Dopamine D2 receptor SPECT with (123)I-IBZM: evaluation of collimator and post-filtering when using model-based compensation-a Monte Carlo study.
In (123)I-IBZM brain SPECT, the main interest is the activity uptake in the striatum relative to the background, and semi-quantitative techniques using regions of interest are typically used for this purpose. Uncertainties in the measured uptakes can however be a problem due to low contrasts and high noise levels. Like SPECT in general, IBZM SPECT should benefit from reconstruction methods that include model-based compensation, but it is important that image acquisition is optimized for this technique. An important factor is the choice of collimator. In this study we compare four different parallel-hole collimators for IBZM SPECT regarding overall quantitative accuracy and measured uptake ratio as a function of image noise and uncertainty. The collimators are low-energy high-resolution (LEHR), low-energy general-purpose (LEGP), extended LEGP (ELEGP) and medium-energy general-purpose (MEGP). The effect of three Butterworth post-filters with cut-off frequencies of 0.3, 0.45 and 0.6 cm(-1) (power factor 8) is also studied. All raw-data projections are produced using Monte Carlo simulations. Of the investigated collimators, the one that is most sensitive to the primary photons, ELEGP, proved to be the most optimal for realistic noise levels. Butterworth post-filtering is advantageous, and the cut-off frequency 0.45 cm(-1) was the best compromise in this study.
Department of Radiation Sciences, Radiation Physics, Umeå University, SE-901 87 Umeå, Sweden. anne.larsson@vll.se
Anne
A
Larsson
Susanna Jakobson
SJ
Mo
Michael
M
Ljungberg
Katrine
K
Riklund
D000465:Algorithms; D001549:Benzamides / Q000493:pharmacokinetics*; D003198:Computer Simulation; D003342:Corpus Striatum / Q000000981:diagnostic imaging* / Q000378:metabolism*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008954:Models, Biological; D015233:Models, Statistical; D009010:Monte Carlo Method; D011759:Pyrrolidines / Q000493:pharmacokinetics*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D001549:Benzamides; D011759:Pyrrolidines; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2; C055743:3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide