Reducing the small-heart effect in pediatric gated myocardial perfusion single-photon emission computed tomography

Background. We compared two reconstruction algorisms and two cardiac functional evaluation software programs in terms of their accuracy for estimating ejection fraction (EF) of small hearts (SH). Methods. The study group consisted of 66 pediatric patients. Data were reconstructed using a filtered back projection (FBP) method without the resolution correction (RC) and an iterative method based on an ordered subset expectation maximization (OSEM) algorithm with the RC. EF was evaluated using two software programs of quantitative gated single-photon emission computed tomography (SPECT) (QGS) and cardioREPO. We compared the EF of gated myocardial perfusion SPECT to echocardiographic measurement (Echo). Results. Forty-eight of 66 patients had an end-systolic volume < 20 mL which was used as the criterion for being included in the SH group, and the SH effect led to an overestimation of EF. While significant differences were observed between Echo (66.9 +/- 5.0%) and QGS-FBP without RC (76.9 +/- 8.4%, P < .0001), QGS-OSEM with RC (76.6 +/- 8.6%, P < .0001), and cardioREPO-FBP without RC (72.1 +/- 10.0%, P = .0011), no significant difference was observed between Echo and cardioREPO-OSEM with RC (67.4 +/- 6.1%) in SH group. Conclusions. In pediatric gated myocardial perfusion SPECT, the SH effect can be significantly reduced when an OSEM algorithm is used with RC in combination with the specific cardioREPO algorithm.