2026-09-19T08:50:38Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/386732022-01-13T07:54:29Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Richard D. Hoge and Elfar Adalsteinsson.
Bolar, Divya Sanam
Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
2007-08-29T20:42:21Z
2007-08-29T20:42:21Z
2007
2007
http://hdl.handle.net/1721.1/38673
163945456
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
Includes bibliographical references (p. 28-29).
Arterial spin labeling (ASL) is the only non-invasive magnetic resonance imaging (MRI) technique that allows absolute quantification of cerebral blood flow (CBF). It involves using radiofrequency pulses designed to invert the spins of water in arterial blood, effectively creating a magnetic bolus. This inverted blood can be considered an endogenous contrast agent; imaging as it traverses the vascular tree allows CBF measurements. Such types of experiments are especially useful for functional neuro-activation studies and in settings of neuropathology. Two flavors of ASL exist: continuous ASL and pulsed ASL. Pulsed ASL has the advantage of not requiring specialized imaging hardware, and can be performed using standard clinical scanners found in most hospitals. Pulsed ASL techniques, however, may yield inaccurate perfusion values and diminished perfusion sensitivity if appropriate labeling parameters are not chosen, particularly during global challenges such as hypercapnia. In this study, the accuracy of QUIPSS II (Quantitative Imaging of Perfusion using a Single Subtraction - second version) ASL for measuring flow changes during a global flow perturbation (hypercapnia) was assessed.
(Cont.) Multiple inversion time ASL experiments were performed to examine bolus delivery dynamics under conditions of normocapnia and hypercapnia and at variable inversion band thicknesses. Tag delivery (inflow) curves revealed that typical published parameter values can cause substantial perfusion error during global challenges and render perfusion increases nearly undetectable. Theoretical criteria for choosing optimal QUIPSS II ASL parameter values are explored, and a multiple inversion time method for empirical determination of tag characteristics presented. Single inversion time functional experiments were subsequently performed to show that by using larger inversion band thicknesses and optimized timing parameters, perfusion accuracy and sensitivity can be substantially improved. Activation maps from block design visual cortex activation experiments and normocapnia-hypercapnia experiments support this conclusion.
by Divya Sanam Bolar.
S.M.
39 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Electrical Engineering and Computer Science.
Accuracy of pulsed arterial spin labeling magnetic resonance imaging in the human brain : tag width and timing effects
Accuracy of pulsed ASL MRI in the human brain : tag width and timing effects
Thesis
application/pdf
false
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="08da37c9-dff5-40c2-9ac1-fb28a694c82d">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>eng</Language>
<Title>Accuracy of pulsed arterial spin labeling magnetic resonance imaging in the human brain : tag width and timing effects</Title>
<Subtitle>Accuracy of pulsed ASL MRI in the human brain : tag width and timing effects</Subtitle>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2007</PublicationDate>
<Authors>
<Author>
<DisplayName>Bolar, Divya Sanam</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://dspace.mit.edu/handle/1721.1/7582</License>
<Keyword>Electrical Engineering and Computer Science.</Keyword>
<Abstract>Arterial spin labeling (ASL) is the only non-invasive magnetic resonance imaging (MRI) technique that allows absolute quantification of cerebral blood flow (CBF). It involves using radiofrequency pulses designed to invert the spins of water in arterial blood, effectively creating a magnetic bolus. This inverted blood can be considered an endogenous contrast agent; imaging as it traverses the vascular tree allows CBF measurements. Such types of experiments are especially useful for functional neuro-activation studies and in settings of neuropathology. Two flavors of ASL exist: continuous ASL and pulsed ASL. Pulsed ASL has the advantage of not requiring specialized imaging hardware, and can be performed using standard clinical scanners found in most hospitals. Pulsed ASL techniques, however, may yield inaccurate perfusion values and diminished perfusion sensitivity if appropriate labeling parameters are not chosen, particularly during global challenges such as hypercapnia. In this study, the accuracy of QUIPSS II (Quantitative Imaging of Perfusion using a Single Subtraction - second version) ASL for measuring flow changes during a global flow perturbation (hypercapnia) was assessed.</Abstract>
<Abstract>(Cont.) Multiple inversion time ASL experiments were performed to examine bolus delivery dynamics under conditions of normocapnia and hypercapnia and at variable inversion band thicknesses. Tag delivery (inflow) curves revealed that typical published parameter values can cause substantial perfusion error during global challenges and render perfusion increases nearly undetectable. Theoretical criteria for choosing optimal QUIPSS II ASL parameter values are explored, and a multiple inversion time method for empirical determination of tag characteristics presented. Single inversion time functional experiments were subsequently performed to show that by using larger inversion band thicknesses and optimized timing parameters, perfusion accuracy and sensitivity can be substantially improved. Activation maps from block design visual cortex activation experiments and normocapnia-hypercapnia experiments support this conclusion.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>