Issn Print: 0143-3636
Publication Date: 2003/03/01
P15. Comparison of 99mTc tetrofosmin gated SPECT measurements of left ventricular volumes and ejection fraction with MRI
Excerpt
The calculation of ejection fraction (EF) using quantitative gated SPECT (QGS) has been widely validated against a range of other techniques. There have been fewer studies validating left ventricular (LV) volumes. We compared QGS values with magnetic resonance (MR) measurements obtained using a turbo gradient echo pulse sequence (TGE) in 17 patients and a steady state free precession sequence (SSFP) in 33 patients. There was good correlation between EF and end diastolic (ED) volume measurements from SPECT and MRI (r = 0.82, r = 0.90, respectively) over a large range in EF and volume but the mean SPECT values were significantly lower (6.6 and 18.4 ml) than those obtained from MRI. SSFP gave a larger difference for ED volume measurement compared to SPECT than did TGE, although this difference did not reach significance. Both SSFP and TGE gave similar values for the difference between MRI and SPECT for EF measurement. We suggest that the difference in EF may be a result of eight frames being used for gating in QGS but 12-18 for MR. Differences in volumes may be related to differing delineation of the endocardial border for MR images, dependent on the particular acquisition sequence. In conclusion, QGS values correlated well with MR, but a correction factor may be needed if direct comparison is made.
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