Abstract
Aims
The importance of cardiac scan with phosphonate-based radiotracers in the diagnosis of cardiac amyloidosis is now well established. Standard imaging is performed 3 h after tracer injection with a planar view on the cardiac region. This study sought to evaluate the predictive role of early-phase myocardial uptake (10 min after injection) of 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) compared compared with standard late acquisition, in patients with suspected hereditary transthyretin-related cardiac amyloidosis (TTR-CA).
Methods and results
Fifty five patients with suspected of TTR-CA with typical aspects of the relative apical sparing at two-dimensional speckle-tracking echocardiography, reported as a specific pattern for cardiac amyloidosis, were enrolled after having signed informed written consent. They have been subjected to a 99mTc-DPD cardiac scintigraphy with planar acquisition at 10 min and 3 h after tracer injection (13 Mbq/Kg). Patients with cardiac uptake on the planar images concluded the examination with a SPECT-CT (cardiac protocol) to assess the affected myocardial segments. On planar images the heart-to-mediastinum-ratio was measured. Subsequently, the diagnosis of amyloidosis has to be confirmed with morphologic examinations such as biopsy and genetic tests. Of the enrolled patients with clinical and echocardiographic aspect of TTR-CA, 22 were positive for cardiac amyloidosis. All of them showed tracer uptake in both early and late images. In patients with positive results, the early-phase showed a Heart-to-mediastinum-ratio >1.2. SPECT/CT showed involvement of almost two myocardial segments: in all patients the ventricular septum showed significant tracer uptake.
Conclusions
Our small group of patients showed that 99mTc-DPD myocardial uptake intensity on early-phase scintigraphy can be used to anticipate the results of late images in diagnosis of TTR cardiac amyloidosis.
Early Phase 99Tc-HMDP Scintigraphy for the Diagnosis and Typing of Cardiac Amyloidosis