Non-invasive detection and differentiation of cardiac amyloidosis using ^99mTc-pyrophosphate scintigraphy and...

To investigate the utility of the combined use of ¹¹C-Pittsburgh compound B (¹¹C-PiB) positron emission tomography (PET) imaging and ^99mTc-pyrophosphate (^99mTc-PYP) scintigraphy for detection and differentiation of three major types of cardiac amyloidosis, i.e. immunoglobulin light chain (AL), hereditary transthyretin (ATTRv), and wild-type transthyretin (ATTRwt) amyloidosis.

Whole-body ¹¹C-PiB PET and ^99mTc-PYP scintigraphy were performed in 17 patients with AL amyloidosis, 22 patients with ATTRv, and eight patients with ATTRwt amyloidosis. The correlations between organ involvement and the uptake of ¹¹C-PiB and ^99mTc-PYP were analyzed in each patient.

Cardiac amyloidosis was detectable by ^99mTc-PYP scintigraphy or ¹¹C-PiB PET in all systemic amyloidosis patients with cardiac involvement. ^99mTc-PYP scintigraphy and ¹¹C-PiB PET showed an interesting complementary relation. Strict combination of positive ¹¹C-PiB and negative ^99mTc-PYP uptake (PiB pattern) was observed in all AL amyloidosis patients with cardiac involvement. In contrast, strict combination of positive ^99mTc-PYP and negative ¹¹C-PiB uptake (PYP pattern) was observed in all ATTRwt amyloidosis patients with cardiac involvement. ATTRv amyloidosis patients with cardiac involvement were divided into two groups: PiB pattern or PYP pattern. All of the early-onset V30M (p.V50M) ATTRv patients showed the PiB pattern, whereas all of the late-onset V30M and non-V30M ATTRv patients showed the PYP pattern.

All three major types of cardiac amyloidosis can be detected and differentiated non-invasively by combined use of the two amyloid imaging methods and TTR gene testing.