Published in:
01-08-2016 | Original Article
Dose reduction in half-time myocardial perfusion SPECT-CT with multifocal collimation
Published in: Journal of Nuclear Cardiology | Issue 4/2016
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Background
Recent technological advances in myocardial perfusion imaging may warrant the use of lower injected activity. We evaluated whether quantitative measures of stress myocardial perfusion defects using Tc-99m sestamibi and low-energy high-resolution (LEHR) collimators are equivalent to lower dose SPECT-CT with cardiac multifocal collimators and software (IQ·SPECT).
Methods
93 patients underwent one-day rest-stress gated SPECT-CT. Following conventional rest imaging, 925-1100 MBq (25-30 mCi) of Tc-99m sestamibi was injected during stress testing. Stress SPECT-CT images were acquired two ways: with LEHR (13 minutes) and IQ·SPECT (7 minutes). Low-dose IQ·SPECT stress was simulated by subsampling the full-dose data to half-, quarter-, and eighth-count levels. Abnormalities were quantified using the total perfusion deficit (TPD) score and dose-specific databases.
Results
The mean ± SD of the differences between LEHR and IQ·SPECT TPD scores were −1.01 ± 5.36%, −0.10 ± 5.81%, 1.78 ± 4.81%, and 1.75 ± 6.05% at full, half, quarter, and eighth doses, respectively. Differences were statistically significant for quarter and eighth doses. Correlation between LEHR and IQ·SPECT was excellent at all doses (R ≥ 0.93). Bland-Altman plots demonstrated minimal bias.
Conclusions
With IQ·SPECT, quantitative stress SPECT-CT imaging is possible with half of the standard injected activity in half the time.