Abstract
BackgroundIn [99mTc]Tc-DPD scintigraphy for myocardial ATTR amyloidosis, planar images 3 hour p.i. and SPECT/CT acquisition in L-mode are recommended. This study investigated if earlier planar images (1 hour p.i.) are beneficial and if SPECT/CT acquisition should be preferred in H-mode (180° detector angle) or L-mode (90°). MethodsIn SPECT/CT phantom measurements (NaI cameras, N = 2; CZT, N = 1), peak contrast recovery (CRpeak) was derived from sphere inserts or myocardial insert (cardiac phantom; signal-to-background ratio [SBR], 10:1 or 5:1). In 25 positive and 38 negative patients (reference: endomyocardial biopsy or clinical diagnosis), Perugini scores and heart-to-contralateral (H/CL) count ratios were derived from planar images 1 hour and 3 hour p.i. ResultsIn phantom measurements, accuracy of myocardial CRpeak at SBR 10:1 (H-mode, 0.95-0.99) and reproducibility at 5:1 (H-mode, 1.02-1.14) was comparable for H-mode and L-mode. However, L-mode showed higher variability of background counts and sphere CRpeak throughout the field of view than H-mode. In patients, sensitivity/specificity were ≥ 95% for H/CL ratios at both time points and visual scoring 3 hour. At 1 hour, visual scores showed specificity of 89% and reduced reader’s confidence. ConclusionsEarly DPD images provided no additional value for visual scoring or H/CL ratios. In SPECT/CT, H-mode is preferred over L-mode, especially if quantification is applied apart from the myocardium.
Highlights
In [99mTc]Tc-DPD scintigraphy for myocardial Amyloid transthyretin (ATTR) amyloidosis, planar images 3 hour p.i. and SPECT/CT acquisition in L-mode are recommended
DPD images provided no additional value for visual scoring or H/CL ratios
In SPECT/CT, H-mode is preferred over L-mode, especially if quantification is applied apart from the myocardium. (J Nucl Cardiol 2021)
Summary
In [99mTc]Tc-DPD scintigraphy for myocardial ATTR amyloidosis, planar images 3 hour p.i. and SPECT/CT acquisition in L-mode are recommended. This study investigated if earlier planar images (1 hour p.i.) are beneficial and if SPECT/CT acquisition should be preferred in H-mode (180° detector angle) or L-mode (90°). Amyloid transthyretin (ATTR) amyloidosis is a potentially life-threatening cause of heart failure caused by accumulation of liver-derived, misfolded transthyretin. Tc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD), plays a key role in identifying myocardial involvement.[1] Quantification of myocardial uptake using single photon emission computed tomography/computed tomography (SPECT/CT) might provide prognostic value[2] or therapy monitoring of the multitude of recently introduced ATTR amyloidosis-specific drugs.[3,4,5]. An earlier time point at 1 hour p.i. is recommended if [99mTc]Tc-pyrophosphate (PYP) is used, while additional imaging at 3 hour p.i. would be recommended if cardiac uptake is superimposed by high blood pool activity at 1 hour p.i.6
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