18F-Fluorodeoxyglucose positron emission tomography for detection of acute cellular rejection after heart transplantation: A single–center retrospective study

TL;DR

This study explores whether 18F-FDG PET/CT can detect heart transplant rejection without invasive biopsies.

Contribution

The study demonstrates that FDG uptake metrics can detect acute cellular rejection after heart transplantation.

Findings

FDG uptake metrics (CMV, SUVmax, TLG) were significantly higher during acute cellular rejection.

18F-FDG PET/CT showed significant increases in metabolic parameters at the time of rejection.

No cases of antibody-mediated rejection were observed in the study population.

Abstract

Although histopathological evaluation of myocardium is essential for detecting both acute cellular rejection (ACR) and antibody-mediated rejection (AMR) following heart transplantation, indeterminate results and complication risks associated with repeated endomyocardial biopsies remain serious problems. We investigated the clinical utility of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to detect rejection.

This retrospective single–center study reviewed the clinical data of heart-transplant recipients at our institution between 2008 and 2022. Patients who underwent 18F-FDG PET/CT scans post-transplant were enrolled. Scans were performed following a high-fat, low-carbohydrate diet initiated 24 hours before imaging and an 18-hour fasting period. FDG uptake was represented as cardiac metabolic volume (CMV), maximum standard uptake value (SUVmax), and total lesion glycolysis (TLG).

During the study period, 132 18F-FDG PET/CT scans in 40 heart-transplant recipients were identified. Age at transplant was 53 [43-62] years old, and 29 patients (73%) were male. We found 10 scans at the time of significant ACR. No patients experienced AMR. At the time of ACR, CMV (88.2 [22.5-275.8] vs 0.0 [0.0-7.3] ml, p < 0.001), SUVmax (9.21 [6.87-16.0] vs 2.98 [2.49-4.48], p < 0.001) and TLG (365.3 [78.3-1,908.7] vs 0.0 [0.0-25.8] g, p < 0.001) were significantly higher compared to those without rejection. From baseline to the time of ACR, significant increases of CMV, SUVmax, and TLG (p < 0.001 for all) were also found.

FDG uptake was significantly elevated at the time of ACR. 18F-FDG PET/CT may represent a promising non–invasive diagnostic adjunct for detecting ACR following heart transplantation.

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