Differences of LV volumes and ejection fraction by gated SPECT and gated PET and related parameters in patients with LV aneurysm: Comparison with MRI

Objectives To investigate the relationship between parameters (myocardial viability and defects) and differences of LV volumes and LV ejection fraction (LVEF) measured by gated SPECT(g-SPECT) and gated PET(g-PET) in patients with LV aneurysm.

Methods Forty-nine patients with LV aneurysm diagnosed by MRI were examined using 99mTc-MIBI g-SPECT and 18F-FDG g-PET. MRI was performed within 2 weeks. End diastolic and systolic volumes (EDV, ESV), and LVEF were assessed using QGS and their differences between g-SPECT and g-PET were calculated.The correlation between differences and parameters, which including summed rest score (SRS), summed FDG score (SFS), mismatch score (MMS, SRS-SFS), viable segments (MMS≥1), scar segments, dyskinetic segments (wall motion score ≥4 or wall thickening (WT) score=3), were analyzed.

Results For EDV and ESV, correlation was high (r=0.90,0.91,SEE=38,37ml) and correlation was moderate for LVEF between g-SPECT and g-PET (r=0.80,SEE10%). Compared with MRI (31±10%), LVEF were underestimated by g-SPECT (28±8%, p<0.01), but overestimated by g-PET (35±12%, p<0.01) and delta-EF was negatively related to the dyskinetic segments by WT (r=-0.44,-0.43, p<0.01). No any parameters were related to delta-EF between g-PET and g-SPECT,whereas delta-EDV was related to SRS, SFS, the scar segments, the dyskinetic segments by both wall motion and WT (r: 0.53, 0.54, 0.4, 0.37, 0.37, respectively, p<0.05). Delta-ESV between g-SPECT and g-PET was related to the dyskinetic segments by both wall motion and WT (r=0.38, 0.46, P<0.01).

Conclusions In patients with LV aneurysm, the difference of EF between g-SPECT and g-PET was unrelated to myocardial viability, but difference of EDV was related to the scar segments. g-SPECT and g-PET seem not to be interchangeable for LVEF and volumes