Comparison of 1- and 2-day protocols for myocardial SPECT: a Monte Carlo study.
BACKGROUND
Myocardial perfusion single-photon emission computed tomography (SPECT) is carried out by combining a rest and a stress study that are performed either on one day or two separate days. A problem when performing the two studies on 1 day is that the residual activity from the first study contributes to the activity measured in the second study.


OBJECTIVE
Our aim was to identify and evaluate trends in the quantification parameters of myocardial perfusion images as a function of separation time between rest and stress.


METHODS
A digital phantom was used for the generation of heart images and a Monte Carlo-based scintillation camera program was used to simulate SPECT projection images. In our simulations, the rest images were normal and the stress images included lesions of different types and localization. Two programs for quantification of myocardial perfusion images were used to assess the different images in an automated and objective way.


RESULTS
The summed difference scores observed with the 2-day protocol were 3 +/- 1 (mean +/- SD) higher for AutoQUANT and 2 +/- 1 higher for 4D-MSPECT compared with those observed with the 1-day protocol. The extent values were 2% points higher for the 2-day protocol compared with the 1-day protocol for both programs.


CONCLUSIONS
There are differences in the quantitative assessment of perfusion defects depending on the type of protocol used. The contribution of residual activity is larger when a 1-day protocol is used compared with the 2-day protocol. The differences, although small, are of a magnitude that results in a clear shift in quantification parameters.
Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund, Sweden. henrik_hussein.el_ali@radfys.lu.se
H H
HH
El-Ali
John
J
Palmer
Marcus
M
Carlsson
Lars
L
Edenbrandt
Michael
M
Ljungberg
D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005080:Exercise Test / Q000379:methods; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods*