Quantification of the magnetic resonance signal response to dynamic (C)O(2)-enhanced imaging in the brain at 3 T: R*(2) BOLD vs. balanced SSFP.
OBJECTIVE
To compare two magnetic resonance (MR) contrast mechanisms, R*(2) BOLD and balanced SSFP, for the dynamic monitoring of the cerebral response to (C)O(2) respiratory challenges.


METHODS
Carbogen and CO(2)-enriched air were delivered to 9 healthy volunteers and 1 glioblastoma patient. The cerebral response was recorded by two-dimensional (2D) dynamic multi-gradient-echo and passband-balanced steady-state free precession (bSSFP) sequences, and local changes of R*(2) and signal intensity were investigated. Detection sensitivity was analyzed by statistical tests. An exponential signal model was fitted to the global response function delivered by each sequence, enabling quantitative comparison of the amplitude and temporal behavior.


RESULTS
The bSSFP signal changes during carbogen and CO(2)/air inhalation were lower compared with R*(2) BOLD (ca. 5% as opposed to 8-13%). The blood-oxygen-level-dependent (BOLD) response amplitude enabled differentiation between carbogen and CO(2)/air by a factor of 1.4-1.6, in contrast to bSSFP, where differentiation was not possible. Furthermore, motion robustness and detection sensitivity were higher for R*(2) BOLD.


CONCLUSIONS
Both contrast mechanisms are well suited to dynamic (C)O(2)-enhanced MR imaging, although the R*(2) BOLD mechanism was demonstrated to be superior in several respects for the chosen application. This study suggests that the R*(2) BOLD and bSSFP-response characteristics are related to different physiologic mechanisms.
Philips Research, 22335 Hamburg, Germany. stefanie.remmele@philips.com
Stefanie
S
Remmele
Hannes
H
Dahnke
Sebastian
S
Flacke
Martin
M
Soehle
Ingobert
I
Wenningmann
Attila
A
Kovacs
Frank
F
Träber
Andreas
A
Müller
Winfried A
WA
Willinek
Roy
R
König
Hans
H
Clusmann
Jürgen
J
Gieseke
Hans H
HH
Schild
Petra
P
Mürtz
D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology*; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D002245:Carbon Dioxide / Q000737:chemistry*; D003952:Diagnostic Imaging / Q000379:methods; D005260:Female; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000097:blood* / Q000737:chemistry; D012680:Sensitivity and Specificity; D013997:Time Factors
D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen