Contrast-enhanced MRI and routine single photon emission computed tomography (SPECT) perfusion imaging for detection of subendocardial myocardial infarcts: an imaging study.
BACKGROUND
Myocardial infarcts are routinely detected by nuclear imaging techniques such as single photon emission computed tomography (SPECT) myocardial perfusion imaging. A newly developed technique for infarct detection based on contrast-enhanced cardiovascular magnetic resonance (CMR) has higher spatial resolution than SPECT. We postulated that this technique would detect infarcts missed by SPECT.


METHODS
We did contrast-enhanced CMR and SPECT examinations in 91 patients with suspected or known coronary artery disease. All CMR and SPECT images were scored, using a 14-segment model, for the presence, location, and spatial extent of infarction. To compare each imaging modality to a gold standard, we also acquired contrast-enhanced CMR and SPECT images in 12 dogs with, and three dogs without, myocardial infarction as defined by histochemical staining.


RESULTS
In animals, contrast-enhanced CMR and SPECT detected all segments with nearly transmural infarction (>75% transmural extent of the left-ventricular wall). CMR also identified 100 of the 109 segments (92%) with subendocardial infarction (<50% transmural extent of the left-ventricular wall), whereas SPECT identified only 31 (28%). SPECT and CMR showed high specificity for the detection of infarction (97% and 98%, respectively). In patients, all segments with nearly transmural infarction, as defined by contrast-enhanced CMR, were detected by SPECT. However, of the 181 segments with subendocardial infarction, 85 (47%) were not detected by SPECT. On a per patient basis, six (13%) individuals with subendocardial infarcts visible by CMR had no evidence of infarction by SPECT.


CONCLUSIONS
SPECT and CMR detect transmural myocardial infarcts at similar rates. However, CMR systematically detects subendocardial infarcts that are missed by SPECT.
Wagner
Anja
A
Northwestern University Medical School Feinberg Cardiovascular Research Institute, Chicago, IL, USA.
Mahrholdt
Heiko
H
Holly
Thomas A
TA
Elliott
Michael D
MD
Regenfus
Matthias
M
Parker
Michele
M
Klocke
Francis J
FJ
Bonow
Robert O
RO
Kim
Raymond J
RJ
Judd
Robert M
RM
D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D006651:Histocytochemistry / Q000592:standards; D006801:Humans; D007089:Image Enhancement / Q000379:methods / Q000592:standards*; D016018:Least-Squares Analysis; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods / Q000592:standards*
D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes; D017256:Technetium Tc 99m Sestamibi