Author + information
- Received January 25, 1993
- Revision received August 9, 1993
- Accepted August 27, 1993
- Published online January 1, 1994.
- Stephen G. Sawada, MD, FACC,
- Kevin C. Allman, MB, BS,
- Otto Muzik, PhD,
- Rob S.B. Beanlands, MD,
- Edwin R. Wolfe Jr., MS,
- Milton Gross, MD,
- Lorraine Fig, MD, ChB, MpH and
- Markus Schwaiger, MD, FACC∗
- ↵∗Address for correspondence: Dr. Markus Schwaiger, Division of Nuclear Medicine, University of Michigan Medical Center, UH B1G505, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109.
Objectives. The purpose of this study was to determine the relative value of single-photon emission computed tomographic (SPECT) imaging at rest using technetium-99m methoxyisobutyl isonitrile (technetium-99m sestamibi) with positron emission tomography for detection of viable myocardium.
Background. Recent studies comparing positron emission tomography and thallium-201 reinjection with rest technetium-99m sestamibi imaging have suggested that the latter technique underestimates myocardial viability.
Methods. Twenty patients with a previous myocardial infarction underwent rest technetium-99m sestamibi imaging and positron emission tomography using fluorine (F)-18 deoxyglucose and nitrogen (N)-13 ammonia. In each patient, circumferential profile analysis was used to determine technetium-99m sestamibi, F-18 deoxyglucose and N-13 ammonia activity (expressed as percent of peak activity) in nine cardiac segments and in the perfusion defect defined by the area having technetium-99m sestamibi activity <60%. Technetium-99m sestamibi defects were graded as moderate (50% to 59% of peak activity) and severe (<50% of peak activity). Estimates of perfusion defect size were compared between technetium-99m sestamibi and N-13 ammonia.
Results. Sixteen (53%) of 30 segments with moderate defects and 16 (47%) of 34 segments with severe defects had ≥60% F-18 deoxyglocose activity considered indicative of viability. Fluorine-18 deoxyglucose evidence of viability was still present in 50% of segments with technetium-99m sestamibi activity <40%. There was no significant difference in the mean (± SD) technetium-99m sestamibi activity in segments with viable (40 ± 7%) and nonviable segments (49 ± 7%, p = 0.84). Of the 18 patients who had adequate F-18 deoxyglucose studies, the area of the technetium-99m sestamibi defect was viable in 5 (28%). In 16 patients (80%), perfusion defect size determined by technetium-99m sestamibi exceeded that measured by N-13 ammonia. The difference in defect size between technetium-99m sestamibi and N-13 ammonia was significantly greater in patients with viable (21 ± 9%) versus nonviable segments (7 ± 9%, p = 0.007).
Conclusions. Moderate and severe rest technetium-99m sestamibi defects frequently have metabolic evidence of viability. Technetium-99m sestamibi SPECT yields larger perfusion defects than does N-13 ammonia positron emission tomography when the same threshold values are used.
☆ This study was completed during Dr. Schwaiger's tenure as an established investigator of the American Heart Association, Dallas, Texas. It was supported in part by the Grant R01HL41047-01 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland and was presented in part at the 65th Annual Scientific Sessions of the American Heart Association, New Orleans, Louisiana, November 1992. Dr. Sawada was supported by Indiana University and The Krannert Institute of Cardiology.
- Received January 25, 1993.
- Revision received August 9, 1993.
- Accepted August 27, 1993.