The Impact of Attenuation Correction and Prone Positioning on Stress-Only Imaging in Cardiac SPECT: An Observational Study.

Abstract

Background: Current guidelines recommend stress-only single photon emission computed tomography myocardial perfusion imaging (SPECT MPI) in select patients to reduce time, cost, and radiation. However, stress-only imaging remains underutilized.

Objectives: We assessed techniques to increase the adoption of stress-only SPECT MPI, specifically evaluating whether prone positioning and CT-based attenuation correction (AC) reduce the need for additional rest imaging.

Methods: Consecutive patients with normal stress SPECT MPI scans were included. The need for additional rest imaging was assessed according to the use of prone-positioning and AC. Radiotracer dose was calculated per the institution's protocol and compared between groups. Survival analysis compared the safety of stress-only protocols compared to stress-rest protocols.

Results: Between 2018 and 2024, 14,274 patients with no stress perfusion defects were included. The use of stress-only imaging increased from 43.6% among patients with neither AC nor prone to 63.4% with AC and 65.7% with prone to 76 % with both techniques. Using multivariable logistic regression, the simultaneous use of prone and AC techniques significantly increased stress-only imaging (OR: 5.0, 95% CI: 4.38-5.72). This was more pronounced among females, obese patients, patients >65 years, and patients with an EF ≥ 55%. Radiotracer dose dropped by 35.6% when both AC and prone were used. Patients with normal stress-only SPECT scans had similar prognoses to those with normal SPECT scans using both stress and rest images, regardless of AC or prone imaging use.

Conclusion: Combined use of AC and prone reduces the need for rest imaging by nearly half and lowers radiotracer doses by a third. Benefits are more pronounced in women, the elderly, patients with obesity, non-diabetics and those with preserved ejection fraction.