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Orphanet J Rare DisOrphanet J Rare DisOrphanet Journal of Rare Diseases1750-1172BioMed Central 1750-1172-10-S1-P4110.1186/1750-1172-10-S1-P41Poster PresentationDisphosphonates cardiac uptake in familial amyloid neuropathy: Comparison between DPD and HMDP Regaieg Hamza 1De Paola Chequer Renata 1Azzouna Rana Ben 1Algalarrondo Vincent 2Mahida Besma 1Slama Michel 2Le Guludec Dominique 1Rouzet François 11 Bichat-Claude Bernard university hospital, Department of nuclear medicine, 75018, Paris, France2 Antoine Béclère university hospital, Department of cardiology (NNERF), 92140, Clamart, France2015 2 11 2015 10 Suppl 1 First European Congress on Hereditary ATTR amyloidosisPublication of this supplement was funded by the First European Congress on Hereditary ATTR amyloidosis.P41 P41 Copyright © 2015 Regaieg et al.2015Regaieg et al.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.2-3 November 2015 First European Congress on Hereditary ATTR amyloidosis Paris, France
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Background
Familial amyloid polyneuropathy (FAP) is a severe hereditary disease, due to production by the liver of a genetic variant transthyretin (TTR) resulting in tissue amyloid deposits. Cardiac involvement is of major prognostic value. Diphosphonate scintigraphy has been proposed as a diagnostic tool for TTR-related cardiac amyloidosis, but there is no consensus on the optimal radiopharmaceutical. Consequently, we compared the cardiac uptake of two 99mTc-labelled tracers: diphosphono-propanedicarboxylic acid (DPD) and hydroxymethylene diphosphonate (HMDP) in patients with TTR-FAP.

Methods
122 consecutive patients with TTR-FAP were prospectively included and received randomly DPD or HMDP. Acquisitions (whole-body (WB) and chest SPECT) were performed 3 hours after intravenous injection of the tracer. Quantification of myocardial uptake on WB acquisitions was performed by use of the ratio between the geometric mean of either total or average counts of a region of interest (ROI) drawn over the heart area and the WB total or average counts (H/WBtotal or H/WBaverage). Quantification on SPECT acquisitions was performed by the ratio between 3D isocount volume of interest generated over the myocardium and a standard volume in the right lung (H/L). Quantification of soft tissues uptake was performed by use of ratio between average counts of a ROI drawn over the lumbar spine and a ROI drawn over soft tissues of the lower limb (B/ST) on the WB acquisition.

Results
The DPD and HMDP groups of patients had similar age (62±15 vs. 59±14 years respectively; p=0.3), sex (males: 67% vs. 58% respectively; p=0.4), TTR mutation (Val30Met: 70% vs. 80% respectively; p=0.3) and activity of the tracer (DPD: 713±86 MBq vs. HMDP: 709±124 MBq; p=0.9). Quantitative parameters derived from whole body acquisition were significantly greater with DPD compared to HMDP (H/WBtotal: 3.8±2.7 vs. 2.4±2.1 respectively; p=0.002 and H/WBaverage: 5.2±2.2 vs. 4.3±1.3 respectively; p=0.01) as well as H/L derived from SPECT acquisition (3.9±3.7 vs. 2.0±1.9 respectively; p=0.001). The uptake by soft tissues was also greater in the DPD compared to HMDP group (B/ST: 3.6±2.0 vs. 5.7±2.9 respectively; p<0.0001).

Conclusion
The present study shows that in patients with TTR FAP, the uptake of DPD in heart and other soft tissues is superior to that of HMDP. This suggests that DPD should be prioritized for initial assessment of patients suspected of cardiac involvement of TTR-related amyloidosis. Further study is required to assess whether this difference impacts the diagnostic performance and whether DPD is more accurate for the assessment of therapy response.


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