Abstract

PURPOSE
To take into account the echo time (TE) influence on arterial spin labeling (ASL) signal when converting it in regional cerebral blood flow (rCBF). Gray matter ASL signal decrease with increasing TE as a consequence of the difference in the apparent transverse relaxation rates between labeled water in capillaries and nonlabeled water in the tissue (δR 2*). We aimed to measure ASL/rCBF changes in different parts of the brain and correct them.
MATERIALS AND METHODS
Fifteen participants underwent ASL measurements at TEs of 9.7-30 ms. Decreases in ASL values were localized by statistical parametric mapping. The corrections assessed were a subject-per-subject adjustment, an average δR 2* value adjustment, and a two-compartment model adjustment.
RESULTS
rCBF decreases associated with increasing TEs were found for gray matter and were corrected using an average δR 2* value of 20 s(-1) . Conversely, for white matter, rCBF values increased with increasing TEs (δR 2* = -23 s(-1)).
CONCLUSION
Our correction was as good as using a two-compartment model. However, it must be done separately for the gray and white matter rCBF values because the capillary R 2* values are, respectively, larger and smaller than those of surrounding tissues.

Links

Publisher Full Text

Authors

Foucher JR, Roquet D, Marrer C, Pham BT, Gounot D

Institution

UdS, Université de Strasbourg, Strasbourg, France; INSERM U666-Physiopathologie et Psychopathologie Cognitive de la Schizophrénie, Strasbourg, France. jack.foucher@laposte.net

Source

Journal of magnetic resonance imaging : JMRI 34:4 2011 Oct pg 785-90

MeSH

Adult
Blood Circulation Time
Cerebral Angiography
Cerebral Arteries
Cerebral Cortex
Cerebrovascular Circulation
Echo-Planar Imaging
Female
Humans
Magnetic Resonance Angiography
Male
Middle Aged
Models, Cardiovascular
Nerve Fibers, Myelinated
Sampling Studies
Sensitivity and Specificity
Spin Labels

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21769973