[Rest and stress myocardial perfusion imaging on the same day with two injections of 99mTc-tetrofosmin].
99mTc-tetrofosmin myocardial perfusion imagings under different protocols were performed at rest and stress on the same day. In the stress/rest protocol, the exercise study was carried out first, and then the rest one followed. Eight patients were involved in the stress/rest protocol. Seven patients were examined in the reverse, rest/stress protocol. In any protocols, the injection interval was 3 hours, and injection doses in the first and second studies were 370 MBq and 740 MBq, respectively. Myocardial counts were obtained by placing region of interest over the myocardial walls in short axial SPECT images. Based on myocardial counts from the first injection and the wash-out rate of tetrofosmin, we calculated, at the second imaging, counts caused from the first injection. Approximately 20-25% of counts in the second study were found to be caused from the residual radiotracer. The residual radiotracers affected the interpretation of imagings of two patients we examined: one with marked reversible ischemia examined in the stress/rest protocol and the other with mild ischemic change examined in the rest/stress one. Our results suggested that some modifications of studies, such as the increase in the injection intervals or the reduce of the first-to-second dose ratio, might be necessary to conduct the same day protocols.
Hashimoto
J
J
Department of Radiology, School of Medicine, Keio University.
Kubo
A
A
Nakamura
K
K
Sammiya
T
T
Iwanaga
S
S
Uno
K
K
Nishimura
H
H
Takahashi
E
E
Mitamura
H
H
Handa
S
S
D005080:Exercise Test; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging; D009943:Organophosphorus Compounds / Q000008:administration & dosage; D015609:Organotechnetium Compounds / Q000008:administration & dosage; D012146:Rest; D015899:Tomography, Emission-Computed, Single-Photon
D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; C078700:technetium tc-99m tetrofosmin