Extracardiac 18F-florbetapir imaging in patients with systemic amyloidosis: more than hearts and minds

T Wagner; J Page; M Burniston; A Skillen; J C Ross; R Manwani; D McCool; P N Hawkins; Ashutosh D Wechalekar

doi:10.1007/s00259-018-3995-2

Extracardiac ¹⁸F-florbetapir imaging in patients with systemic amyloidosis: more than hearts and minds

Eur J Nucl Med Mol Imaging. 2018 Jul;45(7):1129-1138. doi: 10.1007/s00259-018-3995-2. Epub 2018 Apr 12.

Authors

T Wagner¹, J Page², M Burniston³, A Skillen¹, J C Ross², R Manwani², D McCool¹, P N Hawkins², Ashutosh D Wechalekar⁴

Affiliations

¹ Department of Nuclear Medicine, Royal Free Hospital, Pond Street, London, UK.
² National Amyloidosis Centre, University College London (Royal Free Campus), Rowland Hill Street, NW3 2PF, London, UK.
³ Department of Nuclear Medicine, St Bartholomew's Hospital, Barts Health NHS Trust, West Smithfield, London, UK.
⁴ National Amyloidosis Centre, University College London (Royal Free Campus), Rowland Hill Street, NW3 2PF, London, UK. a.wechalekar@ucl.ac.uk.

Abstract

Purpose: ¹⁸F-Florbetapir has been reported to show cardiac uptake in patients with systemic light-chain amyloidosis (AL). This study systematically assessed uptake of ¹⁸F-florbetapir in patients with proven systemic amyloidosis at sites outside the heart.

Methods: Seventeen patients with proven cardiac amyloidosis underwent ¹⁸F-florbetapir PET/CT imaging, 15 with AL and 2 with transthyretin amyloidosis (ATTR). Three patients had repeat scans. All patients had protocolized assessment at the UK National Amyloidosis Centre including imaging with ¹²³I-serum amyloid P component (SAP). ¹⁸F-Florbetapir images were assessed for areas of increased tracer accumulation and time-uptake curves in terms of standardized uptake values (SUV_mean) were produced.

Results: All 17 patients showed ¹⁸F-florbetapir uptake at one or more extracardiac sites. Uptake was seen in the spleen in 6 patients (35%; 6 of 9, 67%, with splenic involvement on ¹²³I-SAP scintigraphy), in the fat in 11 (65%), in the tongue in 8 (47%), in the parotids in 8 (47%), in the masticatory muscles in 7 (41%), in the lungs in 3 (18%), and in the kidney in 2 (12%) on the late half-body images. The ¹⁸F-florbetapir spleen retention index (SRI) was calculated. SRI >0.045 had 100% sensitivity/sensitivity (in relation to ¹²³I-SAP splenic uptake, the current standard) in detecting splenic amyloid on dynamic imaging and a sensitivity of 66.7% and a specificity of 100% on the late half-body images. Intense lung uptake was seen in three patients, one of whom had lung interstitial infiltration suggestive of amyloid deposition on previous high-resolution CT. Repeat imaging showed a stable appearance in all three patients suggesting no early impact of treatment response.

Conclusion: ¹⁸F-Florbetapir PET/CT is a promising tool for the detection of extracardiac sites of amyloid deposition. The combination of uptake in the heart and uptake in the spleen on ¹⁸F-florbetapir PET/CT, a hallmark of AL, suggests that this tracer holds promise as a screening tool for AL.

Keywords: AL; Amyloid; Cardiac amyloid; Florbetapir; PET; TTR.

MeSH terms

Aged
Aged, 80 and over
Amyloidosis / diagnostic imaging*
Aniline Compounds*
Ethylene Glycols*
Female
Humans
Male
Middle Aged
Positron Emission Tomography Computed Tomography*
Prospective Studies

Substances

Aniline Compounds
Ethylene Glycols
florbetapir