Research ArticleBrief Communication

Novel Tracers for the Imaging of Cardiac Amyloidosis

Mrinali Shetty and Saurabh Malhotra
Journal of Nuclear Medicine Technology May 2023, 265568; DOI: https://doi.org/10.2967/jnmt.123.265568

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Endocardial biopsy. Pathognomonic apple-green birefringence (arrows) is seen on Congo red staining of myocardium afflicted with amyloid fibril deposition.

  • FIGURE 2.
    FIGURE 2.

    Binding sites for CA radiotracers: Congo red, thioflavin-T, and its analogs 11C-PIB, 18F-florbetapir, and 18F-florbetaben bind to both ATTR and AL amyloid fibrils. 99mTc bone-seeking tracers show avid uptake in ATTR, possibly related to microcalcification. Increased uptake of 18F-FDG in AL is attributed to inflammation and macrophage infiltration. (Reprinted from (23).)

  • FIGURE 3.
    FIGURE 3.

    Tracers used for imaging of CA. Nuclear medicine tracers used to image CA can be categorized by those that are non–amyloid-specific (bone-avid tracers, antimyosin, and sympathetic innervation tracers) and amyloid-specific (thioflavin-T derivatives, stilbene derivatives, and protease inhibitors). DPD = 3,3-diphosphono-1,2-propanodicarboxylic acid; HMDP = hydroxymethylene diphosphonate; PYP = pyrophosphate.

  • FIGURE 4.
    FIGURE 4.

    Potential use of novel PET tracers to track disease activity with treatment. These are images of 49-y-old woman with diagnosis of cardiac AL. (A) Pretreatment 11C-PiB PET/CT images show diffuse uptake in both ventricular walls (retention index, 0.231; SUVmean, 5.41). (C) Posttreatment 11C-PiB PET/CT images performed after 9 cycles of chemotherapy with bortezombib, lenalidomide, and dexamethasone show marked reduction in cardiac uptake of tracer (retention index, 0.135; SUVmean, 3.2). (B and D) Time–activity curves before (B) and after (D) treatment. a.u. = arbitrary units. (Reprinted from (32).)

  • FIGURE 5.
    FIGURE 5.

    18F-florbetaben in AL CA. Amyloid-specific probes, unlike bone scintigraphy radiotracers, have the added advantage of being able to diagnose AL in addition to cardiac ATTR. Given here are 18F-florbetaben PET (left column in each panel), low-dose CT (middle column), and PET/CT (right column) images of representative AL patient (A), ATTR patient (B), and hypertensive control (C). Of note is diffuse avid 18F-florbetaben myocardial uptake in both AL and ATTR patients but little radiotracer uptake in myocardium of hypertensive control. PET images were windowed to display myocardial boundaries. (Reprinted from (24).)

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