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0Zun et al. Journal of Cardiovascular Magnetic Resonance 2011, 13(Suppl 1):O94 http://jcmr-online.com/content/13/S1/O94 JOlimal Of GardiOVaSCUlar
Magnetic Resonance
ORAL PRESENTATION Open Access
Arterial spin labeled MRI detects clinically relevant increases in myocardial blood flow with vasodilatation
Zungho Zun1*, Padmini Varadarajan2, Ramdas G Pai2, Eric C Wong3, Krishna S Nayak1
From 2011 SCMR/Euro CMR Joint Scientific Sessions Nice, France. 3-6 February 2011
Objective
This study sought to demonstrate the potential for arterial spin labeling (ASL) to differentiate normal and ischemic myocardial segments based on increase in myocardial blood flow (MBF) with vasodilatation.
Background
Myocardial ASL is a promising technique for the assessment of MBF because of the absence of contrast agents. Patients with end-stage renal disease cannot tolerate contrast agent, and therefore stand to potential benefit from myocardial ASL. MBF in healthy myocardium is known to increase by 4 times during vasodilator-induced stress, compared to at rest [1].
first-pass MRI and no significant stenosis on X-ray angiogram. Ten patients had both perfusion defects and stenosis. Four remaining patients showed perfusion defects but no stenosis. Table 1 summarizes the perfusion analysis performed in both whole myocardium and myocardial segments after excluding subjects with signal-to-physiological-noise ratio<2.0 [2]. The normal segments included all six segments [3] of the whole myocardium in normal patients and ischemic segments included the most ischemic segments in the patients with stenosis confirmed by X-ray angiography. MBF increase with adenosine in the global and segmental myocardium in normal patients were both statistically significant with p<0.0001 while MBF increase with
Methods
Twenty nine patients were recruited from those scheduled for routine cardiac MR (CMR) exams. All MRI experiments were performed on a GE Signa 3T scanner. Myo-cardial ASL measurements were obtained from a single mid short-axis slice, using flow-sensitive alternating inversion recovery (FAIR) tagging and balanced steady-state free precession (SSFP) imaging [2]. Rest-stress myocardial ASL scans were incorporated in CMR exam including first-pass imaging during adenosine infusion of 0.14 mg/ kg/min (Figure 1). Based on CMR results, patients who were suspected to have severe ischemic heart disease also underwent X-ray angiography.
Results
Among 29 patients, fifteen patients were found to be normal based on having no visible perfusion defect on
University of Southern California, Los Angeles, CA, USA
Full list of author information is available at the end of the article
Figure 1 Imaging protocolexcerpt.
© 2011 Zun et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons CGntfcll Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Zun et al. Journal of Cardiovascular Magnetic Resonance 2011, 13(Suppl 1):O94 http://jcmr-online.com/content/13/S1/O94
Page 2 of 2
Table 1 MBF at rest and during stress (ml/g/min) and perfusion reserve
Subject Normal whole myocardium Normal myocardial segments Ischemic myocardial segments
N12 66 11
Condition Rest Stress Rest Stress Rest Stress
MBF 1.19±0.46 3.99±1.39 1.20±0.88 3.90±1.30 1.48±0.46 2.17+1.53
Reserve 4.21±3.44 2.87±2.10 1.44±0.97
adenosine in ischemic segments were not statistically significant with p=0.1032, based on paired t-test. Difference in perfusion reserve (MBFstress/MBFrest) between normal and ischemic segments was statistically significant with p=0.0296, based on unpaired t-test.
Conclusion
This study has demonstrated that myocardial ASL is able to capture adenosine-induced MBF increase in normal myocardium while detecting insignificant increase in ischemic myocardium. This suggests that myocardial ASL with vasodilation has a potential to diagnose angio-graphically significant heart disease.
Author details
University of Southern California, Los Angeles, CA, USA. 2Loma Linda University MedicalCenter, Loma Linda, CA, USA. 3University of California, San Diego, La Jolla, CA, USA.
Published: 2 February 2011 References
1. Kaufmann, et al: Am J Physiol Heart Circ Physiol 2007.
2. Zun, et al: MRM 2009.
3. Cerqueira, et al: Circulation 2002.
doi:10.1186/1532-429X-13-S1-O94
Cite this article as: Zun et al.: Arterial spin labeled MRI detects clinically relevant increases in myocardial blood flow with vasodilatation. Journal of Cardiovascular Magnetic Resonance 2011 13(Suppl 1):O94.
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