title: Gated SPECT evaluation of left ventricular function using a CZT camera and a fast low-dose clinical protocol: comparison to cardiac magnetic resonance imaging.
abstract: OBJECTIVE
  CZT technology allows ultrafast low-dose myocardial scintigraphy but its accuracy in assessing left ventricular function is still to be defined.
  
  
  METHODS
  The study group comprised 55 patients (23 women, mean age 63 ± 9 years) referred for myocardial perfusion scintigraphy. The patients were studied at rest using a CZT camera (Discovery NM530c; GE Healthcare) and a low-dose (99m)Tc-tetrofosmin clinical protocol (mean dose 264 ± 38 MBq). Gated SPECT imaging was performed as a 6-min list-mode acquisition, 15 min after radiotracer injection. Images were reformatted (8-frame to 16-frame) using Lister software on a Xeleris workstation (GE Healthcare) and then reconstructed with a dedicated iterative algorithm. Analysis was performed using Quantitative Gated SPECT (QGS) software. Within 2 weeks patients underwent cardiac magnetic resonance imaging (cMRI, 1.5-T unit CVi; GE Healthcare) using a 30-frame acquisition protocol and dedicated software for analysis (MASS 6.1; Medis).
  
  
  RESULTS
  The ventricular volumes obtained with 8-frame QGS showed excellent correlations with the cMRI volumes (end-diastolic volume (EDV), r = 0.90; end-systolic volume (ESV), r = 0.94; p < 0.001). However, QGS significantly underestimated the ventricular volumes (mean differences: EDV, -39.5 ± 29 mL; ESV, -15.4 ± 22 mL; p < 0.001). Similarly, the ventricular volumes obtained with 16-frame QGS showed an excellent correlations with the cMRI volumes (EDV, r = 0.92; ESV, r = 0.95; p < 0.001) but with significant underestimations (mean differences: EDV, -33.2 ± 26 mL; ESV, -17.9 ± 20 mL; p < 0.001). Despite significantly lower values (47.9 ± 16 % vs. 51.2 ± 15 %, p < 0.008), 8-frame QGS mean ejection fraction (EF) was closely correlated with the cMRI values (r = 0.84, p < 0.001). The mean EF with 16-frame QGS showed the best correlation with the cMRI values (r = 0.91, p < 0.001) and was similar to the mean cMRI value (49.6 ± 16 %, p not significant). Regional analysis showed a good correlation between both 8-frame and 16-frame QGS and cMRI wall motion score indexes (8-frame WMSI, r = 0.85; 16-frame WMSI, r = 0.89; p < 0.01).
  
  
  CONCLUSIONS
  Low-dose gated SPECT with a CZT camera provides ventricular volumes that correlate well with cMRI results despite significant underestimation in the measure values. EF estimation appeared to be more accurate with 16-frame reformatted images than with 8-frame images.
authors.affiliation: Fondazione CNR/Regione Toscana "G. Monasterio", Via Moruzzi 1, 56124, Pisa, Italy, asso@ftgm.it.
authors.forename: Assuero
authors.initials: A
authors.lastname: Giorgetti
authors.forename: Pier Giorgio
authors.initials: PG
authors.lastname: Masci
authors.forename: Gavino
authors.initials: G
authors.lastname: Marras
authors.forename: Yasmine K
authors.initials: YK
authors.lastname: Rustamova
authors.forename: Alessia
authors.initials: A
authors.lastname: Gimelli
authors.forename: Dario
authors.initials: D
authors.lastname: Genovesi
authors.forename: Massimo
authors.initials: M
authors.lastname: Lombardi
authors.forename: Paolo
authors.initials: P
authors.lastname: Marzullo
mesh_terms: D002104:Cadmium; D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography / Q000295:instrumentation*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009068:Movement; D009929:Organ Size; D011829:Radiation Dosage; D013691:Tellurium; D013997:Time Factors; D016277:Ventricular Function, Left; D015032:Zinc
chemical_list: C474490:CdZnTe; D002104:Cadmium; D015032:Zinc; D013691:Tellurium