Incomplete redistribution in delayed thallium-201 single photon emission computed tomographic (SPECT) images: An overestimation of myocardial scarring
To determine if incomplete redistribution at 4 h in exercise tomographic thallium-201 studies is always due to a myocardial scar, 141 patients were evaluated before and after a total of 160 successful percutaneous transluminal coronary angioplasty procedures. Thallium studies were analyzed using pol...
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| Published in: | Journal of the American College of Cardiology Vol. 12; no. 4; pp. 955 - 963 |
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| Main Authors: | , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
New York, NY
Elsevier Inc
01-10-1988
Elsevier Science |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | To determine if incomplete redistribution at 4 h in exercise tomographic thallium-201 studies is always due to a myocardial scar, 141 patients were evaluated before and after a total of 160 successful percutaneous transluminal coronary angioplasty procedures. Thallium studies were analyzed using polar “bull's-eye” maps. For both immediate and delayed images, abnormalities were quantified as a thallium score by calculating a standard deviation-weighted sum of pixels > 2.5 SD below gender-matched normal limits. One hundred forty-four of 160 studies indicated abnormalities before angioplasty. Of these 144, incomplete redistribution occurred in 111 (77%): 16 (14%) in patients with and 95 (86%) in patients without prior Q wave myocardial infarction. After angioplasty, improvement in delayed image score occurred in 8 (50%) of 16 patients with prior infarction and 72 (76%) of 95 patients without prior infarction (p < 0.05). After angioplasty, delayed images were normal in 1 (6%) of 16 patients with prior infarction and 32 (34%) of the 95 without (p < 0.05). Before angioplasty. delayed image scores were positively correlated with scores in the immediate postexercise images in patients with (r = 0.84) and those without (r = 0.69) prior infarction.
To determine if additional delayed images could help differentiate scar from ischemia, an 8 to 24 h delayed image was obtained in each of 40 other patients with incomplete redistribution at 4 h. Of 28 patients with prior infarction, 15 had no redistribution and 13 had further redistribution at 8 to 24 h. Of 12 patients without prior infarction, 1 had no redistribution, 7 had further redistribution and 4 had complete redistribution.
Thus, 4 h delayed thallium image defects frequently do not signify myocardial infarction. Their severity is proportional to immediate poststress abnormalities. Additional imaging at 8 to 24 h is recommended in patients with incomplete redistribution and no evidence of prior infarction. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0735-1097 1558-3597 |
| DOI: | 10.1016/0735-1097(88)90461-5 |