18F-Florbetaben PET Detection of Cardiac and Multi-Organ Involvement for Identifying AL and ATTR Cardiac Amyloidosis.

BACKGROUND

18F-florbetaben positron emission tomography (PET) is reported to detect i) cardiac amyloidosis (CA), particularly AL (light chain) forms, and ii) sites of extracardiac AL-amyloid infiltrates.

OBJECTIVES

The purpose of this study was to identify CA and differentiate AL-CA from ATTR-CA (transthyretin) by evaluating cardiac and multi-organ involvement with whole-body 18F-florbetaben PET.

METHODS

Multicentric study of 61 patients with left ventricular hypertrophy due to AL-CA (n = 25), ATTR-CA (n = 25), and aortic stenosis (n = 11, controls). A 20-minute whole-body PET was preceded by a 10-minute dynamic cardiac PET recording started during 18F-florbetaben injection.

RESULTS

Tracer uptake was significantly increased in whole-body PET of CA patients compared to controls, with AL-CA patients, in particular, exhibiting increased uptake in myocardium, lung, and spleen, and decreased uptake in blood, salivary glands, skeletal muscle, and liver. Among cardiac parameters, the myocardial/blood standardized uptake value (SUV)max ratio from whole-body PET best differentiated AL-CA from ATTR-CA, with 90% (55/61) of patients identified correctly (kappa value: 0.819) using SUVmax ratio thresholds of 2-to-4 for ATTR-CA and >4 for AL-CA. When combining cardiac with extracardiac PET variables, the selected multivariate predictors were myocardial uptake volume and the lung and salivary gland SUVmean. Thresholds of myocardial uptake volume >10 mL for CA and lung/salivary gland SUVmean >0.285 for AL-CA correctly identified 93% (57/61) of patients (kappa value: 0.871). PET variables improved the overall prediction provided by the bone scan Perugini score (P < 0.001).

CONCLUSIONS

Whole-body 18F-florbetaben PET identifies CA and differentiates AL-CA from ATTR-CA. These distinctions are strengthened by combining assessments of cardiac and multi-organ involvement.