False-Positive ^99m Technetium-Pyrophosphate Scintigraphy in Two Patients With Hypertrophic Cardiomyopathy

99mTechnetium‐pyrophosphate scintigraphy: a practical guide for early diagnosis of transthyretin amyloid cardiomyopathy

“…False‐positive cases in 99m Tc‐PYP scintigraphy for ATTR‐CM may include Grade 2 or 3 myocardial uptake; a recent history of acute myocardial infarction 54 ; AL amyloidosis 34 , 54 , 69 , 70 , 71 , 72 , 73 ; apolipoprotein AI amyloidosis (AApoAI), apolipoprotein AII amyloidosis (AApoAII), apolipoprotein A‐IV amyloidosis (ApoAAIV), or β2‐microglobulin amyloidosis (Aβ2M) 10 ; hypertrophic cardiomyopathy 74 , 75 ; hydroxychloroquine toxicity 76 ; and cardiac blood pools. 54 Case reports on false‐positive myocardial uptake following intravenous iron injections have been published for 99m Tc‐DPD and 99m Tc‐HMDP scintigraphy.…”

Letter by Falk et al Regarding Article, “False-Positive 99m Technetium-Pyrophosphate Scintigraphy in Two Patients With Hypertrophic Cardiomyopathy”

“…Two of us (R.H. Falk and S. Dorbala) were coauthors on a recent publication which reviewed inappropriate interpretation of PYP scans and which urged physicians to perform imaging with single-photon emission computed tomography (SPECT) scanning and appropriate imaging timing, as well as the need to fully exclude a plasma cell dyscrasia, before considering a scan to be diagnostic for amyloidosis. 1 We were, therefore, most surprised to see our publication referenced in the recent case report by Schafer et al, 2 purporting to show positive PYP scans in 2 patients with hypertrophic cardiomyopathy who had, per the authors, no evidence of cardiac amyloidosis. 2 Review of the published planar PYP images do not show diagnostic images suggestive of amyloidosis, but rather represent typical errors of interpretation such as those we highlighted in our review.…”

“…To confirm our impression, we sent a copy of the case report to the 8 other coauthors of our review article, representing amyloid experts from 6 major academic centers. All responded, and unanimously agreed that the planar images alone published by Schafer et al 2 are uninterpretable without corresponding SPECT images, and almost certainly represent the misinterpretation of blood pool imaging as myocardial uptake. The failure of the case report authors to show SPECT images was deemed particularly striking, and comment was made that even if the SPECT scan were to have been positive in case 2, it may have represented early amyloid infiltration in this patient, who was heterozygous for an amyloidogenic TTR mutation, despite a negative cardiac biopsy.…”

Fat biopsy from a pocket of cardiac implantable electronic device: An alternative diagnostic option for cardiac amyloidosis

“…Radionuclide bone scintigraphy with technetium-labeled bisphosphonates has been widely recognized as a useful test for diagnosing TTR-CA 6 ; however, false-positives in amyloid light-chain amyloidosis, hypertrophic cardiomyopathy, and false-negatives have recently been reported in multiple reports. 7 , 8 , 9 , 10 , 11 Therefore, histological confirmation of the diagnosis of amyloidosis remains essential in some cases.…”