Deciphering adiabatic rotating frame relaxometry in biological tissues
This work aims to unravel the intricacies of adiabatic rotating frame relaxometry in biological tissues. The classical formalisms of dipolar relaxation and were systematically analyzed for water molecules reorienting on "fast" and "slow" timescales. These two timescales are, resp...
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Published in | Magnetic resonance in medicine Vol. 92; no. 6; pp. 2670 - 2682 |
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Main Author | |
Format | Journal Article |
Language | English |
Published |
United States
Wiley Subscription Services, Inc
04.08.2024
|
Subjects | |
Online Access | Get full text |
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Summary: | This work aims to unravel the intricacies of adiabatic rotating frame relaxometry in biological tissues.
The classical formalisms of dipolar relaxation
and
were systematically analyzed for water molecules reorienting on "fast" and "slow" timescales. These two timescales are, respectively, responsible for the absence and presence of
dispersion. A time-averaged
or
over an adiabatic pulse duration was recast into a sum of
and
, but with different weightings. These weightings depend on the specific modulations of adiabatic pulse waveforms. In this context, stretched hyperbolic secant (
) pulses were characterized. Previously published
, continuous-wave (CW)
, and
measures from 12 agarose phantoms were used to validate the theoretical predictions. A similar validation was also performed on previously published
(
=1, 4, 8) and
from bovine cartilage specimens.
Longitudinal relaxation weighting decreases for
pulses as
increases. Predicted CW
values from agarose phantoms align well with the measured CW
values, as indicated by a linear regression function:
. The predicted adiabatic
and
from cartilage specimens are consistent with those previously measured, as quantified by:
.
This work has theoretically and experimentally demonstrated that adiabatic
and
can be recast into a sum of
and
, with varying weightings. Therefore, any suggestions that adiabatic rotating frame relaxometry in biological tissues could provide more information than the standard
and
warrant closer scrutiny. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0740-3194 1522-2594 1522-2594 |
DOI: | 10.1002/mrm.30240 |