Article Figures & Data
Figures
- FIGURE 1.
Amyloid molecular mechanisms and imaging characteristics. Source, protein, misfolding, fibril formation, and deposition are depicted for cardiac ATTR and AL. In ATTR (both wild-type and variant), transthyretin proteins are secreted by liver, fold abnormally, and form fibrils that are deposited in myocardium. In AL, immunoglobulin light-chain proteins misfold and form fibrils that are also deposited in myocardium. Echocardiography, CMR, and PET can detect both types of cardiac amyloidosis. However, nuclear imaging with bone-seeking tracers can differentiate between ATTR and AL, although there is evidence to suggest that a percentage of AL will be positive on nuclear imaging. TTR = transthyretin; Wt = wild-type. (Adapted from (2).)
- FIGURE 2.
Common types of cardiac amyloidosis. Two kinds of amyloidosis account for approximately 95% of all cardiac amyloidosis cases: AL and ATTR.
- FIGURE 3.
Abnormal planar and SPECT 99mTc-pyrophosphate cardiac amyloidosis scans. (A) 99mTc-pyrophosphate planar anterior image showing avid myocardial uptake. (B) SPECT short-axis (top), vertical long-axis (middle), and horizontal long-axis (bottom) images of same patient showing diffuse myocardial uptake. This scan is considered diagnostic of ATTR cardiomyopathy if serum and urine studies for AL are negative. (Reprinted from (2).)
Tables
Subtype Cause Protein Age range (y) Sex frequency Frequency of cardiac involvement Other organ involvement or conditions Associated conditions AL Plasma cell dyscrasia Immunoglobulin light chain 40–80 Men = women 70% Heart, kidney, gastrointestinal, tongue, nerves, liver, soft tissue Multiple myeloma Wild-type ATTR Aging Transthyretin >70 Men > women 100% Heart, peripheral nerves Bilateral carpal tunnel syndrome, lumbar spinal stenosis, atrial fibrillation, biceps tendon rupture Variant ATTR Inherited genetic mutation Transthyretin 55–75 Men > women 30%–100% (depending on mutation) Heart, nerves Bilateral carpal tunnel syndrome, polyneuropathy Parameter Characteristics Standard/optional/preferred Camera type Large-field-of-view γ-camera Standard Cadmium zinc telluride Optional* Energy peak 140 keV Standard Energy window 15%–20% Standard Collimator Low-energy, all-purpose Standard Patient position Supine Standard Field of view Heart/chest Standard Injection-to-imaging time 3 h Standard 1 h Optional Planar Acquisition type Static Standard Whole-body imaging Optional† Detector configuration 90° Standard Views Anterior and left lateral Standard Number of views 2 Standard Counts per view 750,000 Standard Matrix 256 × 256 Standard Magnification 1.46 SPECT or SPECT/CT* Acquisition type Step and shoot or continuous Standard Patient position Supine Standard Upright Optional Orbit 180°/90° Standard 360°/180° Optional Matrix 128 × 128 (minimum, 64 × 64) Standard Magnification 1.46 (180° orbit) Standard 1.0 (360° orbit) Optional Pixel size 2.3–6.5 mm Standard Projections per detector 40/32 Standard Time per projection 20 s/25 s Standard CT attenuation correction Heart Preferred
