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This research addresses the effectiveness of 99m Tc-Pyrophosphate scintigraphy in diagnosing transthyretin amyloid cardiomyopathy when MRI is inconclusive.

April 1, 2026Open Access

Importance of 99mTc-Pyrophosphate Scintigraphy as a Complement to Non-contrast Magnetic Resonance Imaging in the Diagnosis of Transthyretin Amyloid Cardiomyopathy

Key Points

This research addresses the effectiveness of 99m Tc-Pyrophosphate scintigraphy in diagnosing transthyretin amyloid cardiomyopathy when MRI is inconclusive.
Analyzed a case of an 80-year-old man with heart failure and reduced ejection fraction.
Conducted non-contrast cardiac MRI showing asymmetric septal hypertrophy.
Utilized 99m Tc-Pyrophosphate scintigraphy to assess amyloid uptake.
Confirmed diagnosis with biopsy results.
MRI showed normal native T1 and initial suspicion of hypertrophic cardiomyopathy.
99m Tc-PYP scintigraphy demonstrated Grade 3 uptake indicating significant amyloid presence.
Biopsy confirmed transthyretin amyloid cardiomyopathy, highlighting missed diagnosis risks when relying solely on MRI.

Abstract

An 80-year-old man presented with heart failure, left ventricular hypertrophy, and reduced ejection fraction (EF) (12.3%) with normal biomarkers.Non-contrast cardiac magnetic resonance imaging (MRI), performed for renal impairment, showed asymmetric septal hypertrophy but normal native T1 (1089 ms).Although hypertrophic cardiomyopathy (HCM) was initially suspected, 99m Tc-pyrophosphate ( 99m Tc-PYP) scintigraphy demonstrated Grade 3 uptake; biopsy confirmed transthyretin amyloid cardiomyopathy (ATTR-CM).This case illustrates that native T1 mapping can yield "pseudonormal" values as significant myocyte hypertrophy offsets amyloid-induced T1 prolongation.In renal impairment and reduced EF, 99m Tc-PYP scintigraphy is an indispensable diagnostic toolrather than a mere optionto avoid missing advanced ATTR-CM when noncontrast MRI is inconclusive.

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