Cardiac amyloid imaging with [¹¹C]PIB PET/CT: insights from an initial clinical experience

Background

Bone scintigraphy with single-photon emission computed tomography (SPECT) is first-line for detecting cardiac amyloidosis but can yield false negatives in light chain amyloidosis (AL-CA) and the p.V50M variant of transthyretin amyloid cardiomyopathy (ATTR-CM), often requiring biopsy. [¹¹C]PIB positron emission tomography (PET)/CT shows promise for detecting cardiac involvement across subtypes.

Purpose

To describe our experience using [¹¹C]PIB PET/CT in the evaluation of suspected amyloid cardiomyopathy.

Methods

Retrospective, observational, single-centre study including all patients with suspected amyloid cardiomyopathy who underwent [¹¹C]PIB PET/CT. We collected data on clinical manifestations, electrocardiographic and echocardiography variables, and outcomes.

Results

Twenty patients were screened with [¹¹C]PIB PET/CT (60% females, mean age 60.6±13.0), most of them due to suspicion of ATTR-CM (60%), followed by AL-CA (35%) and serum amyloid A amyloidosis (AA-CA) (5%). Of 12 patients with suspected ATTR-CM, 11 had familial amyloid polyneuropathy (64% female, mean age 54.7±9.7), all post-liver transplant (17.3±5.0 years ago) and 11 with pacemakers. NYHA class was I (3), II (4), III (3), IV (1). Echocardiography showed LV wall thickness 15±5 mm, LV EF 58±4%, GLS -9.7±1.7%, mean E/e’ 14±5. None underwent cardiac magnetic resonance or endomyocardial biopsy. [¹¹C]PIB PET/CT showed cardiac uptake in all, with additional uptake in lacrimal (8), salivary (5), brain (4), parotid (2), thyroid (2), spleen (1), and adrenal glands (1). The remaining patient with suspected ATTR-CM had a suggestive echo, but negative DPD bone scintigraphy, negative hematologic studies, and [¹¹C]PIB PET/CT was also negative.

Among seven patients with suspected AL-CA (71% female, mean age 66.3±13.2), three had monoclonal gammopathy of undetermined significance (two IgG kappa, one IgG lambda), two had renal light chain deposition, and one had biopsy-proven pharyngeal amyloidosis. None showed cardiac [¹¹C]PIB uptake, though parotid (1) and spleen (1) uptake occurred.

The remaining patient with suspected AA-CA had nephrotic syndrome and rheumatoid arthritis, being the biopsy contraindicated due to bleeding risk; [¹¹C]PIB PET/CT was negative.

Conclusions

[¹¹C]PIB PET/CT detected cardiac involvement in all patients with familial amyloid polyneuropathy and suspected ATTR-CM, highlighting its potential for non-invasive diagnosis in this population.