Received: 19 October 2001
Revised: 4 December 2001
Accepted: 14 March 2002
Published online: 25 April 2002
© ISS 2002
Abstract Objective: Fat suppression
can be used to improve the diagnostic
confidence in traumatic bone frac-
tures of the extremities. We compared
a three-point Dixon “sandwich” wa-
ter–fat separation (WFS) sequence,
resulting in a water-only and a fat-
only image set after one excitation,
with the STIR sequence on an open
0.35 T superconductive MR system.
Design and patients: T1-weighted,
STIR (2000/40 [TR/TE]), and WFS
(2000/36 [TR/TE]) MR images were
prospectively obtained in 27 patients
with 40 radiologically diagnosed frac-
tures immediately after first-line
treatment. Signal-to-noise (S/N)
ratio, contrast-to-noise (C/N) ratio,
and bone marrow edema volumes
were measured together with qualita-
tive parameters (four-point scale).
Results: WFS was significantly supe-
rior to STIR in all quantitative param-
eters (better S/N ratio, P<0.001; bet-
ter C/N ratio, P<0.001; larger marrow
edema, P <0.023; Wilcoxon signed
rank test). Visibility of bone marrow
edema, visibility of fracture line, and
preservation of anatomical details
were better with the WFS sequence
(P<0.001, P<0.001, P<0.001, respec-
tively; ANOVA). Fat saturation was
rated more homogeneous, however,
with the STIR sequence (not signifi-
cant; P<0.101). Conclusion: On the
basis of qualitative and quantitative
assessments, the three-point Dixon
“sandwich” water–fat separation se-
quence was consistently superior to
the STIR sequence in the delineation
of traumatic fractures.
Keywords Magnetic resonance
imaging, low field · Magnetic
resonance imaging, open · Fractures,
traumatic · STIR · Fat saturation ·
Three-point Dixon
Skeletal Radiol (2002) 31:343–348
DOI 10.1007/s00256-002-0517-9
ARTICLE
Walter A. Wohlgemuth
Frank W. Roemer
Klaus Bohndorf
Short tau inversion recovery
and three-point Dixon water–fat separation
sequences in acute traumatic bone fractures
at open 0.35 tesla MRI
Introduction
The growing application of magnetic resonance imag-
ing (MRI) in traumatic extremity fractures is based on
its superior detection of “occult” fractures and concom-
itant soft tissue injuries [1, 2, 3, 4, 5, 6, 7]. T2-weight-
ed fat-suppression imaging with a short tau inversion
recovery (STIR) sequence has an especially high
proven value in the evaluation of traumatic lesions of
the skeleton [8, 9, 10, 11, 12, 13] and is applicable in
low-field MR systems, which have certain advantages
in the setting of acute trauma. The main drawback of
the STIR sequence is that all signals with a T1 identical
to fat, including hematoma or contrast-enhanced tissue,
are canceled out [14]. Additionally the sequence is vul-
nerable to motion artifacts [15] and the signal-to-noise
(S/N) ratio is poor [16, 17]. In open MRI, the S/N ratio
of this sequence is further decreased with the lower
field strength, which can lead to an impairment of the
visualization of fracture details in 0.2 T MRI [18]. As
spectral fat saturation MRI is not possible in low-field
MRI [19], the Dixon method [20, 21] and its modifica-
tions [22, 23, 24] are an alternative, but they have re-
quired at least two acquisitions to separate water from
fat images, resulting in long scan times and problems
with patient movement [25].
W.A. Wohlgemuth (
✉
) · F.W. Roemer
K. Bohndorf
Department of Radiology,
Klinikum Augsburg, Stenglinstrasse 2,
86156 Augsburg, Germany
e-mail: w.wohlgemuth@online.de
Tel.: +49-821-42453
Fax: +49-821-4003312