Does quantification of myocardial perfusion SPECT study differ while image reconstruction is carried out using iteration algorithm instead of filtered back-projection?--preliminary report.
BACKGROUND
The purpose of this study was to compare the performance of two reconstruction algorithms: conventional filtered back-projection (FBP) and an iterative algorithm--ITW--in quantitative analysis of myocardial perfusion SPECT studies. The defect size and defect severity were assessed on (99m)Tc-MIBI images reconstructed using both methods and estimation of sensitivity in the detection of perfusion deficits and myocardial viability were performed as well.


RESULTS
The study group comprised 43 patients (38 men and 5 women) in the age of 40-73 years (mean 59 years). Heart perfusion scintigraphy was performed following an injection of 22 to 25 mCi 99mTc-MIBI for exercise and rest myocardial perfusion study. Images were reconstructed using FBP and ITW algorithms. Defect size (DS) was quantified by a threshold program and CEqual programme. Defect severity (nadir) was calculated as the ratio of minimal/maximum counts from bull?s eye polar map. Coronary arteriography was performed in all patients.


RESULTS
Defect size calculated by threshold method on resting images did not differ between reconstruction methods (p=0.61 for cut-off 50% and p = 0.24 for cut-off 60%); defect severity was higher on images reconstructed with ITW (CI(0.95) = 2.4%;5.2% of maximal counts).


CONCLUSIONS
Sensitivity for detection of heart perfusion defects and estimation of myocardial viability were similar on images reconstructed by both algorithms.
Department of Nuclear Medicine, Medical University, Gdańsk, Poland. kkedziora@amg.gda.pl
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