Conventional high resolution versus fast T(2)-weighted MR imaging of the heart: assessment of reperfusion induced myocardial injury in an animal model.
Cardiac image quality in terms of spatial resolution and signal contrast was assessed for conventional and newly developed T(2)-weighted fast spin-echo imaging with high k-space segmentation. The capability in revealing regional myocardial edema and cellular damage was examined by a porcine model using histopathologic correlation. Twelve porcine hearts were excised from slaughtered animals and instantly perfused with 1000 mL cold cardioplegic solution. After 4 h of cold ischemia the hearts were reperfused for one hour using a "Langendorff" perfusion model followed by MR imaging at 1.5 Tesla. Three additional pig hearts served as controls and were studied by MR directly after harvesting. Histopathological analysis of regional tissue changes was performed macro- and microscopically. Short axis T(2)-weighted (3000/45 and 90) high quality fast spin-echo (FSE) images were recorded without cardiac action and signal intensity was correlated with histology. These images also served as gold standard for evaluation of newly developed faster sequences allowing measuring times shorter than 20 s. Fast T(2)-weighted imaging comprised single-slice fast spin echo (moderate echo train length of 23 echoes, FSE(m)), and multi-slice single-shot half-Fourier fast spin-echo (71 echoes, FSE(HASTE)) sequences, supplemented by versions with inversion recovery preparation (FSE(m)IR and FSE(HASTE)IR). Systolic function after reperfusion was restored in 10 porcine hearts. Tissue alterations included myocardial edema and contraction band necrosis which was found to be most severe in myocardium with maximum T(2) SI. Especially FSE(m) and FSE(m)IR sequences allowed differentiation of all categories of tissue damage on a high level of significance. In contrast, single-shot FSE(HASTE) and FSE(HASTE)IR sequences did not provide sufficient image quality to discriminate moderate and severe myocardial damage (p > 0.05). Different degrees of myocardial injury after ischemia and reperfusion can be staged by MR imaging, especially using conventional high resolution T(2)-weighted FSE sequences. The animal study indicates that fast T(2)-weighted FSE(m) and FSE(m)IR sequences lead to superior image quality and diagnostic accuracy compared to FSE(HASTE) and FSE(HASTE)IR imaging.
Miller
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Department of Diagnostic Radiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, 72076, Tuebingen, Germany. stephan.miller@uni-tuebingen.de
Schick
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Scheule
A M
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Vogel
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U
Hiller
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R
Strotmann
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Naegele
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Hahn
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Claussen
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CD
D000704:Analysis of Variance; D000818:Animals; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015428:Myocardial Reperfusion Injury / Q000473:pathology*; D018709:Statistics, Nonparametric; D013552:Swine