GRC Amyloid Research Institute, Hôpitaux Universitaires Henri Mondor Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology Early-phase myocardial uptake intensity of 99mTc-HMDP vs. 99mTc-DPD in patients with hereditary transthyretin-related cardiac amyloidosis Abulizi M, Cottereau AS, Guellich A, Vandeventer S, Galat A, Van Der Gucht A, Plante-Bordeneuve V, Dubois-Randé JL, Bodez D, Rosso J, Damy T, Itti E GRC Amyloid Research Institute, Hôpitaux Universitaires Henri Mondor Head shot of author required Institution Picture/Logo Optional Copyright American Society of Nuclear Cardiology

Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology BACKGROUND 1- 99mTc-labelled bone tracers are used for noninvasive diagnosis of cardiac amyloidosis (CA) 2- myocardial uptake of 99mTc-labelled bone tracers is high in transthyretin-related CA (TTR-CA) and absent in light-chain CA (AL-CA) 3- early-phase scanning (10 min post-injection) shows same diagnostic performance than late-phase scanning (3 h post-injection) 4- direct comparison of myocardial uptake of DPD and HMDP in the same patients has never been performed although an in vitro study shows higher affinity of DPD for amyloid fibrils compared with HMDP and PYP Copyright American Society of Nuclear Cardiology

METHODS Study type: observational IRB-approved study Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology METHODS Study type: observational IRB-approved study Study subjects: 6 patients with biopsy-proven hereditary TTR-CA Study endpoints: To compare the intensity of early-phase myocardial uptake of two widely used phosphonate-based radiotracers in Europe, 99mTc-HMDP and 99mTc-DPD To compare the regional distribution within the AHA 17-segment model Study variables: Heart-to-mediastinum ratio, relative segmental uptake Copyright American Society of Nuclear Cardiology

Average of DPD and HMDP segments (%) Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology RESULTS Comparison of heart-to-mediastinum ratio between both radiotracers in the same patients. Bland-Altman plots of the differences in segmental myocardial radiotracer distribution in the 6 patients: pt 1, blue empty circles; pt 2, blue plain circles; pt 3, red empty squares; pt 4, red plain squares; pt 5, green empty triangles; pt 6, red plain triangles. HMDP DPD Heart / Mediastinum ratio . . DPD - HMDP segments (%) . . Average of DPD and HMDP segments (%) Copyright American Society of Nuclear Cardiology

RESULTS 99mTc-HMDP 99mTc-DPD Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology RESULTS Comparison of myocardial uptake (whole-body anterior view with ROIs overlayed and bull’s eye analysis) between 99mTc-HMDP and 99mTc-DPD in the same patient. Heart-to-mediastinum ratio are 1.97 and 2.07, respectively. DPD imaging was performed 4.6 mo after HMDP and patient underwent pacemaker implantation in the mean time (arrow). 99mTc-HMDP 99mTc-DPD Copyright American Society of Nuclear Cardiology

Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology CONCLUSIONS 1- 99mTc-HMDP and 99mTc-DPD show comparable myocardial uptake intensity on early-phase scintigraphy in TTR-CA 2- Regional distribution of myocardial uptake is also similar on Bull’s eye analysis (17-segment model), showing apical/periapical defects and higher uptake of the septum 3- Both tracers can be used alternatively for the diagnosis of hereditary amyloidosis. 4- Further studies using other, FDA-approved tracers, are warranted Copyright American Society of Nuclear Cardiology