Related Experiment Video
Updated: Sep 21, 2026
High-Resolution Cardiac Positron Emission Tomography/Computed Tomography for Small Animals
Published on: December 16, 2022
Artificial intelligence-derived splenic response in cardiac positron emission tomography is associated with major
Giselle Ramirez1, Naga L Dharmavaram1, Aakash Shanbhag1,2
1Artificial Intelligence in Medicine Research Center, Departments of Biomedical Sciences, Medicine, and Cardiology, Cedars-Sinai Medical Center, 6500 Wilshire Blvd, Los Angeles, CA 90048, USA.
Aims:
Inadequate pharmacologic stress may limit the diagnostic and prognostic accuracy of myocardial perfusion imaging (MPI). The splenic ratio (SR), a measure of stress adequacy, has emerged as a potential imaging biomarker. We developed an artificial intelligence (AI) method to derive SR and evaluated the prognostic value in a large multicentre 82Rb-PET cohort undergoing regadenoson stress testing.
Methods And Results:
We retrospectively analysed 16 650 patients from six sites in the REFINE PET registry with clinically indicated MPI and linked clinical outcomes. SR was calculated using fully automated algorithms as the ratio of splenic uptake at stress vs. rest. Patients were stratified by SR into decile groups. The primary outcome was major adverse cardiovascular events (MACE). Survival analysis was conducted using Kaplan-Meier and Cox proportional hazards models adjusted for clinical and imaging covariates, including myocardial flow reserve (MFR ≥2 vs. <2) and presence of ischaemia. The cohort had a median age of 69 years, with 59% male patients. Common risk factors included hypertension (81%), dyslipidaemia (77%), diabetes (35%), and prior coronary artery disease (31%). Median follow-up was 3.4 years. Patients with high SR in the testing cohort (n = 950) had an increased risk of MACE [hazard ratio (HR) 1.19, 95% confidence interval (CI) 1.06-1.34, P = 0.005]. Among testing patients with preserved MFR (≥2; n = 8067), high SR remained independently associated with MACE (HR 1.43, 95% CI 1.20-1.70, P < 0.001). Even among patients with preserved MFR and no ischaemia in the testing cohort(MFR≥2, SDS<2; n = 6508), high SR remained independently associated with MACE (HR 1.54 95% CI 1.26-1.88, P < 0.001).
Conclusion:
Elevated AI-derived SR was independently associated with adverse cardiovascular outcomes, including among patients with preserved MFR. These findings support SR as a novel, automated imaging biomarker for risk stratification in 82Rb PET MPI.
Related Concept Videos
01:28Imaging Studies for Cardiovascular System V: CT
01:21Imaging Studies for Cardiovascular System IV: CMRI
01:29Positron Emission Tomography
One of the main requirements of a PET scan is a positron-emitting radioisotope, which is produced in a cyclotron and then attached to a substance used by the part of the body being...
01:20Imaging Studies for Cardiovascular System III: X-Ray
Definition and Purpose
An X-ray, or radiograph, is a non-invasive method that uses ionizing radiation to take images of internal structures. It is mainly used in cardiac imaging to examine the heart, lungs, and major blood vessels, aiming to identify abnormalities in the heart's size, shape, and position, such as heart failure, congenital defects, and vascular...