1128 Analysis of principal left ventricular dynamics using phase-contrast Vvlocity MRI

Huntbatch, Lee Su-Lin, Firmin David, Yang, Yang Guang-Zhong

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• Publié par: biomed
• Publié le: 01 janvier 2008
• Nombre de lectures: 1
• Langue: English

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Journal of Cardiovascular Magnetic
BioMed CentralResonance
Open AccessMeeting abstract
1128 Analysis of principal left ventricular dynamics using
phase-contrast Vvlocity MRI
Andrew D Huntbatch*, Su-Lin Lee, David Firmin and Guang-Zhong Yang
Address: Imperial College, London, UK
* Corresponding author
th from 11 Annual SCMR Scientific Sessions
Los Angeles, CA, USA. 1–3 February 2008
Published: 22 October 2008
Journal of Cardiovascular Magnetic Resonance 2008, 10(Suppl 1):A253 doi:10.1186/1532-429X-10-S1-A253
<supplement> <title> <p>Abstracts of the 11^thAnnual SCMR Scientific Sessions - 2008</p> </title> <note>Meeting abstracts – A single PDF containing all abstracts in this Supplement is available <a href="http://www.biomedcentral.com/content/files/pdf/1532-429X-10-s1-full.pdf">here</a>.</note> <url>http://www.biomedcentral.com/content/pdf/1532-429X-10-S1-info.pdf</url> </supplement>
This abstract is available from: http://jcmr-online.com/content/10/S1/A253
© 2008 Huntbatch et al; licensee BioMed Central Ltd.
the noise image subtracted has a variance close to that ofIntroduction
Recent improvement in myocardial velocity imaging pro- the underlying noise signal. Manual segmentation of the
vides the opportunity for detailed assessment of myocar- epicardial and endocardial contours using the magnitude
dial contractility for the detection of regional images provided boundaries for the construction of regu-
abnormalities. The use of phase-contrast velocity imaging lar hexahedral models of the LV for each timeframe. The
allows for the analysis of complex myocardial motion velocities were assigned to each element using trilinear
with minimal user interaction. This work investigates the interpolation. These models were then unwrapped to
use of a variational restoration algorithm for improving yield 2D maps of the myocardium in longitudinal and cir-
the internal consistency of the MR velocity data and the cumferential coordinates, with the vertical edges repre-
extraction of the intrinsic motion pattern of the myocar- senting the anterior RV/LV junction.
dium through the use of Principal Component Analysis
(PCA). PCA of the unwrapped models, both for the 3D velocities
and the directional components, was used to examine the
intrinsic motion of the myocardium to evaluate the con-Methods
A Siemens Sonata scanner with a phase-contrast gradient- formance of the LV during contraction and relaxation. Fig-
echo sequence was used to obtain a series of short-axis ure 1.
slices for 7 patients from the basal to the apical regions of
the left ventricle (LV) in three encoding directions (FOV = Results
300 × 300 mm, TR = 53 ms, TE = 7.1 ms, in-plane pixel PCA of the velocity models demonstrates the underlying
resolution = 1.17 × 1.17 mm, VENC = -15 to +15 cms-1). motions of the myocardial tissue. In particular, circumfer-
Free-breathing was allowed through the use of a navigator ential velocities show the torsion motion in agreement
echo placed through the right hemisphere of the dia- with the helical fibre model [2]. The first mode of varia-
phragm for respiratory gating and blood flow artefacts tion accounts for 82.3% of the total variance and shows
were prevented through the use of a black-blood suppres- the expansion and contraction of the myocardium from
sion technique to saturate blood adjacent to the imaging systole to diastole. For individual velocity components,
plane. A typical acquisition yielded 12 short-axis slices at the first mode of variation accounts for 71.5% for the
8 mm intervals over 16 time frames. radial and 92.1% for longitudinal variance while for cir-
cumferential velocity the first two modes account for
A variational restoration algorithm [1] was applied to the 41.1% and 23.4% respectively.
velocity data in order to improve the SNR. The algorithm
consists of an iterative algorithm to reduce the total varia-
tion of the velocity field while applying the constraint that
Page 1 of 2
(page number not for citation purposes)Journal of Cardiovascular Magnetic Resonance 2008, 10(Suppl 1):A253 http://jcmr-online.com/content/10/S1/A253
fFigure 1(a) Cumulative variance of the or longitudinal, (f-g) circumferentiamodel as nod f va(h-i ri) atfoior ran, (b- dialc) f compirst moonentsde of variation for 3D velocity field of the myocardium, (d-e) modes of variation, (b-c) first mode of variatioD the myocar
for longitudinal, (f-g) circumferential and (h-i) for radial components.
Conclusion
We have demonstrated the construction of a compact sta-
tistical model of left ventricular motion, capturing proper-
ties such as ventricular torsion and providing a
preliminary framework for the detection of abnormal car-
diac function. Results from this work demonstrate good
correspondence with the widely-accepted myocardial
band model, showing the expected torsion, longitudinal
and radial motions.
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