Clinical assessment of myocardial viability using MRI during a constant infusion of Gd-DTPA |
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Authors: | Raoul S Pereira Gerald Wisenberg Frank S Prato Ken Yvorchuk |
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Affiliation: | (1) Department of Nuclear Medicine, Imaging Division, Lawson Research Institute St. Joseph’s Health Centre, University of Western Ontario, 268 Grosvenor Street, N6A 4V2 London, Ont., Canada;(2) Department of Medical Biophysics, Division of Cardiology, St. Joseph’s Health Centre, University of Western Ontario, 268 Grosvenor Street, N6A 4V2 London, Ont., Canada |
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Abstract: | This study assessed the accuracy and feasibility of magnetic resonance imaging (MRI) during a constant infusion of gadolinium
diethylenetriaminepentaacetic acid (Gd-DTPA) for the determination of myocardial viability in patients with recent acute myocardial
infarction (AMI). Nine patients were studied within 10 days of AMI. Rest-redistribution201Thallium (201Tl) single photon emission computed tomography (SPECT) was used as a gold standard for viability. Using MRI, regional perfusion
was assessed using dynamic imaging during a bolus injection of Gd-DTPA and viability was assessed during a continuous infusion.
Finally, cine MR images were acquired at baseline, during low-dose dobutamine infusion and after recovery. To assess viability,
the left ventricle was divided into 16 segments and signal intensity in corresponding MRI and redistribution SPECT segments
were compared. Wall thickening index (WTI) was determined at each step during the dobutamine study. The results revealed that
in five patients, reduced perfusion in infarcted regions was observed qualitatively during dynamic first pass imaging. There
was a significant inverse correlation between201Tl uptake and MRI signal intensity, i.e. infarcted tissue (low201Tl uptake) had increased MR signal intensity. Segments were separated into normal (201Tl uptake >90%) and infarcted (<60%). Infarcted MRI segments had greater signal intensity than normal segments (179±50 vs.
102±14%;P<0.0001). WTI in normal segments increased by 18±8.5% (P<0.0001) from baseline to 10 μg/kg per min of dobutamine while infarcted tissue WTI decreased 2.8±7.2% (P=0.17). Thus regions of myocardium that were infarcted as defined by reduced201Tl uptake and absent contractile reserve showed greatly increased MRI signal intensity during a constant infusion of Gd-DTPA.
The use of MRI during a constant infusion of Gd-DTPA is accurate and feasible for the determination of myocardial necrosis
in a clinical setting. |
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Keywords: | MRI Myocardial viability Gd-DTPA Contrast Acute myocardial infarction |
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