Related Experiment Video
Updated: Jun 22, 2025
High-Resolution Cardiac Positron Emission Tomography/Computed Tomography for Small Animals
Published on: December 16, 2022
Prediction of cardiac allograft vasculopathy using splenic switch-off on myocardial PET
Atsushi Yamamoto1, Michinobu Nagao2, Michiru Nomoto3
1Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan; Department of Diagnostic Imaging and Nuclear Medicine, Tokyo Women's Medical University, Tokyo, Japan.
Insights
Splenic switch-off (SSO) detected via 13N-ammonia PET indicates endothelial function and predicts cardiac allograft vasculopathy (CAV) in heart transplant recipients. This finding aids in managing CAV, a major cause of death post-transplant.
Area of Science:
- Cardiology
- Nuclear Medicine
- Vascular Biology
Background:
- Heart transplantation (HTx) is crucial for end-stage heart failure.
- Cardiac allograft vasculopathy (CAV) is the primary cause of mortality post-HTx.
- 13N-ammonia PET offers diagnostic and prognostic insights into CAV.
Purpose of the Study:
- To evaluate splenic adenosine reactivity via 13N-ammonia PET as an index of endothelial function.
- To determine if splenic switch-off (SSO) predicts CAV development or progression.
- To explore the parallel progression of CAV and systemic vascular endothelial dysfunction.
Main Methods:
- Analysis of 48 HTx patients undergoing 13N-ammonia PET.
- Calculation of spleen ratio (stress/rest uptake) to define SSO via ROC analysis.
- Kaplan-Meier analysis to assess SSO predictability for CAV endpoint.
Main Results:
- The endpoint (CAV appearance/progression) occurred in 9 patients over 45 months.
- A spleen ratio cutoff of 0.94 was determined for SSO.
- Patients without SSO showed a significantly higher CAV rate (p=0.022).
Conclusions:
- SSO, measured by 13N-ammonia PET, reflects systemic endothelial function.
- SSO serves as a significant predictor of CAV in heart transplant recipients.
Background:
Heart transplantation (HTx) is a definitive therapy for refractory heart failure. Cardiac allograft vasculopathy (CAV), characterized by diffuse arteriopathy involving the epicardial coronary arteries and microvasculature, is the major cause of death for patients with HTx. 13N-ammonia positron emission tomography (NH3-PET) can offer diagnostic and prognostic utility for CAV. The splenic switch-off (SSO) detected in NH3-PET is a hemodynamic indicator of favorable response to adenosine. We hypothesized that both CAV and SSO reflected a pathology that progresses in parallel with systemic vascular endothelial dysfunction. Therefore, we quantitatively evaluated splenic adenosine reactivity measured using NH3-PET as an index of endothelial function, and examined its predictability for CAV.
Methods:
Forty-eight patients who underwent NH3-PET after HTx were analyzed. The spleen ratio was calculated as the mean standardized uptake value, measured by placing an ROI on the spleen, at stress divided by that at rest. SSO was defined by a cutoff determined using receiver operating characteristic (ROC) analysis for the spleen ratio. The endpoint was appearance or progression of CAV. Predictability of SSO was analyzed using Kaplan-Meier analysis.
Results:
The endpoint occurred in 9 patients during a mean follow-up of 45 ± 17 months. ROC curve analysis demonstrated a cutoff of 0.94 for spleen ratio. Patients without SSO displayed a significantly higher CAV rate than those with SSO (p = 0.022).
Conclusions:
SSO reflects the endothelial function of systemic blood vessels and was a predictor of CAV in patients with HTx.
