Korean J Radiol.  2002 Dec;3(4):235-239. 10.3348/kjr.2002.3.4.235.

The Significance of Perfusion Defect at Myocardial Perfusion MR Imaging in a Cat Model of Acute Reperfused Myocardial Infarction

• Goo HW
• Kim DH
• Lee SS
• Park SB
• Lim TH

• KMID: 1118790
• DOI: http://doi.org/10.3348/kjr.2002.3.4.235

Abstract

OBJECTIVE
To determine whether the size of a perfusion defect seen at myocardial perfusion MR imaging represents the extent of irreversibly damaged myocardium in acute reperfused myocardial infarction. MATERIALS AND METHODS: In nine cats, reperfused myocardial infarction was induced by occlusion of the left anterior descending coronary artery for 90 minutes and subsequent reperfusion for 90 minutes. At single-slice myocardial perfusion MR imaging at the midventricular level using a turbo-FLASH sequence, 60 short-axis images were sequentially obtained with every heart beat after bolus injection of gadomer-17. The size of the perfusion defect was measured and compared with both the corresponding unstained area seen at triphenyl tetrazolium chloride (TTC) staining and the hyperenhanced area seen at gadophrin-2-enhanced MR imaging performed in the same cat six hours after myocardial perfusion MR imaging. RESULTS: The sizes of perfusion defects seen at gadomer-17-enhanced perfusion MR imaging, unstained areas at TTC staining, and hyperenhanced areas at gadophrin-2-enhanced MR imaging were 20.4+/-4.3%, 29.0+/-9.7%, and 30.7+/-10.6% of the left ventricular myocardium, respectively. The perfusion defects seen at myocardial perfusion MR imaging were significantly smaller than the unstained areas at TTC staining and hyperenhanced areas at gadophrin-2-enhanced MR imaging (p < .01). The sizes of both the perfusion defect at myocardial perfusion MR imaging and the hyperenhanced area at gadophrin-2- enhanced MR imaging correlated well with the sizes of unstained areas at TTC staining (r = .64, p = .062 and r = .70, p = .035, respectively). CONCLUSION: In this cat model, the perfusion defect revealed by myocardial perfusion MR imaging underestimated the true size of acute reperfused myocardial infarction. The defect may represent a more severely damaged area of infarction and probably has prognostic significance.

Keyword

Coronary vessels, stenosis or obstruction; Heart, experimental studies; Magnetic resonance (MR), comparative studies; Magnetic resonance (MR), contrast agents; Myocardium, infarction; Myocardium, MR

MeSH Terms

Animal
Cats
Contrast Media
Gadolinium
Gadolinium DTPA/diagnostic use
*Magnetic Resonance Imaging
Mesoporphyrins/diagnostic use
Metalloporphyrins/diagnostic use
Myocardial Infarction/*pathology/therapy
*Myocardial Reperfusion
Myocardium/pathology
Support, Non-U.S. Gov't

Figure

• 

  Fig. 1 Myocardial perfusion MR image and its time-signal intensity curves derived from the left ventricular blood pool, perfusion defect, and normal myocardium. A. Short-axis myocardial perfusion MR image obtained at the left midventricular level shows a perfusion defect at its anterior wall. To obtain time-signal intensity curves, regions of interest were placed in the left ventricular cavity (V), perfusion defect (P), and normal myocardium (N). B. Time-signal intensity curve obtained from the left ventricular blood pool of a representative case shows an initial, steep increase in signal intensity and then a plateau, according to the first pass of contrast agent. C. Time-signal intensity curve obtained from both the perfusion defect and normal myocardium of a representative case demonstrates typical myocardial enhancement for each region. The curve derived from normal myocardium shows a rapid increase and decrease in signal intensity; in contrast, that derived from the perfusion defect shows a slow but steady increase in signal intensity due to disturbed wash-out of contrast agent.

• 

  Fig. 2 Comparison of the size of perfusion defects at myocardial perfusion MR imaging (20.4 ± 4.3% of the area of the left ventricular myocardium [LVM]), hyperenhanced areas at gadophrin-2-enhanced MR imaging (30.7 ± 10.6%), and unstained areas at TTC staining (*) (29.0 ± 9.7%). The first mentioned was significantly smaller than the second and last (p < .01).

• 

  Fig. 3 Correlation between the sizes of abnormal areas at MR (myocardial perfusion and gadophrin-2-enhanced) imaging and true infarct sizes at TTC staining. Spearman's correlation coefficients (r) were 0.64 (A) between myocardial perfusion MR imaging and TTC staining and 0.70 (B) between gadophrin-2-enhanced MR imaging and TTC staining.

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