Περίληψη:
We have compared stress-redistribution and delayed rest thallium-201
with rest technetium-99m methoxyisobutylisonitrile (MIBI) tomograms in
order to compare the tracers for the assessment of myocardial viability
and to validate a rapid protocol combining the two tracers. We studied
30 consecutive patients with known or suspected coronary artery disease
[group 1: 16 with normal left Ventricular function, mean left
ventricular ejection fraction (LVEF) 55%, SD 6%; group 2: 14 with
abnormal function, mean LVEF 28%, SD 8%]. (201)T1 was injected during
infusion of adenosine followed by acquisition of conventional stress and
redistribution tomograms. On a separate day, (201)T1 was injected at
rest with imaging 4 h later. Tc-99m-MIBI was then given at rest and
imaging was performed. Three images were compared: redistribution
(201)T1, rest (201)T1, and rest Tc-99m-MIBI. Tracer activity was
classified visually and quantitatively in nine segments and segments
with > 50% activity were defined as containing clinically significant
viable myocardium. Mean (+/- SD) global tracer uptake as a percentage of
maximum was similar in group I (rest (201)T1 69% +/- 12%,
redistribution (201)T1 69% +/- 15%, rest Tc-99m-MIBI 70% +/- 13%,
ANOVA P > 0.05), but in group 2 mean tracer uptake was significantly
greater in the rest (201)T1 images (59% +/- 16%) than in
redistribution (201)T1 images (53% +/- 17%) or rest Tc-99m-MIBI images
(53% +/- 19%) (ANOVA P = 0.02). Overall agreement for regional uptake
score was excellent (kappa from 0.79 to 0.84), although there were a
significant number of segments with less uptake shown by redistribution
(201)T1 and by rest Tc-99m-MIBI than by rest (201)T1 in group 2 (P <
0.001). The number of segments with significant viable myocardium in
group 1 was very similar between the three images (P > 0.05) but in
group 2 rest (201)T1 identified significantly more segments as viable
than the other images (McNemar P < 0.001). Thus (201)T1 and Tc-99m-MIBI
provide similar information in patients without prior infarction and
with normal left ventricular function (group 1), and a rapid protocol
with stress (201)T1 injection and imaging followed immediately by rest
Tc-99m-MIBI injection and imaging is feasible. In patients with abnormal
left ventricular function and prior infarction (group 2), Tc-99m-MIBI
may underestimate the extent of clinically significant viable
myocardium.
Συγγραφείς:
ANAGNOSTOPOULOS, C
LANEY, R
PENNELL, D
PROUKAKIS, H and
UNDERWOOD, R
