A single CT for attenuation correction of both rest and stress SPECT myocardial perfusion imaging: a retrospective feasibility study.
OBJECTIVE
In the effort to reduce radiation exposure to patients undergoing myocardial perfusion imaging (MPI) with SPECT/CT, we evaluate the feasibility of a single CT for attenuation correction (AC) of single-day rest (R)/stress (S) perfusion.


METHODS
Processing of 20 single isotope and 20 dual isotope MPI with perfusion defects were retrospectively repeated in three steps: (1) the standard method using a concurrent R-CT for AC of R-SPECT and S-CT for S-SPECT; (2) the standard method repeated; and (3) with the R-CT used for AC of S-SPECT, and the S-CT used for AC of R-SPECT. Intra-Class Correlation Coefficients (ICC) and Choen's kappa were used to measure intra-operator variability in sum scoring.


RESULTS
The highest level of intra-operator reliability was seen with the reproduction of the sum rest score (SRS) and sum stress score (SSS) (ICC > 95%). ICCs were > 85% for SRS and SSS when alternate CTs were used for AC, but when sum difference scores were calculated, ICC values were much lower (~22% to 27%), which may imply that neither CT substitution resulted in a reproducible difference score. Similar results were seen when evaluating dichotomous outcomes (sum scores difference of ≥ 4) when comparing different processing techniques (kappas ~0.32 to 0.43).


CONCLUSIONS
When a single CT is used for AC of both rest and stress SPECT, there is disproportionately high variability in sum scoring that is independent of user error. This information can be used to direct further investigation in radiation reduction for common imaging exams in nuclear medicine.
Department of Radiology and Imaging Sciences, National Institutes of Health Bethesda, MD, USA.
Mark A
MA
Ahlman
Department of Medicine, Division of Biostatistics and Epidemiology, Medical University of South Carolina Charleston, SC, USA.
Paul J
PJ
Nietert
Department of Medicine, Division of Biostatistics and Epidemiology, Medical University of South Carolina Charleston, SC, USA.
Amy E
AE
Wahlquist
Department of Radiology and Radiological Sciences, Medical University of South Carolina Charleston, SC, USA.
Jill M
JM
Serguson
Department of Radiology and Radiological Sciences, Medical University of South Carolina Charleston, SC, USA.
Max W
MW
Berry
Department of Radiology and Radiological Sciences, Medical University of South Carolina Charleston, SC, USA.
Pal
P
Suranyi
Department of Radiology and Imaging Sciences, National Institutes of Health Bethesda, MD, USA.
Songtao
S
Liu
Department of Radiology and Radiological Sciences, Medical University of South Carolina Charleston, SC, USA.
Kenneth M
KM
Spicer
Tomography; X-ray computed; emission-computed; myocardial perfusion imaging; radiation dosage; single-photon; tomography; “reproducibility of results”