Validation of gated blood-pool SPECT cardiac measurements tested using a biventricular dynamic physical phantom.
We have developed a biventricular dynamic physical cardiac phantom to test gated blood-pool (GBP) SPECT image-processing algorithms. Such phantoms provide absolute values against which to assess accuracy of both right and left computed ventricular volume and ejection fraction (EF) measurements.


METHODS
Two silicon-rubber chambers driven by 2 piston pumps simulated crescent-shaped right ventricles wrapped partway around ellopsoid left ventricles. Twenty experiments were performed at Ghent University, for which right and left ventricular true volume and EF ranges were 65-275 mL and 55-165 mL and 7%-49% and 12%-69%, respectively. Resulting 64 x 64 simulated GBP SPECT images acquired at 16 frames per R-R interval were sent to Columbia University, where 2 observers analyzed images independently of each other, without knowledge of true values. Algorithms automatically segmented right ventricular activity volumetrically from left ventricular activity. Automated valve planes, midventricular planes, and segmentation regions were presented to observers, who accepted these choices or modified them as necessary. One observer repeated measurements >1 mo later without reference to previous determinations.


RESULTS
Linear correlation coefficients (r) of the mean of the 3 GBP SPECT observations versus true values for right and left ventricles were 0.80 and 0.94 for EF and 0.94 and 0.95 for volumes, respectively. Correlations for right and left ventricles were 0.97 and 0.97 for EF and 0.96 and 0.89 for volumes, respectively, for interobserver agreement and 0.97 and 0.98 for EF and 0.96 and 0.90 for volumes, respectively, for intraobserver agreement. No trends were detected, though volumes and right ventricular EFs were significantly higher than true values.


CONCLUSIONS
Overall, GBP SPECT measurements correlated strongly with true values. The phantom evaluated shows considerable promise for helping to guide algorithm developments for improved GBP SPECT accuracy.
De Bondt
Pieter
P
Nuclear Medicine Division, Ghent University Hospital, Ghent, Belgium. pieter.debondt@rug.ac.be
Nichols
Kenneth
K
Vandenberghe
Stijn
S
Segers
Patrick
P
De Winter
Olivier
O
Van de Wiele
Christophe
C
Verdonck
Pascal
P
Shazad
Arsalan
A
Shoyeb
Abu H
AH
De Sutter
Johan
J
D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods; D015637:Gated Blood-Pool Imaging / Q000295:instrumentation / Q000379:methods*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D019047:Phantoms, Imaging; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D016277:Ventricular Function, Left / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology