Decreasing the number of projections in acquisition of myocardial perfusion scintigraphy may affect image interpretation due to potential loss in resolution in the reconstructed images. This study was performed to compare the uptake and artefact scores in reconstructed stress images derived from 64 projections and 32 projections myocardial perfusion scintigraphy.
Sixty patients were selected retrospectively from the routine patient population. Stress images were acquired with 64 projections and 64*64 matrix size. These images were compressed to 32 projections and all studies reconstructed with butterworth filter (Cut off frequency 0.5 nyquist and order of 5). Reconstructed tomograms were scored by an experienced nuclear physician using a 9 segment model of the left ventricular myocardium with respect to myocardial uptake and artefact due to attenuation, reconstruction and low counts. Thirty studies were scored twice to assess intraobserver variability.
The 64 Vs 32 projection tomograms artefact score was compared by Wilcoxon signed rank test and the uptake score was compared by unweighted Kappa analysis and intraobserver variability was assessed in similar manner. There is no statistically significant variation in quality score (p value −.157), uptake score (Kappa of 0.6278 with 95% CI, attenuation artefact score (p value −.674), reconstruction (p value −.057) and low count artefact score (p value −.058). There is no intraobserver variation with respect to score in uptake (Weighted Kappa value −0.7483 with 95% CI), quality (p value −.739), attenuation artefact (p value −.414), reconstruction artefact (p value −.225) and low count artifact (p value −.414). Conclusion: Image acqusition in myocardial perfusion scintigraphy can be done with 32 projections instead of 64 projections as there is no significant variation in clinical interpretation.
