Myocardial viability in chronic ischemic heart disease: comparison of delayed-enhancement magnetic resonance imaging with 99mTc-sestamibi and 18F-fluorodeoxyglucose single-photon emission computed tomography.

OBJECTIVES

We sought to compare delayed-enhancement MRI (DE-MRI) with 99mTc-sestamibi and 18F-fluorodeoxyglucose (18F-FDG) single-photon emission computed tomography (SPECT) for the assessment of myocardial viability.

METHODS

Thirty-four patients with prior myocardial infarction underwent DE-MRI and 99mTc-sestamibi/18F-FDG SPECT. The area of delayed enhancement by DE-MRI was defined as scar tissue. The region with concordantly reduced perfusion and glucose metabolism was defined as nonviable myocardium. In a 17-segment model, the segmental extent of hyperenhancement was compared with segmental 99mTc-sestamibi and 18F-FDG uptake defect. All segments were divided into five different severities by segmental extent of hyperenhancement in DE-MRI and were classified into different viability situations by segmental 99mTc-sestamibi and 18F-FDG uptake in SPECT.

RESULTS

A total of 578 segments were studied. Sensitivity and specificity of DE-MRI in identifying segments with flow/metabolism match were 61.32 and 95.35%, respectively. Semiquantitatively assessed relative MRI scar tissue correlated well with 99mTc-sestamibi and 18F-FDG SPECT (r = 0.63, P = 0.0284). However, of the 431 segments defined as normal by DE-MRI, 82 segments (19%) were scored as nonviable by 18F-FDG SPECT. During these segments, 48 showed less than 50% reduced 18F-FDG uptake, 25 showed 50-75% reduced 18F-FDG uptake, and nine showed no 18F-FDG uptake.

CONCLUSION

MRI hyperenhancement as a marker of myocardial scar closely agrees with 99mTc-sestamibi and 18F-FDG SPECT. Nuclear technology and DE-MRI show their own predominance and limitation in assessment of myocardial viability and detecting irreversibly injured tissue.