Abstract
P857
Introduction: Light chain cardiac amyloidosis (AL-CA) causes one of the mortal forms of heart failure (HF) with worse survival. So early diagnosis, risk stratification is essential in clinical practice. 18F-Florbetapir PET/CT has been shown promising as a highly sensitive method to detect amyloid deposition. 68Ga-FAPI-04, as a novel PET radiotracer, can reflect activated fibroblasts, which can produce collagen and myocardial fibrosis, thus increasing myocardial stiffness and HF. This prospective study compared diagnostic and risk stratification efficacy of 18F-Florbetapir and 68Ga-FAPI-04 PET/CT in AL-CA.
Methods: 46 consecutive patients with biopsy-proven AL amyloidosis (age, 56.8±9.6 years; 73.9% men) were recruited between September 2021 and July 2022. All patients underwent 18F-Florbetapir, 68Ga-FAPI-04 PET/CT and echocardiography. For 18F-Florbetapir, a 60min dynamic scan (SinoUnion PoleStar m660, China) after radiotracer injection with a dose of 305.5±66.3 MBq. Myocardial retention of 18F-Florbetapir, defined as the active concentration in myocardial tissue between 10 and 30 min, normalized by the integral from 0 to 20 min of the blood pool (left atrium) input function using MIM package. Myocardial RI was defined globally for the entire LV. A cutoff value of more than 0.06 was used for active amyloidosis. The LV mean SUV (SUVmean) was defined as the mean SUV of the total voxels in the volume of interest (VOIs) between 10 and 30 min. SUVR was defined as the SUVmean of the myocardial volume VOIs divided by the SUVmean of the blood pool VOI. In addition, 68Ga-FAPI-04 images were acquired on a PET/CT scanner 60 min after intravenous injection of 153.0±57.1 MBq. For semi-quantitative analysis, the LV maximal SUV (SUVmax), LV SUVmean and SUVR were evaluated. If no visible uptake was appreciated, a circular VOI of 10 mm in diameter was placed on the mid of the interventricular septal (IVS) wall to evaluate the SUVmean and SUVmax. The positive is defined as the cardiac activity higher than blood pool. Pearson’s or Spearman’s correlation analysis was conducted to explore the correlation of 18F-Florbetapir or 68Ga-FAPI-04 PET/CT parameters with clinical, echocardiography parameters.
Results: Of 46 patients, 39 patients were diagnosed with AL-CA whereas 7 patients had no cardiac involvement (non AL-CA). For 18F-Florbetapir, 93.5% patients demonstrated amyloid deposition presenting as RI (0.195±0.092), SUVmean(4.29±2.14), SUVR (8.26±3.65). However, the measurements of amyloid burden were all normal of the other three patients (RI: 0.05 [0.04, 0.05], SUVmean: 1.14 [1.06, 1.36], SUVR: 1.79 [1.71, 2.58]). In addition, 35 patients showed increased 68Ga-FAPI-04 uptake whereas 11 patients had negative uptake in the cardiac. The SUVmean, SUVmax, SUVR in 68Ga-FAPI-04-avid patients were 1.96±0.73, 3.50±1.35, and 3.03±1.28, respectively. In contrast, the LV SUVmean, SUVmax, and SUVR were 0.73±0.16, 0.92±0.21 and 0.79±0.12 in the 68Ga-FAPI 04 non-avid patients. Among 7 non AL-CA patients, 4 patients had positive 18F-Florbetapir uptake whereas 3 patients showed negative uptake. For 68Ga-FAPI-04, only 1 patient showed active uptake, whereas the remaining 6 patients had negative cardiac uptake. The representative patients were in Figure S1. In terms of 18F-Florbetapir, RI, SUVmean and SUVR had a positive relationship with NT-proBNP level (Figure 1). In echocardiography analysis, SUVmean and SUVR were associated with LVPW and E/E’. SUVR was correlated with LAD and RI was correlated with E/A. For 68Ga-FAPI-04, SUVmax and SUVR were positively correlated with Mayo stage. Additionally, SUVmean, SUVmax and SUVR were all significantly associated with NT-proBNP, cTnI, dFLC, IVS, LVEF, LVPW, LAD, E/E’ and E/A.
Conclusions: 18F-Florbetapir PET/CT could identify the earliest detectable manifestations of amyloid deposition and 68Ga-FAPI-04 may potentially reflect disease burden and risk stratification. The combinations could provide information on cardiac molecular characterization and patient management.
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