Validation of Left Ventricular Ejection Fraction with the IQ•SPECT System in Small-Heart Patients

Abstract

The IQ•SPECT system, which is equipped with multifocal collimators (ZOOM) and uses ordered-subset conjugate gradient minimization as the reconstruction algorithm, reduces the acquisition time of myocardial perfusion imaging compared with conventional SPECT systems equipped with low-energy high-resolution collimators. We compared the IQ•SPECT system with a conventional SPECT system for estimating left ventricular ejection fraction (LVEF) in patients with a small heart (end-systolic volume < 20 mL). The study consisted of 98 consecutive patients who underwent a 1-d stress-rest myocardial perfusion imaging study with aTc-labeled agent for preoperative risk assessment. Data were reconstructed using filtered backprojection for conventional SPECT and ordered-subset conjugate gradient minimization for IQ•SPECT. End-systolic volume, end-diastolic volume, and LVEF were calculated using quantitative gated SPECT (QGS) and cardioREPO software. We compared the LVEF from gated myocardial perfusion SPECT to that from echocardiographic measurements. End-diastolic volume, end-systolic volume, and LVEF as obtained from conventional SPECT, IQ•SPECT, and echocardiography showed a good to excellent correlation regardless of whether they were calculated using QGS or using cardioREPO. Although LVEF calculated using QGS significantly differed between conventional SPECT and IQ•SPECT (65.4% ± 13.8% vs. 68.4% ± 15.2%) ( = 0.0002), LVEF calculated using cardioREPO did not (69.5% ± 10.6% vs. 69.5% ± 11.0%). Likewise, although LVEF calculated using QGS significantly differed between conventional SPECT and IQ•SPECT (75.0 ± 9.6 vs. 79.5 ± 8.3) ( = 0.0005), LVEF calculated using cardioREPO did not (72.3% ± 9.0% vs. 74.3% ± 8.3%). In small-heart patients, the difference in LVEF between IQ•SPECT and conventional SPECT was less when calculated using cardioREPO than when calculated using QGS.

Impact of Valve Plane Alignment on the Repeatability of Left Ventricular Ejection Fraction in ECG-gated Myocardial SPECT Using Corridor 4DM

“…LVEF >55% was considered to be normal, 35-55% moderately reduced and <35% markedly reduced. Left ventricles with ESV < 20 ml were considered to be "small hearts" (10,11).…”

New hardware, new software, different results: The estimation of left ventricular volumes and ejection fractions with gated myocardial perfusion SPECT

“…In their Discussion section, the authors comprehensively review studies by other investigators comparing LVEF estimates from gated IQ-SPECT with those from SPECT with parallel hole LEHR acquisition. [8][9][10][11][12] There are clearly differences among the reported results, though a consensus of the reasons for the differences has yet to emerge. In this context, the current article provides important additional information on whether LVEF results from IQ-SPECT are comparable clinically with those from gated SPECT with LEHR collimation.…”

EANM procedural guidelines for myocardial perfusion scintigraphy using cardiac-centered gamma cameras

“…IQ-SPECT produces systematically smaller LV volumes than the conventional LEHR MPS protocols and volume estimates are also software dependent (Hippelainen et al 2017 ). The calculated LVEF may differ between conventional gated SPECT and gated IQ-SPECT depending on the software program used (Yoneyama et al 2017 ; Joergensen and Hansson 2015 ). In general, IQ-SPECT shows higher values.…”