASL) magnetic resonance imaging (MRI) provide valuable essentials to assess the integrity of cerebral tissue. Brain perfusion changes, due to aging, an intervention, or neurodegenerative diseases for example, could be investigated in longitudinal ASL studies with reliable ASL sequences. Generally, pseudo-continuous ASL (pCASL) is preferred because of its larger signal-to-noise ratio (SNR) compared to pulsed ASL (PASL) techniques. Available pCASL versions differ regarding their feature details. To date only little is known about the reliability and reproducibility of CBF and ATT measures obtained with the innovative Hadamard encoded pCASL variant, especially if applied on participants in old age. Therefore, we investigated an in-house developed Hadamard encoded pCASL sequence on a group of healthy elderly at two different 3 Tesla Siemens MRI systems (Skyra and mMR Biograph) and evaluated CBF and ATT reliability and reproducibility for several regions-of-interests (ROI). Calculated within-subject coefficients of variation (wsCV) demonstrated an excellent reliability of perfusion measures, whereas ATT appeared to be even more reliable than CBF [e.g., wsCV(CBF) = 2.9% vs. wsCV(ATT) = 2.3% for a gray matter (GM) ROI on Skyra system]. Additionally, a substantial agreement of perfusion values acquired on both MRI systems with an inter-session interval of 78 ± 17.6 days was shown by high corresponding intra-class correlation (ICC) coefficients [e.g., ICC(CBF) = 0.704 and ICC(ATT) = 0.754 for a GM ROI]. The usability of this novel Hadamard encoded pCASL sequence might improve future follow-up perfusion studies of the aging and/or diseased brain.

Arterial spin labeling magnetic resonance imaging at short post-labeling delay reflects cerebral perfusion pressure verified by oxygen-15-positron emission tomography in cerebrovascular steno-occlusive disease

2020 ◽  
pp. 028418512091711
Author(s):  
Hiroshi Itagaki ◽  
Yasuaki Kokubo ◽  
Kanako Kawanami ◽  
Shinji Sato ◽  
Yuki Yamada ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Arterial Spin Labeling ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Spin Labeling ◽  
Occlusive Disease ◽  
Resonance Imaging ◽  
Arterial Transit Time ◽  
The Right

Background Arterial transit time correction by data acquisition with multiple post-labeling delays (PLDs) or relatively long PLDs is expected to obtain more accurate imaging in cases of the cerebrovascular steno-occlusive disease. However, there have so far been no reports describing the significance of arterial spin labeling (ASL) images at short PLDs regarding the evaluation of cerebral circulation in ischemic cerebrovascular disease. Purpose To clarify the role of short-PLD ASL in cerebrovascular steno-occlusive disease. Material and Methods Fifty-three patients with cerebrovascular steno-occlusive disease were included in this study. All patients underwent ASL magnetic resonance imaging and 15O-PET within two days of each modality. To compare the ASL findings with each parameter of PET, the right-to-left (R/L) ratio, defined as the right middle cerebral artery (MCA) value/left MCA value, was calculated. Results There is a significant correlation between the ASL images at a short PLD and the ratio of cerebral blood flow and cerebral blood volume by 15O-PET, which may accurately reflect the cerebral perfusion pressure. A receiver operating characteristic curve analysis indicated that ASL images at PLD 1000 and 1500 ms were more accurate than at PLD 2000–3000 ms for the detection of a ≥10% change in the PET cerebral blood flow. Conclusion ASL images at shorter PLDs may be useful at least as a screening modality to detect the changes in the cerebral circulation in cerebrovascular steno-occlusive disease. We must evaluate ASL images at multiple PLDs while considering the arterial transit time of each case at present.

scholarly journals The spatial coefficient of variation in arterial spin labeling cerebral blood flow images

2017 ◽  
Vol 37 (9) ◽  
pp. 3184-3192 ◽  
Author(s):  
Henri JMM Mutsaerts ◽  
Jan Petr ◽  
Lena Václavů ◽  
Jan W van Dalen ◽  
Andrew D Robertson ◽  
...  
Keyword(s):  
Blood Flow ◽  
Spatial Distribution ◽  
Cerebral Blood Flow ◽  
Coefficient Of Variation ◽  
Arterial Spin Labeling ◽  
Spin Labeling ◽  
Maximum Relative Error ◽  
Signal Distribution ◽  
Arterial Transit Time ◽  
Age And Sex

Macro-vascular artifacts are a common arterial spin labeling (ASL) finding in populations with prolonged arterial transit time (ATT) and result in vascular regions with spuriously increased cerebral blood flow (CBF) and tissue regions with spuriously decreased CBF. This study investigates whether there is an association between the spatial signal distribution of a single post-label delay ASL CBF image and ATT. In 186 elderly with hypertension (46% male, 77.4 ± 2.5 years), we evaluated associations between the spatial coefficient of variation (CoV) of a CBF image and ATT. The spatial CoV and ATT metrics were subsequently evaluated with respect to their associations with age and sex – two demographics known to influence perfusion. Bland–Altman plots showed that spatial CoV predicted ATT with a maximum relative error of 7.6%. Spatial CoV was associated with age (β = 0.163, p = 0.028) and sex (β = −0.204, p = 0.004). The spatial distribution of the ASL signal on a standard CBF image can be used to infer between-participant ATT differences. In the absence of ATT mapping, the spatial CoV may be useful for the clinical interpretation of ASL in patients with cerebrovascular pathology that leads to prolonged transit of the ASL signal to tissue.

scholarly journals Arterial Spin Labeling (ASL) fMRI: Advantages, Theoretical Constrains and Experimental Challenges in Neurosciences

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Ajna Borogovac ◽  
Iris Asllani
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Function ◽  
Arterial Spin Labeling ◽  
Spin Labeling ◽  
Absolute Quantification ◽  
Full Potential ◽  
Neuroscience Research ◽  
Essential Parameter ◽  
The Brain

Cerebral blood flow (CBF) is a well-established correlate of brain function and therefore an essential parameter for studying the brain at both normal and diseased states. Arterial spin labeling (ASL) is a noninvasive fMRI technique that uses arterial water as an endogenous tracer to measure CBF. ASL provides reliable absolute quantification of CBF with higher spatial and temporal resolution than other techniques. And yet, the routine application of ASL has been somewhat limited. In this review, we start by highlighting theoretical complexities and technical challenges of ASL fMRI for basic and clinical research. While underscoring the main advantages of ASL versus other techniques such as BOLD, we also expound on inherent challenges and confounds in ASL perfusion imaging. In closing, we expound on several exciting developments in the field that we believe will make ASL reach its full potential in neuroscience research.

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