240 Blood oxygen-sensitive ssfp imaging for probing the myocardial perfusion reserves of patients with coronary artery disease: a feasibility study

Dharmakumar Rohan, Green Jordin, Flewitt Jacqueline, Voehringer Matthias, Filipchuk, Li Debiao, Friedrich

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

Extrait

Journal of Cardiovascular Magnetic
BioMed CentralResonance
Open AccessMeeting abstract
240 Blood oxygen-sensitive ssfp imaging for probing the myocardial
perfusion reserves of patients with coronary artery disease: a
feasibility study
1 2 3Rohan Dharmakumar* , Jordin Green , Jacqueline Flewitt ,
3 3 1Matthias Voehringer , Neil G Filipchuk , Debiao Li and
3 G Friedrich
1 2 3Address: Northwestern University, Chicago, IL, USA, Siemens Medical Solutions, Calgary, AB, Canada and University of Calgary, Calgary, AB,
Canada
* 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):A101 doi:10.1186/1532-429X-10-S1-A101
<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/A101
© 2008 Dharmakumar et al; licensee BioMed Central Ltd.
Introduction Methods
Myocardial oxygen deficits secondary to coronary artery Data acquisition
stenosis may be detected with blood-oxygen-level- Nine patients with coronary artery disease underwent
dependent (BOLD) MRI. Similar to the first-pass per- CMR studies using procedures and protocols approved by
fusion technique, BOLD MRI identifies functionally sig- our institution. Studies were performed using a Siemens
nificant coronary artery stenosis based on regional Avanto 1.5 T scanner. Following whole-heart manual
myocardial signal intensity differences at stress (pharmo- shim, a mid-ventricular slice was identified. This was fol-
cological vasodilation). While the advantages of BOLD lowed by acquisitions of 2D SSFP images at mid-ventricle
MRI have been long recognized, long scan times, poor during rest and stress. First-pass perfusion scans at rest and
image quality and/or oxygen sensitivity have limited the stress, and late-enhancement scans covering the mid-ven-
clinical utility of this technique. BOLD MRI based on tricular slice of interest were also obtained. Adenosine
steady-state free precession (SSFP) is a promising studies were performed 3 minutes after starting an intra-
approach to overcoming many of these obstacles. It has venous infusion of Adenosine (140 μg/kg body weight/
been used to detect regional myocardial oxygen differ- min). Imaging parameters for 2D SSFP scans were: T /T =R E
ences in canine models with experimental coronary artery 5.8/2.9 ms; flip angle = 90°; single-breath hold (13–20 s)
stenosis. with retrospective gating (20 cardiac phases); and voxel
3size = 1.5 × 1.5 × 5 mm .
Purpose
This work investigates whether SSFP BOLD MRI can detect Data analysis
regional myocardial perfusion deficits in patients who End-systolic frames obtained before and during Adenos-
have been tested positive for coronary artery disease via x- ine were analyzed in a segmental fashion using the AHA
ray angiography and Thallium SPECT. 6-segment model. Based on Thallium SPECT, segments
were classified as healthy, mildly affected, severely
affected, or infarcted. Infarcted segments (fixed defect on
SPECT and positive on late enhancement images) were
excluded from further analysis. Segmental SSFP signal
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(page number not for citation purposes)Journal of Cardiovascular Magnetic Resonance 2008, 10(Suppl 1):A101 http://jcmr-online.com/content/10/S1/A101
intensities at rest and stress were measured and the signal Discussion
intensity ratio (Stress/Rest) was calculated. One-way In the absence of coronary artery stenosis, pharmacologi-
ANOVA with Tukey post-hoc analysis was used to deter- cal stress is expected to increase basal myocardial per-
mine the statistical significance of regional differences. fusion and vascular oxygenation. The progression of
coronary artery stenosis reduces this vasodilatory capacity,
Results resulting in oxygenation changes in corresponding myo-
Fig. 1 shows representative example mid-ventricular short cardial territories. Since SSFP signals are directly depend-
axis SSFP-based myocardial BOLD images obtained under ent on blood oxygenation, the signal intensity ratios
rest (A) and stress (D) from a patient with 70% narrowing between rest and stress conditions can be used to identify
of the left anterior descending artery. For reference, mid- ischemic territories of the myocardium.
ventricular short axis first-pass perfusion (B, rest and E,
stress) and SPECT (C, rest and F, stress) images are also Conclusion
shown. Note the discriminating signal loss in the stress This work demonstrated that 2D SSFP CMR at 1.5 T may
images (relative to rest) in the anterior zones of the myo- provide a robust non-contrast technique capable of iden-
cardium and its close correspondence to first pass and tifying regional myocardial oxygen deficits in patients
SPECT images. Statistical results (Fig. 2) show that there with known coronary artery stenosis. Further studies are
are significant differences in Stress/Rest values computed warranted to establish the sensitivity and specificity of the
from healthy, mildly and severely affected segments (p < technique.
0.05).
Mid-ventricular sh7Figure 10% stenosis of the left ante ort-axis SSFP rior BOLD, Fir descending (st-p LaAss perfusion D) coronary ar(FPP), terand Thallium Sy at rest and stress PECT images obtained from a patient with st-pa(FPP), Pes obtain
70% stenosis of the left anterior descending (LAD) coronary artery at rest and stress. For each imaging method, the windowing
and leveling of images obtained at rest and stress are the same. The myocardial signal in the rst BOLD, FP, and SPECT images
are relatively homogenous. However, under stress, the territory supplied by the LAD (larger arc subtended by arrow) does
not increase in the BOLD images as expected. This pattern of regional signal differences is also evident in the FP and SPECT
images.
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SFigure 2tatistical results from the myocardial BOLD signal analysis
Statistical results from the myocardial BOLD signal analysis. Statistically significant differences in Stress/Rest values obtained
from affected segments are lower, in comparison with healthy segments, consistent with previous findings in animals that SSFP
signals obtained under pharmacological stress are significantly reduced in myocardial territories supplied by stenotic arteries.
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