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Copyright 2003 CMP Media LLC
Diagnostic Imaging
May 1, 2003
SECTION: SPECIAL SECTION: SCMR CONFERENCE REPORTER; Pg. 67
LENGTH: 1218 words
HEADLINE: Late-enhancement MRI finds diagnostic roles -- Tests outperform PET
and SPECT in studies presented at SCMR meeting
BYLINE: James Brice
HIGHLIGHT:
Radiologists have long held great expectations for cardiac MRI in the diagnosis
of coronary artery disease. Its developers envisioned comprehensive applications
encompassing the diagnosis of myocardial infarction, detection and measurement
of coronary artery stenoses, and assessment of myocardial viability.
BODY:
Overcoming MRI's poor temporal resolution to realize that vision has proved
difficult, however. Despite some progress, coronary artery MRA is still not
ready to challenge x-ray angiography, and although first-pass perfusion MRI may
match the accuracy of stress echocardiography and thallium-201 SPECT, it remains
difficult to perform.
These shortcomings provided an opening for MRI myocardial viability
assessment. Since 1997, studies by Dr. Charles Higgins, Dr. Robert M. Judd, Dr.
Raymond Kim, Dr. Christoph Klein, Dr. Joao A. Lima, and Dr. Jorn J. Sandstede
and others have shown that late-enhancement MRI accurately predicts whether
patients will benefit from revascularization.
Dr. Ernest E. Van der Wall, a professor of cardiovascular radiology at the
University of Leiden in the Netherlands, said at the SCMR meeting that the
clinical efficacy of delayed-enhancement MRI is no longer in doubt.
"Bright is dead," he said, referring to the hyperenhanced depiction of
myocardial infarction on late-enhancement images.
Other studies reported at the SCMR meeting reinforced that conclusion and
suggested that late enhancement can play other roles.
Dr. Peter Hunold, a resident in radiology at University Hospital in Essen,
Germany, presented a study of 12 CAD patients in which late-enhancement MRI was
shown to be more specific and to have a higher positive predictive value than
FDG-PET for predicting the success of revascularization. No significant
difference in negative predictive values for the two modalities was seen.
Based on the evaluation of 1008 myocardial segments, the sensitivity and
specificity of MRI for predicting functional recovery was 95% and 72%,
respectively. The FDG-PET results for these measures were 97% and 47%,
respectively.
"The specificity of MRI is not optimal, but it is remarkably higher than PET,
because MRI is generally less optimistic than PET," Hunold said.
The PPV and NPV for regional myocardial improvement were 66% and 96% for MRI
and 52% and 97% for PET.
"Our answer to the question whether MRI should be the new gold standard for
myocardial viability would certainly be 'yes,'" he said.
SPECT COMPARISON
In a study of 53 patients with left ventricular dysfunction following MI, Dr.
Matthias Regenfus, a cardiovascular radiology researcher at Frederick Alexander
University in Erlangen Nurnberg, Germany, found a close correlation between
late-enhancement contrast-enhanced MRI and thallium-201 SPECT for evaluation of
myocardial viability. The segmental extent of infarction was significantly less
pronounced on the SPECT studies, however, and SPECT failed to identify 70 of 352
myocardial segments that hyperenhanced on CE-MRI.
Regenfus credited CE-MRI's relatively high spatial resolution for its
superior performance.
"It allows late-enhancement CE-MRI to better depict the transmural extent of
myocardial infarction and detect small myocardial necroses that escape detection
with SPECT," he said.
Research from Duke University indicates that CE-MRI may be a better way to
diagnose silent MI, according to Dr. Han Kim, a cardiovascular MRI research
fellow.
The hypothesis that CE-MRI may be more sensitive to silent MI than
Q-wave/non-Q-wave ECG, the current diagnostic gold standard, was supported by a
study of 100 patients with suspected silent MI. Hyperenhancement of infarction
with CE-MRI was observed in 57% of the cases, a rate four times higher than the
14% rate of unrecognized MI detected with the Q-wave test, Kim said.
Follow-up evaluations after an average of 21 months found that the extent of
hyperenhancement was the only statistically significant predictor of death (p =
0.002). The risk of death rose when the hyperenhanced infarction involved more
than 5% of the left ventricular myocardium.
Several studies at the SCMR conference examined how to distinguish acute from
chronic MI with CE-MRI. Dr. Hassan Abdel-Aty, a cardiology researcher at the
Franz-Vohard Clinic in Berlin, found that late-enhancement imaging combined with
short T1 inversion recovery (STIR) imaging can play that role.
In a study of 119 patients (74 with acute MI, 27 with chronic MI, and 18
healthy controls), late-enhancement MRI was 100% sensitive to infarction but was
unable to differentiate acute from chronic disease. STIR, however, revealed
transmural hyperintensity among 71 of 74 acute infarcts and no transmurality
among the chronic lesions. The sensitivity and specificity of the paired tests
were 96% and 100%, respectively.
IMAGING CARDIOMYOPATHY
Late-enhancement CE-MRI may also find a role in the diagnosis of
cardiomyopathies. Dr. Marcelo Hadlich, a radiology researcher associated with
the D'Or Hospital Network in Rio de Janeiro, Brazil, reported that
delayed-enhancement MRI can detect irreversible myocardial disease in patients
with myopericarditis.
A preliminary study of five patients found delayed hyperenhancement in 40% of
the left ventricular segments examined. Those areas were small, diffusely
distributed, and not restricted to any specific coronary territories, Hadlich
said. The same hyperenhancement appeared when imaging was repeated three months
later, suggesting irreversible myocardial injury.
The work of Dr. James C.C. Moon and colleagues at Royal Brompton Hospital in
London, U.K., suggests that cine CMR and CE-MRI myocardial hyperenhancement may
diagnose early hypertrophic cardiomyopathy and serve as a marker for clinical
risk.
In a study of 30 patients from 13 families with mutations of troponin I,
echocardiography found hyperenhancement (LVH+) and exaggerated wall thickness in
15 subjects, and no abnormal enhancement and normal wall thickness among 15
(LVH-) individuals who are either in the early stages or disease-free.
Abnormal cine CMR and abnormal regional hypertrophy were found in 100% of the
LVH+ and 27% of the LVH- subjects. Hyperenhancement appeared in 86% of the LVH+
and 20% of the LVH- groups.
The overall extent of hyperenhancement was related to the risk of sudden
death and total left ventricular mass, and it was inversely related to left
ventricular ejection fracture, Moon said.
Although no age-related pattern was observed for the group as a whole,
hyperenhancement increased with age compared with the subjects' family members.
This pattern suggests that increasing hyperenhancement patterns over time
reflect disease progression, he said.
Chagas disease, also called South American trypanosomiasis, is caused by a
blood-borne parasite and can lead to myocardial fibrosis, typically in apical
and basal inferolateral left ventricular segments. Dr. Carlos E. Rochitte at the
Heart Institute of the University of Sao Paulo Medical School in Brazil found
that delayed-enhancement MRI identified fibrosis in 22 of 25 Chagas disease
patients and in 31% of the myocardial segments that were observed. More midwall
and subepicardial involvement was documented than was considered typical with
the disease. The extent of myocardial fibrosis correlated well with left
ventricular ejection fraction.
Although more investigative work is needed to refine these applications,
late-enhancement CE-MRI is quickly gaining favor among researchers responsible
for the creation and development of cardiac MRI.
Copyright (c) 2003 CMP Media LLC
LOAD-DATE: June 9, 2003
Diagnostic Imaging
May 1, 2003
SECTION: SPECIAL SECTION: SCMR CONFERENCE REPORTER; Pg. 67
LENGTH: 1218 words
HEADLINE: Late-enhancement MRI finds diagnostic roles -- Tests outperform PET
and SPECT in studies presented at SCMR meeting
BYLINE: James Brice
HIGHLIGHT:
Radiologists have long held great expectations for cardiac MRI in the diagnosis
of coronary artery disease. Its developers envisioned comprehensive applications
encompassing the diagnosis of myocardial infarction, detection and measurement
of coronary artery stenoses, and assessment of myocardial viability.
BODY:
Overcoming MRI's poor temporal resolution to realize that vision has proved
difficult, however. Despite some progress, coronary artery MRA is still not
ready to challenge x-ray angiography, and although first-pass perfusion MRI may
match the accuracy of stress echocardiography and thallium-201 SPECT, it remains
difficult to perform.
These shortcomings provided an opening for MRI myocardial viability
assessment. Since 1997, studies by Dr. Charles Higgins, Dr. Robert M. Judd, Dr.
Raymond Kim, Dr. Christoph Klein, Dr. Joao A. Lima, and Dr. Jorn J. Sandstede
and others have shown that late-enhancement MRI accurately predicts whether
patients will benefit from revascularization.
Dr. Ernest E. Van der Wall, a professor of cardiovascular radiology at the
University of Leiden in the Netherlands, said at the SCMR meeting that the
clinical efficacy of delayed-enhancement MRI is no longer in doubt.
"Bright is dead," he said, referring to the hyperenhanced depiction of
myocardial infarction on late-enhancement images.
Other studies reported at the SCMR meeting reinforced that conclusion and
suggested that late enhancement can play other roles.
Dr. Peter Hunold, a resident in radiology at University Hospital in Essen,
Germany, presented a study of 12 CAD patients in which late-enhancement MRI was
shown to be more specific and to have a higher positive predictive value than
FDG-PET for predicting the success of revascularization. No significant
difference in negative predictive values for the two modalities was seen.
Based on the evaluation of 1008 myocardial segments, the sensitivity and
specificity of MRI for predicting functional recovery was 95% and 72%,
respectively. The FDG-PET results for these measures were 97% and 47%,
respectively.
"The specificity of MRI is not optimal, but it is remarkably higher than PET,
because MRI is generally less optimistic than PET," Hunold said.
The PPV and NPV for regional myocardial improvement were 66% and 96% for MRI
and 52% and 97% for PET.
"Our answer to the question whether MRI should be the new gold standard for
myocardial viability would certainly be 'yes,'" he said.
SPECT COMPARISON
In a study of 53 patients with left ventricular dysfunction following MI, Dr.
Matthias Regenfus, a cardiovascular radiology researcher at Frederick Alexander
University in Erlangen Nurnberg, Germany, found a close correlation between
late-enhancement contrast-enhanced MRI and thallium-201 SPECT for evaluation of
myocardial viability. The segmental extent of infarction was significantly less
pronounced on the SPECT studies, however, and SPECT failed to identify 70 of 352
myocardial segments that hyperenhanced on CE-MRI.
Regenfus credited CE-MRI's relatively high spatial resolution for its
superior performance.
"It allows late-enhancement CE-MRI to better depict the transmural extent of
myocardial infarction and detect small myocardial necroses that escape detection
with SPECT," he said.
Research from Duke University indicates that CE-MRI may be a better way to
diagnose silent MI, according to Dr. Han Kim, a cardiovascular MRI research
fellow.
The hypothesis that CE-MRI may be more sensitive to silent MI than
Q-wave/non-Q-wave ECG, the current diagnostic gold standard, was supported by a
study of 100 patients with suspected silent MI. Hyperenhancement of infarction
with CE-MRI was observed in 57% of the cases, a rate four times higher than the
14% rate of unrecognized MI detected with the Q-wave test, Kim said.
Follow-up evaluations after an average of 21 months found that the extent of
hyperenhancement was the only statistically significant predictor of death (p =
0.002). The risk of death rose when the hyperenhanced infarction involved more
than 5% of the left ventricular myocardium.
Several studies at the SCMR conference examined how to distinguish acute from
chronic MI with CE-MRI. Dr. Hassan Abdel-Aty, a cardiology researcher at the
Franz-Vohard Clinic in Berlin, found that late-enhancement imaging combined with
short T1 inversion recovery (STIR) imaging can play that role.
In a study of 119 patients (74 with acute MI, 27 with chronic MI, and 18
healthy controls), late-enhancement MRI was 100% sensitive to infarction but was
unable to differentiate acute from chronic disease. STIR, however, revealed
transmural hyperintensity among 71 of 74 acute infarcts and no transmurality
among the chronic lesions. The sensitivity and specificity of the paired tests
were 96% and 100%, respectively.
IMAGING CARDIOMYOPATHY
Late-enhancement CE-MRI may also find a role in the diagnosis of
cardiomyopathies. Dr. Marcelo Hadlich, a radiology researcher associated with
the D'Or Hospital Network in Rio de Janeiro, Brazil, reported that
delayed-enhancement MRI can detect irreversible myocardial disease in patients
with myopericarditis.
A preliminary study of five patients found delayed hyperenhancement in 40% of
the left ventricular segments examined. Those areas were small, diffusely
distributed, and not restricted to any specific coronary territories, Hadlich
said. The same hyperenhancement appeared when imaging was repeated three months
later, suggesting irreversible myocardial injury.
The work of Dr. James C.C. Moon and colleagues at Royal Brompton Hospital in
London, U.K., suggests that cine CMR and CE-MRI myocardial hyperenhancement may
diagnose early hypertrophic cardiomyopathy and serve as a marker for clinical
risk.
In a study of 30 patients from 13 families with mutations of troponin I,
echocardiography found hyperenhancement (LVH+) and exaggerated wall thickness in
15 subjects, and no abnormal enhancement and normal wall thickness among 15
(LVH-) individuals who are either in the early stages or disease-free.
Abnormal cine CMR and abnormal regional hypertrophy were found in 100% of the
LVH+ and 27% of the LVH- subjects. Hyperenhancement appeared in 86% of the LVH+
and 20% of the LVH- groups.
The overall extent of hyperenhancement was related to the risk of sudden
death and total left ventricular mass, and it was inversely related to left
ventricular ejection fracture, Moon said.
Although no age-related pattern was observed for the group as a whole,
hyperenhancement increased with age compared with the subjects' family members.
This pattern suggests that increasing hyperenhancement patterns over time
reflect disease progression, he said.
Chagas disease, also called South American trypanosomiasis, is caused by a
blood-borne parasite and can lead to myocardial fibrosis, typically in apical
and basal inferolateral left ventricular segments. Dr. Carlos E. Rochitte at the
Heart Institute of the University of Sao Paulo Medical School in Brazil found
that delayed-enhancement MRI identified fibrosis in 22 of 25 Chagas disease
patients and in 31% of the myocardial segments that were observed. More midwall
and subepicardial involvement was documented than was considered typical with
the disease. The extent of myocardial fibrosis correlated well with left
ventricular ejection fraction.
Although more investigative work is needed to refine these applications,
late-enhancement CE-MRI is quickly gaining favor among researchers responsible
for the creation and development of cardiac MRI.
Copyright (c) 2003 CMP Media LLC
LOAD-DATE: June 9, 2003
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