Clinical value of stress-only Tc-99m SPECT imaging: Importance of attenuation correction

Abstract

Background. In selected patients, stress-only SPECT imaging has been proposed as an alternative to rest-stress SPECT imaging to improve laboratory efficiency and reduce radiation exposure. The impact of attenuation correction (AC) upon interpretation, post-test patient management and cardiac risk stratification in relation to stress-only imaging is not well understood.Objectives. The purpose of this study was to determine the clinical value for laboratory throughput and predicting outcomes of normal and abnormal stress-only SPECT imaging with AC in a consecutive series of clinically referred patients.Methods. A retrospective analysis of 1,383 consecutive patients who were scheduled for stress-only SPECT imaging for symptom assessment of suspected myocardial ischemia was performed. All images had been interpreted and categorized using the standard 17-segment model without AC followed by AC. Follow-up data for 2.1 ± 1.3 years after SPECT imaging for the occurrence of cardiac events (non-fatal MI, cardiac death, and cardiac revascularization) previously collected by routine methods were reviewed.Results. Non-AC SPECT image interpretation revealed that 58% (802/1383) of patients had abnormal stress images. AC image interpretation of the abnormal non-AC images re-classified 83% (666/802) of these as normal. Among patients with abnormal stress images after AC (136/ 1383), 63% (86/136) returned for additional rest scans, while the remaining 37% (50/136) were clinically managed without further rest images. The incidence of cardiac death or non-fatal MI was very low in patients with normal stress-only scans (0.7%).Conclusion. A strategy of stress-only imaging with AC in symptomatic patients is an efficient method which appropriately identifies at risk and low-risk patients yielding a low percentage requiring rest imaging. Clinical decisions can be made based on abnormal stress-only imaging without further rest imaging if clinically appropriate. (J Nucl Cardiol 2013;20:27-37.)

Effect of a patient-specific minimum activity in stress myocardial perfusion imaging using CZT-SPECT: Prognostic value, radiation dose, and scan outcome

“…They report annual hard cardiac event rates varying between 0.6 and 1.3% for normally interpreted stress-only scans and between 1.2 and 1.4% for normally interpreted stress-rest scans. [32][33][34][35] These rates seem slightly higher than encountered in the present study which could be due to differences in the pre-test likelihood and the use of conventional instead of CZT-based SPECT cameras.…”

Attenuation correction in stress-only myocardial perfusion imaging

“…7 Although the use of AC in SPECT MPI is emerging and there is evidence of superiority in diagnostic confidence and accuracy of AC over non-corrected SPECT MPI, information on the prognostic value of AC on SPECT MPI studies are limited, particularly when using stress-only imaging. [8][9][10] Hence, the work of van Dijk and co-workers is an important step forward in the direction of patient-centered care promoting stress-only imaging using the latest SPECT technology.…”

Approaches to Reducing Radiation Dose from Radionuclide Myocardial Perfusion Imaging

“…Attenuation correction using radionuclide or CT-based transmission scans significantly reduced the need for rest MPI imaging in as many as 37%-48% of patients scheduled for stress-first SPECT imaging (31,37). Indeed, the primary application of cardiac CT with SPECT and PET MPI is for attenuation correction, with a radiation dose ranging from 0.3 to 1.3 mSv with appropriate cardiac CT dose reduction methods (Supplemental Table 4) (13).…”