ArticlesContrast-enhanced MRI and routine single photon emission computed tomography (SPECT) perfusion imaging for detection of subendocardial myocardial infarcts: an imaging study
Introduction
The frequency of non-Q-wave myocardial infarction has increased in the past two decades,1, 2, 3 partly because of changes in treatment strategies—eg, increasing rate of early reperfusion1, 3—and partly as a result of the availability of more sensitive methods of diagnosis of acute myocardial infarction.4 Non-Q-wave infarcts probably represent small infarcts, which are associated with a morbidity and mortality comparable to that of larger infarcts.5, 6, 7, 8, 9
In the absence of biochemical and electrocardiographic evidence of infarction, myocardial infarcts can be detected by cardiac imaging techniques. Single-photon emission computed tomography (SPECT) myocardial perfusion imaging is an established procedure used for diagnosis of infarcts. However, results of studies10, 11, 12 suggest that SPECT misses small infarcts. One reason that infarcts might not be identified by SPECT is the fairly poor spatial resolution of about 10×10×10 mm full width half maximum,13, 14 suggesting that infarcts smaller than this size are difficult to see. Contrast-enhanced cardiovascular magnetic resonance (CMR) is a new technique that allows visualisation of transmural and subendocardial myocardial infarcts.15, 16, 17 A potential advantage of contrast-enhanced CMR is its high spatial resolution of about 1·4×1·9×6·0 mm—ie, about 60-fold greater than SPECT. We postulated, therefore, that CMR would be able to detect subendocardial infarcts missed by SPECT.
Section snippets
Patients
Between Jan 28, 1999, and Sept 2, 2001, we consecutively enrolled patients who underwent clinically indicated stress-rest SPECT perfusion imaging for known or suspected coronary artery disease at Northwestern Memorial Hospital or Veterans Affairs Lakeside Hospital, and studied them by contrast-enhanced CMR. We defined known coronary artery disease as a 50% or greater stenosis in one or more of the coronary arteries at cardiac catheterisation or a history of myocardial infarction, or both. The
Results
We enrolled 91 patients (24 women and 67 men, mean age 57 years [SD 13]) who had known (n=35) or suspected (n=56) coronary artery disease. All patients had CMR and SPECT within 2 months (mean 10 days, SD 17) of each other. No patient had a clinically recognised myocardial infarction within the 3 months before CMR or between the CMR and SPECT scans. We also studied 15 dogs, in which we produced myocardial infarction by occlusion of the left anterior descending coronary artery (n=9) or the left
Discussion
Our findings show that although SPECT and CMR detect transmural myocardial infarcts at similar rates, CMR systematically detects subendocardial infarcts that are missed by SPECT. A comparison of the CMR findings in animals confirmed that the subendocardial infarcts detected by CMR corresponded to infarcts defined histologically.
The general idea that SPECT misses small infarcts has been previously suggested.10, 11, 12 A possible reason for this lack of sensitivity is that the spatial resolution
References (26)
- et al.
Non-Q- and Q-wave infarction after thrombolytic therapy with intravenous streptokinase for chest pain and anterior ST-segment elevation
Am J Cardiol
(1991) - et al.
Non-Q wave myocardial infarction: recent changes in occurrence and prognosis: a community-wide perspective
Am Heart J
(1987) - et al.
Myocardial infarction patients in the 1990s: their risk factors, stratification and survival in Canada: the Canadian Assessment of Myocardial Infarction (CAMI) study
J Am Coll Cardiol
(1996) - et al.
Detection of unsuspected myocardial necrosis by rapid bedside assay for cardiac troponin T
Am Heart J
(1997) - et al.
The short- and long-term prognosis of patients with transmural and nontransmural myocardial infarction
Am J Med
(1976) - et al.
Superimposition of transmural infarction following acute subendocardial infarction: how frequent?
Chest
(1976) - et al.
A nonischemic electrocardiogram does not always predict a small myocardial infarction: results with acute myocardial perfusion imaging
Am Heart J
(2001) - et al.
Visualisation of presence, location, and transmural extent of healed Q-wave and non-Q-wave myocardial infarction
Lancet
(2001) - et al.
The myth of acute “mild” myocardial infarction
Ann Intern Med
(1977) - et al.
Prognosis after first myocardial infarction: comparison of Q-wave and non-Q-wave myocardial infarction in the Framingham Heart Study
JAMA
(1992)
Long-term prognosis of patients after a Q wave compared with a non-Q wave first acute myocardial infarction: data from the SPRINT registry
Eur Heart J
A clinicopathologic correlation study of thallium-201 myocardial scintigraphy in diagnosis of myocardial infarction
Jpn Heart J
Infarct size after acute myocardial infarction measured by quantitative tomographic 99mTc sestamibi imaging predicts subsequent mortality
Circulation
Cited by (1100)
Comparative Accuracy of Noninvasive Imaging Tests in Stable Chest Pain: Does It Matter?
2023, Journal of the American College of CardiologyStress Perfusion Cardiac Magnetic Resonance vs SPECT Imaging for Detection of Coronary Artery Disease
2023, Journal of the American College of CardiologyIsolated myocardial edema in cardiac magnetic resonance – in search of a management strategy
2023, Trends in Cardiovascular MedicineAdvances in image-guided drug delivery for antibacterial therapy
2023, Advanced Drug Delivery Reviews