| Objective:In this study,we compared IQ-SPECT and LEHR-SPECT gated myocardial perfusion imaging(GMPI)for the estimation of LVEF in patients with small hearts(males: EDV≤60ml,ESV≤25 ml;females: EDV≤45 ml,ESV≤20 ml),using cardiac magnetic resonance(CMR)as the "gold standard".And we investigated the impact of different reconstruction parameters on measuring EDV,ESV,LVEF in IQ-SPECT GMPI,to select the best reconstruction parameters of IQ-SPECT in patients with small heart size.Methods:The study consisted of 49 consecutive patients(20 normal and 29 with small heart size.The small heart group was defined EDV≤60 ml and ESV≤25ml for malesand EDV≤45ml and ESV≤20ml for females,The normal heart group was defined by EDV61-120 ml and ESV>25ml for males and EDV 41-110 ml and ESV>20ml for females)who underwent IQ-SPECT resting gated myocardial perfusion imaging(GMPI)at the Nuclear Medicine Department of our hospital from November 2019 to December 2022.The patients underwent IQ-SPECT GMPI followed by LEHR-SPECT GMPI,after which they underwent CMR examination within 1 week.ESV,EDV,and LVEF were calculated using quantitative gated SPECT(QGS).The data were reconstructed using filtered back projection(FBP)for LEHR-SPECT and orderedsubset maximum expected value(OSEM)for IQ-SPECT.Six different reconstructionparameters(3-10,5-12,5-15,8-12,8-15,8-18)were used to compare the EDV,ESV,LVEF measured by IQ-SPECT and LHER-SPECT with CMR values.To determine the optimal ordered-subset reconstruction parameters,we compared the LVEF from SPECT to the corresponding measurement from with the Bland-Altman method.Results:1.Comparison of cardiac function parameters between IQ-SPECT,LEHR-SPECT and CMR: In the small-heart group,EDV,ESV,LVEF measured by IQ-SPECT and LEHR-SPECT were statistically significant(P<0.05).Detection by LEHR-SPECT underestimated EDV and ESV compared with CMR examination were statistically significant(P<0.05).LVEF of LEHR-SPECT was higher than the LVEF of CMR.There were no significant differences in LVEF measurements made by IQ-SPECT and CMR(62.10±7.79% vs.64.61±8.83%,P=0.120);In the normal group,EDV,ESV,LVEF measured by IQ-SPECT and LEHR-SPECT were statistically significant(P<0.05).Detection by LEHR-SPECT underestimated EDV and ESV compared with CMR examination were statistically significant(P<0.05).LVEF of LEHR-SPECT was higher than the LVEF of CMR.There were no significant differences in LVEF measurements made by IQ-SPECT and CMR(50.55±4.33% vs.53.15±5.82%,P=0.258).2.As the numbers of iterations and subsets increased,EDV and ESV graduallyincreased,and LVEF gradually decreased in the normal heart and small heart groups.3.Comparison of IQ-SPECT with CMR cardiac function parameters under different reconstruction conditions: In the smal-heart group,No significant differences were observed in the LVEF examined by the 5-12 method and by CMR(62.10±7.79% vs.64.61±8.83%,P=0.120),but there were significant differences in this value as determined by the other 5 methods and by CMR(P<0.05).There were significant differences in EDV as measured by all six GMPI methods and by CMR(P<0.05).There were no significant differences in ESV as determined by the 8-18 method and by CMR(24.76±7.29 ml vs.28.06±10.63 ml,P=0.054),and there were significant differences in ESV as determined by the other five methods and by CMR(P<0.05).In the normal group,there were significant differences in EDV and ESV as measured by the six GMPI for 3-10,5-12,5-15,8-12,8-15,8-18 methods and by CMR(P<0.05).There were no significant differences in LVEF as measured by the 3-10 method,the 5-12 method,and CMR(50.55±4.33% vs.53.15±5.82%,P=0.117;49.95±4.32% vs.53.15±5.82%,P=0.056).However,there were significant differences in LVEF detected by the other four methods and CMR(P<0.05).4.In the small-heart group,the results showed that the 5-12 method and CMR had the smallest bias,with an estimate of 2.5%.The bias produced by the 3-10 method and CMR was lowest for the normal heart group,with an estimate of only 2.6%.Conclusion:With CMR as the standard,IQ-SPECT yields more reliable LVEF values than conventional SPECT for populations with small heart size.The best reconstruction parameters from IQ-SPECT were 5 subset and 12 iterations for patients with small hearts. |
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