Use of coronary calcium score scans from stand-alone multislice computed tomography for attenuation correction of myocardial perfusion SPECT.

PURPOSE: To evaluate the use of CT attenuation maps, generated from coronary calcium scoring (CCS) scans at in- and expiration with a 64-slice CT scanner, for attenuation correction (AC) of myocardial perfusion SPECT images.

METHODS: Thirty-two consecutive patients underwent( 99m)Tc-tetrofosmin gated adenosine stress/rest SPECT scan on an Infinia Hawkeye SPECT-CT device (GE Medical Systems) followed by CCS and CT angiography on a 64-slice CT. AC of the iteratively reconstructed images was performed with AC maps obtained: (a) from the "Hawkeye" low-resolution X-ray CT facility attached to the Infinia camera (IRAC); (b) from the CCS scan acquired on a 64-slice CT scanner during maximal inspiration (AC(INSP)) and (c) during normal expiration (AC(EXP)). Automatically determined uptake values of stress scans (QPS, Cedars Medical Sinai) from AC(INSP) and AC(EXP) were compared with IRAC. Agatston score (AS) values using AC(INSP)versus AC(EXP) were also compared.

RESULTS: AC(INSP) and AC(EXP) resulted in identical findings versus IRAC by visual analysis. A good correlation for uptake values between IRAC and AC(INSP) was found (apex, r=0.92; anterior, r=0.85; septal, r=0.91; lateral, r=0.86; inferior, r=0.90; all p<0.0001). The correlation was even closer between IRAC and AC(EXP) (apex, r=0.97; anterior, r=0.91; septal, r=0.94; lateral, r=0.92; inferior, r=0.97; all p<0.0001). The mean AS during inspiration (319+/-737) and expiration(317+/-778) was comparable (p=NS).

CONCLUSION: Attenuation maps from CCS allow accurate AC of SPECT MPI images. AC(EXP) proved superior to AC(INSP), suggesting that in hybrid scans CCS may be performed during normal expiration to allow its additional use for AC of SPECT MPI.