Influence of CT-based attenuation correction in assessment of left and right ventricular functions with count-based gated blood-pool SPECT

Abstract

Objective: Influence of CT-based attenuation correction (CT-AC) in assessment of left and right ventricular functions with count-based gated blood-pool SPECT (GBPS) was evaluated in a mixed population.

Methods: Thirty-two patients (81% male; mean age 56 ± 12) referred for various symptoms or heart diseases were prospectively included. Data from 32 GBPS acquisitions were reconstructed using an iterative algorithm with (IRAC) and without (IRNC) CT-AC and analyzed using previously described segmentation software based on the watershed algorithm. LV and RV EF and volumes were assessed with and without CT-AC and compared.

Results: EF and volumes were correlated (P < .001 for all parameters with r = 0.97 for LV and RV EF; r = 0.96 for LV EDV; r = 0.98 for LV ESV; r = 0.96 for RV EDV and ESV). The mean values using IRAC and IRNC were different for all parameters with lower EF (respectively, 49% ± 19% vs 51 %± 18%; P = .002 for LV EF and 50% ± 14% vs 54%±15%; P < .001 for RV EF) and higher volumes (respectively, 142 ± 41 mL vs 133 ± 40 mL; P < .001 and 79 ± 45 mL vs 71 ± 42 mL; P < .001 for LV EDV and ESV; 91 ± 32 mL vs 86 ± 31 mL; P = .003 and 48 ± 28 mL vs 43 ± 26 mL; P < .001 for RV EDV and ESV). Limits of agreement were -11% to 6% and -11% to 4% for LV and RV EF. We found wider limits of agreement for LV volumes (-13 to 32 mL for EDV and -10 to 27 mL for ESV) than for RV volumes (-13 to 23 mL for EDV and -9 to 20 mL for ESV). Taking into account all volumes, we found a trend with a significant positive correlation between means and differences in volumes assessed with and without CT-AC.

Conclusion: Assessment of both left and right ventricular functions by count-based GBPS with CT-AC showed higher volumes and lower EF. Differences were slight, especially for the range of normal to subnormal ventricular volumes.