Is 16-frame really superior to 8-frame gated SPECT for the assessment of left ventricular volumes and ejection fraction? Comparison of two simultaneously acquired gated SPECT studies.
OBJECTIVE
Conflicting data exist about the difference between 8- and 16-frame gated single-photon emission computed tomography (SPECT) left ventricular volumes and ejection fraction (EF); moreover, the influence of framing on detection of stress-induced functional changes is unknown.


METHODS
In 133 patients, two separate gated SPECT studies, one with 8 and one with 16 frames, were simultaneously acquired during a single gantry orbit using dedicated software. In 33 of 133 patients, two additional studies (with 8 and 16 frames, respectively) were acquired using arrhythmia rejection. Left ventricular EF and volumes were calculated using the QGS software. Stress-induced ischemia was identified on summed perfusion images.


RESULTS
Arrhythmia-rejection did not influence volumes and EF independently of framing rate. Using data without arrhythmia-rejection, there was a significant difference in volumes and EF between 8 and 16 frames both in resting and post-stress gated SPECT. However, the difference was small: 2.6% for resting and 2.8% for post-stress EF. Both using 8 and 16 frames, there were significantly larger volumes and lower EF in patients with than without stress-induced ischemia. A stress-induced decrease >5 EF units was observed in 26 of 133 patients using 8 and in 23 of 133 using 16 frames, respectively, with finding agreement in 19 patients.


CONCLUSIONS
Comparing two simultaneously acquired studies, the use of 16 instead of 8 frames has minor and predictable influence on functional data. Furthermore, there are no differences in the detection of stress-induced functional changes. The advantage of 16 over 8 frames in the daily clinical practice appears questionable.
Montelatici
Giulia
G
Nuclear Medicine Unit, Department of Clinical Physiopathology, University of Florence, Viale Morgagni 85, 50134, Florence, Italy.
Sciagrà
Roberto
R
Passeri
Alessandro
A
Dona
Manjola
M
Pupi
Alberto
A
D001145:Arrhythmias, Cardiac / Q000000981:diagnostic imaging / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013312:Stress, Physiological; D013318:Stroke Volume; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D016277:Ventricular Function, Left