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

J Nucl Med Technol. 2017 Sep;45(3):201-207. doi: 10.2967/jnmt.116.188680. Epub 2017 Jun 13.

Abstract

The IQ•SPECT system, which is equipped with multifocal collimators (SMARTZOOM) 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). Methods: The study consisted of 98 consecutive patients who underwent a 1-d stress-rest myocardial perfusion imaging study with a 99mTc-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. Results: 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%) (P = 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) (P = 0.0005), LVEF calculated using cardioREPO did not (72.3% ± 9.0% vs. 74.3% ± 8.3%). Conclusion: 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.

Keywords: IQ-SPECT; cardioREPO; echocardiographic measurement; left ventricular ejection fraction; small heart.

Publication types

  • Evaluation Study
  • Validation Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Equipment Design
  • Equipment Failure Analysis
  • Female
  • Humans
  • Image Interpretation, Computer-Assisted / instrumentation*
  • Image Interpretation, Computer-Assisted / methods*
  • Male
  • Middle Aged
  • Myocardial Perfusion Imaging / instrumentation*
  • Myocardial Perfusion Imaging / methods*
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Stroke Volume*
  • Tomography, Emission-Computed, Single-Photon / instrumentation*
  • Ventricular Dysfunction, Left / diagnostic imaging*